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Anaopthalmia
no development of the eye
Microphtalmia
rudimentary, smaller eye
cyclopia
failure of the division of the optic primordium into paired symmetric optic stalks development of a single midline globe
synophtalmia
one globe, but with paired segments within it
coloboma
lack of ocular tissue due to the defect of closure of ocular fissure
Choroid hypoplasia
autosomal dominant
exophtalmos
accumulation of fluid, exudate or tumour cells within the orbit
Enophtalmos
destruction of orbital tissue and loss of adipose tissue
strabismus
dysfunction of ocular muscles
nystagmus
errors in innervation
Glaucoma definition
clinical syndrome characterised by sustained increase of intraocular pressure
pathogenesis of glaucoma
- Ischemic damage: pressure increase in ocular channel and vitreous with collapse of the retinal, optic nerve and choroid blood vessels
- Excitotoxicity – release of excitatory compounds, causing retinal ganglion cell apoptosis
- Impairment of anterograde and retrograde axoplasmic flow – compression of axons, causing impairment of the flow and disruption of neurotrophic factors
Glaucoma, affects, cause, macro and micro
Affects: most common in dogs
Cause: inflammation, trauma, neoplasia
Macro: Buphtalmos, corneal edema, pupillary dilation and optic nerve head cupping
Micro: inner retinal atrophy, collapse of the iridocorneal angle, optic nerve head cupping and scleral thinning
primary glaucoma
- No acquired intraocular lesions to explain the increase of intraocular pressure
- Gondiodisgenesis: abnormally and insufficiently developed iridocorneal angle
- Open angle glaucoma: no visible abnormalities in the structure of the iridocorneal angle
secondary glaucoma
- There are acquired lesions responsible for the diminished outflow of aqueous humour
- Obstruction of IC angle: neoplasia, cellular infiltrates
- Pupillary block: extension of preiridal fibrovascular membranes
- Aqueous humor misdirection: accumulation of aqueous humor within the vitreous or between vitreous and retinana
- Angle recession: blunt trauma separation of the ciliary body from the sclera
dermoid
Definition: developmental anomaly
Pathogenesis: local failure in differentiation of fetal ectoderm (doesn’t differentiate into cornea), instead there remains normal haired skin structures
Macro: a nodule with hair
ulcer
Definition: collapse of the globe
Cause: progressive desiccation, chemical irritants, trauma, infections (Moraxella bovis in cattle, herpes in cat)
Pathogenesis:
1. Loss of epithelium
2. Osmotic resorption of water from the tear film into the anterior chamber
3. Focal superficial stromal edema
4. If there’s infection migration of leukocytes from the tear film and limbus destruction of the stroma
Macro: red peripheral rim of ingrowing blood vessels
Keratitis
Definition: inflammation of the cornea
Cause: acute (trauma, bacteria and fungi), chronic (lymphocytes and plasma cells)
Keratoconjunctivitis sicca
Eosinophilic keratitis
Pannus keratitis
keratitis
• Mostly in German shepherds
• Begins at the lateral limbus as red conjunctival thickening, lesion spreads to the cornea vascular stromal infiltrate (both eyes) vascularisation of the cornea
• Aetiopathogenesis: UV radiation modifies certain antigens in cornea immune response – genetic predisposition
Infectious bovine keratoconjunctivitis (pink eye)
Affects: Cattle
Cause: Gram negative coccobacillus Moraxella bovis
Transmission: flies, direct and indirect contact
Predisposition for development: UV light and simultaneous infection with BHV-1
Bacterial virulence factors: cytotoxin and fimbriae
Pathogenesis:
1. Initially shallow ulcers, infiltration of neutrophils
2. Focal suppurative stromal keratitis
3. Release of collagenases from the neutrophils, corneal epithelium and keratocytes
4. Keratomalacia
5. Healing during few weeks
conjunctivitis
Definition: acute (edema, increased lacrimation), chronic (hyperplasia of the epithelial cells, squamous metaplasia and keratisination)
Cause: viral, chlamydial, mycoplasmal, parasitic, allergic and idiopathic
Macro: dependent on cause – serous to mucopurulent exudate, hyperaemia
Micro: depend on cause – epithelial necrosis, if viral maybe intranuclear inclusions, eosinophils if parasitic, lymphocytes and plasma cells if immune mediated
cataracts
Definition: consequence of hydropic swelling or lens fibres degeneration + attempts of regeneration by proliferation and adaption of lens epithelium
Cause: diabetes
Pathogenesis:
1. Hyperglycaemia
2. increased glucose levels in aqueous humour
3. overloading of hexokinase pathway
4. excess glucose is shifted to the sorbitol metabolic pathway
5. production and accumulation of sorbitol within the lens
6. increased lenticular osmotic pressure
a. lenticular swelling and disrupted architecture
b. apoptosis of lenticular epithelial cells
Macro: clouding of the lens, lens swelling
uveitis
Definition: inflammation of the middle ocular tunic (iris + ciliary boy + choroid)
Cause: FIP
Pathogenesis:
Macro: accumulation of proteinaceous material within the anterior ocular chamber and/or vitreous
Micro: most of the cases anterior uveitis, dominantly neutrophilic, with various areas of granulomatous inflammation
moon blindness
Definition: repeated episodes of uveitis – periods of active inflammation alternating with periods of quiescence
Affects: horse
Cause: unknown, correlation between disease and Leptospira infection
Pathogenesis:
1. considered multifactorial immune-mediated disease
2. Leptospira antibodies to Leptospira have cross reactivity for equine cornea, lens, ciliary body
3. Epitope spreading – immune damage of ocular tissue exposes new antigens previously unrecognised by the macroorganisms against which new antibodies get elaborated
Macro: maybe glaucoma/cataracts
Micro: lymphoplasmacytic uveitis, cataracts, retinal ablation, glaucoma
Consequence: glaucoma and blindness
retinal ablation
Definition: separation between the neuroretina from the retinal pigment epithelium (RPE)
Cause: uveitis, neoplasia, trauma, retinitis
Pathogenesis:
1. Exudative – accumulation of exudate or blood in the subretinal space
2. Rhegmatogenous – leakage of liquefied vitreous in subretinal space
3. Tractional – vitreal or preretinal membranes, pull the neuroretina from the RPE
Macro: blindness and glaucoma
Micro: visible accumulation of material within the subretinal space, atrophy of the outer retinal layer and hypertrophy of the RPE
Consequence: blindness and glaucoma
meibomian gland neoplasia
Definition: are sebaceous glands at the eyelid margins
Macro: well demarcated, nodular masses on the eyelid margins
Micro: well differentiated enlarged lobules of sebaceous glands with variable proportion of reserve and mature sebaceous cells
ciliary dyskinesia
Cause: autosomal recessive inheritance, structural defect in flagellum of spermatozoa
Consequence: immotile/hypomotile spermatozoa, female infertility due to defective function of cilia in uterine tubes, oligospermia/azoospermia, also affects nasal and bronchial mucosa, affects ependyma so can cause hydrocephalus
ocular neoplasia
Feline diffuse iris melanoma, feline post traumatic ocular sarcoma, equine intraocular melanocytic neoplasia, canine uveal melanocytic neoplasia, iridociliary adenoma and meibomian gland adenoma
osteoporosis
Definition: Increase in bone density due to a failure in bone resorption by osteoclasts
Affects: Different animal species
Cause: Mutation that impairs generation or function of osteoclasts; viral infections (BVD)
Macro: Spicules of bone fill the medullary cavity
Micro: dense and irregular bony trabeculae
osteogenesis imperfecta
Definition: Inherited connective tissue disorder
Cause: mutations in collagen 1 gene
Affects: Calves, lambs, kittens, puppies and mice
Macro: bones are fragile and break easily, blue sclera and fragile (pink) teeth, joint laxity
Micro: reduced trabecular bone, evidence of fractures and delay in compaction of cortical bone
Consequence: bone fractures and joint laxity, defective dentin and fragile teeth, blue sclera
osteochondrosis
Definition: focal or multifocal growth cartilage retention due to the inability to become mineralised and replaced by bone
Affects: young animals, pigs, dogs, horses, cattle and poultry
Cause: unknown (genetics, trauma, rapid growth, vascular factors)
Macro: Flat, smooth nodule of avascular bone with overlying articular cartilage and layer of fibrocartilage is usually present on bony surface
Micro: articular cartilage often with calcification, disorganised dentin
Latens: well-demarcated area of necrosis of epiphyseal cartilage, centred around necrotic blood vessels and only visible microscopically
Manifesta: when centre of ossification reaches area of necrosis there’s failure of endochondral ossification and retained necrotic epiphyseal cartilages is grossly visible
osteoporosis
Definition: group of skeletal disorders that are characterised by loss of bone mass (osteopenia), pain and fractures in bones.
Affects: numerous
Cause: lack of physical exercise, malnutrition, hyperadrenocorticism, prolonged use of corticosteroids
Pathogenesis: Imbalance between bone resorption and bone formation
Macro: vertical trabeculae in spine
Micro: Bone cortices are thin and porous, bone trabecular reduced in number and size
Consequence: pain and fractures
rickets and osteomalacia
Definition: Young animals (rickets) and older animals (osteomalacia), bone pain
Affects: swine, cattle, goat, sheep (?)
Cause: Vit D deficiency and phosphorus
Pathogenesis: Rickets – osteoid gets formed but there’s no mineral to get deposited on, osteomalacia – osteoid gets laid down but doesn’t mineralise
Macro: Enlarged and widened growth plates, cortical bone soft and deformed
Micro: disorganised bone trabeculae and mineralised bone is irregular
Consequence: bone pain, pathologic fractures and deformities
osteosarcoma
Definition: malignant neoplasms, cell of origin unknown.
