GI diseases of adult sheep Flashcards
Which teeth are used to age sheep?
Incisors - get one pair every year
e.g. lamb will have no permanent incisors
2 year old will have 4 permanent incisors
4 years will have 8 permanent incisors
What else can be assessed when looking at incisors?
Check for broken mouth – missing or broken incisors
What issues can arrive due to molar teeth?
Uneven wear
Sharp edges
Painful and difficult to eat and cud
When examining a sheeps mouth, what should be palpated for externally?
Jaw
Lymph nodes
Face
Halitosis
External palpation for pain /discomfort molar teeth
What is quidding?
A molar teeth problem
- cant chew properly, drops the cud
What are some generalised causes of dental disease is sheep?
Aging
Periodontal disease
Bacteria
Malocclusion
Diet
Wooden tongue is caused by?
Actinobacillosis lignerisei
Lumpy jaw is caused by?
Actinomycosis bovis
What are some other mouth/pharyngeal problems of sheep, other than dental disease
- Overshot/undershot jaws
- Fractures
- Tumours
- Cysts
What is the most common cause of pharyngeal trauma?
Dosing guns - few days, weeks after drenching, number of sheep affected
What are the clinical signs of pharyngeal trauma?
- Dull, depressed, inappetant, weight loss
- Halitosis, pain, cellulitis
What is the prognosis of pharyngeal trauma?
Poor
- Euthanasia
- Penicillin prolonged courses
What are some features of ‘iceberg diseases’?
- Often long incubation periods
- Clinical disease only is visible part of the infected animals in the flock
- Underneath lots of subclinical and infected
Name 4 iceberg diseases of sheep
- Maedi visna
- Ovine pulmonary adenomatosis
- Border disease
- Johnes
What is the cause of Johnes in sheep?
Mycobacterium avium paratuberculosis
How is Johnes spread?
Faeces
Colostrum/milk’
In utero
What are the impacts of Johnes in sheep flocks?
- Weight loss
- Ewe mortality
- Poor performance
When is the key risk period for Johnes infection?
first 3-4 months of life
Where does Johnes replicate in the body?
GI lymph nodes and GIT
Clinic disease is seen in animals of what age?
3-4 years old
Long incubation period
Describe the pathology of Johnes
- Cellular infiltration, thickening of intestines
- Malabsorption and protein losing enteropathy
- Hypoalbuminaemia
What are the clinical signs of Johnes in sheep
Weight loss
Anaemia
Bottle jaw
Sheep over 1yo
High parasite burdens
How can Johnes be diagnosed?
- Often undetected in a flock
- Postmortem
- Histopathology
- Serology ELISA antibody
- PCR faecal test
- Faecal culture
Where in the body would you take histopathology samples for Johnes?
- Ileocaecal junction
- Enlarged distal mesenteric lymph nodes
Describe the specificity and sensitivity of the serology ELISA antibody test for Johnes
Low sensitivity (false negatives)
Good specificity (useful for clinical cases, not subclinical)
Describe flock tests for johnes
- Select older thinner ewes (greater than 3 years old)
- Can be done pooled, for sample sizes discuss with laboratory
- PCR faecal antigen
- Or/ Faecal culture plus PCR
How can flocks be monitored for Johnes?
PME on selection thin cull ewes annually, can be used to monitor for other disease MV, OPA, Fluke
Describe the Johnes vaccination for sheep
- Does not prevent infection but reduces clinical cases and excretion of bacteria
- Reduces deaths by 90%
- Gudair (Virbac)
- All lambs 4 and 16 weeks old
- Repeated annually
How can johnes be controlled in a herd?
- Lamb older and thinner ewes away from younger breeding ewes
- Keep separate till lambs are 6 months old ideally
- Keep stocking rates as low as possible
- Use plenty of bedding and disinfection
- Test and cull suspected/confirmed cases asap
