Farm Animal Diarrhoea Flashcards
What are the factors that are involved in development of farm animal diarrhoea?
Pathogens Calf factors (immune status, stress) Environment and Management
What are the pathogens that can cause farm animal diarrhoea?
E. coli Coronavirus Rotavirus Cryptosporidium Salmonella Coccidiosis Can also get mixed infections
What is ETEC?
Enterotoxigenic E.coli
What age to animals get ETEC?
Within the first 5 days post partum
How does an animal become infected with ETEC? And what other pathogen is associated with infection?
Ingestion, the bacteria colonise the small intestine. Rotavirus is commonly associated with this type of infection.
What genes are needed for E.coli to become pathogenic and how are they transmitted between bacteria?
Adhesive fimbrae and enterotoxin genes Conferred by plasmids, these can be on seperate plasmids or on the same plasmid
Which adhesive fimbrae serotypes of ETEC are zoonotic?
CFA I and CFA II
What is the mechanism of diarrhoea in ETEC infected animals?
Labile Toxin binds to Gs ADP-R subunit and leads to increased cAMP and activation of the CFTR (Cloride) channel. Cl is therefore secreted and Na and H20 follow this. Therefore there is a secretory diarrhoea.
How can ETEC infection lead to death?
Dehydration, metabolic acidosis and electrolyte loss can be fatal.
What are the two types of toxin of ETEC and are both vaccinatable against?
Labile Toxin - can vaccinate with (i.e. in colostrum) Stable toxin - too small to elicit an immune response
How is ETEC determined from a faecal smear/culture.
Adhesive fimbrae AND enterotoxin genes must be demonstrated.
How does rotavirus diarrhoea differ to that of ETEC induced diarrhoea?
Rotavirus results in malapsorbtion rather than active water secretion.
How is rotavirus related to mortality and how will general hygiene relate to its potential to infect?
High morbidity but low mortality. It persists in the environment and is shed by adults and older calves.
Where is coronavirus located in the gut?
Ileum, caecum and colon.
When is salmonella culture significant?
ALWAYS and it is a REPORTABLE disease to the AHVLA.
How does cryptosporidium cause disease?
It causes villous atrophy resulting in a malabsorpative diarrhoea.
When does coccidiosis need to be investigated?
In older weaned calves (>3 weeks) that are losing weight as well as having diarrhoea/generally not doing well. Other signs include tenesmus and blood stained faeces.
How are the pathogens describes diagnosed?
With faecal SAMPLE not swabs sent to a competent laboratory. Typing is necessary.
Is the appearance of diarrhoea helpful in determining disease?
No
What is the most common cause of diarrhoea on a farm?
Dietary issues.
At what age are the different pathogens likely to be the cause of diarrhoea?
What calf factors affect the chances of infection?
Accessability to colostrum
Dystocia
Competition
Cow factors - quality of colostrum, down cow, allowing to suck?
What would a perfect individual cow pen be like?
- Water and feed buckets outside of pens to avoid faeces getting into them - also clear out regularly to prevent pathogen build up
- Not too close contact between calves - defecation into surrounding pens
- Litter cleared out not just deep litter
- Clean/seperate calving pens
- Ventilation
What should calves be fed?
Water - calves drinking milk for thirst will have it enter the rumen which will lead to diarrhoea.
Milk replacer
Cake for intestinal villi development
What can cause diarrhoea in growing/adolescent animals?
- Endoparasites
- Ostertagia
- Coccidia
- Fluke
- Nutritional
- Rumen accidosis
- Copper deficiency
- Infectious
- Salmonella
- Mucosal disease
What can cause diarrhoea in adult cows?
- Infectious
- Johne’s disease
- Salmonella
- Coronavirus
- Nutritional
- SARA
- Parasitic
- Fluke
- Ostertagiosis
What should one do when assessing diarrhoea/general farm health?
Inspect faecal appearance and particle size on the whole farm
What causes Johne’s disease?
Mycobacterium avium paratuberculosis (MAP)
What is the treatment for MAP?
There isn’t one. Adult cows with Johne’s will remain infectious. They should be culled on humane grounds. They could also be bred to beef.
What age animals can be affected by MAP?
Young animals can be infected but disease only occurs in cows >2 years old.
How can infection spread be prevented/controlled?
- Prevent faeces from older animals
- Calf pens/calving pen
- Don’t spread slurry
- Stop infected colostrum being fed
- Dont pool colostrum
- Prevent in utero
- Detect subclinical adults
- Dont buy infected stock
*
What are the different tests for Johne’s disease and their effectiveness?
ZN stain - sensitivity and specificity low
ELISA - low sensitivity but high specificity
PCR faecal - same as ELISA
Faecal culture - gold standary but only 60% sensitivity
Necropsy - 100% both
