GI 4, 5, 6 and Practical Flashcards
What is atresia?
Therefore what is intestinal atrasia?
What species does it most frequently occur?
What is anal and rectal atrasia?
Species?
Atresia- congenital absence, pathological closure, opening, passage or cavity
Intestinal atresia- usually ileum and colon
complete lack of some part or blind ends, but muscular and CT layers
Most frequent in calves
Anal and rectal atresia- failure in developing anal opening
Most frequent in piglets
What species can develop megacolon?
What are the two causes?
Dog, cat, horse, pig
1) aplasia of neurons in large intestine myenteric ganglion-
lack of peristalsis so fills up
2) idiopathic- old cats
recurrent and progressive episodes, intractable constipation
most common
What are the three types of intestinal displacement/misalignment can occur?
Herniation- protrusion of an organ/tissue through an opening in its surrounding
Intussusception- invagination- telescoping of segment into another
Volvulus- a torsion/twisting at root of mesenteric attachment
What are the two causes of hernias?
What are the three different types of hernias?
Hernias can be acquired or congenital
- Diaphragmatic- intestines into thorax
- Horse- SI into epiploic foramen
- Inguinal hernia- back end
This image shows potential herniation in a horse
What is the name of the condition?
With diaphragmatic herniation what can the compression lead to?
Epiploic foramen- small intestine can pass through
Compression of lungs with diaphragmatic herniation can lead to pulmonary atelectasis (collapsed lung)
What causes intussusception?
Therefore what diseases can cause intussusception?
What species is more commonly affected by volvulus and where?
Hyperactive bowel movement
Dog- mainly SI- parvovirus, distemper
Horse- mainly ileum into caecum- tapeworm
Horse-
jejunum, ileum- 180
pedunculated lipoma around the intestine
What are the consequences of intestinal misalignment/displacement?
- Misalignment leads to occlusion of veins
- Leads to persistence of arterial blood supply but not drainage
- Increased blood pressure and O2 deficit/hypoxic damage
- Causes capillary fragility- necrosis and haemorrhagic infarction or haemorrhage
What are the three alterations of the intestinal lumen?
Obstruction
Stenosis- narrowing
Functional paralysis
What can cause intestinal obstruction?
- Ingesta- large colon impaction/coprostasis (horse)
- Foreign bodies- enteroliths, corn cobs, string
- Parasites
- Bezoars- impacted hair
- Neoplasms
- Haematoma
- Abscesses
String (linear foreign body) causes ‘dislocation’
What can cause intestinal stenosis?
Compression/strangulation
e.g pedunculate lipoma
Fibrosis after ulceration surgery
What causes functional paralysis in horses?
What are the gross lesions?
What is the causative agent?
What horses are usually affected?
Grass sickness- primary dysautonomia
Gross lesions- stomach and SI filled with watery food contents, large intestine
Aetiology- clostridium botulinum
necrosis and loss of neurons in sympathetic ganglia
variable presentation
Frequent in UK, young horses kept on pasture
What is the name for intestinal inflammation?
What does intestinal inflammation lead to and why?
Enteritis
Enteritis leads to diarrhoea
Pathological mechanisms-
- Maldigestion- lack of enzymes for digestion, impaired villous epithelial cell functions (villous atrophy)
- Malabsorption- reduced resorptive area due to loss of villous epithelial cells
- Hypersecretion- secretion of electrolytes due to enterotoxins
- Increased motility
What agents can cause enteritis and diarrhoea from the following mechanisms?:
Maldigestion
Hypersecretion
Maldigestion- lack of enzymes, impaired villi
rotavirus, coronavirus, enteropathogenic E.coli
Hypersecretion- electrolytes due to enterotoxins
Enterotoxic E.coli, yersinia enteroclitica
How can catarrhal enteritis present differently?
What can cause it?
Either acute or chronic
With-
epithelial loss, hyperaemia, moderate lymphocytic infiltration of submucosa
Aetiologies
ID- viral, bacteria
Chemical- poisons
Who is more commonly affected by viral catarrhal enteritis?
What does it generally cause?
What are the common agents?
what do they cause specifically and what lesions do they cause?
Mainly young animals- loss of villous tip epithelial cells so villous atrophy, causes vomiting, diarrhoea, poor fluid intake/dehydration
Coronavirus- calves, piglets, puppies
Rotavirus- calves, lambs, foals, piglets, puppies- jejunum and ileum
Canine parvovirus type 2- replication in mitotic cells
oropharyngeal infection- viraemia- infection: lymphatic tissues, intestine, BM
Enteric form- acute catarrhal enteritis with crypt loss and secondary villous atrophy
Feline parvovirus infection
Lesions similar to canine
Enteric- acute fibrinous enteritis
Affinity for crypt epithelium- loss of crypt cells- lack of new, villous shortening, empty crypts, infection in dividing crypt epithelium
What agent is commonly associated with bacterial catarrhal enteritis?
