Dogs and Ticks


By John Andersen, DVM

“Claude” is a six-year-old Labrador mix from Crozet. He hit the jackpot when he was adopted from the SPCA into a loving family who spoils him and takes him hiking regularly. One Saturday morning, I got a call from Claude’s mom:

“Claude is really sick. We noticed he wasn’t quite right a few days ago, he was a little sore on one of his front legs and didn’t eat well that night, but we had gone on a long hike and I thought he just overdid it a bit. But yesterday he seemed stiff all over and refused dinner, which is totally unusual. Now this morning he won’t even get up and he just looks like he’s dying.”

I had them bring Claude in right away. We had to bring out a stretcher to get him into the hospital because he wouldn’t even stand up. His left front leg was swollen, his temperature was 104.2 and he just felt terrible, totally “un-Claude.” As it turned out, Claude was suffering from Lyme disease and was feeling great a few days later.

Actually, I was quite suspicious of Lyme disease as soon as I got off the phone with his owner, mainly because we now see it so frequently, and this is the classic presentation. Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted to dogs and people via the bite of an infected tick. The disease gains its name from the town of Lyme, Connecticut, where it was first diagnosed in 1975. Lyme disease is now the fastest spreading infectious disease in the U.S. and has certainly established itself here in central Virginia. In the U.S., Lyme disease is transmitted almost exclusively by blacklegged/deer ticks. And if you’re not up on your tick life cycles, it’s important to know that it’s in the nymph stage ticks that are most likely to bite and transmit Lyme disease. During this stage of their life cycle, ticks measure about 1/16th of an inch! Try finding that on your Black Lab!

Interestingly, 90 percent of dogs who are exposed to Lyme disease through a tick bite will not get sick. Their body’s immune system will naturally fight off an infection. In the 10 percent that do get sick, the majority will present just like Claude with fever, lethargy, and aching joints/lameness. These signs often develop over just one or two days and can become quite severe. As sick as they are, most dogs respond rapidly to a course of antibiotics. They are often dramatically improved in 24 to 48 hours.

Diagnosing Lyme disease often proves difficult in both people and pets and ultimately becomes a judgment call based on history, clinical signs, and lab tests. Most veterinary hospitals have a quick in-house blood test available (which, incidentally, is a combination test with the heartworm test), which is very sensitive at detecting antibodies to Lyme disease. This test often causes confusion however, because being “positive for Lyme disease” does not mean your dog actually has Lyme disease.

Uh … what?

Well, when your dog is “positive for Lyme disease,” it means that your dog was naturally exposed to Lyme disease via a tick bite. His immune system was exposed and made antibodies that will persist in his bloodstream for years. Remember, 90 percent of dogs who are exposed do not ever develop illness. But they will have a positive antibody test.

It has now become prudent protocol in otherwise healthy dogs who have a positive antibody to simply discuss Lyme disease signs, tick prevention, and simply do nothing. And of the 10 percent who do become ill, 90 percent of those will respond rapidly and completely to a simple course of antibiotics. But there is just no way to know which dogs who have antibodies actually have the Lyme organism hiding in their body, waiting to cause illness in a few weeks or months. So again, it’s a judgment call. So far this spring, I’ve been seeing and treating about one or two dogs sick with Lyme disease per week, which is much more than just five years ago.

How can you prevent Lyme disease from becoming a problem with your dog? It’s all about tick control. Products like Frontline and Advantix are great. They kill ticks, but only after they’ve attached. Hopefully the tick dies before it has had time to transmit the disease. But at day 28 of a once-monthly treatment, things can happen. There’s really nothing better than just doing a tick check after you’ve been out in the woods, both on your dog and your kids and yourself. If your dog has had Lyme exposure, there are Lyme-infected ticks where you’ve been, too, and you should always call your doctor if you suspect a family member is showing any signs of Lyme disease.

So, although it should garner a bit more fear than the Crozet Cougar, don’t stop going into the woods or going on walks for fear of Lyme Disease. Just put the Frontline on your dog, do a good tick check, and happy romping!

Contact Dr. Andersen at cvillevet at