Farm animal diarrhoea Flashcards
Is diarrhoea a serious condition in young calves
Yes can be fatal
What are the 3 factors involved in diarrhoea in farm animals?
- pathogens
- calf factors (immune system, stress - dystocia etc)
- environment and management
What causes other than pathogens should always be considered when looking at LA diarrhoea?
Dietary problems
Give 6 pathogens that may cause calf diarrhoea
- E. Coli
- Rotavirus
- Coronavirus
- Cryptosporidium
- Salmonella
- Coccidiosis
> mixed infections common
What is E. COli infection in lambs often called?
Watery mouth
Is diarrhoea always present in an infected calf?
NO - find out why!?
Why can E. Coli cultures not show definitive Dx?
All feaces will grow E. Coli when cultured (normal inhabitant of the colon)
When can E. Coli cause problems?
- Extra intestinalinfectin (colisepticaemia)
- enteric disease from special strains (ETEC)
- public health: special strains (STEC)
What is watery diarrhoea referred to as?
Scours
What causes scours?
Enterotoxigenic E. Coli (ETEC)
Small intestine E Coli numbers increase from 10^4 -> 10^9/ml
- Coupled with management / lack of colostrum
Does the pathogenesis of scours differ in different animals?
No
What age does neonatal enteritis due to ETEC occour?
1 - 3 weeks, younger = more common
Are the serotypes of E. Coli relevant to their pathogenicity?
No - there is an association but no correlation/causation
What is the pathogenesis of ETEC?
- ingestion
- colonisation of lower SI
> other agents - D+
- stunting of villi
What other pathogen is often seen in conjunction with ETEC?
Rotavirus - diseases excacerbate each other
What 2 factors does ETEC require to become pathogenic? Where are these encoded?
- adhesive fimbriae (colonisation factor)
- enterotoxin
> encoded on plasmids (may be both on the same plasmid)
How are adhesive fimbriae/colonisation factors referred to on drug packets?
K= old style
F=more modern terminolgoy (fimbrial)
K88 (pigs) F4
K99 (pig, cow) F5
Which colobnisation factors are responsible for “travellers diarrhoea”?
CFA1, CFAII
- zoonotic
What are the two types of enterotoxin? What are their actions? Can they be protected against?
> LT - labile toxin
- Ab in colostrum so vax possible
- similar to cholera toxin - attaches to brush border of SI cells
- causes Cl- channel activation -> secretion of Cl-, Na+ and water from tissues -> active secretion
-> metabolic acidosis, dehydration, electrolyte loss, can be fatal.
ST stable toxin
- mechanism less well understoof
- too small to trigger immune response
How is diagnosis of ETEC decided?
- clinical grounds
- culturing feaces will always yiled E. Coli (indistinguishable from pathogenic strains)
- to demonstrate ETEC must show
> LT Toxin or gene
> K88 fimbriae or gene
in the same organism! - Takes time and money.
What does STEC stand for? What was in previously known as?
Shigga-toxin producing E Coli
- previously EHEC (enterohaemorrhagic E coli)
What does STEC cause?
Some diarrhoea and haemorrhagic colitis in calves
-> contaminated beef can infect humans and -> haemorrhagic colitis and healolytic uraemic syndrome -> renal failure in humans
What age does rotavirus affect calves?
1-3 weeks
Where does rotavirus affect? Morbidity mortality?
- duodenum and jejunum
- ^ morbidity v mortality
How is rotavirus spread and which animals is it commonly seen in?
- Shed by cows and older calves, persists in environment
- Esp seen in beef where adults and calves kept at pasture together
What age does coronavirus affect calves?
1 - 4 weeks, usually slightly older
Where does coronavirus affect? Morbidity mortality?
- ileum, ceacum and colon
- slightly higher mortality than rotavirus due to LI involvement
How is coronavirus spread?
Shed by cows and older calves, persists in environment - cohabiting with rotavirus?
Give a reportable zoonotic public health risk infection of cattle. How is this treated?
Salmonella - culture of salmonella is ALWAYS significant.
Treated with antibiotics
What age animal is affected by salmonella? What are the clinical signs associated with infecton?