Why does the presentation vary?
What does the image of a pigs intestine show, what presentation is this?
What other presentations are possible?
E.coli
Presentations depend on the species of E.coli- enterotoxin, enteropathogenic, septicaemia and Shiga-like
Oedema disease-
pigs, usually post-weaning, a massive growth of E.coli which produce Shiga-like toxins, oedema in subcutis, stomach wall and mesenteric lymph nodes
Enterotoxic E.coli (ETEC)- calves, lambs, piglets
often after low colostrum, adhere to enterocytes- toxin production, diarrhoea
Enteropathogenic E.coli (EPEC)-
adhere loosely to enterocytes but lead to microvilli destruction
E.coli septicaemia- calves, lambs, foals, piglets, puppies
Oral/umbillical/ immunocompromised
How is fibrino-necrotising enteritis characterised?
What are the different aetiologies and agents?
Fibrinous exudate and deep mucosal damage- necrosis
Viral and Bacterial aetiologies
Viral- classical swine fever
Bacterial- salmonellosis, porcine proliferative enteropathy
What kind of bacteria is salmonellosis?
How are animals infected?
What is the general pathogenesis?
How do lesions vary in animals?
Gram-negative- many species (host-adapted or general)
Infection- faeco-oral
Path- colonisation of SI, adherence and penetration of enterocytes into lamina propria, proliferation both free and within macrophages
Lesions
- young animals- peracute (septicaemia), acute (catarrhal or fibrinous), chronic (fibrino-necrotising typhlocoloitis)
- Adult horses- fibrino-nectrotising or haemorrhagic typhlocolitis
- Swine- necrotising enteritis, ulcerative proctitis with subsequent renal strictire
What causes porcine proliferative enteropathy?
What kind of bacteria is it?
How does it cause fibrino-necrotising enteritis?
Describe the pathogenesis
What are the different forms of the disease?
Lawsonia intracellularis
Gram -ve, rod, obligate intracellular
Infects crypt epithelial cells, and needs cell division to replicate
Spreading in epithelium by cell proliferation
Infection of basal crypt enterocytes, propagation through cell division, extrusion of infected cells, degenerate cells release bacteria, infection of other crypt cells
Forms
Porcine proliferative enteropathy
Proliferative haemorrhagic enteropathy
Necrotic enteritis
Terminal ileitis
With each form of porcine proliferative enteropathy describe the lesion location and appearance
From the image which presentation is which?
Porcine proliferative enteropathy- lesions mainly in ileum, post-weaning pigs, mucosal hyperplasia
Proliferative haemorrhagic enteropathy- over 4mo, high mortality
Necrotic enteritis- due to mucosal necrosis, high mortality
Terminal ileitis- chronic, could be healing of necrotic enteritis
Image-
top left- terminal ileitis
top right- necrotic enteritis
bottom left- proliferative enteropathy
bottom right- haemorragic enteropathy
What bacterial agent caused this haemorrhagic enteritis?
Haemorrhagic enteritis- blood in the intestinal lumen
Anthrax- bacillus anthracis
Acute course
Notifiable
What diseases can cause granulomatous enteritis?
What agent causes them?
How do the lesions grossly appear?
Paratuberculosis- Johne’s disease
Mycobacterium avium subsp paratuberculosis
Cattle- early infection, development in months to years
Oral and intrauterine infection- macrophages in mucosa and GALT
chronic lesions mainly in the terminal ileum
granulomatous inflammation- giant cells containing acid-fast bacteria
Lymphoproliferative and eosinophilic enteritis- IBD
lymphoplasmacytic- most common idiopathic IBD in dogs and cats
chronic vomiting and diarrhoea
What is malabsorption?
What do affected dogs present with?
What causes malabsorption?
How is it characterised PM?
Malabsorption- failure of absorption of nutrients from the intestinal tract
Affected dogs- persistent vomiting and diarrhoea, loss of weight, steatorrhoea
Causes- pancreatic enzyme insufficiency, acute and chronic enteritis
Characterised by-
Dilated whitish villi- lymphangiectasia (dilated lymph vessel)
Small granulomas in subserosa and mucosa
Dilated subserosal and mesenteric lymphatic vessels- protein loss mainly due to ruptured vessels and increased permeability
What intestinal circulatory disorders can occur in animals?
