Fall Alert: Lyme Disease in Dogs

Steven A. Levy, VMD is president of Veterinary Clinical and Consulting Services, LLC. He is a globally known, highly respected researcher & educator and is considered the premier expert on Canine Lyme Borreliosis. He holds numerous professional memberships and has received countless industry awards recognizing his expertise, his cutting-edge research and his leadership contributions to the veterinary community and beyond. As fall is known as the “second season” for ticks, in this special column, goodnewsforpets gets the inside story from Dr. Levy about this important disease that affects both dogs and humans.

1. How long has Lyme disease been around? Is it still an East Coast disease?

Lyme disease was first reported as a dermatologic lesion in humans in the late 1800s in a Scandinavian medical journal so it’s been around a long time. The Lyme arthritis outbreak in Old Lyme, Connecticut that put Lyme disease on the cover of Time Magazine occurred in 1975. The first cases of canine Lyme were recognized in the 1980s.

Lyme disease was probably never an exclusively East Coast disease; it was just recognized here as a distinct clinical entity. The first US report of Lyme in a human was actually from Wisconsin in the 1960s but this involved the skin lesion, erythema migrans, and never got the attention that the serious Lyme arthritis syndrome received. Lyme in man and dogs is now widely recognized from Virginia north to Canada. It is found in states to the west of the eastern coastal states and is as common in Minnesota and Wisconsin as it is in Connecticut. On the west coast Lyme risk areas run from San Francisco north to British Columbia. In my travels to teach my colleagues about canine Lyme disease I have met with veterinarians who are seeing positive Lyme tests and cases in dogs in Illinois, Iowa, Indiana, Michigan, West Virginia, and Ohio.

2. Is there anything “new” about the disease and/or its treatment and prevention?

There is always something new about Lyme disease and the etiologic organism Borrelia burgdorferi (Bb). One of the hallmark “new” findings about Bb was presented in 1994 when the organism was shown to be able to change its outer surface proteins as a survival mechanism as it transitions through the very different environments in the free-living tick vectors (Ixodes scapularis and Ixodes pacificus) and the mammalian host. From a clinical standpoint the data we presented in the 1993 Compendium on Continuing Education paper still hold-up when describing canine Lyme arthritis, the rare cardiac syndrome, and the deadly nephritis associated with Bb. Treatment is still focused on antibiotic therapy in dogs with clinical episodes. What is new are findings that treating Lyme infected dogs with antibiotics before they have clinical signs of disease can be very effective, especially when coupled with vaccination. We know that antibiotics kill Bb and we know that vaccination can prevent new infection. I have treated and safely vaccinated thousands of cases of Bb infected dogs and observed these dogs to remain free of clinical signs for years.

There is nothing new about the notion that immunizing dogs at risk of an infected tick bite before they are exposed to ticks is the best strategy. We made this recommendation in our first paper demonstrating Lyme vaccine safety and efficacy in 1993 and it still holds. What I find challenging is that veterinarians in areas of Lyme expansion need to learn this lesson through personal experience. By the time vaccination becomes a common practice dogs in many expansion areas are already showing significant rates of infection. This trend of personal experience, by the way, is not just a veterinary trend. Physicians also are reluctant to recognize the threat nor presence of Lyme disease in their patients. Physicians, however, do not even have the option of vaccinating their patients since the human vaccine was removed from the market just 2 years after it was released.

3. Can you tell us how you became interested in specializing in this disease?

Human Lyme arthritis was first characterized in Old Lyme, Connecticut in 1975 and published by Allen Steere, MD and colleagues in 1977. I arrived in Connecticut, just about 20 miles away from Old Lyme, in June of 1977. In the early 1980s I became active in Lyme disease public health education and was a regular attendee at Lyme meetings at the Connecticut Agriculture Experiment Station (CAES) in New Haven where I met Dr. Steere and pathologist Paul Duray, MD. CAES scientists Dr. Lou Magnarelli and Dr. John Anderson were studying the basic immunology and life cycle of the organism.

In 1986 I had an emergency visit with a German Shepherd dog that was experiencing syncopal episodes related to complete heart block. I was aware of the human syndrome involving heart block in Lyme carditis and made the association. I started the dog on antibiotics but the owners declined pacemaker implantation. I shared the clinical presentation and ECG of this dog with Drs. Steere, Magnarelli, and Anderson at one of the CAES meetings. My patient only survived for 6 weeks without a pacemaker. After humane euthanasia the owners allowed me to perform a necropsy. I took tissues to Magnarelli and Anderson for an attempt to culture Bb and they passed the tissue to Paul Duray who demonstrated spirochetes in the cardiac tissue. Paul had done many catheter biopsies and one autopsy on human Lyme carditis patients and he suggested we publish the case. When our paper appeared in the summer 1988 issue of the Journal of Veterinary Internal Medicine veterinarians started calling me to discuss Lyme cases and researchers were asking for data and serum samples to integrate into their ongoing studies. That was it for me! I had wanted to do clinical research since I was in vet school and I jumped at the opportunity for collaborative research. One of the byproducts of the collaborations was free laboratory testing for my patients. I began to collect clinical data and correlate it with laboratory data and soon published more peer-reviewed studies.