Affects: common in cats and dogs, rare in other domestic animals (older and giant dogs)
Pathogenesis:
• Metaphysis of long bones
• Growth = rapid, aggressive, locally invasive and painful
• Classified: simple, compound or pleomorphic
• Site of origin: central, juxtacortical or periosteal
Macro: grey/white, containing variable amounts of mineralised bone, random areas of haemorrhage
hip displacement
Affects: Large breed dogs
Cause: Gradual deformation of the hip joints after birth
Pathogenesis: gentle mechanical forces when persistently applied, may lead to progressive deformation of the normal bone structure. Conformation and inadequate muscle strength, produce biomechanical forces that induce slippage of the femoral head out of the acetabulum, eventually resulting in DJD
arthritis
Definition: inflammation of joint cartilage and synovial membrane
Cause: immune-mediated, idiopathic, bacteria, mycoplasma and viruses
Pathogenesis: small animals usually infected via penetrating wounds and is monoarticular. Large animals usually infected hematogenously and is polyarticular
Keratoconjunctivitis sicca
- Diffuse opacity of the cornea is a consequence of hyperplasia and keratinisation of the corneal epithelium
- Dry conditions led to adaptive changes of the corneal epithelium
Eosinophilic keratitis
- Most common in cats, +/- horses
- Macro: white to pink mass that outgrows from lateral limbus
- Micro: eosinophils always present, but other inflammatory cells also present
pannus keratitis
• Clinically and histologically – superficial stromal
cryptorchidism
Definition: incomplete descent of testis
Affects: dog, horse, boar, ram
Cause: exposure to oestrogen-like compounds, failure of normal production of testosterone, failure of regulation by 1 or more genes for production of testosterone or androgen receptor
Location: anywhere from caudal to kidney to inguinal ring but usually in the abdomen by the inguinal ring
Macro: testis is small and fibrotic
Micro: has interstitial collagen deposition, hyaline thickening of tubular basement membrane, degeneration of germinal epithelium
Consequence: cryptorchid testis more prone to neoplasia
testicular hypoplasia
Definition: tubules are reduced and interstitium appears to be increased
Cause: inadequate diet, endocrine abnormalities and cytogenic abnormalities
orchitis
Affects: bull, stallion
Cause: unknown (infectious = brucella)
Types: interstitial, suppurative, necrotising and granulomatous
Micro: lymphocytes between tubes and perivascular
seminoma
Definition: germ cell neoplasia
Affects: most common in aged stallion and second most common in canine
Macro: homogenous, white or pink-grey and firm, bulges on cut section, fine fibrous trabeculae
Micro: intratubular or diffuse, neoplastic cells – large, round, scant cytoplasm, large nucleus, prominent nucleolus
leydic cell tumour
Definition: interstitial endocrine cell neoplasm
Affects: dog, bull and stallion
Macro: bronze-orange colour, visible bleeding; round and well-circumscribed, sometimes secretes hormones including oestrogens
Micro: large round, polyhedric to spindle cell with abundant and vacuolated cytoplasm containing brown pigment’ visible necrosis and bleeding but isn’t invasive and is encapsulated
Sertoli cell tumour
Definition: third most common in dog
Macro: circumscribed, expansile, firm, white, lobulated (fibrous bands), enlargement
Micro: abundant fibrous tissue, intratubular/diffuse arrangement of Sertoli cells
epididymitis
Definition: acute and chronic, focal, multifocal and diffuse
Cause: non-infectious (traumas, congenital and acquired obstructions), infectious (brucella ovis/canis)
Micro: large number of lymphocytes and plasma cells in interstitium
prostatis
Definition:
Affects: dogs most frequent
Cause: brucella canis, E.coli, proteus vulgaris, strep, staph
Pathogenesis: catarrhalis acinar inflammation spreading to the interstitium formation of the abscess replacement of the abscess by the connective tissue
vesicular stomatitis
Affects: dogs and cats, large animals
Cause: virus (eg foot and mouth), rhabdoviridae
Pathogenesis: epithelial damage intracellular edema cell lysis vesicle/bulla rupture erosions/ ulcers cellular infiltration scab/granulation tissue
Macro: ulcers or scab
swine vesicular disease
Definition: typically, a transient disease of pigs
Cause: picornaviridae
Pathogenesis: transmitted by direct or indirect contact via oral route or through skin abrasions
Macro: vesicular lesions on the feet
erosive and ulcerative stomatitis
Cause: BVD, MCF, blue tongue, feline calicivirus
Pathogenesis: epithelial necrosis and inflammation without vesiculation, in squamous epithelium of mouth
necrotising deep stomatitis (types)
- Calf diphtheria – fusobacterium necrophorum – causes oral necrobacillosis, ulcers are covered by yellow/grey pseudo membranes
- Wooden tongue – actinobacillosis lignieressi – causes granulomatous glossitis – loss of tongue muscle and its replacement with fibrous tissue during healing
- Eosinophilic stomatitis – mostly seen in cats – affects upper lip, gums, palate, tongue and pharynx. Characterised by eosinophils, flame figures and chronic inflammatory cells
- Lymphoplasmacytic stomatitis – idiopathic – immune mediated in cats infected with FIV or FeLV
papular stomatitis
Affects: mainly young
Cause: parapoxvirus
Pathogenesis: epithelial degeneration, hyperplasia and inflammation papule ulceration and slow healing
Macro: pa-pules are elevated, dome-shaped or flat-topped lesions
Micro: epithelial degeneration, hyperplasia and inflammation
foot and mouth disease
Definition: highly contagious, high morbidity, low mortality
Affects: ruminants and pigs
Cause: picornavirus
Pathogenesis: viral ingestion or inhalation pharynx viremia epidermis lesions in sites subjected to mechanical injury
Macro: scab on oral mucosa, feet and teats
Micro: inflammatory cells
papilloma
Definition: wart
Affects: young dogs, calves and foals
Macro: pedunculated, papilliform or cauliflower – like masses
megaesophagus
Definition: dilation due to insufficient/absent/uncoordinated peristalsis
Cause: innervation or denervation disorders, physical obstruction
Congenital: dogs, dilated portion is cranial to the heart is due to persistent right 4th aortic arch, hereditary in GSD, irish setters and grey hound
Acquired: idiopathic, muscle disease (myasthenia gravis, hypothyroidism)
Macro: regurgitation
Micro: no microscopic lesions
bloat
Definition: over distension of the rumen and reticulum with gases of fermentation
Primary: known as legume bloat, dietary bloat or frothy
Secondary: physical obstruction or stenosis of the oesophagus (due to tumours, foreign bodies)
Affects: ruminants
Pathogenesis: legumes release of chloroplast particles rumen microbes colonise particles and degrade proteins gas bubbles get trapped among the particles and do not coalesce stable foam. Organic acids (from legumes) + salivary bicarbonates CO2, blockage of cardia, increased intra-abdo pressure and death
Macro: abdominal distension, animal found dead and rolled on back, bloat line
Micro:
traumatic reticuloperitonitis
Definition: hardware disease
Affects: ruminants
Cause:
Pathogenesis: sharp foreign bodies accumulate in the reticulum penetrate reticular wall peritonitis penetrate diaphragm and enter pericardium pericarditis. Affected serosal surfaces thickened by white fibrous tissue that enclose an accumulation of fibrinous and purulent exudate
grain overload
Definition: extension from oral and oesophageal infections
Affects: cattle
Cause:
Pathogenesis: sudden change to high easily fermentable diet overgrowth of gram + bacterial increased lactic and dissociated fatty acids pH <5 and ruminal atony
Macro: hyperaemia, erosion,
Micro: cellular infiltration and vesiculation of the mucosa
Sequelae: bacterial rumenitis, liver abscesses, mycotic rumenitis
gastric dilation and volvulus
Affects: large dog breeds, rarely pigs, great Dane, German Shepard
Cause: failure of eructation and pyloric outflow
Pathogenesis: excessive gas/ functional obstruction of cardia and pylorus dilation rotation on its mesenteric axis (volvulus) compression of diaphragm, vena cava and portal vein venous return decreased cardiac output and perfusion to abdo viscera shock
Macro: severe abdo distension, rotation of ventrodorsally axis (180-360), haemorrhagic infarction, rupture of stomach, congestion of intestines
Micro: mucosal degeneration
Consequence: stomach rupture and death
gastric ulcers
Definition: imbalance between acid secretion and mucosal protection (gastric mucosal barrier)
Cause: local mucosal injury, high gastric acidity, local ischemia, steroids and NSAIDs (Vit E deficiency)
Pathogenesis: epithelial necrosis erosion ulceration bleeding perforation peritonitis
Macro: single, round or oval, sometimes elongated, it looks “punched” out
Micro: muscle wall replaced with fibrous tissue, granulation tissue
gastritis
Definition: inflammation of the stomach
Affects: all
Cause: cattle (c. septicum, c. perfringens), cats and dogs is by uraemia, parasitic reaction and helicobacter, pigs = sepsis due to colibacillosis or salmonellosis
Pathogenesis:
Macro: loss of gastric glands
Micro: loss of epithelium, scattered neutrophils and haemorrhage in mucosa
megacolon
Definition: reduction/absence of ganglion cells of myenteric plexus
Cause: congenital or aquired
Congenital: in pigs, dogs, foals and humans. Developmental lack of myenteric plexuses so there’s a failure of migration of neuroblasts from neural crests to colorectal myenteric plexuses
Acquired: secondary to damage to colonic innervation – usually traumatic – dog hit by car
obstruction
Definition: results in death from toxaemia, shock and starvation
Cause: congenital anomaly
Macro: distended abdomen, dilated bowel proximal to obstruction, collapsed and empty distal part, congested/infarcted area of obstruction
intussusception
Definition: one segment becomes telescoped into the distal segment
Pathogenesis: vascular strangulation congestion/edema ischemia infarction gangrene
Macro: irritability or hypermotility, edema and ischemia
herniation
Definition: displacement through a foramen
Internal: foramen epiploicum, omental or mesenteric tears and renosplenic ligament
External: diaphragmatic, ventral, umbilical and scrotal/femoral
Sequelae: incarceration, strangulation, perforation, adynamic ileus
diarrhoea
Definition: secretion of abnormally fluid faeces accompanied by an increased volume of faeces and an increased frequency of defecation
Affects:
Malabsorption: defective digestion/absorption stools with increased osmolarity
Osmotic: exerted by luminal solutes
Hypersecretion: excessive intestinal fluid secretion induced by enterotoxins
Exudation: increased capillary or epithelial permeability
Deranged motility: intestinal hypermotility decreased intestinal transit time malabsorption, decreased motility increased intestinal transit time bacterial overgrowth malabsorption
Pathogenesis: bacterial overgrowth malabsorption diarrhoea
viral enteritis
Affects: most common in young animals
Cause: rotavirus, coronavirus, parvovirus, pestivirus
Examples: BDV, malignant catarrhal fever, transmissible gastroenteritis, porcine rotavirus enteritis
bovine viral diarrhoea
Definition: mucosal disease
Affects: young calves
Cause: pestivirus, BVDV1 and BVDV2
Pathogenesis: cytopathic (CP) and noncytopathic (NCP) biotypes. Transmission: inhalation, ingestion, transplacental and vaccination
1. If NCP crosses placental barrier during first 4 months of gestation may result in fetal resorption, mummification, abortion and congenital anomalies
2. If calf survives persistently infected (PI) calf they shed the virus
3. They become exposed to CP develop mucosal disease
Macro: ulcerative esophagitis, lameness, ulcerations in mucosa of the cecum, sharply demarcated ulcers in tongue, palate, oesophagus
Micro: foci of necrosis in epithelium over GALT, ulcers, lympholysis
Consequence: more susceptible to mannheimiosis, chronic pneumonia and polyarhritis
malignant catarrhal fever
Definition: infectious systemic disease
Cause: gamma-herpes virus
Pathogenesis: mechanism of injury dysfunction and lysis of vascular endothelial cells and hyperplasia, dysfunction and lysis of lymphocytes in lymphoid tissues virus – ingestion or inhalation mucosa – sub/mucosal lymphoid tissue infect lymphocytes leukocyte trafficking to regional lymph nodes
Macro: erosion/ ulceration of mucosae, CNS signs, eye lesions and lymphadenopathy, alopecia
Micro: accumulation of lymphocytes
Consequence: fatal
transmissible gastro-enteritis
Definition: high mortality and high morbidity
Affects: porcine less than 2 weeks old
Cause: coronavirus, rotavirus
Pathogenesis: feco-oral infection viral replication necrosis and sloughing of enterocytes release of viral particles extensive loss of enterocytes villous atrophy impaired digestion and absorption diarrhoea
Macro: dehydration, diarrhoea, small intestine is thin, indigestive milk
Micro: villous atrophy, proliferation of crypts
feline panluekopneia
Definition: also, feline parvovirus enteritis in cats
Affects: feline, racoons, minks
Cause: feline parvovirus enteritis
Intestinal lesions: segmental, crypt necrosis and loss, intranuclear inclusions
Pathogenesis: divides in intestine, bone marrow and lymphoid organs
Macro: segmental, crypt necrosis
Micro: villous atrophy, intranuclear inclusions, crypt squamous metaplasia and hyperplasia, lymphoid necrosis
parvo
Affects: canine and feline – death by endotoxemia shock
Cause: parvovirus
Pathogenesis: virus replicates in lymphoid tissue cause lymphoid depletion crypt cell destruction
Macro: hyperaemic intestine with serositis, SI maybe fluid-filled and haemorrhagic
Micro: basophilic intranuclear inclusion bodies In enterocytes, necrosis of crypt epithelial cells, permanent villous distortion and atrophy
colibacillosis
Definition: common disease of new-born
Predisposing factors: heavily contaminated environment, failure to receive colostrum, milk substitutes, cold stress, overcrowding and concurrent infections
Cause: E.coli
Forms: enterotoxic colibacillosis, postweaning colibacillosis, septicaemic and edema disease
