GI diseases of adult sheep

Question 1

Which teeth are used to age sheep?

Answer 1

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

Question 2

What else can be assessed when looking at incisors?

Answer 2

Check for broken mouth – missing or broken incisors

Question 3

What issues can arrive due to molar teeth?

Answer 3

Uneven wear
Sharp edges
Painful and difficult to eat and cud

Question 4

When examining a sheeps mouth, what should be palpated for externally?

Answer 4

Jaw
Lymph nodes
Face
Halitosis
External palpation for pain /discomfort molar teeth

Question 5

What is quidding?

Answer 5

A molar teeth problem
- cant chew properly, drops the cud

Question 6

What are some generalised causes of dental disease is sheep?

Answer 6

Aging
Periodontal disease
Bacteria
Malocclusion
Diet

Question 7

Wooden tongue is caused by?

Answer 7

Actinobacillosis lignerisei

Question 8

Lumpy jaw is caused by?

Answer 8

Actinomycosis bovis

Question 9

What are some other mouth/pharyngeal problems of sheep, other than dental disease

Answer 9

• Overshot/undershot jaws
• Fractures
• Tumours
• Cysts

Question 10

What is the most common cause of pharyngeal trauma?

Answer 10

Dosing guns - few days, weeks after drenching, number of sheep affected

Question 11

What are the clinical signs of pharyngeal trauma?

Answer 11

• Dull, depressed, inappetant, weight loss
• Halitosis, pain, cellulitis

Question 12

What is the prognosis of pharyngeal trauma?

Answer 12

Poor
- Euthanasia
- Penicillin prolonged courses

Question 13

What are some features of ‘iceberg diseases’?

Answer 13

• Often long incubation periods
• Clinical disease only is visible part of the infected animals in the flock
• Underneath lots of subclinical and infected

Question 14

Name 4 iceberg diseases of sheep

Answer 14

• Maedi visna
• Ovine pulmonary adenomatosis
• Border disease
• Johnes

Question 15

What is the cause of Johnes in sheep?

Answer 15

Mycobacterium avium paratuberculosis

Question 16

How is Johnes spread?

Answer 16

Faeces
Colostrum/milk’
In utero

Question 17

What are the impacts of Johnes in sheep flocks?

Answer 17

• Weight loss
• Ewe mortality
• Poor performance

Question 18

When is the key risk period for Johnes infection?

Answer 18

first 3-4 months of life

Question 19

Where does Johnes replicate in the body?

Answer 19

GI lymph nodes and GIT

Question 20

Clinic disease is seen in animals of what age?

Answer 20

3-4 years old
Long incubation period

Question 21

Describe the pathology of Johnes

Answer 21

• Cellular infiltration, thickening of intestines
• Malabsorption and protein losing enteropathy
• Hypoalbuminaemia

Question 22

What are the clinical signs of Johnes in sheep

Answer 22

Weight loss
Anaemia
Bottle jaw
Sheep over 1yo
High parasite burdens

Question 23

How can Johnes be diagnosed?

Answer 23

• Often undetected in a flock
• Postmortem
• Histopathology
• Serology ELISA antibody
• PCR faecal test
• Faecal culture

Question 24

Where in the body would you take histopathology samples for Johnes?

Answer 24

• Ileocaecal junction
• Enlarged distal mesenteric lymph nodes

Question 25

Describe the specificity and sensitivity of the serology ELISA antibody test for Johnes

Answer 25

Low sensitivity (false negatives) Good specificity (useful for clinical cases, not subclinical)

Question 26

Describe flock tests for johnes

Answer 26

* 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

Question 27

How can flocks be monitored for Johnes?

Answer 27

PME on selection thin cull ewes annually, can be used to monitor for other disease MV, OPA, Fluke

Question 28

Describe the Johnes vaccination for sheep

Answer 28

- 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

Question 29

How can johnes be controlled in a herd?

Answer 29

- 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