- The tapeworm in the dogs produces eggs, which are passed to pasture in their faeces, where are then ingested by sheep or goats.
- After ingestion, the eggs penetrate the intestinal tract, are moved around the sheep or goat in their blood, then shift out of the blood to muscle tissues and form cysts.
- These cysts are in turn infective to dogs.
- Over a period of months, most cysts are killed by the immune system of the sheep or goat and hard, fibrous or calcified lesions are left as defects in the carcass, other cysts can remain alive indefinitely.
How do dogs get infected in the first place?
- Dogs become infected by eating raw or untreated meat or offal infected with live cysts, which are very infective, & often difficult to see.
- Infection can be avoided by ensuring that dogs do not have access to untreated sheep or goat meat (meat scraps, offal, carcasses).
- Refer here for safe treatment guidelines.
(Click image to enlarge)
How do sheep and goats get infected?
- Infected dogs pass many thousands of (T.ovis) eggs in their faeces onto the pasture
- Sheep and goats eat these eggs (which may survive for some months)
- Eggs can also become distributed over large areas by wind and by flies.
- On farm dogs pose the biggest risk, but infection also results from visiting farm dogs, neighbours dogs and visiting town dogs.
- Check here for treatment of dogs and for limiting on-farm contamination from visiting dogs.