GI - Bovine pathology Flashcards
What should you consider if you find vesicles?
Foot and mouth
What is a differential for foot and mouth disease which is a notifiable disease?
Vesicular stomatitis (rhabdoveridae) - indistinguishable from foot and mouth without lab conformation
What is a differential for foot and mouth which is usually not a clinically significant infection but is zoonotic?
Bovine papular stomatitis (poxveridae)
What is a differential for foot and mouth which can cause acute stomatitis with a thin grey film of catarrhal exudate on the mouth mucosa?
Bovine viral diarrhoea/mucosal disease (Pestivirus) - BVD
What is a differential for foot and mouth that involves the whole alimentary tract with focal areas of necrosis, erosion and ulceration?
Infectious bovine rhinotracheitis
What is a differential for foot and mouth that causes corneal opacity, mouth ulceration and nasal discharge in cattle, but is asymptomatic in sheep?
Malignant catarrhal fever
What is a differential for foot and mouth that is transmitted by culicoides and causes ischaemic necrosis and ulceration/necrosis from vascular damage?
Bluetongue
What is a differential for foot and mouth that is a secondary bacterial invader following mucosal damage, causing ulceration and necrosis in the mouth?
Fusobacterium necrophorum - calf diphtheria
What is a differential for foot and mouth that causes pyogranulomatous lesions and abnormal production of granulation tissue in the tongue?
Wooden tongue - actinobacillus (gram negative commensal)
What is a differential for foot and mouth that causes pyogranulomatous mandibular and maxillary osteomyelitis?
Lumpy jaw - actinomyces bovis (gram positive bacteria)
What are the different types of stomatitis?
Vesicular
Erosive/ulcerative
Necrotising
Lymphoplasmacytic
Granulomatous
Papular
What is primary tympany?
Frothy bloat - when foam prevents gas from being eructated
What causes primary tympany?
Eating high levels of legumes eg. alfalfa and clover
These contain soluble proteins which get denatured by the ruminal microflora and become insoluble creating foam
What are the consequences of ruminal tympany?
Distended rumen activates the vago-vagal reflex which compromises respiratory function and other organs
What is secondary ruminal tympany?
Generally chronic physical or functional defect in eructation
What are some causes of secondary ruminal tympany?
Vagal damage
Failure of oesophageal groove closure - ruminal drinkers (bucket fed calves
FB/tumour/obstruction
What can be mistaken for ruminal tympany?
Post mortem rumen distention
What is the normal rumen pH?
6-7
What pH means ruminal acidosis?
Less than pH=5
What causes ruminal acidosis?
High carb/fermentable feedstuff diet
How does high carbohydrate diet cause ruminal acidosis?
High carbs produce lots of fatty acids which reduce the pH
The good bacteria die and gram negative bacteria are favoured, especially lactobacillus
What are the consequences of ruminal acidosis?
Ruminal atony - volatile fatty acids inhibit receptors of motility via vasovagal reflex
Increased osmotic pressure in rumen - fluids move in causing dehydration, shock and death
Secondary fusobacterium infection - necrosis, embolise to liver
How can fungi affect the rumen?
Mycotic rumenitis - very serious
Opportunist fungi grow and penetrate the rumen wall causing peritonitis
What side does tee abomasum usually go to during abomasum displacement?
Left
What are the predisposing factors to abomasum displacement?
Abomasal atony - enteric nervous system problems
What concurrent problems can you get with abomasum displacement?
Hypocalcaemia
Ketosis
Metritis/retained placenta
What type of abomasum displacement can progress to abomasa volvulus?
Right displacement - rotates around loop of omasum and duodenum
What are the consequences of abomasum volvulus?
Chloride build up - metabolic alkalosis
Necrotic ischaemia
Rupture
Nerve damage
What is thought to cause abomasal ulceration in calves?
Dietary change - weaning, stress
What is thought to cause abomasal ulceration in dairy cows?
Post partum
Concurrent disease
What factors cause abomasitis?
Not enough colostrum - failure of passive transfer
Rapid diet change, high volume feeds
Causes bacterial overgrowth
What bacteria overgrow most during abomasitis?
Clostridia
More common in sheep
What other pathogen causes abomasitis?
Parasite ostertagiosis
What are the 4 mechanisms of diarrhoea?
Secretion
Malabsorptive
Increased permeability/effusion
Altered motility
What pathogen causes altered secretion and absorption of electrolytes and water by enterocytes but there is minimal/no damage to the mucosa?
Enterotoxigenic E. coli
What pathogen affects young animals and humans by causing villus atrophy?
Cryptosporidium
What pathogen causes lysis/exfoliation of enterocytes which decreases absorption of sodium, glucose and water?
Rotavirus
How does salmonella cause diarrhoea?
invades enterocytes inducing apoptosis and neutrophil recruitment
Tissue injury, inflammation and vascular damage causes loss of mucosal integrity
What disease infects macrophages to cause focal granulomatous inflammation, villus atrophy and therefore malabsorption and excess secretion into the gut?
Johne’s disease
Where does johnes disease invade the gut epithelium?
Ileal peyers patches