- Passive hyperaemia, oedema, haemorrhagic infarction- with misalignment
- Ishaemia- shock, misalignment, thrombosis of intestinal arteries
- Equinr strongylus vulgaris infection associated lesions
What different equine strongylus vulgaris associated lesions can affect circulation in intestined?
Ishaemic intestinal infarction with
major colonic/caecal arterial thrombosis
multifocal smaller arteriolar thrombosis
Haemomelasma ilei
focal small dark grey or black subserosal nodules discolouration along vessels
mainly ileum
due to thrombosis of small arterioles or sequelae to haemorrhage
Why do parasites cause intestinal pathogenic effects?
Deprivation of host nutrients
Blood sucking- anaemia, hypoproteinaemia
Mechanical effects- mucosal alterations, obstruction
Toxic or allergic metabolites
What protozoan cause intestinal lesions?
Coccidiosis
all species- cattle and rabbit especially (host specific species of Eimeria)
Cestodes- generally host-specific, upper small intestine
massive infection in juveniles, often incidental
ruminants, horses, dogs, cats
Nematodes
Strongyles- horses, ruminants, swine
What does this image show?
What causes this disease?
Shows L3 induced granulomas in wall of colonic/caecum mucosa
Causes by cyathostomiasis
What intestinal tumours can be seen in small and large animals?
Colorectal polyps
benign, mainly seen in dogs
Adenocarcinoma
mainly seen in sheep, horses and dogs
sheep horse- SI, dogs- rectum
often with severe fibrous tissue proliferation
metastasis to regional lymph nodes, invasion of adjacent tissues, contact metastases
Malignant lymphoma
mainly seen in cats and dogs- can in horse and cattle
diffuse or nodular thickening of the intestinal wall
cat- older animals, no FeLV association, B cell lymphomas
Anal sac adenocarcinoma- dogs, can produce parathyroid-like hormone
Give a gross description of this image
What is the morphological diagnosis?
GD- Ileum, diffusely the mucosa is thickened by approx 2cm thick and mucosal surface is corrugated, the ridges of the corrugated areas are pale tan, valleys reddish
MD- ileum, severe diffuse chronic histiocytic enteritis
[Johne’s disease]
The following image shows a high power section of an ileal lesion (cow)
What are the arrows pointing to?
A Ziehl-Neelsen stain is used and shows areas of pink
What does this mean and what disease/aetiology is likely?
Mostly macrophages
Arrows show epithelioid cells
Arrowheads show two large multinucleated giant cells
ZN stain shows acid-fast bacteria
Johne’s- paratuberculosis- mycobacterium avium subspecies paratuberculosis
What is abnormal about this histological slide of the jejunum?
What disease could this be in a dog?
- Superficial coagulative necrosis of villi
- Extensive necrosis and loss of epithelial lining in intestinal crypts
- Lymphocytes, plasma cells and macrophages expanding lamina propria
Canine parvovirus 2
This image shows a lesion that was multifocally affecting caudal aspect of the tongue, pharynx, larynx with pale to tan masses
Give a histological description of the lesion
What is the morphological diagnosis
What is the aetiology
HD- focally there is exophytic, well-demarcated, non-encapsulated neoplasm,
Papillary fronds composed of thickened keratinising squamous epithelium
neoplastic cells in cords of keratinising squamous epithelium, cells are polygonal with distinct cell borders, mitotic figures are rare
MD- tongue papilloma
A- bovine papillomavirus 4
These two slides are from a 4 month old female goat with profuse watery diarrhoea and death- several others in the herd are affected
The left slide shows a villi of the jejunum
The right side shows the higher power
What can you identify
What are the arrows pointing to?
What disease can cause this?
The jejunum has mucosal hyperplasia
Coccidial parasites
Macrogametocytes- arrows
Microgametes- arrow heads
A german shepherd dog was euthanised due to severe respiratory problems
The right tonsil is diffusely enlarged red to the pale mottled surface with an irregular large mass
What is the black line showing?
What do the black stars and white starts show?
What type of neoplasm is this?
Tonsil, the basal membrane (black line) is multifocally interrupted and infiltrated by chords and nests of neoplastic cells that deepen in the lymphoid tissue
Tonsil neoplastic epithelium (black stars)
Infiltrating/replacing normal lymphoid tissue (white stars)
Squamous cell carcinoma
The image shows a 4 year old holstein cow tongue with an incidental finding
Give a gross description
What causes this?
Tongue, in musculature there are multiple, well demarcated, pale tan to yellow, up to 5mm diameter soft pyogranulomas
Also multifocally to coalescing through out are pale tan to white, firm, irregular streaks (fibrosis)
Wooden tongue
Actinobacillus ligniersii
