Tuesday, September 28, 2010

Lyme Is Lame (Pun Intended)

by Lorie Huston, DVM

Lyme disease is a tick-borne disease that affects both dogs and people. Though you cannot get Lyme disease directly from your dog, you can get Lyme disease from the same ticks that transmit the disease to your dog. This fact makes Lyme disease an important disease for both of you.

Deer tick. Photo Today's Homeowner.
 What is Lyme Disease?
    
Lyme disease is passed to you or to your dog by the bite of an infected tick. The disease itself is caused by a bacteria known as Borrelia burgdorferi. Lyme disease is more common in some geographical areas than in others. Your veterinarian should be able to tell you how prevalent Lyme disease is in your area.
    
What are the Symptoms of Lyme Disease in Dogs?
    
Lyme disease in dogs is entirely different in its presentation compared to Lyme disease in people. The most common symptom of Lyme disease in dogs is lameness and joint pain. This lameness may shift from one leg to another. Fever may also be seen.
    
A more serious form of Lyme disease involves glomerular damage, a form of kidney disease. This form of Lyme disease can become life-threatening and is much more dangerous for your dog. This form of Lyme disease is believed to be an immunologic reaction to the long-term presence of the Borrelia organism.
    
In dogs, the heart problems (arrhythmias) and neurologic symptoms that are seen in some people occur very rarely.
    
How is Lyme Disease Diagnosed in Dogs?
    
There are readily available blood tests that can detect antibodies to the Borrelia burgdorferi organism. The most commonly used test is the C6 peptide test (also known as the SNAP3DX or the SNAP4DX test, though these specific tests also check for other tick-borne diseases as well.) The C6 peptide is part of a protein on the outer surface of the organism (the protein is known as an Osp).
    
Borrelia burgdorferi can express various Osps depending on where the organism is attached. For instance, if the organism is attached to the midgut of a tick, the Osp expressed is different than that expressed if the organism is attached to the connective tissue of a mammal. The Osp can also change depending on the stage of infection in mammals. However, the C6 peptide remains present regardless of the Osp being expressed. As a result, it is almost always detectable, unlike antibodies to the individual Osps. In addition, the C6 peptide is not part of the vaccinations available against Lyme disease and vaccination will not result in a positive Lyme disease test.
    
The confusion about Lyme disease and its diagnosis arises from the fact that many dogs have positive tests without being sick. In the Northeastern United States, it is estimated that as many as 90% of dogs have antibodies to Lyme disease and thus have positive Lyme disease tests. However, very few dogs actually develop symptoms of disease. Further, antibodies can persist in the blood stream for years. This makes it difficult to distinquish an active infection from one that is inactive and not currently causing disease. It also creates a quandary in deciding whether to treat the dog or not.
    
Treatment for Lyme Disease in Dogs
    
If your dog is showing signs of Lyme disease, there is no doubt that he should be treated. Lyme disease normally responds very well to treatment with antibiotics. The most commonly used is doxycycline, but other antibiotics such as the penicillins are also effective.
    
If your dog is suffering from the glomerular (kidney) form of the disease, he will likely need much more aggressive treatment aimed specifically at treating the kidney disease, in addition to antibiotics. This form of Lyme disease carries a much more guarded prognosis than the more commonly seen lameness with or without fever.
    
The confusion regarding treatment arises when a dog tests positive for Lyme disease without showing any signs of disease. Some veterinarians recommend treating with a course of antibiotics in this situation. However, when treating Lyme disease in dogs, it is not reasonable to expect to clear the organism from the dog's body. The Lyme disease organism has an uncanny knack for hiding, even from the immune system of the dog, because of its ability to change its Osp proteins. In addition, tests can remain positive for years even in inactive infections. As a result, the treatment of healthy dogs with positive Lyme disease tests is controversial. It is unknown at the current time whether treatment actually reduces the chance of the organism causing disease and more research is needed in this area before a definitive answer to this question can be formulated.
    
If your dog tests positive for Lyme disease but is clinically healthy, it is important to monitor proteins in the urine regardless of whether you and your veterinarian elect to treat your dog for Lyme disease. Protein leaking through the glomeruli and into the urine is one of the early indicators of impending kidney disease and will be detectable before clinical signs appear. (Glomeruli are part of the filtering apparatus of the kidneys.)

Prevention of Lyme Disease

The most effective way to prevent Lyme disease is to prevent your dog from getting ticks. Here are some of the ways that you can do that.
  • Avoid taking your dog into tick infected areas.
  • Check your dog regularly for ticks and remove them promptly when you find them.
  • Consider using a monthly topical medication to prevent ticks.
There are vaccinations available against Lyme disease and your veterinarian may recommend that your dog be vaccinated if he is at risk. However, vaccination against Lyme disease remains controversial and not all veterinarians recommend its use. Vaccination against Lyme disease does not preclude the need to prevent ticks because there are many other tick-borne diseases that are even more dangerous for your dog than Lyme disease and the vaccine does not prevent those diseases.

***

Lorie Huston has been practicing veterinary medicine for over 20 years. Besides a successful career in a busy small animal hospital in Providence, RI, Lorie is also a successful freelance writer specializing in pet care and pet health topics. Currently, she is the feature writer for the Pet Care section at Suite101.com and the National Pet Health Examiner at Examiner.com. Lorie also publishes her own blog, The Pet Health Care Gazette and manages an increasingly popular facebook page, The Voice of Pet Care. In addition, she co-moderates DogTalk, a weekly twitter chat that focuses on a variety of dog topics.

6 comments

  1. Something I have found effective at deterring ticks is 'Tick Tubes' (www.ticktubes.com). They are biodegradable tubes filled with permethrin-treated cotton which you place around your property every few yards. The contents attract mice, (which are one of the main hosts of the ticks), who use the cotton as bedding thereby ridding themselves of ticks. I use them as well as topical applications on my dog, and feel I have done pretty much all I can to protect her.

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  2. Interesting, I will look into that.

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  3. Around here, our vet all but strongarms us into getting a vaccine against Lyme disease. What is better, do you think? Topical, vaccine, prevention/detection/treatment?

    I think we're going with the vaccine. It gets bad here in the summer sometimes. Too high risk - and topical has been known to have little effect. Have you ever heard of that? I hear of a lot of people who use it and their dogs get ticks anyway. Are they doing something wrong? Or is something else going on?

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  4. Hi JJ. It is my understanding that the vaccine isn't "fool-proof" but does help. I think the decision depends on the amount of exposure and amount of infestation in your area.

    Also I understand that if removed within 2 hours from attachment the tick no disease transmission occurs.

    We don't have many ticks here and up north Lyme has not been reported, so we are just keeping this at the back of our minds.

    How many ticks do you guys have where you are?

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  5. As a vet in an area where we Lyme disease is a huge problem (NE PA, Poconos Mtns), I have vaccinated thousands of dogs for lyme disease.

    The vaccine certainly has it's flaws, and necessity really must be evaluated dog by dog. I have seen more reactions to this vaccine than any other unfortunately (no deaths). Still, I have never had a patient that was vaccinated test positive. I know it happens, but I haven't seen it.

    For that main reason, I usually do recommend it, but not always. I do like administer complimentary diphenhydramine injections to decrease the chance of a reaction. That has worked well for me.

    It can be such a frustrating disease to treat. Can't wait until we learn more! Thanks for a wonderfully thorough article Dr. Hutson!

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  6. Dear Dr. Laci

    Is it not true that infection happens only if the tick remains attached for longer or two hours or so? If removed properly in timely manner it should substantially decrease the risk?

    Read that so wondering.

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