Lyme disease in dogs | Dr. Justine Lee, DVM, DACVECC, DABT, Board-Certified Veterinary Specialist

Posted by justinelee in Animal Safety, Blog

Ah, Lyme disease. Not only is it the #1 mispronounced disease of the summer (it’s Lyme, not Lymes disease, folks!), but it’s probably the #1 misdiagnosed disease out there too. This Gram-negative spirochete (bacteria-like) organism Borrelia burgdorferi was originally discovered in Old Lyme, Connecticut in the mid-70s. Nowadays, over 90% of the cases of human Lyme disease come from Connecticut, Delaware, Massachusetts, Maryland, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island, and Wisconsin. Regardless of what state you live in, pay attention, as this disease can be devastating to your dog.

I know it’s the start of Autumn, but we’re not completely out of danger until your area has had a very hard, cold frost…

Thankfully, cats are rarely affected by Lyme disease. Why? It’s likely because they are such fastidious groomers that those ticks don’t have a chance of attacking on! That said, if your cat spends a lot of time outside, they need flea and tick medication too, as they can get some deadly tick infections too like Cytauxzoonosis.

So, what exactly is Lyme disease?
Lyme disease, an infection that causes shifting-leg lameness, arthritis, joint swelling, fever, platelet abnormalities, and rare heart arrhythmias, is usually transmitted by the Ixodes deer tick (Ixodes scapularis or I. pacificus). In severe cases, it can cause protein loss through the kidneys (called protein-losing nephropathy or “PLN” or “Lyme nephritis”), resulting in fatal kidney failure – this is particularly common in golden retrievers and Labradors.

What clinical signs can we see from Lyme disease?
The manifestation of Lyme disease varies between humans and dogs. The majority of humans do develop clinical signs and disease from Lyme. Clinical signs of acute illness include a erythema migrans rash (the “target” lesion rash) and flu-like signs. More chronic signs include arthritis, possible skin changes, neurologic signs (e.g., meningitis), and cardiac signs. The majority of dogs do not develop clinical signs (depending on the seroprevalence in your state). In dogs, three states of Lyme disease can be seen. With acute Lyme disease, dogs typically develop transient fever, lethargy, depression, hesitance to move, anorexia, pain, enlarged lymph nodes, and acute arthritis. Joints may be inflamed and warm to the touch. Sub-acute signs may also be seen, where lameness can last several weeks. While clinical arthritis may be transient, inflammatory changes to the synovial fluid may be ongoing and potentially persistent. Typically, lameness in dogs occurs months after tick exposure. Chronic signs include cardiac changes (e.g., a slow heart rate), neurologic signs, arthritis and changes related to Lyme nephritis (estimated to occur in 1-2% of dogs affected by Lyme disease).

Next week, I’ll talk about how to go about diagnosing Lyme disease – it’s more complicated than you think, and it’s important to know what a “positive” Lyme test really means. We’ll also focus on how – and if – we should be treating it.

Most importantly, how do I prevent my dog from getting Lyme disease?
When in doubt, prevention is the key. Prevention includes tick-picking with Tick Twisters, flea and tick medication, and even vaccination.

While tick-picking isn’t the most reliable way to stay Lyme free (as nymphs are as small as the head of a pencil), make sure to check your pet (and you!) carefully after a walk in the woods. Check the inside thighs, the ears, and the trunk of the belly, where these tiny ticks like to hide… and then do it again the next day – if a tick bites your dog, the tick will be big enough to find by then. Remember it takes about 24-48 hours for a tick to transmit Lyme disease, so you have a narrow window to find and pull those plump ticks off. Simply pull the tick off with a pair of tweezers as close to the base (skin) of the tick as you can.

While there is a Lyme vaccine available for dogs, I don’t typically vaccine for Lyme unless you live in one of the above mentioned states; you own a hunting dog; and you’re both off hiking in the woods frequently. If you live in a deer-free area, or aren’t in one of the aforementioned states before, then your dog doesn’t typically need the Lyme vaccine. Instead, use preventatives like monthly prescription-strength tick preventative (like Bravecto, Nexgard, Simparica, Advantix, Vectra, etc.). If you’re in a severely tick infested area, I also use these in conjunction with an additional prescription-strength tick collar (e.g., Preventic or Seresto too – especially if your dog is at high risk!

When in doubt, prevention is really important with Lyme disease. As I’m based out of Minnesota, and just picked two ticks off my dog yesterday, I often see the devastating and potentially fatal effects of PLN, and it’s not worth changing exposure to your dog.

References:
1. Littman MP, Goldstein RF, Labato MA, et al. ACVIM small animal consensus statement on Lyme disease in dogs: Diagnosis, treatment, and prevention. J Vet Intern Med 2006;20(2):422-34.

As previously posted on www.pethealthnetwork.com by Dr. Justine Lee.