Weight loss in adult cows Flashcards
what causes Johne’s disease
Mycobacterium avium subsp. paratuberculosis (MAP)
what is Johne’s characterised by
wasting and diarrhoea
T/F pasteurisation effectively kills MAP in milk
False
When does infection with Johne’s occur
<60 days of life
How is Johne’s shed
In faeces intermittently
increases as the cow develops clinical disease
List 5 sources of Johne’s infection
Faeces from shedding cattle
Colostrum/ milk from infected cattle
Faeces from shedding goats/sheep
Environment and fomite spread
Wildlife reservoirs
T/F susceptibility to Johne’s decreases as the cow gets older
True
List the clinical signs of Johne’s
diarrhoea - intermittent becoming chronic
decreased production
weight loss/ emaciation
+/- oedema (‘bottle jaw’)
at what age do clinical signs of Johne’s tend to occur at
2-6 years of age
List 8 possible Differentials for weight loss and diarrhoea in cows
Liver fluke
Johne’s
Peritonitis
displaced abomasum
abdominal neoplasia
chronic salmonellosis
parasitic gastroenteritis
copper deficiency
List the 2 approaches to diagnosing Johne’s
Detect MAP in faeces
Detect immune response to MAP
what is the problem with diagnosing Johne’s through decting in faeces
MAP only intermittently shed in faeces so sensitivity quite poor
Describe how to diagnose Johne’s
PCR on faeces
ELISA to detect Ab in milk or blood
what is faecal PCR used for when diagnosing Johne’s
mostly used as confirmatory test
what is the sen and spec of faecal PCR
20-65% sensitivity (lots of false neg)
>99% spec (not many false positives)
Why is detecting Ab to johnes better than faecal PCR
cheaper and quicker than faecal testing
more sensitive
what are blood and milk Ab tests used for when testing for Johnes
blood- mostly for indivual cases and beef herd screening
milk- used for dairy herd screening
Can we treat Johnes
No
How long can MAP survive on pastue
over a year in the right environment
List 6 ways to reduce likelihood of calves getting infected with Johne’s
reduce stocking density in calving pens
keep Johne’s positive cows separate
Buy Johne’s free accredited animals
Clean calving pen after every calving
don’t allow new born calves to suckle from johne’s positive cows
keep calving pens clean
what disease has Johnes disease been linked to in humans
Crohn’s disease
how can we differentiate Johnes from liver fluke
Lab work
describe how to differentiate TRP from Johnes
TRP will have other signs such as pyrexia or abdominal pain
how to differentiate Johnes from a displaced abomasum
a displaced abomasum can be identified on clinical exam and will usally be more acute
why is it difficult to diagnose Johnes antibodies or antigens early in the disease
because the cell mediated immune response is high and this keep the antigens low, and the antibodies have not had time to build up yet
