Toxoplasma is not a fussy parasite: it will happily infect any warm-blooded animal, even humans! In fact one third of the human population have toxoplasma cysts in their body. Most infected animals and people show little reaction to being infected, but it can cause serious problems in pregnant sheep, goats and women.
The natural host for the parasite, Toxoplasma gondii, is the cat. When the cat eats prey or meat (raw or undercooked) that contains Toxoplasma gondii, the parasite enters the cells of the cat’s intestines and undergoes sexual reproduction causing the cat to shed eggs of the parasite in its faeces. Any warm blooded animal that comes into contact with that faeces, and ingest the eggs, becomes infected. When the eggs hatch inside the new host they enter the cells of the intestines and eventually make their way to encyst in body tissue – often in areas that have a high blood flow such as the brain, heart and muscles. The parasite wants this stage to occur in small prey animals so a cat might kill and eat them and the lifecycle would continue. Interestingly Toxoplasma infection in rodents has been shown to change their behaviour, making them less fearful and hence more likely to get eaten by a prowling cat and so the parasite continues its spread!
Our problem comes when the wrong animal ingests the Toxoplasma eggs. If a sheep or goat has not been exposed to Toxoplasma before, and is infected for the first time during pregnancy, the parasite can invade the uterus, placenta and foetus causing pregnancy resorption, frank abortion, still births, mummification or weak born offspring.
What can be done?
Unfortunately in the face of Toxoplasma related abortions there is nothing that can be done. At this stage the parasite is already in place, but fortunately it is not something that can be passed from ewe to ewe.
Here are 4 tips to help on your way to parasite prevention…
- Keep a couple of adult healthy neutered cats. It is mostly young or feral cats that excrete Toxoplasma eggs. If you have resident healthy neutered cats this should dissuade other cats from coming into the farm.
- Dissuade any cats from toileting around sheep feed and forage to keep disease spread to a minimum.
- Vaccinate all breeding stock. This is only normally needed for younger stock as once immunity is established pregnancy is rarely affected.
- Medicate ewe feed during pregnancy to prevent further problems.
Medication can be included in the feed to prevent abortions and perinatal losses due to toxoplasmosis.
Deccox® 6% Premix for Medicated Feeding Stuff for Sheep & Cattle contains 60 g/kg decoquinate. Indicated for the treatment and prevention of coccidiosis in lambs and calves. For information about side effects, precautions, warnings and contra-indications for this product, please refer to the product packaging. For further information please contact Zoetis UK Limited, Walton Oaks, Dorking Road, Tadworth, Surrey KT20 7NS. www.zoetis.co.uk Customer Support: 0845 300 8034. Use medicines responsibly (www.noah.co.uk/responsible). Date of preparation: March 2018. AH043/18