Keeping guardian dogs with a sheep or goat herd is a popular way to keep them safe from predators.
But because they are best left to bond with the livestock and not given much human interaction, their health may not be monitored as closely as pets.
In such cases, if they develop canine tapeworm infections, they may pass the bugs on to the sheep or goat herd, said MAFRI sheep and goat specialist Mamoon Rashid.
It’s not just guardian dogs. The culprit could be a pet or stock dog that runs in the pasture or pens with the livestock, or it could be from coyotes or foxes that have feasted on dead animals and picked up the parasite. Then the canines excrete the tapeworm eggs onto the pasture where they are picked up by the sheep, which act as an intermediate host, and the cycle continues.
“If you have dogs and they are not being dewormed on a regular basis or they are not being checked by a veterinarian on a yearly basis, then your sheep may get into this problem,” he said.
“It’s not a food safety or a health issue, there are no clinical signs, it does not kill the sheep or lambs, but what it does is kill your profit.”
The tapeworms steal nutrients in the digestive tract, and apart from some weight or wool loss, it doesn’t affect the health of most animals, unlike roundworms, which cause blood loss.
But it does form visible white cysts on the carcass within weeks of infection. Then when those animals are slaughtered, the inspectors may notice white spots on the heart, liver or abdominal cavity and condemn the carcass as unfit for human consumption, leading to a total loss of the value of the animal.
“We’re hearing more and more about this from the feedlot guys, auction marts and processors in Ontario,” said Rashid. “The control method is to treat your dog, and not let your dogs eat the dead carcasses of sheep or other dead animals.”
MAFRI vet Dr. Wayne Tomlinson said guardian dogs that live on pasture with the sheep should be dewormed every six to eight weeks, stock dogs double that, and pets at least once a year to avoid problems.
Ivermectin dewormers won’t work on tapeworms in dogs, even though they do work for roundworms and fleas on canines.
But in any case, don’t give Ivomec to border collies or puppies, because it could kill them, added Rashid.
Once an effective traceability system is up and running, he said that it will be much easier to trace condemned carcasses at the slaughter plant back to the farm where they originated.
Currently, the buyers are left holding the bag. One eastern buyer has complained that he lost $80,000 last year due to this problem, which seems to be coming more common in lambs from the West, said [email protected]