SHEEP producers have been told to assume their flock has been exposed to the parasite that causes toxoplasmosis and aim to protect young ewes well before they go to the ram later this year.
Fiona Lovatt, independent sheep vet from Barnard Castle-based Flock Health Ltd, said Toxoplasma gondii is the world’s most common parasite.
“It has been estimated that more than 90 per cent of sheep flocks in England, Scotland and Wales have had some exposure to it,” she said.
“Consequently, sheep producers who are not already vaccinating against toxoplasmosis should assume that it’s only a matter of time before new ewes succumb to an infection and plan ahead accordingly.”
A potential toxoplasmosis problem often first shows itself at scanning time with a high empty rate, but the disease can also cause abortion and weak lambs. Experiencing dead or sickly lambs during the lambing period is typically the time when sheep producers feel its impact most acutely.
Dr Lovatt said: “Certainly, if you’ve had more than two per cent of your flock aborting during the 2017 lambing season you should ask your vet to investigate while the issue is still in the front of your mind.
“Now is the time to work out what caused this year’s problems with a view to avoiding similar next year. But your real focus should be on preventing infection in pregnant ewes in the first place and the best way to do that is to vaccinate replacement ewes, well before they go to the ram.”
Stephanie Small, MSD Animal Health livestock veterinary adviser, said: “Sheep are very vulnerable to picking up the toxoplasma parasite from the environment, so normal biosecurity measures are not enough to control the disease.
“Fortunately, toxoplasmosis can be controlled effectively by a simple vaccination regime.What’s more, an investment in vaccination will payback handsomely by a reduction in future flock barren and abortion rates.
“The clear industry advice now is that every ewe should have been vaccinated before it breeds, but we estimate that less than one in five female flock replacements actually get protected before they go to the ram for the first time.”
Ms Small said ewe lambs can be vaccinated from five months of age. Shearlings and older ewes can be vaccinated anytime between four months and three weeks before tupping.
She said: “Immediately post-lambing and up until the typical autumn breeding season there’s a very wide window of opportunity to vaccinate most female breeding sheep against toxoplasmosis, so it makes sense to schedule this crucial intervention as soon as possible, alongside other routine summer procedures.
“Correct pre-tupping vaccination will protect ewes for two breeding seasons.”