Hello again friends of GVH! Today we are going to talk about Lyme disease in dogs. At your dog’s annual exam, we have probably a) discussed and possibly recommended a lyme vaccine, b) given a lyme vaccine booster, and/or c) done an annual “heartworm and tick-borne diseases test” which is a blood test that checks for antibodies to heartworm, ehrlichia, anaplasma, and lyme disease. Also, being that we live in Connecticut, you have probably either been personally affected or know someone who has been personally affected by Lyme disease. But what are the risks to dogs? Is it worth giving them another vaccine? Why do we test every year, even in vaccinated dogs that are on a preventative?
Let’s start with the basics — Lyme disease is spread by ticks, mainly deer ticks. It was discovered in Lyme, Connecticut (hence the name “Lyme disease”) so here in Guilford we are a mere 30 minutes away from ground zero of lyme disease. Ticks live all over in this area – grassy yards, the woods, marshy areas – and are always looking for a warm body to get a blood meal from. When a tick bites a dog, after it has been attached for 24-48 hours it can transmit bacteria from the bite into a dog’s blood stream. The spiral shaped bacterium that causes Lyme disease is known as Borrelia Burgdorferi. The bacteria can spread via the bloodstream to other parts of the body. The immune reaction that the body mounts creates antibodies to the lyme disease bacterium, and as part of the immune response when they are first infected, some dogs will have a fever for a few days during the “acute” or initial phase of the infection. They might seem a bit off, not wanting to eat, lethargic or not wanting to play — usually this phase happens about 48 hours after a tick bite. Other more serious signs can be lameness in more than one leg that comes and goes (a “shifting leg lameness”) with no history of trauma, generalized stiffness, and swollen joints. These signs often happen during the “chronic” phase of the infection after it has been established in the body, and can happen on and off over the course of weeks or months. Dogs do not get the classic “bulls-eye” rash that people do.
It is important to remember that it takes the body a while to develop a significant level of antibodies to a disease, so sometimes a test can come up negative even when a dog has recently been infected with Lyme disease if it is just too early to detect antibodies in a dog’s blood stream.
If we determine that a dog has been exposed to lyme disease, we will often discuss whether or not to treat based on clinical symptoms taken in conjunction with antibody level and sometimes additional tests looking at urine. Why look at urine? In severe cases Lyme disease can cause serious kidney inflammation and damage called Lyme nephritis. It is thought that immune complexes from the immune response to lyme disease get lodged in the kidneys (which act as filters for the body) and cause dysfunction there. This type of kidney damage is irreversible, and too often, fatal. In rare but even more severe cases Lyme disease can cause neurological symptoms as well.
Treatment usually consists of about 30 days of antibiotics — doxycycline is the top choice, but there are alternatives if that antibiotic will not work for a particular dog. Sometimes one round of antibiotics will treat it, but other times it is more difficult to clear and several rounds or types of antibiotics are needed. We can also treat with anti-inflammatories if the joints are affected. However, rather than being reactive and risking joint or kidney damage, we would definitely recommend being proactive by using flea and tick preventative year-round and considering vaccinating against lyme disease. Why do both and keep testing? No preventative method is 100%, so we do not want to miss a case if it slips through the protective net — and maybe life happens and you forget to give the tick preventative one month, or maybe a pandemic happens and the annual vaccine appointment gets pushed off by a few months. Some people stop using preventatives during the wintertime, which we do not recommend — the winters are not quite as cold as they used to be, and since we seem to have days that get into the 40s even in January and February, the ticks don’t ever completely go away around here anymore. Also, if a dog has been infected once, it can get re-infected again — whether or not it has been treated for the first infection. The antibodies that a dog’s body makes are not protective. There are numerous different strains of lyme disease, and one theory is that the more times they are infected the more likely they are to have lasting joint and kidney damage.
Definitely talk to your veterinarian about options for flea and tick preventative — there are topicals, collars, and chew tablets out there, but not all are created equal in terms of efficacy. If you find a tick on your dog, remove it right away. And if you haven’t had a conversation about whether or not your dog is a good candidate for the lyme disease vaccine, now is a good time! Even dogs that are “mostly indoor” can be at risk in their backyard or if you bring a tick into your house on your clothing or person. If you have cats, good news — thus far it does not appear that Lyme disease occurs in cats. And remember, your dog cannot give you or any other people or dogs in your household Lyme disease: it must come directly from a tick bite. The bacterium needs that stage in the tick host to become infectious.
Here is some more information about lyme disease for anyone who is interested in some extra reading:
From the American Veterinary Medical Association:
From the Centers of Disease Control and Prevention:
From the Companion Animal Parasite Council:
Lyme disease prevalence map:
Please give us a call if you think that your dog may have been exposed to lyme disease, you want to talk about preventatives, or you have any other concerns!
— Dr. Dana Muir