Diseases transmitted by ticks

It's that time of year when we start talking about parasite prevention again. In recent years, temperatures have been much milder earlier and later in the season. The weather now begins to warm up as early as March and stays mild until December. When we talk about "mild" weather in the context of parasite prevention, we're referring to any temperature above 0°C, as this is when ticks become active again. So, here's a quick recap of diseases transmitted by ticks and the recommendations from veterinarians regarding dogs.

What is 4DX and when should I test my dog?

The 4DX is a test performed in-clinic that detects four diseases: heartworm (transmitted by mosquitoes), Lyme disease, anaplasmosis, and ehrlichiosis (the latter three transmitted by ticks). The 4DX test checks for the presence of antibodies against Lyme disease, anaplasmosis, and ehrlichiosis in the blood. Antibodies develop only when the dog has been exposed to the pathogen.

The test is recommended every 2 years for dogs that receive their parasite prevention rigorously. By "rigorous," we mean:The dog receives prevention as soon as the temperature reaches at least 0°C. Prevention is continued until the ground freezes (December or January, depending on the year). Doses are administered on the same date every month. If the animal does not receive prevention according to these standards, we recommend the 4DX test annually to ensure the animal has not contracted any tick-borne diseases. If a tick is found on an animal, the 4DX test is recommended 4 to 6 weeks after the bite.

Quick reminder: Oral tick preventatives (e.g., Nexgard, Nexgard Spectra, Simparica, Simparica Trio) are active in the animal's bloodstream. This means that a tick MUST bite the dog to come into contact with the preventative. Therefore, it is possible to see a tick crawling on a dog that is on these preventatives, as it searches for the best spot to feed. Once it starts feeding, it will come into contact with the product and eventually fall off the animal.

Lyme disease

Lyme disease is the most well-known tick-borne illness in Quebec. It is transmitted by the deer tick, also known as the black-legged tick or Ixodes scapularis. Deer ticks account for 71% of all ticks in Quebec.

Dogs that test positive for Lyme disease may never develop the illness. There is no way to predict whether a dog will develop the disease or not. A dog cannot transmit Lyme disease to another animal or to humans. If the dog does develop the disease, symptoms may include lameness and fever. If left untreated for a long time, the disease can eventually attack the kidneys. Treatment for Lyme disease involves a course of oral antibiotics.

Anaplasmosis and Ehrlichiosis

These two diseases have similar clinical signs and treatments. Anaplasmosis is transmitted by Ixodes scapularis (the black-legged tick), while ehrlichiosis is transmitted by the brown dog tick (representing 8.7% of ticks in Quebec).

Most dogs infected with one of these diseases develop mild signs that resolve on their own. Dogs that develop severe signs often have a co-infection. Symptoms of these diseases include: Fever, lethargy, loss of appetite, thrombocytopenia (low platelet count), anemia, musculoskeletal pain, with or without lameness. Treatment involves antibiotics (if there are changes in hematology) and symptomatic care to address appetite loss or discomfort associated with musculoskeletal pain.

How to protect my dog well?

It is important to understand that there is no 100% effective prevention method. By using a combination of techniques, we can maximize the chances of effectively protecting our dogs.

1. Always use ectoparasite prevention (for fleas and ticks).

2. Avoid areas known to be infested with ticks.

3. After every hike, pet and feel your dog to check for the presence of ticks.

4. If you frequently visit tick-infested areas with your dog, vaccination against Lyme disease provides additional protection (note: vaccination is not recommended as a first-line defense, as ticks transmit other diseases not covered by this vaccine).

To conclude, a study has shown that ticks found at the end of winter (December, January) and the beginning of spring (March, April) are more likely to be infected than those found in late autumn. Often, the months of October, November, and especially December are overlooked by dog owners, and some may skip these crucial months of prevention. Remember, ticks remain active as long as the temperature stays above 0°C, and even a thin layer of snow does not stop them. Soon, the recommendation may be to provide year-round prevention, and this should come as no surprise!

Myriam G., Technicienne en santé animale certifiée