4. How does a dog get Lyme disease?

A dog gets Lyme disease the same way any susceptible animal or human gets it, from the bite of an infected vector tick.

5. Can a cat or other pets get Lyme disease?

I believe that cats can get Lyme disease but there is no laboratory model for the disease in the cat. Cats are often presented for fever and lameness, the hallmark signs in Lyme arthritis, but the differential diagnosis for these signs includes bite wounds. Bb infection is treated with amoxicillin or amoxicillin clavuronate and these are the common antibiotics used to treat bite wounds. I often say that Lyme disease in cats is a deficiency of amoxicillin. I think we sometimes treat feline Lyme arthritis without a definitive diagnosis.

Horses are certainly susceptible to infection by Bb and many veterinarians in Lyme areas diagnose and treat the disease in horses. While it is essential to note that being infected with Bb does not mean an individual has Lyme disease it is possible to use the SNAP 3 and 4Dx tests for dogs to detect infection in cats and horses. I published a paper in Veterinary Therapeutics in 2003 using the dog kit for cats and a similar study was published in for horses in 2008. It is important to repeat that a positive test indicates infection but a diagnosis of disease in any species is based on the paradigm of clinical signs, rule-outs, supportive laboratory data, and epidemiologic evidence of exposure as we presented in the 1993 Compendium paper.

6. Can a person get Lyme disease from their dog?

No. Lyme disease is only transmitted by the bite of an infected tick. This is part of the CDC case definition for human Lyme disease.

7. What are the best prevention methods for a dog and his or her owner?

Lyme is an essentially preventable (and thus eradicable) disease through proper vaccination. Vaccinating dogs before an infected tick bite can prevent infection and thus prevent disease. In my large clinical study examining the effect of antibiotic therapy and vaccination on asymptomatic Lyme positive dogs I observed the absence of clinical episodes in these dogs for up to 5 years of follow-up before I sold my practice in Durham and lost contact with these patients. Data from many of these dogs was published in the 2008 paper in Clinical Vaccine Immunology. There is a large body of research that demonstrates that antibiotic therapy kills Bb but there is also a large body of research that demonstrates that the infection is chronic. Combining antibiotic therapy and immunization has been very successful as a strategy for managing Lyme positive dogs.

8. What are the symptoms a pet owner should look for if they suspect their pet has Lyme disease?

Pet owners should seek the assistance of their veterinarian anytime a pet is acting ill. It is the owner’s job to recognize that there pet is not right and it is our job to diagnose and treat the pet. Lyme arthritis is typified by lethargy, fever, inappetence, lameness, severe pain and lymphadenomegaly. Dogs with Lyme carditis have heart block. Renal Lyme disease causes azotemia, hyperphosphatemia, hypoalbunemia and often protein loosing nephropathy in dogs with typical signs of renal failure. Personally, I am not sure that dogs have a clearly defined neurologic syndrome.

9. Are there certain “seasons” that ticks carry the disease?

Lyme infected ticks are found throughout the year. August is often a quiet month for Ixodes scapularis. On the west coast Ixodes pacificus is active in the cooler months. Ixodes scapularis has a 2-year life cycle. The adult stage likes to feed on dogs and we see a spike in adult feeding activity in the fall when the nymphs moult to adults and again in the spring when unfed adults that persisted through the winter are again host seeking. Ixodes scapularis “likes” places that have a cold season. Tick collections in the winter on days with temperatures above freezing can be high yield. It is interesting to note that a new study examining Ixodes scapularis infected with Anaplasma phagocytophilum found the ticks are protected from freezing by a glycol secreted by the Anaplasma. Ixodes scapularis and pacificus are often coinfected with both Bb and Analpasma phagocytophilum.

10. Where can a pet owner go for more information?

It is so easy to just say search the internet but the internet is a dangerous place. There are so many sites with opinions unsupported by scientific data that a pet owner is as likely to get bad advice as good. Even veterinarians may be working with notions that are out of date or unfounded. I always refer veterinarians to the primary literature to read the original studies but we cannot do this with most clients.

I think it is the veterinarian’s job to read the literature and develop a protocol for dealing with Lyme prevention, treatment, and management of infected dogs. The veterinarian may then use his information to educate clients.

Bio of Steven A. Levy

The information contained in this column does not constitute medical advice and the accuracy is not guaranteed. It is provided for general information purposes. Professional and media contacts requesting further information may contact Dr. Levy at [email protected]. As Dr. Levy is not able to respond to specific medical questions from pet owners, he encourages all pet owners to seek medical advice for their pet from their own veterinarian.

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