Lyme Disease in Dogs: The Feared Canine Disease that's Mostly Benign

Listen as Dr. Becker discusses how to recognize the symptoms of Lyme disease, how to effectively treat them, and your own dog's chances of getting sick with a Lyme infection.
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By Dr. Becker

Last year over 20,000 people in this country were diagnosed with Lyme disease, making it the most common vector-borne disease in the U.S. A vector-borne disease is one that is transmitted to humans or other animals by an insect or other arthropod.

Dogs acquire the condition as well, but because there’s no central reporting agency for pet diseases, we don’t know exactly how many dogs are infected annually.

What we do know is canine Lyme disease diagnoses are on the rise.

But there is debate in the veterinary community as to the real extent of the problem. How many dogs are truly infected?

In other words, how many are harboring the disease and will become symptomatic vs. the number that are simply seropositive. If a dog is seropositive for Lyme disease , it means he’s been exposed, but has effectively cleared it from his system.

The Beagle Experiment

In study conducted at the University of Pennsylvania a few years ago on Lyme disease in canines, beagles were experimentally infected with the disease. None of the adult dogs got sick and in fact, not one showed a single symptom of the disease.

Beagle puppies in the same study showed about four days of transient symptoms of infection such as fever and lameness.

After four days of on-and-off symptoms, the pups became asymptomatic, which means their bodies cleared the infection without help and they were fine.

The incubation of the disease in this study was from two to five months. In other words, after being infected, it took the puppies from two to five months to develop their mild, transient symptoms of fever and lameness which lasted a few days. Their bodies were able to clear those symptoms quickly and completely.

The adult dogs never exhibited any signs of Lyme infection – no rash, no flu symptoms, no cardiac or neurologic issues – which is quite interesting.

Beagle Study Results Are No Fluke

The results of the beagle study correlate closely to what veterinarians are finding in the field among their canine patients.

About 95 percent of dogs that test positive for Lyme disease are coming out of just 12 states. These are states in which Lyme disease is endemic (pervasive) – states with heavy infestations of deer ticks, also known as Ixodes ticks or black-legged ticks. All are names for the same bug -- the tick that transmits Lyme disease.

There are certainly more cases of Lyme disease than in just those 12 states, but in areas where the disease is rare dogs are not routinely tested for it unless they are symptomatic.

In Lyme-endemic areas of the country, veterinarians test regularly for the disease even in healthy dogs. And what they are finding is that a large percentage of dogs are seropositive, meaning they have the Lyme-related antibodies in their blood from exposure to the disease. However, they have no clinical symptoms of infection.

According to Meryl P. Littman, VMD, Dipl. ACVIM, at the University of Pennsylvania’s School of Veterinary Medicine, canine exposure to Lyme disease is common, but the disease is not:

“Ninety-five percent of exposed dogs don’t get sick, but they become Lyme antibody-positive on tests, which may scare people into thinking they need to be treated,” she says. “We don’t treat asymptomatic dogs, but we check their urine for protein. In some areas in New England, 70 to 90 percent of healthy dogs are Lyme-positive. At PennVet, we found about 40 percent of healthy dogs are Lyme-positive in our area.”

Again, these are not sick dogs but dogs that have been exposed to the disease.

It’s clear from these statistics the immune systems of seropositive dogs have identified the Lyme disease pathogen and mounted an appropriate, effective response. So even though they test positive, they do not become sick with the disease.

Minor Symptoms, Effective Treatment

Only about five percent of dogs exposed to Lyme disease actually develop symptoms of the infection, including:

  • Fever
  • Lameness
  • Lethargy
  • Malaise
  • Shifting joint pain

These symptoms are quite successfully treated with the antibiotic doxycycline.

It’s also important to note that dogs that are positive for Lyme disease cannot infect humans. Infections in both people and their pets are transmitted only by the bite of an infected tick.

What About My Dog?

We’ve established that 95 percent of dogs exposed to Lyme disease never get sick from it. These dogs will, however, test positive for years down the road.

Hopefully your dog, if infected, will fall into that large group.

But if your pup winds up one of the five percent that becomes ill with Lyme symptoms, I recommend you have your vet run a SNAP-4Dx blood test. Dogs that test positive for Lyme disease with the 4Dx test are typically symptomatic. This test actually detects multiple vector-borne diseases, not just Lyme disease, so it can be useful to rule in or rule out certain other types of bacteria and parasites as well.

Your vet may also do a urinalysis to find out if your dog is excreting protein in her urine.

If the doctor determines your pet’s symptoms are indeed from a Lyme infection, treatment with the antibiotic doxycycline should be instituted.

In a very small percentage of dogs with active Lyme infection – much smaller than the five percent that show symptoms – chronic Lyme disease can result in significant kidney problems and also autoimmune polyarthritis. The latter is a type of joint degeneration secondary to an undiagnosed, untreated Lyme infection.

If you suspect your pet has symptoms of Lyme disease, it’s important to have him seen by a veterinarian.

Are Cats at Risk for Lyme Disease?

According to the experts, lyme disease in cats is rare.

If you live in a tick-infested region and are concerned about ticks on your cat, it’s important to check her for ticks just as you would a dog (see below).

Many tick repellents are toxic to kitties, so if you feel the need to protect your cat from ticks, talk with your veterinarian to determine what products are safe for her.

Lyme Disease Prevention Tips

  • In the spring, summer and fall, avoid tick-infested areas.
  • If you live where Lyme disease is endemic or you inadvertently wind up in a tick-infested area, check your pup for ticks twice each day. Look over his entire body, including hidden crevices like those in the ear, underneath his collar, in the webs of his feet, and underneath his tail.
  • Use a tick repellant. There are natural anti-tick products on the market, however, in Lyme endemic regions of the U.S., many veterinarians will recommend you use a chemical repellent. It’s important you investigate the risks and benefits of any medication before you give it to your pet, as most have side effects.
  • There is a vaccine available for Lyme disease, but I don’t recommend it for a couple of reasons.
    1. This vaccine is known to send the canine immune system into overdrive, triggering a number of serious secondary reactions including autoimmune disease.
    2. Many pet owners believe the vaccine will prevent ticks from attaching to their dog. This isn’t the case – you will still need to apply a topical tick repellent to your pet.

    For dog owners who have their pets vaccinated for Lyme disease and use chemical repellents, it means a double dose of toxins for the animal, which of course means two potential triggers for toxicosis, a disease condition due to poisoning.

    For this reason, more and more veterinarians are recommending that dog owners skip the vaccine and use only topical anti-tick products to prevent ticks from attaching to your pet.

  • One of the most important things you can do to keep your pet safe is to create strong vitality in him by feeding a species-appropriate diet.
  • Parasites are attracted to weaker animals. By enhancing your pet’s vitality, you can help him avoid the ill effects of a Lyme infection or any other opportunistic pathogen he comes in contact with.

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