March Animal Health Series: Preventing and controlling coccidiosis

The third part of the March Animal Health Series in association with MSD Animal Health Ireland looked at how to prevent and control coccidiosis in calves and lambs.

The latest episode, broadcast yesterday evening (Thursday, March 23), featured Helena Madden, ruminant veterinary manager with MSD Animal Health Ireland, speaking with Co. Galway-based vet Conor Geraghty.

The conversation took place on the farm of Seamus Quigley near Ballinasloe, Co. Galway. Seamus himself contributed to the discussion to give a farmer view of controlling coccidiosis.

Conor explained coccidiosis is a parasite that invades the wall of the intestines, damaging the wall of the gut. This is associated with bleeding, which farmers may notice as black scour.

The parasite will also cause ill-thrift in calves for a long time after initial infection, stopping them from reaching their potential.

Calves with coccidiosis will often also experience tenesmus, or trying to force passing of feces without needing to.

An infection with coccidiosis will leave some calves more prone to pneumonia, Conor explained.

The vet also noted that, when a number of calves in a group are showing clinical signs of infection, a larger number are likely to be infected without clinical signs. These calves will still, however, see a lack of thrive.

For that reason, it is recommended that the entire group be treated for coccidiosis.

Conor said that infection can be picked up in housing or in paddocks. But as every farm is different, farmers are recommended to talk to their vet or isolate where the exposure is on their particular farm.

The farmer, Seamus, has seen a lot of coccidiosis in his calves. However, he said that, when all calves are treated, the problem doesn’t arise again in that group of calves.

Conor highlighted that, with coccidiosis, what is seen clinically is “only the tip of the iceberg”, as coccidiosis will impact the calves ability to absorb nutrients.

“Once the intestinal wall is damaged there will be scaring on that wall, so they won’t have the same absorption area to absorb nutrients,” the vet said.

He added: “For farmers that have gotten on top of it, it has made a huge difference in the bloom and thrive of the calves, but also reducing other things like pneumonia.”

In terms of the timeline for vaccination, Geraghty said that best practice is to allow the calves to get some exposure to coccidiosis first, with vaccination to follow before clinical signs begin to show.

“10-12 days after exposure is the ideal time to treat. They’ll be exposed and developing an immune response and you’ll treat before damage is caused.”

Seamus noted that, in his experience, it is cheaper in the long run to prevent against coccidiosis, as it takes calves a long time to come back from it, saying “prevention is better than cure”.

Conor commented that coccidiosis is a “very hardy parasite”, and is very difficult to get rid of, even by cleaning sheds.

He explained: “You either have to limit the exposure of animals to highly contaminated areas of the farm, or try to modify them so they’re less exposed.

“Cleaning, while difficult, will reduce the exposure. Outside it tends to favour the moist, wet areas, or muddy areas, such as around water troughs, gates, and gaps. Improving underfoot conditions there helps, and moving troughs to fresh areas avoids build up of any parasite or bacteria.”

Even if the parasite cannot be completely avoided, taking some measures can reduce the viral load of coccidiosis, which can make a difference.

“The difference in the high load and low load is that the high load sometimes overwhelms the animal, and you get severe disease that’s hard to cure, whereas, with the low load, as with any disease, it’s going to be easier to cure,” Conor explained.

He noted that, in cases were farmers need to dose for coccidiosis a second time, that’s usually because they went in with the first dose too soon, before the animal was exposed.

“The one size does not fit all. You need to understand where they’re getting exposed on an individual farm. There can be a bit of trial and error in that.”

Looking at the specific circumstances for lambs, they will generally build up an immunity to coccidiosis if exposed in the first 48 hours of life.

However, Conor said that there’s a challenge in that it’s hard to get lambs out within the first 48 hours unless the weather is good.

With lambs, he noted that coccidiosis infection may be accompanied by other issue which may mask the infection.

“You can have a lot of losses with lambs, because it just pulls the lamb down a little bit immunity-wise, and you can see them having more cases of meningitis, pneumonia, and other things that you may not relate to coccidiosis,” he said.