Lyme disease in dogs a warning to humans, local vets say
By Jenn Watt
Published June 14, 2016
Of the four main types of ticks that could latch onto your pup, it’s the blacklegged deer tick pet owners in Ontario should be most concerned about, says local veterinarian Joan Grant.
About the size of the end of a pencil eraser when engorged, it can be hard to spot the deer ticks, also known as Ixodes scapulars.
But it’s important to get to know this tiny insect, which is found on long grasses and bushes, as it is the carrier of Lyme disease, which can affect dogs and humans – though it is a much bigger problem for the latter.
Thanks to climate change and migrating birds, Lyme disease has made its way to Ontario and is becoming more common in the Highlands.
“This year alone we’ve had six positive Lyme cases this spring,” says Grant, who works at the Haliburton Veterinary Clinic. “We had three total in 2015.”
The Minden Animal Hospital has been dealing with four cases of Lyme disease this spring, says the clinic’s owner, veterinarian Jenn Morrow.
“We’ve had four positives this year. Two of them were previously diagnosed positive and two of them were new this year,” she says.
Cats don’t seem to get Lyme disease, but dogs that have been bitten by infected ticks can contract the disease – however, unlike in humans, dogs don’t show symptoms of the disease very often.
“The good news is that in dogs, 90 to 95 per cent of dogs that get infected with Lyme disease never show any clinical signs. It’s the opposite to people. Most people who get Lyme disease get very sick and that’s why it’s important for us to know about ticks and Lyme disease,” Grant says.
According to the Haliburton Kawartha Pine Ridge District Health Unit, Lyme disease is on the rise in this region. They found 17 blacklegged ticks carrying the bacteria that causes the disease in a study of the area last year – more than they’ve found in the area over the last five years.
In 2015, there were three confirmed cases of Lyme disease in humans in the HKPR catchment and five probable cases.
“Recent findings show Lyme disease is on the rise in this area,” says Richard Ovcharovich, manager of environmental health with the health unit.
Symptoms include “fever, headache, tiredness, muscle and joint pain and skin rashes.” It is treated with antibiotics.
In the small percentage of dogs that react to the disease, symptoms are similar: fever, lack of appetite, “shifting lameness” due to joint pain, swollen joints and swollen lymph nodes.
“They don’t get it right away,” Grant says. “You may have forgotten about the tick or don’t even know it’s happened because if they’re going to get sick, it’s often two to five months after getting the tick bite, in general.”
Lyme disease starts in the white-footed mouse and other small rodents, a common host for ticks when they are in their nymph stage. They feed on the mice and then carry the disease to their next host such as deer and other wildlife, dogs and humans. The disease is caused by the Borrelia burgdorferi bacteria.
Grant says that each year a whopping 200 million ticks come to Canada on migratory birds. Not all of those are blacklegged ticks and not all of those carry Lyme disease.
Another common tick in Ontario is called the American dog tick, or dermacentor. In the United States, this tick can carry Rocky Mountain spotted fever, which vets advise pet owners about when they travel.
In Ontario, however, the American dog tick should not be a concern, but it is sometimes confused for the blacklegged tick.
The best way to tell the difference between the two is the small plate-like scutum on their back. The American dog tick has an ornate design on its mostly white scutum. The blacklegged tick, which can carry Lyme disease, has a dark brown sputum.
Grant and Morrow advise dog owners to treat their pet with a product that will repel ticks. This can be an oral treatment obtained from your vet or can be topical. (Pet owners should be careful when treating dogs with topical insecticide if cats are in the home. They can be poisoned if they come in contact with the dog before it dries.)
Dog owners should check their animals’ skin for ticks and if ticks are present they should be removed right away using tweezers with gentle, but firm pressure.
“People should try to remove the tick carefully because if you catch them before they become engorged, they can’t transmit Lyme disease. In the first 24 hours when they’re first latching on and starting to suck blood they can’t transmit it,” Grant says.
If you’re uncomfortable removing a tick yourself, the vet can do that for you.
Grant also warns dog owners to be sure it’s a tick they’re pulling on as sometimes people think a small skin tag or nipple is a tick and will injure the dog trying to remove it.
“If it doesn’t have legs, it’s not a tick,” Grant says.
Detecting Lyme disease in dogs comes down to a blood test, which also scans for other diseases including heart worm, which is more serious.
Those dogs with Lyme disease are only sometimes treated, depending on whether symptoms are present.
“It’s a bit controversial. There’s not one right answer,” says Morrow. “Technically, if they are asymptomatic, so showing no clinical signs of a problem, then you don’t treat anything. Because even though they’re infected doesn’t mean they’re sick.”
Practices vary with some vets treating dogs that have high levels of the disease in their blood and others not treating the animal at all unless symptoms present themselves.
Lyme disease in dogs can be treated with a relatively low-cost medication.
The increasing presence of Lyme disease in the Highlands is affecting dogs, but the consequences are less serious than other diseases, Grant says.
“It’s not like getting heartworm, say, or certain other diseases that can be fatal like leptospirosis. [That’s] one that we have in Ontario that’s passed in the urine of deer and raccoons and other rodents. If your dog gets leptospirosis it can die … that is one nasty bacterium to get.”
If your dog gets Lyme disease, it cannot transfer it to you, however, that idea persists because pet owners often go where their pets go. If you travel to an area endemic with Lyme disease, you are more likely to be bitten by a deer tick yourself.
“If your dog is positive, that’s something you may want to look into more yourself if you’re not feeling well, says Morrow.