Lyme disease

Lyme disease is caused by a bacteria known as Borrelia Burgdorferi that is transmitted mainly through a deer tick (Ixodes). This bacteria multiplies within the tick and penetrates the animal once the tick has finished its blood meal 36 to 72 hours after its attached itself to its host. At the bite’s site, the organism multiplies, then begins its migration through the tissues. The animal then becomes a carrier of the organism.

The disease can affect humans, dogs and cats, though cats serve mostly as vectors of the parasite and are rarely sick. The tick lives in temperate regions and the disease is more often reported between the months of may and November. The risks of a dog being bitten by a tick are higher if it roams in areas where vegetation is dense, although it is still possible for city dogs to be infested by ticks. As mentioned, Lyme disease can also affect humans, but they cannot acquire the infection directly from dogs.

In dogs, symptoms are apparent in only 5 to 10% of cases, and have a tendency of appearing two to five months after infection. We will observe limping with arthritis in one or its many joints, an increase of volume in the lymph nodes, despondency, as well as fever. These symptoms disappear in about 3 days. More severe symptoms also exist, though, they are less frequently associated to Lyme disease where the kidneys, the heart and nervous system are affected.


In order to reach a diagnosis of the disease, we will rely on the symptoms that the animal presents as well as serological tests that consist in verifying the presence of antibodies in the blood directed against the organism. Among the different serological tests that are available, the test that we use at L’Hopital Veterinaire de l’Est is the Snap 4DX from Idexx laboratories. This test detects the antibodies aimed against the “Lyme peptide C6”. This peptide is shown only when there is infection, which permits us to distinguish dogs that have been exposed “naturally” compared to dogs that have been exposed to the Lyme disease vaccine. Since this is a very reliable screening test, we can be reassured that the dog has never been exposed to the organism with a negative result.

In the case of a positive result, we recommend sending the animal’s blood to a laboratory so that we may have the precise number of antibodies that are present in its blood. This permits us to have basic values in which we will be able to compare subsequent results when following-up to treatment. When a diagnosis of infection has been made, it is also recommended that the presence of proteins in the urine be verified, which may indicated whether that the organism has reached the kidneys.


As far as treatment of the disease is concerned, we can ask ourselves the following question: must we treat all the dogs that are seropositive, even if they have no symptoms? The answer is clear for those with symptoms. The treatment consists of administering an antibiotic, Doxycycline being the medication of choice, for 4 to 6 weeks. For those without symptoms, we can wonder if it is worth spending money on treatment, especially when we consider that dogs may remain injected with a weak number of organisms having been treated or not. Though it has not been proven, it would seem that the treatment will result in the reduction in antibody titers much more quickly than if the dog had not been treated. For now, we recommend treatment for all dogs that have antibody titers of above a certain value and then evaluate the response to the treatment by rechecking the antibody levels 6 months later. If a dog carries infected ticks in its fur, it can infect its owner's immediate environment. Therefore, it is important to prevent this danger by removing any tick found on the animal and treating it preventively with the appropriate medication durant the warm season.


Prognosis is good only for dogs presenting arthritis and fever since, most respond well to antibiotics. On the other hand, the prognosis varies between guarded and poor, once the kidneys are affected.

Considering that it takes a certain amount of time for an infected tick to transmit the organism, its worth checking your dog everyday for tick infestation and to manually remove them as soon as you see them. The tick’s head is buried into the animal’s skin, its body and legs are free. The way in which to remove the tick is to apply constant tension on its body with a pair of tweezers. After a few minutes, the tick should release itself. Care must be taken as to not tear the tick and therefore leave the mandibules in the skin which may create a more or less local inflammatory reaction. It is important that gloves be worn when removing a tick to avoid human transmission.

Other means for preventing tick infestation includes the following measures; mow your lawn regulary, and use approved products for the control of ticks. At our hospital, Hopital Veterinaire de l’Est, we recommend using the product Revolution. It is a liquid that we apply onto the skin in the area of the neck and is absorbed and distributed throughout the body by the blood stream. The tick that ingests the blood dies within 48 to 72 hours. It is important to understand that although this product is effective in controlling tick population, it is not effective in preventing transmission of the disease since the tick may have transmitted the organism to its host before dying.

There exists a vaccine against Lyme disease. Up until now, its use was controversial because it could cause glomerulonephritis in predisposed individuals. However, according to a recent study in which the results have yet to be published, it would seem that there is no reason to worry when vaccinating a seronegative dog. As for vaccinating seropositive dogs, than vaccination may be potentially risky, especially if the antibody titer is very high and with a certain type of vaccine. Different protocols involving treatment before vaccination and then use of a vaccine expressed recombinant are presently being studied as to reduce risks related to the vaccination of seropositive dogs. At l’Hopital Veterinaire de l’Est, we recommend the vaccination of all dogs with the exception of those kept indoors at all times (or mostly), whether they be seropositive or seronegative. Indeed, even though seropositive dogs possess antibodies, it does not guarantee that their immune system is strong enough to prevent the disease. The risk of a super infection would be more damaging than the possible negative effects related to the vaccination. It is, however, important to remember that the control of the ticks is essential, because, a heavy load of the organism responsible for Lyme’s disease could exceed the vaccination’s protection.