Pathogenesis: toxins induce hypersecretion of Cl- and reduce the absorption of NaCl and water massive loss of water in the gut lumen diarrhoea, dehydration and metabolic acidosis
Macro: dehydration, diarrhoea, rough hair coat, serous atrophy of fat, petechial haemorrhages on tongue, gingivitis
Micro: infiltration of lymphocytes and macrophages
edema disease
Definition: enterotoxemic colibacillosis, disorder of rapidly growing healthy feeder pigs being fed a high ration diet
Affects: 6-14 weeks old, dietary changes
Cause: angiotoxin absorbed from intestines, E.coli
Pathogenesis: dietary changes intestine absorbs angiotoxin fibrinoid necrosis of arteries/arterioles generalised edema cerebral edema
Macro: generalised edema, cerebral edema
Micro: fibrinoid necrosis of arteries/arterioles, swine cerebral angiopathy
Consequence: most 4-8 weeks die within 48hr and neurological signs without diarrhoea
salmonellosis
Definition: zoonosis
Affects: humans, poultry and swine
Cause: salmonella
Pathogenesis: feco-oral route of transmission organisms invade enterocytes and macrophages enteritis, septicaemia and endotoxemia
Peracute/septicaemic: S. cholerasuis, widespread petechial haemorrhages
Acute: fibrinonecrotic enterocolitis, necrosis of Peyer’s patches and mesenteric lymphadenopathy
Chronic: vasculitis thrombosis infarct button ulcers
Macro: button ulcers, fibrinonecrotic enterocolitis
Micro: necrosis of peyer’s patches
clostridial enteritis
Affects: sudden death in well-nourished animals
Cause:
• alpha toxin: haemorrhagic/necrotic enteritis and abomasitis (horse and rabbits), colitis X in horse
• alpha, beta, epsilon: lamb dysentery
• alpha, beta: bloody diarrhoea in neonates, struck in adults
• alpha, epsilon: pulpy kidney disease in lambs and encephalomalacia
• alpha-1: enteritis in lagomorphs: enterotoxaemia in ruminants
Pathogenesis: diet change rapid growth of clostridial organisms angiotoxin endothelial damage haemorrhages, encephalomalacia and nephrosis rapid death
Macro: soft, dark-red kidney, pericardial effusion,
Micro: gram positive bacilli in intestinal mucosa
Johne’s disease
Definition: paratuberculosis
Affects: ruminants
Cause: mycobacterium avium ssp. Paratuberculosis
Pathogenesis: oral and transplacental transmission
Macro: lepromatous form – prominent mucosal folds (cattle), tuberculoid form – caseating granulomas (sheep, goat and deer)
Micro: thickening of ileal mucosa
lawsonia enteritis
Affects: pigs > 4 weeks
Cause: Lawsonia intracellularis
Pathogenesis: affects ileum, has low morbidity and high mortality
Macro: mucosa is partially covered by yellow fibrinonecrotic pseudo membrane, large fibrinous cast is present in the lumen
Micro: hyperplasia of crypt epithelium, resulting in necrosis of the crypt
swine dysentry
Definition: high morbidity and 30% mortality
Affects: pigs
Cause: brachyspira hyodysenteriae and anaerobic bacteria
Pathogenesis:
Macro: haemorrhage, colonic malabsorption syndrome, bloody faeces
Micro: necrosis of superficial mucosa and luminal spirochetes
IBD
Definition: inflammatory bowel disease
Affects: dogs and cats
Cause: immune mediated, parasite of dietary hypersensitivity
Macro: vomiting, diarrhoea and weight loss
Micro: villus atrophy, epithelial necrosis, crypt illation
excitotoxicity
Definition: mechanism involved in the development of neuronal necrosis
Cause: trauma, compression and crushing
Pathogenesis:
1. Initial injury
2. Persistent activation of glutamine receptor of affected neurone
3. Influx of extracellular Ca2+ ion
4. Impaired mitochondrial functioning and development of ROS
5. Damage to lipid membranes of nerve
wallerian degeneration
Definition: changes occurring in nerve after axon transection/breakdown in PNS and CNS
Cause: nerve stretching injury and intoxication
Pathogenesis:
• Changes proximal to the site of injury: central chromatolysis
• Changes distal from injury site: Wallerian degeneration (axonal swelling and fragmentation of myelin- degeneration)
cerebral infarction
Definition: necrosis due to arteriolar obstruction
Cause:
• Interrupted circulation in the brain
• Sudden hypotension
• Drop in oxygen concentration in the inhaled air
• Methemoglobinemia
• Cyanide intoxication
Macro: liquefactive necrosis, grey substance infarction = haemorrhagic, white substance infarction = pale (ischemic)
brain edema
Definition: elevated intracranial pressure due to some trauma
Types:
• Cytotoxic: cell swelling with normal blood vessel permeability
• Vasogenic: tissue swelling due to increase of extracellular fluid volume
• Hydrostatic- interstitial: increase of CSF volume and leaking of CFS through ependymal layer
• Hypo-osmotic: irregular ion concentration and distribution into the blood and nerve tissue
Vasogenic:
• Consequence of inflammation, hematoma, contusion, neoplasia, infarction
• Breakdown of haematoencephalic barriers plasma and electrolyte entering the perivascular and extracellular brain space
Cytotoxic:
• Hydropic degeneration of the CNS cells – intracellular fluid accumulation
• evenly affects white and grey matter
• Swelling develops several seconds after injury disruption of Na/K pump water and sodium reducing volume of extracellular fluid and increasing ion concentration –. Transfer of capillary fluid and CSL into the extracellular space of the cells
cerebellar hypoplasia
Definition: small, undeveloped cerebellum
Affects: kittens, calves, piglets
Cause: primarily due to intrauterine viral infections, parvovirus or pestivirus
Pathogenesis: infiltrate and destroy undifferentiated cells of the outer granular layer in intensive replication that should migrate and build an inner granular layer
Macro: size of cerebellum is reduced
Micro: loss of outer granular layer, loss of purkinje cells, malposition of purkinje cells, edema and bleeding in the white matter, focal cavitation and white matter atrophy and lymphocytic leptomeningitis
Consequence: may be incompatible with life depending on severity of hypoplasia
hydrocephalus: def, types and affects
Definition: abnormal accumulation of CSF in brain cavities (ventricular and subarachnoid space)
Affects: brachycephalic of miniature breeds, first 3 months of life
Types:
Noncommunicating congenital hydrocephalus:
• Obstruction within system in rostral/lateral opening of 4th ventricle
Communicating congenital hydrocephalus
• Rare, communication between ventricular and subarachnoid space, blood pressure increase
• Aetiology: arteritis, subarachnoid bleeding and meningitis
Compensating congenital
• Occurs secondary due to loss/lack of brain tissue, as part of the progression of hydrocephaly
Uncommunicating acquired hydrocephalus:
• Injuries of ependyma of obstruction, there’s no change in skull bones
• Aetiology: compression of abscesses and neoplasm, blockage of fluids
Compensating acquired hydrocephalus:
• Secondary after losing of neural tissue, uni/bilateral
• Consequently to: brain infarction or brain aging
hydrocephalus cause and pathogenesis, micro and macro
Cause: blockage of: interventricular foramen, mesencephalic duct, lateral openings of the 4th ventricle
Pathogenesis:
1. Due to non-absorption, CSL pressure in brain ventricles increases
2. Ventricles widen, ependyma is multifocally disrupted
3. CSL compress periventricular white matter
4. Hydrostatic edema of the white matter
5. Degeneration and atrophy of myelin and axons
6. Loss of tissue
7. Expansion of the ventricles
Macro: thin bones, enlargement of cranium, thinning of white matter
Micro: atrophied ependyma, loss of cells in white matter
brain abscess
Definition: relatively uncommon
Cause: white (Escherichia, klebsiella), yellow (strep, staph), pseudomonas
Pathogenesis:
Macro: abscess single or multiple, discrete or coalescing
thrombotic meningoencephalitis
Affects: Cattle
Cause: histophilus somni
Pathogenesis:
1. Bacteria binds to endothelial cells
2. Contraction and desquamation of vascular endothelial cells
3. Vasculitis
4. Thrombosis
5. Infarcts
6. Additional bacterial multiplication in infarct tissue
7. inflammation
Macro: irregular, small to large foci of bleeding and necrosis, randomly scattered on the surface of the brain and most common – cerebrum, causes septicaemia
Micro: vasculitis and perivasculitis, vascular necrosis
listeriosis
Definition: bacterial disease with particular affinity for the CNS
Affects: domestic ruminants
Cause: poor silage, L. monocytogenes
Pathogenesis: phospholipase and hemolysine
1. oral mucosa invasion of sensory and motor branches of n. trigeminus
2. migration via sensory axons to trigeminal ganglion/brain-spinal cord
3. migration to motor axons – directly to midbrain, spinal cord
4. rostral and caudal extension of bacteria in the brain
Macro: usually negative, sometimes: opacity of the leptomeninges, focal necrosis, opaque CSF
Micro: neutrophils, macrophage foci, leptomeningitis, vasculitis
Types: meningoencephalitis, abortions- stillbirth and septicaemia
rabies
Cause: Lyssavirus fam. Rhabdoviridae
Pathogenesis:
1. initial replication
2. entry into the nerve through nicotine and acetylcholine receptors
3. retrograde axonal transport – to the dorsal root ganglion to the spinal cord
4. travels to the brain with ascending and descending tracts
5. infects the brain and spreads among neurones through antegrade axonal transport
6. infects the eye and salivary glands (secreted by saliva)
• centripetal spreading is towards the brain and centrifugal spread away from brain
Macro: most often not found
Micro: lymphomonocytic meningoencephalitis, Negri bodies, spongiform lesions in grey matter
Stages: prodromal (2-3 days, changes in temperament), excitatory and paralytic
Types: furious (excitatory stage dominates) and dumb (excitatory stage is short)
canine distemper
Affects:
Cause: Morbillivirus, fam paramyxoviridae
Pathogenesis: aerosol with virus upper respiratory tract infection local mucosal invades macrophages regional lymph nodes replication within regional LN and causes viremia infects almost all cells of the body, particularly epithelial cells and brain decreases immune response, decreases cytokine production and predisposes for secondary bacterial infection
Macro: white matter softening, diffuse interstitial pneumonia, pneumocyte type 2 hyperplasia
Micro: demyelination, status spongiosus, intracytoplasmic and intranuclear primarily in astrocytes
Consequence: secondary bacterial infection, hyperkeratosis of nose and foot pads
FIP
Affects: Feline
Cause: feline enteric coronavirus which mutates to FIP virus
Types:
• strong cell-mediated immunity resistance to virus, so no disease
• partial cell-mediated immunity dry (noneffusive) form (leptomeningitis)
• absence of cell-mediated immunity, just humoral immunity wet (effusive) form (serositis, accumulation of modified transudate)
Pathogenesis: cats ingest the virus through contact with virus contaminated faeces or with carrier cats feline enteric coronavirus replicates in enterocytes and causes diarrhoea or is asymptomatic virus mutates, replicates in macrophages and causes systemic infection
Macro: pyogranulomatous inflammation vascular necrosis infarcts
Micro: granulomas and phlebitis
Consequence: granulomatous pneumonia, pyogranulomatous interstitial nephritis and vasculitis
bovine malignant catarrhal fever
Definition: sporadic highly fatal viral disease
Affects: cattle and other ruminants
Cause: ovine herpesvirus 2, caprine herpesvirus 1,2
Pathogenesis:
Macro: necrotising vasculitis, hyperaemia and cloudiness of the leptomeninges
Micro: nonsuppurative meningoencephalomyelitis and vasculitis, lymphocytic perivascular accumulation and necrotising vasculitis leptomeninges and brain
pseudorabies
Definition: Aujesky’s disease “mad itch”
Affects: pigs primarily, domestic mammals severe, frequently fatal (piglets can die, mature pigs remain latent carriers)
Cause: pseudorabies virus (suid herpesvirus 1)
Pathogenesis: enters into upper respiratory tract, tonsils and local LN enters the sensory nerve ends transports to the trigeminal ganglia and bulbus olfactorious brain. Glycoproteins on the surface of the virus allow binding and entry into the cell
Macro: leptomeningeal congestion
Micro: nonpurulent meningoencephalomyelitis, intranuclear eosinophilic inclusions and degeneration and necrosis
visna
Definition: distinct viral strain of the ovine maedia-visna virus - lentivirus
Pathogenesis: immune reactions of macrophages and lymphocytes cytokines, other inflammatory mediators neuronal and oligodendroglia damage (initial stage) demyelinisation due to oligodendroglia cell infection (later phase)
Macro: yellowish-creamy areas on the cross section
Micro: nonpurulent encephalomyelitis, pleocytosis and edema
cryptococcosis
Affects: cat, dog, horse and cattle
Cause: FIV, FeLV, ehrlichia canis, C neoformans and C gattii
Pathogenesis: direct spread after sinus or nasal infection within macrophages
Macro: within CNS and leptomeninges – multiple small cysts of gelatinous appearance
Micro: multicellular-monocellular fungi, without inflammatory reactions, with mild/moderate infiltration of neutrophils, eosinohpils
toxoplasmosis
Affects: cats
Cause: toxoplasma gondii
Pathogenesis: infection and destruction of endothelial cells by tahizosis vasculitis haemorrhagic infarcts, edema
Macro: acute: bleeding, necrosis, chronic: yellow-brown, necrotic foci
Micro:
• acute: swelling of endothelial cells, infarctions, edema,
• subacute: necrosis and bleeding often of extensive lymphocytic and macrophage pervascular infiltrates
• chronic: cysts with bradyzoits
Consequence: abortion
neosporosis
Affects: dog, cat, cattle and sheep, horse
Cause: neospora caninum
Macro: foci of haemorrhage and necrosis distributed
polioencephalomalacia
Cause: lack of thiamine
Macro: brain swelling, yellowish discolouration, edema and prominent areas of atrophy
Micro: laminar cortical necrosis and astrocyte swelling, monocyte infiltration and phagocytosis of cellular debris
clostridium
Definition: pulpy kidney disease, overeating disease
Affects: sheep goat and cattle
Cause: epsilon toxin
Pathogenesis: vascular injury and failure of haematoencephalic barrier binding of epsilon toxins to endothelial cells opening of tight junctions increase of vascular permeability vasogenic edema swelling of astrocytic processes necrosis
Macro: bilaterally symmetrical foci of encephalomalacia, extra neural changes
