Climate change puts parasites on watch list

Treatments lacking for goats | Intestinal parasites are becoming more common with longer, wet springs

Climate change could affect how parasites affect goat herds, says veterinarian Dr. Chris Clark.

The Saskatchewan winter climate didn’t support much parasite survival until five years ago, the Western College of Veterinary Medicine professor told the Saskatchewan Goat Breeders Association annual meeting.

“Things are changing,” he said.

“Yes, the environment here is good (to raise goats) but those long wet springs are dangerous.”

Intestinal parasites are common around the world, but no anti-parasitic drugs are licensed for goats in Canada.

A veterinarian can prescribe drugs off-label, but Clark said the industry will have to lobby for change if it wants better treatment options, particularly if more or different parasites adapt to the climate.

Coccidiosis is one parasite that bears watching.

It shows up mainly indoors, in goat kids and in bedding because the eggs need the warmth and moisture that bedding provides.

It is shed in feces and often gets worse as kidding progresses. Kids pass a large number of eggs, which are taken up when grazing or licking.

“We can see it as early as eight days of age,” Clark said.

However, it more commonly shows up from two weeks to one month of age. Signs of the parasite include scours and straining.

“In a group you can see high morbidity,” he said.

The eggs are tough to kill, but there are ways to break the disease cycle.

Clark said Baycox, a newer product from Bayer Animal Health, shows promise. It can be administered at two to three weeks of age to help prevent the spread.

Haemonchus is another parasite to watch. It is sometimes called barber pole worm for its striped colouring.

Clark said the worm, which is found in the abdomen, is limiting small ruminant production around the world.

The disease is rare on the Prairies, but the longer, wetter springs are creating conditions for it to survive.

It needs temperatures of 18 to 26 C and 100 percent humidity at ground level. Kids don’t present with scours, but they don’t do well and develop what’s called bottle jaw.

Repeated deworming has been the traditional control method, but resistance has become an issue.

“This parasite is resistant to a lot of drugs,” Clark said.

“Ivermectin doesn’t even seem to touch this anymore.”

Applications can sometimes result in only a 10 percent reduction in eggs when it should be more like 90 percent, he said.

Still, fall deworming remains a good idea. Most eggs in the pasture will die over the winter.

Moving kids to new pastures at weaning can also help.

Clark said it is important to provide the correct dose of any control products.

All new additions to a herd should be treated as part of on-farm biosecurity protocol.

“Weigh, them, dose them with dewormer and wait three to four days before turning them out,” he said.

He also said dewormer classes should not be rotated because that increases the chances of resistance.