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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