Micro: vasogenic edema, hyalinisation of capillary walls and endothelial cells swelling
astrocytoma
Definition: classified according to degree of differentiation
Affects: dogs (5-11yrs) brachiocephalic breeds, rarely cats
Cause: degree of malignancy is inversely proportional to the degree of differentiation
Macro: compressive atrophy of the surrounding tissue, well differentiated
Micro: tumour cells are arranged around the blood vessels
oligodendroglioma
Definition: most common neuroectodermal neoplasia of the CNS, affect the white matter of cerebrum
Affects: most common In dogs 5-11yrs (brachiocephalic breeds), cats and cattle
Macro: well restricted, grey/pink, soft creamy with bleeding areas
Micro: highly cellular, expressed nucleus, pale or translucent cytoplasm
meningioma
Definition: most common mesodermal neoplasm of CNS, originate from arachnoidal cap cells
Affects: older cats, especially over 10 yr, dogs 7-14 yrs
Located: in 3rd ventricle, surface of the brain and at base of the brain
Macro: compressive atrophy
Micro: form a vortex layer configuration, grouped to: epithelial, fibroblastic, transitional, psammomatous, angioblastic and anaplastic
equine dysautonomia
Definition: disease that affects the postganglionic sympathetic and parasympathetic neurones
Affects: horse
Cause: ingestion of food contaminated with toxin of the Cl. botulinum
Pathogenesis:
Macro: no macroscopic changes on PNS
Micro: chromatolysis, degeneration – neurones of autonomic and enteric ganglia within the ileum
myasthenia gravis
Definition: disorder of neuromuscular impulse transmission
Inherited: too small number of acetylcholine receptors on the muscular plates of neuromuscular joints
Acquired: thymoma, development of antibodies that binds to acetylcholine receptors on postsynaptic muscle membranes
Macro: skeletal muscle weakness and megaoesophagus development
Micro: none
peripheral nerve sheath tumour
Definition: tumours of peripheral nerve system
Affects: dogs older, cattle and cats older, in cranial nerve 5 (dogs), cattle CN 8
Macro: nodular thickening to the nervous trunk or nerve roots, soft to hard elastic, white to grey
Micro: densely cellular, monomorphous spindle cells and various rich collagen stroma
encephalitis
Definition: inflammation of brain
Cause: bacteria, listeria monocytogenes, Haemophilus, virus, mycoplasma
Macro: congestion, haemorrhage, tiny abscess
Micro: necrosis of neurons, infiltration by neutrophils and lymphocytes
meningitis
Definition: inflammation of meninges
Cause: virus, trauma, bacteria, toxoplasma, Leptospira
Macro: congestion, petechial haemorrhage
Micro: fibrosis, infiltration of neutrophils and lymphocytes and thickening of meninges
hydranecephaly
Definition: formation of large fluid filled cavities in the brain
Cause: BVD, orbivirus and rift valley
Pathogenesis: virus infect and destroy differentiating neuroblasts and neuroglial cells in developing foetus in utero
Macro: thin-walled, fluid filled cysts in cerebral hemispheres
Micro: necrosis of undifferentiated cells surrounding the fluid filled cavities
Consequence: denervation atrophy of limb muscles, arthrogryposis, non-suppurative encephalitis
renal failure
Definition: uraemia and consequences of urinary disease
Affects:
Cause: prerenal (decreased circulation), intrarenal (infections, toxins), postrenal (obstruction of tract)
Pathogenesis:
Alteration: decreased ultrafiltration, intratubular obstruction, fluid back leak and intrarenal vasoconstriction
renal fibrosis
Definition: replacement of renal parenchyma with mature fibrous CT
Cause: infarction, glomerulonephritis and tubulointerstitial disease
Pathogenesis: irreversible and progressive
Macro: pale, shrunken and pitted kidney
Micro: increase in interstitial CT, small cysts in cortex and medulla, lymphoplasmacytic infiltrates in interstitium
Consequence: fibrous osteodystrophy and renal secondary hyperparathyroidism
nephrotic syndrome
Definition: seen with severe glomerular lesions
Pathogenesis: proteinuria (increased permeability), hypoproteinaemia, edema (decreased oncotic pressure), hypercholesterolemia (from protein loss)
renal dysplasia
Definition: altered structural organisation resulting from abnormal differentiation with presence of structures
Pathogenesis: asynchronous differentiation of nephrons
Macro: small and/or misshapen
Micro: small hypercellular glomeruli, atypical tubular epithelium, presence of cartilaginous and/or osseous tissue
renal cyst
Definition: can be associated with renal dysplasia or can occur as primary entities
Congenital: can occur as a primary entity or in cases of renal dysplasia
Pathogenesis:
1. Obstruction of the nephron elevated luminal pressure and secondary dilatation
2. Defective tubular basement membranes allow saccular dilatation of tubules
3. Derange function of renal tubular cilia epithelial hyperplasia and production of new BM increased tubular secretion
4. Dedifferentiation of tubular epithelium loss of polarity of cells – abnormal cell arrangements decreased absorption of fluid dilation
Macro: spherical, thin walls, clear watery fluid
polycystic kidney
Definition: have many cysts that involve numerous nephrons
Affects: occur sporadically in all species and may be inherited in some pigs and lambs
Cause: mutation in PKD1 and 2
Pathogenesis: mutation in PKD-1 and PKD-2 genes altered function of related proteins modify cilia function, cell proliferation and migration tubular epithelial proliferation and increased fluid secretion
Macro: “swiss cheese”
viral glomerulitis
Cause: occurs in acute systemic viral disease (hog cholera, infectious canine hepatitis)
Macro: swollen kidneys, smooth capsular surface, pinpoint red dots on the cut surface
Micro: intranuclear inclusions in endothelial cells, endothelial hypertrophy, necrosis and haemorrhage
chemical glomerulitis
Cause: direct Injury to glomerular epithelial and endothelial cells
Pathogenesis: induction of immunologic reaction and inflammatory responses immune complexes deposition, formation of ANA-s and anti-GBM antibodies
Micro: interstitial fibrosis
embolic glomerulonephritis
Cause: result of bacteriemia cause multiple foci of inflammation, actinobacillosis, erysipelothrix
Pathogenesis:
Macro: multifocal, random, raised, 1mm foci
Micro: glomerular capillaries contain numerous bacterial colonies mixed with necrotic debris and neutrophils
immune mediated glomerulitis (glomerulonephritis)
Cause: glomerular lesions is immunologic damage.. direct (antibody responding to an antigen in the glomerulus), indirect (from formation of antigen-antibody complexes)
Pathogenesis:
Macro: (acute) kidneys slightly swollen, smooth capsular surface, slightly pale, glomeruli. (chronic) cortex becomes shrunken, granularity of capsular surface, glomeruli – pinpoint pale grey dots
Micro:
• According to morphology: proliferative, membranous and membranoproliferative
• According to localisation and distribution: diffuse, focal, global and segmental
renal tubular necrosis
Definition: most common cause of acute renal failure, injury resulting in the death of tubular epithelial cells
Affects:
Cause: heavy metals (mercury, lead), antibacterial agents (tetracyclines), NSAIDS (aspirin, naproxen), mycotoxins, plants (pigweed, yellow wood tree, easter lily), Vit D, antifreeze
Pathogenesis:
Macro: white to tan cortex
Micro: pyknotic nuclei indicative of cell necrosis, swollen or granular cytoplasm, hyaline casts and cell death
papillary necrosis
Definition: form of tubular necrosis and interstitial necrosis
Affects: dogs and cat
Cause: NSAIDs
Pathogenesis: NSAIDs interfere with production of renal prostaglandins alteration in prostaglandins cause vasoconstriction and loss of perfusion to the distal tissues of the kidney papilla became ischemic and then necrotic
Macro: necrotic area is yellow-grey, green or pink and sloughs and is friable
Micro: necrotic areas, cross section is narrowed
tubulointerstitial nephritis
Definition: inflammation of interstitium and tubules
Affects: horse, cattle, sheep, pigs and dogs
Cause: H (equine viral arteritis), C (Escherichia coli septicemia), S (sheeppox), P (leptospira interrogans), dogs (infectious canine hepatitis and leptospira interrogans)
Pathogenesis:
Acute: interstitial infiltrates of inflammatory cells are present including neutrophils and plasma cells
Chronic: progresses to interstitial fibrosis and loss of tubules
Macro: swollen kidneys, cut surface bulges
Micro: inflammatory cells, aggregate of lymphocytes, monocytes, plasma cells
leptospirosis
Pathogenesis: leptospiremia localisation in renal interstitial capillaries migration through endothelium persist in interstitium invade tubules through lateral interstitial junctions associate with epithelial microvilli persist in phagosomes of epithelial cells of proximal and distal tubules induce degeneration and necrosis of epithelium induces interstitial inflammatory reaction
granulomatous nephritis
Definition: interstitial disease that accompanies chronic systemic disease characterised by multiple granulomas
Affects: domestic animals, pig, cattle
Cause: coronavirus, mycobacteria, fungi, protozoa, parasites
Micro: fibrosis
pyelonephritis
Definition: inflammation of renal parenchyma and renal pelvis
Affects: anything that predisposes the animal to UTI
Cause: usually from ascending urinary tract infection, E.coli, klebsiella, staph, strep
Pathogenesis: abnormal reflux of bacteria-contaminated urine from lower tract to pelvis and collecting ducts, infection ascends ureters via vesicoureteral reflux pelvis of kidney becomes infected bacteria gain access to renal parenchyma by collecting ducts and direct invasion across erosions in pelvic urothelium
Macro: pelvis and ureter dilated, purulent exudate, papilla necrotic with haemorrhage
Micro: large number of neutrophils, sloughed tubular epithelial cells, necrosis of collecting ducts
Consequence: if chronic, there will be fibrosis of the kidney
hydronephrosis
Definition: dilation of the renal pelvis and accompanying renal atrophy
Affects: all domestic animals
Cause: partial or complete obstruction of urine outflow causing a progressive increase in pelvic pressure
Pathogenesis: increase in intratubular pressure glomeruli remain functional glomerular filtrate diffuses into interstitium intrapelvic pressure increases
Macro:
Micro: thin walled
renal carcinoma
Definition: most common primary renal neoplasia
Affects: most frequent in older dogs
Cause: virus, chemical carcinogens and autosomal dominant gene mutations
Pathogenesis:
Macro: large, typically spherical to oval and firm, on section they may be pale yellow with areas of haemorrhage and cystic degeneration, pale yellow
Micro: cuboidal to columnar epithelial cells in solid sheets, tubules or papillary projects
embryonal nephroma
Definition: nephroblastoma
Affects: young animals but may not be diagnosed until they reach a very large size
Cause: arises from metanephric blastema
Pathogenesis:
1. Result from malignant transformation during normal nephrogenesis
2. Arise from malignant transformation in nests of embryonic tissue that persists in postnatal kidney
Macro:
Micro: typically, have loose myxomatous mesenchymal tissue
urolithiasis
Definition: presences of stones (calculi, uroliths), in the urinary collecting system
• Renal pelvis (nephroliths), ureter (ureterolith), urinary bladder (urocystolith), urethra (urethrolith)
• Mini schnauzers – struvite calculi, dalmatian dogs – uric acid
Consequence: predispose to infection, obstruction, haemorrhage and necrosis, cloudy urine
Predisposing factors: cystitis, urine pH, reduced wate intake, Vit A deficiency, NSAIDs
Cause: when familial, congenital and pathophysiological factors occur together and cause the precipitation of excretory metabolites in urine into grossly visible stones, mineral imbalance
Pathogenesis:
Macro: calculi, cloudy urine, haemorrhage, distension of ureters and urinary bladder, enlarged kidneys
Micro: crystals, degeneration and necrosis of tubular eptihelium
cystitis
Definition: inflammation of the urinary bladder
Acute:
Predisposing factor: stagnation of urine, vaginoscopy, more common in females, klebsiella
Macro: haemorrhage, fibrinous and suppurative, necrotising, thickened bladder wall, cloudy urine
Micro: epithelial denudation, bacterial colonies and lamina propria edema
Chronic:
• If bacteria isn’t destroyed the infection may persist and become chronic
• The wall becomes thickened due to fibrosis
• Often mucosal proliferation as well – polypoid cystitis
• Hyperplasia of lymphoid nodules in lamina propria – follicular cystitis
Mycotic cystitis
Cause: Candida albicans, aspergillus
Affects: immunosuppressed animals or subjected to prolonged antibiotic therapy
Pathogenesis: mucosa is usually ulcerated with proliferation of underlying LP accumulation of neutrophils, lymphocytes, plasma cells, macrophages thickening of the bladder wall
Toxic cystitis (brackern fern and enzootic hmaturia)
Cause: plant pteridium
juvenile panhypopituitarism
Definition: autosomal recessive mode of inheritance
Affects: German shepherd, spitz, toy pinscher
Cause: molecular defect in LHX3 gene-deletion in exon 5 Low GH, TSH, prolactin and gonadotropic, ACTG normal or low
Pathogenesis:
Macro: slower growth, retention of puppy hair coat, bilaterally symmetric alopecia, skin hyperpigmentation
Consequence: slow/subnormal growth, retention of woolly puppy coat and hyperpigmentation and bilaterally symmetrical alopecia
neoplasms of adenohypophysis
Definition: adenoma of pars intermedia
Affects: equine – old age
Pathogenesis: compression of hypothalamus by large neoplasms polyuria, polydipsia, muscle weakness, hyperthermia, hypertrichosis – hirsutism
Cell of origin: cells that produce proopiomelanocortins (POMC)
Symptoms: hypertrichosis, chronic laminitis, weight loss and abnormal distribution of fat
Consequences: can compress hypothalamus so PUPD, polyphagia and hirsutism
cushing
Definition: cortisol excess
Affects: adult and aged dogs, infrequently in cats and rare in other domestic animals
Cause: functional neoplasm, ACTH-secreting adenoma of pituitary gland, iatrogenic excess of corticosteroids
Pathogenesis: increased gluconeogenesis, lipogenesis and protein catabolism.
