Understanding coccidiosis in lambs
After a wetter than usual spring, lambs on many sheep farms are approaching the peak risk period for coccidiosis. Sheep farmers need to be aware of this potentially costly disease.
As part of a recent OviCast podcast, Dr. Orla Keane, Senior Researcher in the Animal & Bioscience Department in Teagasc, joined Ciaran Lynch to discuss the key risk periods, clinical signs and treatment options available.
Coccidiosis can have a severe impact on naïve animals by causing damage to the intestine once lambs ingest the oocysts. A single-celled parasite, the coccidia that infect sheep are sheep specific Dr. Keane explained, before noting that it is transmitted via the faecal-oral route.
“The high-risk period is usually from three to four weeks up to about three months of age in lambs. After about three months of age, lambs should develop immunity” Dr. Keane explained.
Dr. Keane added: “Coccidia oocysts or eggs are shed in the dung, and they develop and are ingested by other lambs. It does tend to be present on all farms. It is a particular risk for young lambs that have no immunity, that haven’t seen coccidia before or haven’t had the opportunity to develop immunity to coccidia. It does tend to be a problem at this time of year.”
Identifying coccidiosis
As regards to the clinical signs of infection, bloody or mucus-filled scouring, straining, dehydration and poor thrive are common.
“In severe cases it can do fairly long-lasting damage to the gut as well that can prevent lambs thriving in the future, even when the parasites themselves have been cleared out,” Dr. Keane said.
Faecal egg counts are quite limited for coccidia detection, Dr. Keane noted, for a couple of reasons: “The first one is the parasite may be present before oocysts are shed. But a second major reason is there are lots of different species of coccidia out there and only a limited number of them cause disease. If you just get an egg count, you don’t know whether the eggs are from harmless coccidia or coccidia that cause disease.”
“It’s really the age of the lamb, the time of year, the clinical signs. Egg counts can feed into that, but they are not a particularly reliable indicator by themselves of disease for the reasons I outlined,” she said.
Treatment
On treatment, Dr. Keane noted that, at the end of last year, veterinary antiparasitic products went onto veterinary prescription.
“In order to procure these products now, you need a prescription from a vet, so it is really important that you contact your vet about your parasite control, not just for coccidia but for all parasites out there and have a parasite control plan in place,” Dr. Keane added.
For controlling coccidia, Dr. Keane said there are two active ingredients used in oral anti-coccidia medicines: toltrazuril and diclazuril.
“They have slightly different effects. The toltrazuril is effective against all the life stages of the coccidia parasite, so the immature and adult stages, and it has a little bit more persistency. The diclazuril mainly targets the slightly older coccidia and it’s fast acting with less persistent activity,” she explained.
For full insights, listen to the full episode of the OviCast podcast below:
For more information on the effective control of parasites in sheep, click here.
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