If you live in certain areas of the U.S., it’s pretty likely that you know someone who’s contracted Lyme disease. While dogs are certainly susceptible to Lyme disease, only about 5%-10% of those infected develop symptoms of the disease.
So, should you worry about your dog getting Lyme disease? The answer is a resounding “YES!”. Why? Because even though Lyme disease doesn’t always make dogs sick, when it does, it can be serious, painful, and devastating.
Lyme disease, also known as borreliosis due to the fact that the organism that causes the infection is Borrelia burgdorferi, is transmitted to a dog when it is bitten by a certain species of tick. In the U.S., these ticks live mainly in the northeastern and central Atlantic states. Because ticks hatch in the spring, and because it’s the juvenile or “nymph” tick that typically feeds on dogs, now is a great time to brush up on your Lyme disease knowledge, starting with how to recognize that your dog might be ill.
Finding a tick on your dog
As mentioned above, only one general type of tick carries the bacteria that causes Lyme disease. It’s called the Ixodes tick, and unfortunately it has no distinct markings that would allow you to recognize it if you found one on your dog.
Research suggests that the infection is only transmitted into the dog after the tick has fed for some time, usually 48 hours or more. So a good routine to get into is checking your dog all over as thoroughly as possible for ticks once daily. Since most dogs love being caressed and handled by their owners, I’m sure your dog will welcome this type of attention.
If you find a tick, use a pair of tweezers to grasp it as close to the skin as possible, then gently tug until it comes loose. If the tick appears to be engorged and there’s concern for Lyme disease where you live, make an appointment to see your vet.
An even better strategy is to use a tick preventative regularly. There are a number of excellent products on the market, including Advantix and Frontline, that only require monthly dosing to keep ticks from attaching to your dog.
Fever
Lyme disease doesn’t produce any one specific clinical sign that you could point at and shout, “Look! It’s Lyme disease!”. But like many other diseases we treat, it produces a number of changes in a dog’s physical exam findings and test results that make us highly suspicious.
Most dogs with Lyme disease will have a slight fever. This is something that you can check at home by simply keeping a digital thermometer on hand (I recommend PROMINENT labeling to indicate that it’s dedicated to the dog) along with a bit of lubricant, such as baby oil. Put a little bit of lubricant on the end of the thermometer, press the activation button on the thermometer, lift your dog’s tail, and (gently!) insert the end of the thermometer into the dog’s rectum. You only have to get the thermometer in about one centimeter, but I do recommend having help in holding and distracting your dog, since they don’t usually find this procedure amusing. Normal Fahrenheit temperature for a dog is between 98.5 and 102.2 degrees. In Celcius that’s about 36 to 39 degrees.
Decreased appetite
Another non-specific sign. Lyme causes a general feeling of unwellness, similar to how you feel when you have the flu. Most dogs live to eat and love to eat, so eating less or refusing food completely should be cause for concern.
Swollen joints
This one is more subtle that the others, but it’s one of the more specific signs you’ll see with Lyme. Because the Borrelia organism has an affinity for connective tissue, after it enters the body at the site of the tick bite it migrates towards the cartilage that lines the joints, which is made of connective tissue. Because of this, often we’ll notice swelling in the joint nearest to the site of the tick bite. As the disease progresses, other joints will become swollen.
How exactly do you recognize a swollen joint? I always recommend that people be comfortable with what their dog’s body looks and feels like normally, so they can recognize when it’s abnormal. Swollen, inflamed joints look different from normal joints. When you press on them with a thumb or finger, you’ll likely notice that they are squishy, and that they “give” a little. They’ll also sometimes feel warm to the touch. It’s easier to recognize this temperature difference if you hold one apparently normal joint in one hand while holding the other in your other hand.
Lameness affecting more than one leg
Lameness that affects one leg, then another, is called “shifting leg” lameness. It’s confounding, because you’ll bring your dog in to see the vet being absolutely convinced that your dog has been lame on it’s right forelimb, only to find that he’s now favoring the right hindlimb instead.
When Lyme disease spreads throughout the system and attacks the cartilage in multiple joints it causes something called nonerosive polyarthritis. “Nonerosive” arthritis is different from the osteoarthritis that we’re used to talking about, that’s often a result of aging and joint damage. The cartilage isn’t wearing away in this disease, but the organism is causing severe inflammation within the joint. The term “polyarthritis” just means that more than one joint is affected, which you would expect to be the case with systemic infectious disease.
Enlarged lymph nodes
Just like many infectious diseases we deal with, Lyme disease can cause the lymph nodes to become enlarged. This is the result of the immune system gearing up to fight the invader, and as such the lymph nodes get bigger as they struggle to produce cells to fight the infection.
Know the location of your dog’s lymph nodes! They come in pairs, and routinely you aren’t able to feel them - they’re the size of a kidney bean. There’s one under each jaw, one in front of each shoulder, one in each armpit, one on each side of the groin, and one behind each knee.
“Bulls-eye” lesion on the skin
Something called erythema migrans is often seen on the skin of people who have been bitten by Ixodes ticks. It’s something of a bulls-eye type lesion. This can occasionally be seen in dogs, but not always. Certainly the presence of fur makes this an unreliable indicator anyways. Also, certain spider bites, such as those from the brown recluse, cause similar lesions as well.
Kidney failure
In its most deadly form Lyme disease causes something called Lyme nephropathy. This is an extremely serious form of the disease, resulting in severe kidney failure and usually involving massive protein loss from the body. These dogs are extremely sick, and often cannot be cured. Dogs that have been diagnosed with Lyme disease and recover should be monitored for the remainder of their lives for development of Lyme nephropathy. The first detectable sign is usually finding protein in the urine.