Macro: increased appetite, weakened and atrophied muscles, hepatomegaly, skin lesions, pedunculus abdomen
Micro: atrophy of skeletal muscles
addison
Definition: adrenal cortical insufficiency
Affects: young sexually mature dog
Cause: autoimmune disorders
Pathogenesis:
Macro: decreased blood volume, pressure, hyperpigmentation
Micro: lymphocytes and plasma cells are distributed diffusely throughout adrenal cortices
goitre
Definition: nonneoplastic and noninflammatory enlargement of the thyroid gland
Cause: goitrogenic compounds, deficiency or excess of iodine, genetically determined defects
Pathogenesis:
Types:
• Diffuse hyperplastic
o Follicles irregular in size and shape
o Thyroid gland enlarged and dark-red
• Multifocal nodular
o Usually, endocrinologically inactive
• Congenital
o Autosomal recessive, alteration in synthesis of thyroglobulin or thyroid peroxidase, lambs, kids, calves, dogs and cats
• Colloid
o Hyperplastic follicular cells continue to produce colloid but endocytosis of colloid is decreased, thyroid glands lighter in colour
Micro: hyperplasia of the gland
hyperthyroidism
Definition: excessive secretion of thyroid gland hormones
Affects: cats
Cause: elevated circulating T4 and T3 concentrations, tumourin thyroid
Pathogenesis: purified IgG increases H-thymidine incorporation into DNA and stimulates follicular cell proliferation
Macro: increased basal metabolic rate, bulging of eyeballs
Micro: nodules
hypothyroidism
Definition: reduced secretion of thyroid hormones
Affects: golden retriever, Doberman pinscher, dachshund, miniature schnauzer
Cause: adult, older dogs
Pathogenesis:
• Decreased basal metabolic rate gain in body weight without changes in appetite
• Increased cholesterol atherosclerosis
• Thinning of hair coat and symmetric alopecia, hyperkeratosis, hyperpigmentation
Macro: decreased basal metabolic rate, obesity
Micro: follicles lined by low cuboidal or flattened epithelial cells
neoplasms of chemoreceptor organ
Definition: sensitive indicators of changes in the blood CO2, pH and oxygen tension
Affects: brachycephalic breeds
Cause: unknown
Pathogenesis:
• Carotid – near the bifurcation of carotid artery, genetic predisposition aggravated by chronic hypoxia, unilaterally and slow growing
• Aortic – near the base of the heart – attached to the adventitia of the pulmonary artery, more common than carotid body and most common in boxers. Non-functional but cause heart failure due to compression, solitary mass or multiple nodules
Macro: neoplastic tissue is lobulated by fibrous trabeculae
Micro: neoplastic cells are aligned along small vessels and are round to polyhedral and closely paced with pale eosinophilic, finely granular
chediak-higashi syndrome
Definition: rare, autosomal recessive defect in lysosomal trafficking regulator
Affects: cattle, persian cats, orca, mice and humans
Problems: severly impaired innate immunity due to neutropenia, impaired leukocyte chemotaxis, tendency to bleed and prone to infection
Macro: oculocutaneous albinism due to altered distribution of melanin granules
Micro: giant granules in phagocytic cells and melanocytes
ischemic myopathy
Definition: sensitivity to ischemia: myofibers > satellite cells >fibroblasts
Affects: cow, horse
Cause: external pressure on the muscle by objects, compartment syndrome and vasculitis
Pathogenesis: increased intramuscular pressure during prolonged periods of recumbency compression to arteries decreased blood flow
Macro: areas of muscle pallor, haemorrhage may occur particularly with compartment syndrome
Micro: myofiber coagulative necrosis, sometimes accompanied by haemorrhage
white muscle disease
Definition: extensive coagulative necrosis of muscles
Affects: horse, cattle, sheep and goats
Cause: deficiency of Vit E and selenium, stress
Pathogenesis:
Macro: marked by mineralisation of skeletal and/or cardiac muscle, pale sometimes white streaks and maybe gritty when cut, becomes pale pink, yellowish red, grey or white. Becomes dry, inelastic and firm
Micro: early lesions are characterised by rounded, large, hyalinised myofibers with or without fragmentation
Monday morning disease
Definition: equine rhabdomyolysis
Affects: riding and racing horses
Cause: following exertion, usually, brief rest results in recovery with few consequences, accumulation of lactate, lack of oxygen and high glycogen store
Pathogenesis: changes are thought to involve the strongly glycoltic type II fibres
Macro: myoglobinuria, swelling of affected muscle group, increased serum CK and AST, urine is dark brown, tonic spasms, atrophy, edema
Micro: same as nutritional myopathy, necrosis of muscle fibres, hyaline degeneration
bacterial myositis - black leg
Definition: acute, noncontagious infectious disease
Affects: cattle
Cause: clostridium chauvoei
Pathogenesis: ingested spores are absorbed from the intestinal tract disseminated via the bloodstream to the skeletal musculature and other tissues remain latent but can begin to proliferate if a bruise is present spores activate after trauma, bacteria proliferate and produce toxins cause capillary damage, haemorrhage, edema and necrosis
Macro: yellow gelatinous exudate, blood and gas bubbles are present in the subcutaneous and intermuscular CT, affected muscles are swollen, dark red to black and typically porous, spongy and dry
Micro: intramuscular blood and gas bubbles separate swollen eosinophilic myofibers, myofibers are fragmented, with shredded or granular sarcoplasm and pyknotic nuclei
polymyositis
Definition: immune mediated myositis disease
Cause: no specific cause, maybe ehrlichia canis
Macro: pain during manipulation, elevated serum muscle enzyme
Micro: focal, multifocal or diffuse necrosis, phagocytosis and lymphoplasmacytic infiltrates
masticatory myositis
Definition: progressive destruction of the masticatory muscles with eventual fixation of the jaw
Affects: immune mediated in dogs
Cause: humoral antibody response against myosin type 2, found in masticatory muscles
Macro: lesions are bilaterally symmetric
Micro: during acute phases there’s severe infiltrates of eosinophils and fewer lymphocytes, neutrophils and plasma cells, plasma cells are most numerous and eosinophils less common in chronic lesions during periods of quiescence
extraocular muscle myositis
Definition: immune-mediated attack directed specifically at extraocular muscles
Affects: golden retrievers predisposed
Macro: acute onset of bilateral exophthalmos
malignant hyperthermia
Definition: porcine stress syndrome, pale soft exudative pork
Affects: pig
Cause: genetic defect, stress
Pathogenesis: genetic defect results in abnormal activity of the skeletal muscle ryanodine receptor uncontrolled intracytoplasmic Ca release excessive contraction with resultant heat production
Macro: affected muscle pale, soft, swollen and appears “cooked”
hyperplasia
increasing of cell number
dysplasia
unnaturally large or morphologically irregular cells
hypoplasia
reduced number of haemtopoietic cells
aplasia
absence of development of certain vectors of haematopoietic blood cells
aplascit anaemia
destruction of all three blood cell lines
myelodysplastic syndrome
disorder of hematopoietic stem cell clones
myelophthisis
replacement of haematopoitic bone marrow tissue by abnormal tissue
pancytopenia
reduced blood cell concentration of all three lines
anaemia
Definition: reduction of erythrocyte concentration
Types: Regenerative anaemia (bleeding/haemorrhage or haemolysis), nonregenerative anaemia (primary bone marrow disease and extramedullary diseases)
Aplastic anaemia: cause: stem cell destruction (chemical, infectious and idiopathic)
erythropoietic porphyria
Affects: cattle and cat
Cause: porphyria = inherited defects of enzymes
Pathogenesis: inherited defects of enzymes involved in the synthesis or porphyrin and other haemoglobin proteins accumulation of toxic components of porphyrin haemolytic anaemia, accumulation of pigment, photosensation of non-pigmented skin
babesiosis
Definition: intraerythorycitc protoszona organism
Affects: horse, cattle, dog and cat
Cause: babesia: equi, bovis, canis, cati, felis…
Pathogenesis: intravascular and extravascular haemolysis due to direct or indirect damage by the parasites, immune mediated destruction massive immunostimulation and release of cytokines causes shock and systemic inflammatory response which can lead to multiple organ failures
Macro: anaemia, icterus, splenomegaly, haemoglobinuria, gallbladder filled
Micro: degeneration and necrosis of centrolobular hepatocytes
theileriosis
Cause: tick borne intralymphocytic or monocytic shizonts, intraerythrocytic pirpoalsms
equine infectious anaemia
Affects: equine
Cause: EIA virus, lentivirus fam
Pathogenesis: virus infects monocytes which then become macrophages macrophrage produce inflammatory chemo+cytokines arrival of new monocytes and lymphocytes then infected/destroyed
Macro: anaemia, jaundice, hepatomegaly, splenomegaly
Micro: subcapsulat bleeding, Kupfer’s cells with phagocytosed erythrocytes
Consequence: acute period of fever, depress + thrombocytopenia potentially fatal but usually subsides within a year and then horse becomes lifelong carrier
multiple myeloma
Definition: malignant tumour of plasma cell- bone marrow origin
Pathogenesis: significant increase in number of plasma cells, often found in aggregates causing monoclonal gammopathy
Micro: osteolysis, promoting survival of osteoclasts and bone destruction
histolytic neoplasia
Definition: malignant neoplasia of histiocytic origins
Affects: dog breeds predisposed (bernes mountain, rottweiler)
rhinitis
Definition: inflammation of the nasal mucosa, upset in the balance of microbial flora
Serous rhinitis: clinically the mildest form of inflammation, hyperaemia, serous discharge, mild irritants – cold air, viral infections, mild allergic reactions
Catarrhal rhinitis: serous fluid, significant amount of mucus, thick, translucent viscous discharge, few desquamated and inflammatory cells and detritus
Purulent rhinitis: severe damage, necrosis and secondary bacterial infection, characterised by purulent exudate, mucosal necrosis and bacterial infection. Macro = exudate is thick, dull green-brown in colour, blockage of the nasal passages
Fibrinous rhinitis: severe damage, severely impaired vascular permeability – exudation of fibrinogen coagulating into fibrin, macro= fibrin – yellowish-brown, rubbery. Micro= perivascular edema and fibrin
Granulomatous rhinitis: accumulation of mononuclear cells in the mucosa and submucosa, polypoid nodules, cause chronic allergy, infections
sinusitis
Definition: inflammation of the sinus mucosa
Affects: domestic animals
Pathogenesis: serous catarrhal, fibrinous, purulent or granulomatous. There’s poor drainage so exudate tends to accumulate causing mucocele
viral rhinopneumonitiis
Affects: horse (young racehorse and weaning foals
Cause: equine herpes virus EHV1,4
Pathogenesis: aerogenous
Macro: bronchopneumonia, bacterial rhinitis and pharyngitis
influenza
Definition: highly contagious common disease
Affects: horse
Cause: influenza virus type A
Pathogenesis: virus spreads through inhalation multiples in respiratory epithelium
Macro: conjunctivitis, rhinitis, interstitial pneumonia and edema, erosions in mucosa
Micro: hyaline membrane formation on bronchiolar and alveolar epithelium
strangles
Definition: infectious and highly contagious
Affects: horse, mostly foals and young horses
Cause: strep equi
Pathogenesis: susceptible horse comes into contact with feed, exudate or air droplets containing the bacterium after penetration through nasopharyngeal mucosa strep drains to regional lymph nodes
Macro: purulent rhinitis and lymphadenitis, enlarged LN
Bastard strangles: hematogenous dissemination of strep results in metastatic abscess in organs
Micro: lymphoid depletion in spleen, infiltration of neutrophils, degeneration and necrosis in liver
glanders
Definition: zoonosis, hematogenous dissemination after p/o infection
Affects: horse
Cause: burkholderia mallei
Pathogenesis: through ingestion of contaminated feed and water contaminated by nasal discharge spread also through inhalation invades the intestinal wall invades regional lymph nodes proliferates at pharyngeal LN
can be transmitted to carnivores but ingestion of infected horsemeat
Macro: pyogranulomatous nodules in submucosa, ulcers in nasal passage, edema of LN, lymphadenitis
Micro: chronic granulomas with necrotic centres, macrophage infiltration
infectious bovine rhinotracheitis
Definition: mannheimia haemolytica
Affects: cattle
Cause: BHV-1
Pathogenesis: nasal exudate and coughed up droplets aerosol or droplet infection entry into respiratory system multiples in nasal cavity and upper respiratory loss of cilia in trachea spreads from nasal mucosa through trigeminal ganglion causing non-suppurative encephalitis
Macro: severe hyperaemia, ulcers, pneumonia
Micro: necrotic lesions, infiltration of lymphocytes, hyaline membrane pneumonia
Consequence: bronchopneumonia and diphtheritic inflammation
PRRS
Definition: porcine reproductive and respiratory syndrome
Cause: arterivirus
Transmission: through bodily fluid and trans placentally,
Pathogenesis: virus enters via mucosa and replicates in macrophages viremia and dissemination of macrophages to the lungs, liver and spleen
Macro: haemorrhage in umbilical cord, ascites, hydrothorax, enlarged LN, rib impressions on lungs, endometritis and myometritis
Micro: segmental arteritis, thickened alveolar septal walls in lung, interstitial pneumonia
Consequence: late term abortion and predisposition to secondary bacterial infections
ARDS
Definition: acute respiratory distress syndrome – lung shock
Cause: sepsis, major trauma, burns, pancreatitis or aspiration of gastric content
Pathogenesis: injury provokes hyperactive macrophages which triggers a cytokine storm causes formation of free radicals and cytotoxic enzymes causes alveolar and endothelial damage which cause lung edema
Macro: pulmonary hypertension, hyaline membranes and lung edema
Micro: intravascular aggregation of neutrophils and diffuse alveolar damage
atrophic rhinitis
Affects: swine
Cause: combined infection – Bordetella bronchiseptica and Pasteurella
Pathogenesis: cytotoxins stimulate osteoclastic bone resorption
Macro: inflammation and atrophy of the nasal concha with deformation of the snout and septum
Micro: osteoclastic hyperplasia
infectious feline rhinotracheitis
Affects: feline (kittens)
Cause: FHV-1 frequent
Pathogenesis: causes impairment of pulmonary defence predisposing cats to secondary bacterial infection replication of virus in nasal, conjunctival, pharyngeal causes degeneration and exfoliation of cells
Macro: oculonasal discharge, severe rhinitis, conjunctivitis, interstitial pneumonia
Micro: ulcerative keratitis, hepatic necrosis, epithelial degeneration and desquamation
feline calcivirus infection
Definition: common disease
Affects: cats
Cause: calicivirus
Pathogenesis: affects lining of the mouth and lungs
Macro: mucopurulent conjunctivitis and rhinitis, arthritis, diffuse interstitial pneumonia and ulcers on tongue
inflammation of air sac in horses
Definition: aerocystitis
Affects: horse
Cause: fungal infection
Pathogenesis: pathogens infect the diverticula
Macro: guttural pouch mycosis and guttural pouch empyema
Micro: severe necrotic inflammation of the mucosa and submucosa and vasculitis and necrosis of the wall
atelectasis
Definition: decreased air volume in the lungs, incomplete alveolar distension
Affects: all