- any age of animal
- systemic illness and pyrexia
Who do reportable disease have to be reported to? What are the next steps following reporting?
VLA (Vterianry laboritoris agency) now AHVLA (Animal health vet lab authority)
What age are clinical signs of cryptosporidium seen? What is the PPP of crypto?
- clinical signs 5-14 days, PPP 2-7d
Where does cryptosporidium affect? Pathogenesis? Clinical signs?
- lower SI/colon
- villous atrophy -> malabsorption
- often concurrent disease
- RESISTANCE develops with age
> white pasty diarrhoea
> immunosuppression -> 2* infections
Can cryptosporidium persist in the environment?
Yes
What age does coccidiosis affect calves?
> 3 weeks
weaned calves
What are the clinical signs associated with coccidiosis?
Heamatochezia, tenesmus
Subclinical -> poor growth rate, 2* infections due to immunocompromise
How can coccidiosis be diagnosed? What must be remembered?
NB: pathogens can be present in the absence of clinical signs
- take faecal sample (not swab)
- sample healthy AND affected animals (as many as possible)
- bacteriology, virus isolation and typing necessary at lab
Is faecal appearance a good indicator of the type of disease?
NO
List 6 pathogens able to cause diarrhoea in cattle and the age they are likely to occour.
- E Coli: < 5d
- Cryptosporidium parvum: 5-14d
- Rotavirus: 1-2weeks
- Coronavirus: 1-3 weeks
- Coccidiosis: >3 weeks
- Salmonella: all ages
Give 4 calf factors that may influence development of diarrhoea
- accessibility to colostrum
- dystocia -> stress, weakness, v feeding, ^ time on ground
- competition
- cow factors - quality of colostrum, allowing calf to suck?
How does colostrum affect mortality rates?
Calves with inadequate colostral status = 4x more likely to die than those with good status
Give examples of good and bad husbandry and management practice related to calf diarrhoea
Good:
- buckets outside pens - prevents faecal contamination and knocking over
- water - otherwise will drink milk for thirst -> rumen cause problems
- spaced pens (but lack of social contact bad)
- clean calving pen
Bad:
- deep litter
- starving calves to encourage earlier weaning onto solids (lowers immunity)
- feeding insufficient CMR (calf milk replacer) - should be fed 15-20% body weight per day in volume
What are the 3 main reasons for diarrhoea in he growing/adolescent cow? Give egs.
> endoparasites - ostertagia - coccidian - fluke > Nutiritonal - rumen acidosis - cu deficiency > Infectious - salmonella - mucosal disease (BVD PI) - non cytopathic mutates to cytopathic, 6-18months
What other symptoms would be seen with Cu deficiency?
Coat changes - spectacled appearance
What are the 3 main reasons for diarrhoea in the adult cow? Give egs.
> endoparasites - fluke -ostertagiosis > nutritional - SARA > infectious - Johnes disease (MAP) - Salmonella - Coronavirus (winter dysentery - transient 4-5d scour)
What pathogen causes Johnes disease?
Mycobacterium avium subspecies patratuberculosis
What are the clinical signs of Johnes? What route is infection by?
- severe D+
- weight loss
- dull
- off milk
- faecal-oral route, all cows infectious escpecially feaces
What is the treatment for Johnes?
None - must be culled on humane grounds
Is Johnes zoonotic?
Potentially - may be involved in Chron’s IBD in humans
WHen is Johnes disease acquired?
Youngstock - but remains subclinical until at least 2 years later.
How can Johnes be controlled?
Prevent neonates becoming infected from feaces older animals/colostrum
- avoid pooled colostrum
- test before buying in
- don’t spread slurry
BUT can be infected in utero
Breed to beef so that culled offspring are economically useful
How can subclinical Johnes be detected?
Can’t very easily - issues with lab tests
How is Johnes diagnosed? What is the accuracy of these tests? What is the gold standard diagnostic test?
> ZN smear (cheap)
ELISA blood test has low sensitivity but high specificity - ie. + is + but - is NOT necessarily - (cheap)
milk test also available
faecal PCR slightly more specific
Individual feacal culture = Gold standard (expensive)
test is more sensitive in clinically infected cows than subclinical
necroscopy PM
