Sheep Diseases

Question 1

Pink Eye

Give definition, how it is contracted, live animal, inspection and food safety considerations

Answer 1

Defn: Contagious ophthalmia is acute or chronic inflammation of the eye caused by bacteria

Contracted from carrier animals in same mob.
Characteristics: PINKISH tinge to the iris of the eye, some cases ULCERATION & secondary bacterial infection

Live: conjunctivitis, tears, dread of light

Inspection: if heads are saved for human consumption = condemned

Food safety: not zoonotic, secondary infection may contam hands, equip and other product.

Question 2

Actinomycosis

Give definition, background, characteristics, states, judgements & intensified carcass inspection procedures

Answer 2

Definition:
Lesions found in the mouth and tongue

Background:
Two types
1. Lumpy Jaw: Caused by bacterium Actinomyces bovis. Affects hard tissues, mostly jaw bones, hence the name ‘lumpy jaw
2. Woody Tongue: Caused by bacterium Actinobacillus lignieresi. Affects soft tissues, mostly tongue and head lymph nodes

Etiology:
Lesions caused by bacteria entering wounds in the membranes of the mouth

Characteristics:

1. Lumpy Jaw: Affects hard tissues, mostly jaw bones which can appear as bony growths
2. Woody Tongue: Abscesses & lesions in lymph nodes characterised by thick fibrous tissue formation

States:
Numerous and widespread
• In prolonged infections the organisms may invade surrounding tissues and initiate further development of abscesses
• Infective organisms from eroding suppurating head lesions may be swallowed and cause infection in the gastro-intestinal tract and lungs
Associated emaciation or oedema
• Animals unable to take in sufficient food will have lost condition, and because of diminished protein supply, will become oedemic
Localised
• Most common form, lesions confined to head lymph nodes, tongue or jaw

Judgements:
Any LN involvement in head
Condemn head and tongue △

Lesion in jawbone only
Condemn head △
Tongue can be passed

Localised
Condemn the affected parts and corresponding LN’s △

Generalised
Numerous and widespread lesions with emaciation or oedema condemn in toto △

Intensified carcass inspection procedures
For actino lesions in the head, viscera or carcass:
1. Incise and view the subiliac LN’s
2. Incise and view the superficial cervical LN’s
3. Issue the ACTINO indicator ticket

Question 3

CBovis

Give definition, background, characteristics, states, disposition, judgements, intensified procedures

Answer 3

Definition: Cystic stage of a tapeworm found in humans. Only affects cattle.

Background: Taenia saginata – lives attached to intestinal walls in humans. Egg filled segments in human poo are excreted onto pasture where they are ingested by cattle. Larvae transported in blood supply and lodge in (5) muscle tissues

Characteristics:
• Cysts found in (5) skeletal muscles, the heart, diaphragm, cheeks, tongue, and oesophagus
• Not a food safety issue

States:
• VIABLE: Each larvae forms a 5-10mm blister-like cyst that contains one scolex which can be seen as a small white object in the cyst fluid
- A viable cyst is alive and able to generate a new tapeworm if ingested by humans
- Soft, clear elliptical cyst with a visible head
- Difficult to detect by palpation, but visible
• NON-VIABLE: Hard, 10-15mm pea-shaped cyst, thick fibrous capsule built around it and contains a pale green pus. Easy to palpate

Disposition:
(palpate all skeletal muscle)
Palpate shin, hind leg, Invert flank, fillet muscles, intercostals, palpate back of carcass, external shoulder muscles & brisket

Judgements:
2 x viscera or head/tongue AND
1 x carcase = Condemn in Total △

Ticketing/Screen???
Ovis V = OML + pass, if nothing in Carcase?
Ovis = OVIS + retain if found in Carcase?

Intensified procedures:
1. Found during routine inspection
Make 2 additional incisions, each parallel to and midway between the edge of the heart and the incision that was made into the internal surface of the ventricle
2. Surveillance farms
For all cattle from surveillance farms, the following additional procedures are carried out:

After the internal and external cheek muscles have been dropped or removed from the head, make 2 deep incisions into the external cheek, and one deep incision into the internal muscle. View and palpate all exposed muscle surfaces

After the tongue has been dropped or removed, view and palpate, then make a ventral longitudinal midline incision through the suspensory muscle and view

Make an incision into each INSIDE ROUND exposing the muscles cross-section:
Make a transverse incision into each FORELIMB commencing 5-8cm above the point of the olecranon and extending to the humerus:

Incise the diaphragm and its pillars

Incise the thin diaphragm