Congenital: in new-borns that fail to inflate their lungs, caused by obstruction (aspiration), or when cannot remain distended due to alteration in quantity and quality of surfactant
Acquired: compressive (pneumothorax, hydrothorax), obstructive (foreign body, inflammation, parasites), contraction (pulmonary fibrosis)
Pathogenesis:
Macro: dark blue-reddish colour, without air
Micro: collapse of the alveoli, tissue resembles an interstitium
Consequence: if congenital = brain damage due to hypoxia, surviving foals = wanderes due to lack of fear and ammbling
emphysema
Definition: increased amount of air in the lungs
Affects: secondary in domestic animals (with bronchopneumonia)
Cause: alveolar destruction of the alveolar wall and formation of vesicles to bulla. Interstitial – predominantly in cattle, accumulation of air in the interstitium
Pathogenesis:
Macro: bronchopneumonia, bronchitis, bronchiolitis, cut surface is smooth and dry
Micro: hyperplasia of lymphoid tissue, alveoli are distended
pulmonary edem
Hemodynamic edema: increased transudation due to: increased hydrostatic and decreased osmotic pressure. Fluid first accumulates perivascularly and then penetrates the alveoli (heart failure)
Neurogenic edema: consequence of increased intracranial pressure, cause – head injury, brain tumour,
bleeding in the brain
Macro: lungs are moist and heavy, black red, bronchi and trachea filled with foamy fluid
Micro: inflammation
bronchitis
Definition: inflammation of the bronchi
Affects:
Cause: Pasteurella, virus, parasites
Pathogenesis: catarrhal, purulent, fibrinous and granulomatous
Macro: mucous exudate in lumen, congestion
Micro: hyperplasia/necrosis of bronchiolar epithelium, accumulation of mononuclear cells
bronchiectasiae
Definition: most severe consequence of chronic obstructive bronchitis
Cause: severe consequence of chronic obstructive bronchitis, secondary bacterial infections with P. multicoda, T.pyogenes, or M. haemolytica
Pathogenesis: permanent dilation of bronchi due to accumulation of exudate and partial rupture of wall
Macro: bacterial infection causes purulent bronchopneumonia, distinguish from an abscess macroscopically
bronchiolotis
Cause: viral damage, action of oxidants and ROS
Pathogenesis: bronchiolar fluid becomes mucinous – cannot be removed from bronchioles bronchiolar obstruction with consequent emphysema and atelectasis
COPD
Cause: consequence of allergy to dust or mould from food, unknown
Macro: faint changes, mostly emphysema
Micro: bronchiolitis with goblet cell metaplasia and mucus hypersecretion, small number of eosinophils, goblet cell metaplasia, mucus hypersecretion and some eosinophils
feline asthma
Definition: repeated episodes of bronchoconstriction, cough and dyspnoea
Affects: feline
Cause: allergy to dust, smoke, parasitic proteins
Pathogenesis: type 1 hypersensitivity to inhaled allergens
Macro: bacterial pneumonia, mucosal edema
Micro: inflammation of the bronchioles, infiltration of leukocytes
interstitial pneumonia
Definition: inflammation affects a single layer of the alveolar wall and the adjacent bronchial interstitium
Cause: aerogenic – damage to the alveolar epithelium, gases, viruses
Acute: begins in the exudative phase due to damage to pneumocytes 1 and/capillary endothelium with the formation of alveolar hyaline membranes
Chronic: characterised by alveolar fibrosis, accumulation of mononuclear cells in the interstitium and persistence of pneumocytes II, colour is reddish grey, rubbery in consistency and fleshy in cross-sectional appearance
Pathogenesis: aerogenous injury to alveolar epithelium inhalation of toxic gases can damage epithelium spores combine with antibodies and deposit antigen-antibody complexes in alveolar wall (type 3)
Macro: cut surface “meaty”, lungs pale/dark red in colour
Micro: thickening of alveolar septum, infiltration of mononuclear cells
fibrinous pneumonia
Definition: inflammation characterise by presence of fibrin in alveoli
Cause: bacteria, virus, parasites
Macro: lungs deep red, surface is covered by fibrin sheet, congestion
Micro: interlobular septa prominent, BALT hyperplasia, sequestration, pleural adhesion
embolic pneumonia
Definition: bacteria in the blood
Cause: trueperella pyogens, fusobacterium necrophorum, strep and staph
Macro: small round foci, haemorrhagic edge (in all pulmonary lobes)
granulomatous pneumonia
Definition: characterised by granuloma formation
Causes: resistant to phagocytosis – granulomatous inflammation, cryptococcus neoformans
Macro: pyogranulomas and calcified with dissemination of infection
Micro: interstitial macrophages, lymphocytes, few neutrophils and some giant cells
bronchopneumonia - purulent + fibrinous
Definition: most common type of pneumonia, affected cranioventral parts of the lungs
Affects: domestic animals (most common)
Cause: aerogenic infection with bacteria and mycoplasma
Purulent: lobular distribution especially in cattle and pigs, lungs are hyperaemic and oedematous. Healing occurs within a month and common causes are Pasteurella multocida, Bordetella bronchiseptica
Fibrinous: leads to pleuropneumonia, Causes: manheima, histophilus, mycoplasma
Macro: active hyperaemia and edema, mediastinal LN swollen
Micro: inflammatory exudate accumulates in the bronchi, bronchioles and alveoli, infiltration of neutrophils
pulmonary manheimiosis
Definition: shipping fever
Affects: cattle
Cause: mannheimia haemolytica – biotype A, serotype 1
Pathogenesis: bacteria releases toxins (endotoxin, lipopolysaccharides, adhesion, leucotoxin) which kills macrophages and neutrophils these release TNF-alpha, IL1 and 8, histamine necrosis of alveolar and bronchial epithelium
Macro: severe fibrinous bronchopneumonia, fibrinous pleuritis
Micro: neutrophil infiltration
Consequence: death in acute phase, severe toxaemia and scars, pleural adhesions and abscesses
swine influenza
Definition: highly contagious acute respiratory viral disease
Affects: pigs
Cause: adaption of type A virus (human influenza), uncomplicated secondary P.multocida, T pyogens
Pathogenesis: aerosol, oral route SIV attaches to and replicates within epithelial cells of upper respiratory tract spreads throughout nasal, tracheal and bronchial mucosa
Macro: bronchopneumonia, severe alveolar and interstitial edema
Micro: necrotising bronchitis – bronchiolitis, bronchointerstitial pneumonia
enzootic swine pneumonia
Definition: highly contagious disease
Affects: pigs
Cause: M. hypopneumoniae, poor management
Pathogenesis:
Macro: cranioventral loss of cilia, neutrophils and macrophages
Micro: fibrous pleural adhesions
swine pleuropneumonia
Definition: highly contagious
Affects: pigs (young)
Cause: actinobacillus pleuropneumoniae
Pathogenesis: transmission by respiratory route bacteria attaches to cells produce pores in cell membranes damage capillaries and alveolar walls vascular leakage and thrombosis
Macro: fibrinous bronchopneumonia
Micro: coagulative necrosis, surrounded by thick cluster of leukocytes, bronchioles filled with oedematous fluid, fibrin, neutrophils and few macrophages
ovine pulmonary adenocarcinoma
Definition: contagious, retrovirus-induced lung neoplasia
Affects: adult, rarely young sheep
Cause: retrovirus
Pathogenesis: undergoes horizontal transmission
Macro: enlarged lungs, heavy, consolidation – cranioventral nodules
Micro: neoplastic proliferations – cubic to prismatic cells that form papillary or acinar gland like structures
pleuritis
Definition: Inflammation of visceral or parietal pleurae
Types: fibrinous, purulent, haemorrhagic granulomatous and combinations
Affects: Cats, pigs, cattle, pig,
Cause: haemophilus parasuis, strep, Escherichia coli, Pasteurella, mycoplasma
pneumonia or without pulmonary involvement
Pathogenesis: bite wounds or penetration of foreign material
Macro: pyogranulomas, congestion, pleural effusion
Micro: thickening of pleura
bovine tuberculosis
Affects: bovine
Cause: mycobacterium bovis
Pathogenesis: infection of the lungs by inhalation (adult cattle), ingestion of infected milk (young animals)
Macro: pearl disease
pleural effusion
Definition: accumulation of any fluid in thoracic cavity
Hydrothorax: fluid is serous, clear and odourless, caused by increased hydrostatic and decreased oncotic pressure, inflammation and neoplasia
Haemothorax: blood in thoracic cavity, caused by rupture of major blood vessel
Chylothorax: accumulation of chyle in thoracic cavity caused by rupture of major lymph vessels (thoracic neoplasia, trauma, congenital abnormalities)
splenomegaly
Definition: spleen enlargement
Cause: blood accumulation, increase in MMS cell number, lymphoid hyperplasia, inflammation and neoplasia
Uniform: (bloody) torsion, euthanasia with barbiturates, inflammation and septicaemia, (meaty) phagocytosis, cellular debris
Nodular: uneven contraction, hematoma, haemangioma, hemangiosarcoma, infarcts
anthrax
Affects: cattle and sheep
Cause: bacillus anthracis – gram positive bacteria forming endospores
Pathogenesis: spores proliferate in intestine LN spleen
Macro: splenomegaly, disseminated serosal haemorrhages, swollen and oedematous lymph nodes
Micro: rod shaped bacteria in blood, congestion, lymphangitis, haemorrhage
Necropsy and histopathology aren’t recommended
Types: alimentary and pulmonary
Consequence: death, haemorrhage
splenic Hemangiosarcoma
Definition: malignant neoplasia of vascular endothelium
Affects: most often in dogs
Macro: one or more round masses, reddish to violet colour, fragile coherence
Micro: irregular and poorly define vascular spaces constructed from anaplastic endothelial cells
lymphoid hyperplasia
Definition: follicular hyperplasia (B lymphocytes)
Macro: addition to the enlargement, capsules’ tensions, the cut surface is protruding
Micro: LN – increased due to numerous new lymphoid follicles – secondary lymphoid follicles with pronounced germination centres
acute lymphadenitis
Definition: due to the drainage of the area affected by inflammation, the LN becomes infected
Macro: enlargement due to fluid accumulation, tissue protrusion on the cut surface, very wet
Micro: beginning, infiltration of the neutrophils, followed by more macrophages
chronic lymphadenitis
Pathogenesis: • Skin wound regional LN • Suppurative lymphadenitis • Abscess • Collision of the abscesses • Caseous necrosis • Fibrous capsule
suppurative lymphadenitis
Definition: suppurative inflammation of LN
Cause: Strep equi, strep porcinus, Corynebacterium pseudotuberculosis
Pathogenesis: LN becomes infected after completing drainage of the area affected by inflammation C.pseudotuberculosis enters through a break in the skin and spreads to LN
Macro: LN enlargement due to fluid accumulation, tissue protrudes on cut surface and is very wet
Micro: neutrophil infiltration followed by macrophages, infection with C.pseudotuberculosis there will be eosinophils
Consequence: strangles = dysphagia, guttural pouch empyema, c.pseudotuberculosis will progress to caseous inflammation and encapsulated abscesses will form
leishmania
Definition: tissue and organ damage is caused by the proliferation of macrophages and the immune response of the host
Transmission: sand fly
Cause: causative agent multiples in macrophages
Cutaneous form
Macro: ulcers in the location of the insect bite, inflammation
Micro: neutrophils lymphocytes and plasma cells
Visceral form
Macro: generalised Lymphadenomegaly, splenomegaly, hepatomegaly, plasma cell hyperplasia, thrombocytopenia, chronic interstitial nephritis
histioplasmosis
Cause: histoplasma capsulatum
Pathogenesis: organism enters the respiratory system increase of tracheobronal LN hematogenic and lymphatic dissemination in organism
Macro: generalised Lymphadenomegaly, thickening of the colon wall due to infiltration of macrophages and other inflammatory cells
Micro: coalescing granulomas
lymphoma
Definition: various groups of neoplasia that develop from lymphoid tissue outside the bone marrow
Classification: location (multicentric, alimentary, mediastinal), immunophenotypic, cell morphology (size, nuclear morphology), histological architecture (diffuse/follicular), biological behaviour (indolent, aggressive)
Indolent: slow progression and small, matured and well differentiated lymphocytes. Weak breakdown of the organ structure and a small number of mitosis
Aggressive: characterised by rapid progression and large, undifferentiated lymphoblasts. Significant breakdown of the organ structure and large number of mitosis
Macro: increased LN, bulging cut surface, grey-white to yellowish, infiltration of spleen, intestinal wall thickness, frequent ulcers
Micro: lymphocytes
CD34=all
pattern of hepatocellular degeneration and necrosis
Random: necrosis of individual cells, multifocal necrosis and piecemeal necrosis
Zonal: centrilobular, paracentral, midzonal, periportal and bridging
Massive
types of hepatitis
Acute hepatitis: inflammation, hepatocellular necrosis and apoptosis
Chronic hepatitis: fibrosis with accumulation of mononuclear cells
Non-specific reactive hepatitis: diffuse and nonspecific process; response to some systemic disease
Cholangitis: neutrophilic, lymphocytic and destructive
Cholangiohepatitis
response to hepatocellular injury
Regeneration: needs good vascularisation and preserved biliary tree, nodular proliferation
Fibrosis: replacement by fibrous tissue, increased amount of fibrous tissue within liver, can be focal, multifocal, diffuse and biliary
Biliary hyperplasia: proliferation of bipotential progenitor cells from which biliary ducts and/or periportal hepatocytes can develop
liver cirrhosis
Definition: irreversible change characterised by diffuse fibrosis and conversion of normal liver architecture into structurally abnormal lobules
Affects: all
Cause: chronic toxicity, chronic cholangitis, chronic congestion, congenital dysfunction, salmonella
Pathogenesis:
Macro: becomes hard and firm, surface Is uneven and nodular, liver atrophy, yellowish, grey
Micro: increased fibrous tissue within and around lobules, infiltration of macrophages and lymphocytes and hepatocytes show degenerative and necrotic changes
Consequence: hepatic failure
lipidosis
Definition: excessive lipid within the liver
Cause: nutritive causes (def of Vit B12, cobalt), toxic/ anoxic injury, ketosis and fatty liver syndrome of cattle
Pathogenesis: Increased dietary intake of fats and carbs increased esterification increased fat mobilisation from fatty depots decreased oxidation due to energy deficiency decreased synthesis of apoproteins decreased secretion of lipoproteins from liver
Macro: enlarged, yellow liver, mild cases: only pronounced lobular pattern
Micro: microvesicular steatosis, macrovesicular steatosis
Consequence: significance depends on cause, severity and duration. Hepatocellular necrosis, fatty cysts, fat embolism and liver rupture which can lead to haemoabdomen
glycogen accumulation
Definition: glucose is stored within hepatocytes in the form of glycogen
Affects: observed in dogs secondary to excess glucocorticoids
Cause: goes with diabetes and glycogen storage diseases
Macro: pallor and swelling
Micro: hepatocytes are swollen with lacy vacuolated cytoplasm
amyloidosis
Definition: accumulation of proteins in beta-pleated sheets
Affects: most domestic animals
Cause: deposition of insoluble proteins in tissue
Types: primary – plasma cell tumours, secondary – long standing inflammation, inherited or familiar
Macro: livers enlarged, friable and pale
Micro: hepatic amyloid appears as bright eosinophilic amorphous deposits
infectious canine hepatitis
Affects: dogs
Cause: canine adenovirus 1
Pathogenesis: oral infection tonsilitis viremia.
• Tropism for hepatocytes, endothelial cells and renal epithelium
Macro: haemorrhage, enlarged fragile liver, enlarged and hyperaemic tonsils and lymph nodes, gall bladder wall edema
Micro: smaller centrilobular necrosis of single cell hepatocellular necrosis, large intranuclear inclusions, endothelial damage with haemorrhage and minimal inflammation
bacillary haemoglobinuria
Definition: acute and highly fatal disease
Affects: cattle and sheep
Cause: clostridium haemolyticum
Pathogenesis: bacterial spores are ingested and concentrate within Kupffer cells fluke migration, hepatic injury proliferation of vegetative forms of bacteria in anaerobic environment egzotoxins hepatocellular necrosis and intravascular haemolysis which is characteristic for the disease haemoglobinuria
Macro: large pale foci of necrosis surrounded by hyperaemic zone, red to yellow fluid within serosal cavities
Micro: one or several areas of necrosis with visible bacteria
infectious necrotic hepatitis
Affects: most common in cattle and sheep, rare in pigs and horse
Cause: clostridium novyi
Pathogenesis: spores lowered concentration of oxygen bacterial proliferation exotoxin coagulation necrosis, haemorrhages, less commonly haemolysis possibly death
Macro: similar as bacillary haemoglobinuria, faster putrefaction
Micro: well demarcated areas of necrosis, with gram + rods in necrotic areas
tyzzer’s disease
Affects: rodents, young or immunocompromised animals
Cause: clostridium piliforme
Pathogenesis: causative agent in rodent intestine peroral infection via portal vein into liver lesion
Macro: hepatic enlargement, edema, enterocolitis
Micro: multifocal necrotising hepatitis, necrotic colitis and stacks of long filamentous bacteria
equine serum hepatitis
Affects: horse
Cause: unknown – equine parvovirus hepatitis (?)
Macro: encephalopathy and icterus, liver is green-brown/dark brown
Micro: centrilobular degeneration and hepatocellular necrosis, mild fibrosis and regeneration
chronic active hepatitis
Definition: is microscopic changes similar to humans
Affects: dog
Cause: not clear – leptospirosis, canine adenovirus 1, pharmaceuticals and copper toxicosis
Pathogenesis:
Macro: smaller liver
Micro: portal and periportal mononuclear cellular infiltrate, intrahepatic cholestasis, bridging fibrosis and regenerative nodules
hepatic neoplasia
Definition: most malignant tumours are metastatic ones
Originating from hepatocytes: benign (hepatocellular adenoma) malignant (hepatocellular carcinoma)
Originating from biliary epithelium: benign (Cholangiocellular adenoma), malignant (Cholangiocellular carcinoma)
Affects: adenomas mostly in young ruminants
Macro: (adenoma)single, unencapsulated, variably size and red or brown masses, spherical, (carcinoma) friable, grey-white or yellow brown tissue
Micro: one or very few portal tracts
gallstones (cholelithiasis)
Affects: most common in ruminants, frequently in domestic animals
Pathogenesis: concretions of normally soluble components of bile form when these components arise due to supersaturation and precipitation of the bile
pancreatic hypoplasia
Definition: hypoplasia of the exocrine pancreas
Affects: sporadically in calves; less common sheep, goats and dogs
Pathogenesis:
• Difficult to differentiate between atrophy – with atrophy there’s lipofuscin within atrophic cells, which isn’t present in hypoplasia
Macro: pancreas is small and pale, sometimes there are only visible small wisps of white-cream tissue within the mesentery
Micro: acinar tissue is present but scarce, organised in small clusters of cells; poorly differentiated cells without zymogen granules
juvenile pancreatic atrophy
Affects: German shepherd dogs and rough coated collies
Cause: inheritance is complex, likely involving multiple genes and environmental factors, could be atrophy driven by autoimmune disease which precedes loss of normal pancreatic parenchyma
Pathogenesis:
Macro: pancreas is small, visible loss of parenchyma
Micro: islands of normal exocrine pancreatic tissue usually remain but otherwise tissue is markedly depleted
pancreatitis (def + path)
Definition: characterised primarily by necrosis and varying degrees of inflammation of the pancreas
Affects: dogs and cats
Pathogenesis:
1. Obstruction of the duct (cholelithiasis, parasites, neoplasia)
2. Direct injury to the acinar cells (infectious microbes, toxicants, drugs, trauma, ischemia)
3. Disturbances of enzyme trafficking within the cytoplasm of acinar cells
pancreatitis acute
Acute: most commonly in dogs, less in cats, rare in other animals. Most common in cocker spaniel
Macro: edema pancreas, grey-white areas, chalky white foci, abdo cavity contains blood, peritonitis
Micro: focally extensive areas of haemorrhage, coagulation necrosis of parenchyma, fibrinous exudate and necrosis of fat in mesentery
Cats: 1. Acute pancreatic necrosis 2. Suppurative pancreatitis
pancreatitis chronic
Chronic: characterised by fibrosis and parenchymal atrophy, all animal species, consequence of obstruction of the pancreatic ducts, more common in cockers, king Charles, collie and boxer
Macro: distorted, shrunken, nodular with fibrous adhesions to adjacent tissues
Micro: interlobular and periductular fibrosis and inflammation
nodular hyperplasia
Affects: older dogs and cats (can be cattle)
Macro: multiple raised, smooth, nodules which are uniformly grey or white on the cut section
Micro: nodules consist of unencapsulated aggregates of acinar cells that may lack zymogen granules
pancreatic carcinoma
Affects: uncommon in domestic species; most common in dogs and cats
Macro: solitary/multiple nodules, grey-white to pale yellow, firm to hard consistency
Micro: well, differentiated with tubular patterns of undifferentiated carcinomas with solid patterns
heart failure
Definition: heart failure is the inability of the heart to maintain adequate circulation
Acute: refers to sudden, significant loss of cardiac function, without blood pumping through the body, the brain cells die within minutes. Causes: monensin toxicity, myocardial infarct
Chronic: heart failure for which there are premonitory signs. Causes: cor pulmonale, ventricular septal defect, fibrosis pericarditis
Cause: decreased blood pumping into the aorta or inability to adequately empty the venous reservoirs
Pathogenesis: long term overload-induced cardiac hypertrophy is accompanied by myocardial cell death and cardiac fibrosis
Macro: cardiac tamponade, pulmonary congestion
Micro: myocardial necrosis,
atrial/interventricular septal defect
Atrial septal defect: communication between LA and RA, failure of closure of foramen ovale, defect at another site because of failure development of the interatrial septum (boxer and Doberman)
Interventricular septal defect: failure of complete development of the interventricular septum allows the shunting of blood between ventricles (common in English bulldog and springer)
tetralogy of fallot
Definition: complicated cardiac anomaly – 4 lesions:
1. Primary defects: ventricular septal defect, pulmonic stenosis, dextroposition of the aorta
2. Secondary defect: hypertrophy of RV myocardium
Affects: inherited in keeshond dogs and frequent in bulldogs
Pathogenesis: increased pressure in the right side shunts unoxygenated blood to the underdeveloped left side systemic hypoxia and polycytemia
pulmonic, aortic and sub aortic stenosis
Pulmonic stenosis: frequently occurring anomaly in dogs (inherited in beagle), subvalvualr stenosis, valvular stenosis and pressure overload on RV concentric hypertrophy
Aortic and subaortic stenosis: frequently in pigs and dogs, fibrous ring that arises from the endocardium below the aortic valve may extend to involve cranioventral leaflet of the mitral valve (pigs and dogs)
Macro: hypertrophy
Micro: A+ S stenosis = altered endocardial tissue has loosely arranged elastic fibres, mucopolysaccharide ground substance and collagen fibres
hydropericardium
Definition: accumulation of clear, light yellow, watery, serous fluid
Affects: animals with: hypoproteinaemia, heart failure or vascular injury
Causes: diseases that have generalised edema, renal failure
Macro: pericardial surfaces are smooth and glistening
hemopericardium
Definition: accumulation of whole blood in the pericardial sac
Causes: blunt force trauma, rupture of hemangiosarcoma, rupture of intrapericardial aorta (horse)
pericarditis
Definition: inflammation of pericardium
Fibrinous: frequently – with bacterial septicaemia
Macro: both surfaces are covered by yellow fibrin deposits
Micro: eosinophilic layer of fibrin with admixed neutrophils
Suppurative: mainly in cattle as complication of traumatic reticuloperitonitis, pericardial surfaces
Constrictive: chronic inflammatory lesion accompanied by extensive fibrous proliferation and formation of adhesions. Severe lesion constricts the heart with fibrous tissue and can interfere with cardiac filling and thus cardiac output
endocardiosis
Affects: dogs – predisposed king Charles, cocker and yorkies
Cause: degenerative process
Macro: bulbous enlargements on the valve edges, jet lesions without valvular insufficiency
Micro: myxomatous degeneration of the valve leaflets
endocarditis
Definition: inflammation of endocardium
Affects: often in pigs
Cause: arcanobacterium pyogenes, strep, strongylus vulgaris (in horse)
Pathogenesis: extra turbulence damages the valve edges if bacteria nearby when the valves are damaged, they move in further thrombosis occurs and bacteria is then protected multiply
Macro: proliferation around the bacteria (vegetative endocarditis), cauliflower like lesions
Micro: accumulated layers of fibrin and numerous embedded bacterial colonies
Consequence: heart failure, stenosis, embolism and death due to cardiac failure
hypertrophy
Definition: chamber of the heart gets too big, or walls of one chamber gets thickened
Eccentric: chamber size can be big and cardiac myocytes within the wall are working overtime, it’s associated with volume overloads
Concentric: walls of cardiac chambers are really thick and the chamber seems smaller, results from pressure overload
Pathogenesis: initiation stable hyperfunction deterioration of function associated with degeneration of hypertrophies myocytes
hypertrophic cardiomyopathy
Definition: generalised disease of myocardium
Affects: frequent in cats, infrequent in dogs
Cause: (primary) idiopathic, (secondary) specific heart muscle diseases
Pathogenesis: hypertrophic: sarcomeric defects in cardiomyocytes of which two mutations in cardiac myosin binding protein C have been identified altered sarcomeric function results in myocytes hypertrophy – LV progressively thickens and lumen narrows diastolic failure
Macro: concentric enlargement
Micro: myofiber disarray, fibres instead of lining up in their regular, orderly fashion
dilated (congestive) cardiomyopathy
Affects: most common in dogs (Doberman, pinschers, dalmatians) also in cats and cattle
Cause: inherited as an autosomal recessive mode in Portuguese water dog and dominant in Doberman..
Macro: heart rounded because of biventricular dilation
Micro: attenuated wavy fibre, fatty infiltration-degenerative type
restrictive cardiomyopathy
Definition: increased stiffness (due to increase myocardial/endocardial fibrosis) of the myocardium that leads to diastolic heart failure
Affect: cats, others (?)
Pathogenesis: increased stiffness of the myocardium, due to increased fibrosis and infiltration with leukocytes diastolic heart failure
Macro: endocardial thickening
myocarditis
Definition: results of infections spread hematogenously to the myocardium
Suppurative: localised of pyogenic bacteria in myocardium (mostly from vegetative valvular endocarditis)
Necrotising: toxoplasmosis
Haemorrhagic: haemorrhagic and necrotising – often in blackleg
Lymphocytic: viral infections: parvoviral myocarditis in puppies; encephalomyocarditis virus infection in pigs
Eosinophilic: parasite invasion, idiopathic
Cause:
Pathogenesis: complete resolution, scattered residual myocardial scars, progressive myocardial damage with cardiac failure
Consequence: resolution, scattered residual myocardial scars, progressive myocardial damage with acute/chronic cardiac failure
hemangiosarcoma
Definition: neoplasia of vascular endothelium
Primary: often arise in the right atrium, specifically the right auricle
Secondary: metastasis from spleen
Affects: common in German shepherds
Macro: red, bloody nodules
Consequence: rupture leading to hemopericardium and death from cardiac tamponade
patent ductus arteriosus
Definition: ductus arteriosus fails to close after birth (smooth muscle in ductus arteriosus fails to contract)
Affects: frequent in poodle, collie, Pomeranian, chihuahua, poodles (inherited polygenic trait)
Pathogenesis: blood goes from aorta into the lung too much blood in the lung lung hypertension pressure overload on the right heart, which undergoes concentric hypertrophy
Consequence: blood goes from aorta to lungs and there’s too much blood in the lungs so pulmonary hypertension and increased preload to LV. Pressure overload on right side so concentric hypertrophy. Blood can start shunting from right to left side so unoxygenated blood going to the body
arteriosclerosis
Definition: intimal fibrosis of large elastic arteries
Affects: age- related
Cause: probably haemodynamic influences (hypertension)
Pathogenesis:
Macro: slightly raised, firm, white plaques
Micro: accumulation of mucopolysaccharides, later proliferation of smooth muscle cells and fibrosis
atherosclerosis
Definition: accumulation of deposits of lipid, fibrous tissue and calcium in vessel walls luminal narrowing
Affects: infrequent in animals (pig, rabbit, chicken, dogs with hypothyroidism and diabetes)
Pathogenesis: damaged endothelial wall allows lipoproteins to accumulate within intima oxidised by free radicals generated by macrophages these are directly toxic to endothelium and smooth muscle cells cellular debris is ingested by macrophages and form foam cells
Macro: arteries – thickened, firm, yellow-white, accumulation of lipids throughout the wall
Micro: hyalinisation of CT, proliferation of smooth muscles
mulberry heart disease
Definition: dietary microangiopathy, firm contraction of heart
Cause: deficiency of Vit E and/or selenium
Pathogenesis: deficiency of Vit E and/or selenium fibrinoid necrosis and thrombosis of small vessels microhaemorrhages discolouration of the epicardial surface, hydropericardium
Macro: haemorrhage
Micro: endothelial damage, fibrinoid necrosis of small muscular arteries
hog cholera/classic swine fever
Definition: highly contagious febrile haemorrhagic disease
Affects: pig
Cause: pestivirus – RNA virus
Pathogenesis: inhalation of virus from direct contact with infected pigs or by ingestion of uncooked infected pork penetrates oral mucosa viral replication (tonsils) viremia damage of endothelial, epithelial and cells of the immune system
Macro: widespread petechial haemorrhages, infarction of spleen “button ulcers” of colonic mucosa
Micro: hydropic degeneration of endothelial cells, fibrinoid necrosis of blood vessels
Consequence: death
chimerism and mosaic
Definition: blood vessels of the placentas from two different foetuses fuse and exchange blood between foetuses
Freemartin: female of a set of male and female twins
Affects: chimeras most common in DSD
Macro: clitoris is enlarged, small ovaries, hypoplastic vagina
Micro: Sertoli cells and seminiferous cordlike structure in ovaries
infectious pustular vulvoaginitis
Affects: in cattle
Cause: bovine herpesvirus 1
Pathogenesis: AI, mating and maybe nose to vulva contact
Macro: focal ulceration of mucosa of the vestibule, multiple white regions
Micro: eosinophilic intranuclear inclusions, ballooning degeneration and apoptosis and desquamation
pyometra
Definition: accumulation of pus within the uterine lumen
Cause: consequence of endometritis or metritis, E.coli (viscous brown exudate), strep (creamy yellow)
Macro: necrotic, ulcerated haemorrhagic areas in endometrium
Micro: cystic endometrial hyperplasia
Consequence: widespread extramedullary haematopoiesis and immune complex glomerulopathy
endometriosis
Definition: endometrium is found on serosal surfaces, around the ovary
metritis
Definition: inflammation of the uterus
Cause: bacterial infections (klebsiella), mechanical, thermal and chemical factors, strep, staph
Pathogenesis:
• (acute) Catarrhalic endometritis, septic metritis, necro bacillary metritis, contagious equine metritis
• (chronic) suppurative, nonsuppurative and granulomatous = pyometra
brucellosis
Definition: infectious bacterial disease
Cause: Br ovis, abortus, canis
Pathogenesis: ingestion/inhalation –> multiply in reg LN –> through intestinal epi and Peters patches –> lymphatics
Macro: foetus edema, bronchopneumonia, pleuritis
Micro: inflammation, edema and mononuclear and few neutrophils
ovarian cysts
Follicular cysts, lutein cysts, cystic corpus luteum
Affects: all domestic animals
Cause: hormonal and nutritional disorders and toxins
follicular cysts
Definition: (not ruptured graafian follicle)
Affects: cows, pigs
Cause: E.coli
Pathogenesis:
1. Abnormality in the hypothalamus – pituitary-ovary axis
2. Associated with infection (E.coli)
3. Increased prostaglandin due to bacterial endotoxin
4. Increased cortisol
5. LH suppression
6. Cysts formed increased ACTH or cortisol
7. Inhibition of release of GnRH and decreased expression of LH receptor in ovary cysts
Macro: cyst fluid – rich in oestrogen
cystic corpus luteum
Definition: formed from corpus luteum – after ovulation and the extension of the follicular areas
Cause: hormonal, eating disorders and toxins
Pathogenesis: not clarified
granulosa cell tumour
Affects: cows, mares and bitches (mostly benign), cats and bitches (malignant)
Pathogenesis:
Macro: unilateral, smooth surface, round, solid, cystic
Micro: cells similar to granulosa cells, round or cylindrical, stroma is scant to abundant
mastitis
Definition: inflammation of parenchyma (mastitis) and excretors channels (galactophoritis)
Classification: severe, suppurative, subclinical and granulomatous
Cause: bacteria and mycoplasma
Infection: galactogenic, hematogenic and lymphatic
Predisposing factors: high producing, excessive high vacuum, presence of lesions, contamination, poor hygiene and certain flies
gangrenous mastitis
Affects: cow
Cause: G+ (staph, strep)
Pathogenesis:
Macro: edema of the mamma and surrounding areas, milk is watery, contains fibrin
severe mastitis
Definition: without clinically apparent necrosis of tissue or with necrosis
Affects:
Cause: Gram – and + bacteria
Pathogenesis:
Macro: edema, fibrin exudation, neutrophilic infiltration
Micro: necrosis and sequestration of glandular tissue
suppurative mastitis
Definition: pus forming
Affects: dry cows
Cause: trueperella pyogenes, mcyoplasma bovis
Pathogenesis:
Macro: lesions are centred on lactiferous ducts and sinuses
Micro: neutrophils
granulomatous mastitis
Cause: microbes, candida
Pathogenesis:
Macro: glands, hot, swollen, multiple abscesses, small white particles in exudate
Micro: granulomas and pyogranulomas surrounded by fibrous tissue – gland being replaced by framework of fibrous tissue surrounding pockets of inflammatory cells and central necrotic debris
streptococcal mastitis
Definition: most important in bovine
Affects: bovine
Cause: strep, inadequate mammary hygiene and efficient antibacterial drugs
Pathogenesis: bacteria persists in lactiferous sinus and multiples
Macro: strands/clumps of debris or pus are present in the milk, parenchymal edema, alveoli with retained secretion
Micro: interstitial edema, neutrophils infiltration, alveolar epithelium, macrophages and inflammatory cell
staphylococcal mastitis
Definition: most severe form of this is gangrenous form
Affects:
Cause: staph
Pathogenesis:
Macro: blue-black colour, fluid exudation
Micro: severe interstitial edema
coliform mastitis
Definition:
Affects:
Cause: gram – bacteria (klebsiella, Escherichia coli)
Pathogenesis: endotoxin and subsequent cytokine release
Macro: fluid in lactiferous sinus
Micro: edema of the interlobular septa, fibrin thrombi in lymph vessels, epithelium of ducts and alveoli necrotic
mycoplasma mastitis
Definition:
Affects: cows
Cause: mycoplasma bovis
Pathogenesis: hematogenous spread and contamination of the papilla
Macro: affected quarters are enlarged, firm, light brown, nodular parenchyma
Micro: vacuolisation, degeneration of alveolar epithelia, fibrosis
acantholysis
Definition: disruption of intercellular junctions between keratinocytes
Cause: immune mediated injury (pemphigus), exfoliative toxins from staph
Pathogenesis: damage of transmembrane glycoproteins splitting of extracellular core of desmosomes desmosomes plaque dissolve and intermediate filaments retract
Micro: varies depending on location, vesicles/pustules and free-floating keratinocytes
vesicle and bullae
Vesicles: fluid-filled cavities within or beneath the epidermis less than 1cm
Bullae: vesicle greater than 1cm
epitheliogenesis imperfecta
Definition: incomplete development of skin epithelium ulceration
Affects: cattle, dogs, pigs and sheep
Cause: secondary bacterial infection bacteriemia
Consequence: tissue is easily traumatised leading to secondary bacterial infections and bacteraemia, death from infection of dehydration and electrolyte imbalance
Macro: sharply demarcates areas devoid of the epidermis and adnexa or mucosa
Micro: no epidermis
congenital alopecia and hypotrichosis
Definition: alopecia – absence of hair from skin where hair is usually present, hypotrichosis – less than the normal amount of hair
Affects: most domestic animals
Cause: hereditary conditions caused by spontaneous genetic mutations
photosensitisation
Definition: activation of photodynamic substances in skin with UVA
Type 1: Primary, ingestion of photodynamic substances in food (hypericin) or medicines, in the intestine is transformed into a photoreactive metabolite
Type 2: abnormal metabolism of porphyrin – inherited disease (cattle and cat)
Type 3: hepatogenous photosensitisation – occurs secondary to primary liver damage
Pathogenesis: activation of photodynamic substances in skin with UVA ROS formation mast cell degranulation inflammatory mediators damage of cell membranes, nucleic acids, proteins and organelles erythema, edema, exudation and necrosis
Macro: lesions in areas with unpigmented skin exposed sunlight, peracute development erythema, edema, vesicle and necrosis
Micro: coagulative necrosis of the epidermis, fibrinoid vascular degeneration and secondary bacterial infections
aural lick dermatitis
Cause: persistent licking or chewing
Pathogenesis:
Macro: erythematous, haired or hairless, ovoid, eroded plaque
Micro: hyperkeratosis, acanthosis, erosions, ulcers; dermis thickened by fibrosis and capillaries
contagious echthyma
Definition: contagious pustular dermatitis
Affects: sheep and goat
Cause: parapoxvirus
Pathogenesis: abrasions infections lesions characteristic for poxvirus
Macro: ulcers
lumpy skin disease
Affects: cows, bishops
Cause: capripoxvirus
Pathogenesis: infections of the skin viremia systemic infection endothelial damage vasculitis eruption of numerous, well-restricted nodules on the skin, edema, generalised lymphadenopathy
Micro: vasculitis, lymphangitis, thrombosis, changes In epidermis
herpesvirus
Pathogenesis: infection epithelial cells – replication lysis of nuclei viral particles enter the cytoplasm degeneration of cytoplasmic organelles, cytoplasmic lipid accumulation and protein precipitation
Macro: vesicles that rupture ulcers crusts
Micro: balonising and reticular degeneration – acantholysis, occasionally syncytial cells, intranuclear inclusions
papillomavirus
Definition: species and site specific pathogens
Affects:
Cause:
Pathogenesis: infects squamous epithelium, fibroblasts cause benign, less commonly malignant tumours
Virus in the cell – 3 possible outcomes:
1. Virus remains in circular DNA episome replicate but latent
2. As basal cells mature virus convert to productive infection with typical morphological changes
3. Virus can become integrated into the genome of host cells malignant transformation neoplasia
Macro: warts, ulcerated fibrous growths
Micro: epithelial hyperplasia (thickened)
sarcoid
Definition: locally aggressive, nonmetastatic fibroblastic tumour, frequently in areas subjected to trauma
Affects: Equine
Cause: BPV 1 and 2
Pathogenesis:
Macro: Occult (flat grey hairless, circular), verrucous (grey, scabby, solid), nodular (multiple, discrete), fibroblastic (fleshy mass), mixed, malevolent (rare + aggressive)
Micro: epithelial hyperplasia
dermatophilosis
Affects: horse, cattle and sheep
Cause: dermatophilus congolensis
Pathogenesis: repeated cycles of bacterial growth, inflammation and epithelial regeneration formation of stratified pustular crusts
Macro: crusty lesions
greasy pig disease
Definition: exudative epidermitis of pigs
Cause: staphylococcus hyicus – toxin
Pathogenesis: bacteria release exfoliatin toxin which erodes straum corneum
Macro: brownish malodorous exudate, hardens, cracks and becomes scaly
Micro: sub corneal pustular dermatitis, superficial suppurative folliculitis, thick crusts of keratin, microabscesses and cocci
Consequence: if acute, it’s fatal in neonatal piglets
hypersensitivity
Definition: atopic dermatitis (atrophy, allergic inhalant dermatitis)
Cause: genetically predisposed inflammatory and pruritic allergic skin disease
papilloma definition
Definition: benign tumour of stratified squamous or transitional epithelium
• Well differentiated tumour, exophytic growth, papillae or plaques, hyperplasia of epidermis and hyperkeratosis, gentle fibrovascular stroma
squamous cell carcinoma
Definition: most common malignant epithelial tumour
• Poorly demarcated, locally invasive, rare metastasis
Affects: cats
Cause: UV rays
melanoma
Definition: malignant, more common (oral mucosa)
Affects:
Cause:
Pathogenesis: high pleomorphism and atypia, degree of pigmentation
Macro: spindle, round, epithelioid, vesicular cells, higher mitotic count
Micro:
mast cell tumour
Definition: malignant neoplasm of connective tissue or mucosal mast cell origin
Affects: dogs, cats, pig and cattle, most common in dogs, mainly in the back of body and scrotum
Grading:
Macro: can look like inflammation due to degranulation and release of mediators
Micro: eosinophils, flame figures and with toluidine blue stain, mast cells are purple
cutaneous histiocytoma
Definition: benign tumour
Affects: young dogs
Macro: oval, solitary, fast growing, rising above the skin, alopecia
Micro: solid infiltrative growth, pleomorphic histiocytes, frequent mitosis
hyperkeratosis
Definition: disorder of cornification, characterised by an increase in the thickness of stratum corneum
Cause: non-specific response to trauma, inflammation or sun exposure, primary seborrhoea of cocker spaniels and vitamin A deficiency
Orthokeratosis: keratinocytes undergo complete cornification and become anuclear, there’s also hypergranulosis
Parakeratosis: keratinocytes undergo partial/incomplete cornification and retain their nucleus. There’s also hypogranulosis
Types: basket weave, compacted or laminated
Diffuse parakeratosis occurs in hepatocutaneous syndrome
