All About Lyme Disease In Your Dog
What To Do When Your Dog Tests Positive
Ron Hines DVM PhD
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What Is Lyme Disease ?
This bacteria is transmitted by certain ticks. Borrelia belong to a family of bacteria called spirochetes. They are not particular as to the species they attack.
Borrelia burgdorferi has always been around – we just didn’t pay much attention to it until recently. It has been called Lyme disease ever since 1975, when an astute doctor recognized it in a cluster of children near the town of Lyme, Connecticut. (ref)
Much of the information on the web concerns Lyme disease in people and many pet owners reading it online, equate the information to their dogs. However, Lyme disease will not affect your dog in the same way it affects people. People often develop a rash at the point where the tick attached as well as flu-like symptoms. In dogs the most common symptoms are joint pain and fever that usually do not start until 2-5 months after being bitten. A few dogs develop swollen lymph nodes and very, very few ever develop the heart and neurological problems seen in Lyme disease in humans. When lyme-positive dogs develop kidney problems, it is late in the disease process.
Lyme disease is a perplexing condition because it can present itself in so many different ways. No two cases are alike and the wide variety of symptoms that Lyme can produce can be confused with many other dog diseases. Because if this, it is sometimes called the Great Pretender. The fact that Borrelia usually produces no immediate symptoms at all in most dogs, makes the situation even more confusing.
In the United States, more than 90% of the Lyme cases occur in the Northeast and North Central states. Northwestern California and Mississippi also see a large number of positive dogs.
How Did My Dog Catch Lyme ?
Your dog was almost certainly bitten some time ago by a tick that carried Lyme organisms. We call these particular ticks deer ticks – but they feeds on many other types of animals. It is a small tick and it can be easily overlooked.
At a previous stage in its life, that tick sucked blood from a deer mouse. These have nothing to do with deer. They are the cute little mice you see that can zip up trees. That mouse was itself carrying Borrelia and passed it on to the tick. When that tick later fed on your pet, it passed the Borrelia on to your dog. We think it takes a day or two on your dog for the tick to inject its Borrelia cargo as it sucks blood.
What Are The Symptoms Of Lyme Disease In My Dog ?
The majority of dogs that are infected with Lyme disease show no symptoms at all. Most of these dogs are identified through routine yearly testing at veterinary hospitals. We do not know why some dogs are affected with symptoms and others are not. In some animal species, the age at which they are infected has a lot to do with the development of symptoms - younger animals were affected more severely than more mature ones. (ref)
However, a small portion of infected dogs do develop sore, painful joints weeks or months after infection. Some of these dogs run low-grade fevers. The signs you read about in humans with Lyme almost never occur in pets.
Simple arthritis is usually constant in the joints it affects. But lameness due to Lyme disease often shifts from leg to leg. These swollen joints are usually hot and painful and occasionally the lymph nodes at the base of the legs may be slightly enlarged as well.
The front leg are most commonly affected. When they are, it is the lymph node on the shoulder of that leg that may be enlarged. Many of the sick dogs are depressed. They may yelp when these joints are pressed and be quite reluctant to walk. When they do walk, they walk with a stiff shuffling gait and an arched back because of the pain.
Ticks may still be present on your pet to bring Lyme Disease to mind.
In longstanding cases, destructive chronic inflammation can occur in your pets heart, kidneys and nervous system.
Your Pet’s Kidneys In Lyme Disease
Although it appears that most dogs live in relative tranquility with the Lyme organism, the kidneys of some Lyme-positive dogs appear to suffer. Lyme organisms contain proteins that cause your pet’s immune system to produce antibody molecules in large number. Although these antibodies are not very effective in killing off the Borrelia, they are large enough to become trapped in the filtering mechanism of your pet’s kidneys. There they can stimulate destructive changes called immune complex glomerulonephritis. This disease slowly destroys the blood-cleansing ability of the kidneys.
Because this occasionally occurs in dogs that are chronic carriers of Lyme, many veterinarians suggest that lyme-positive pets have yearly tests that detect early signs of kidney failure. The test most commonly performed is a urine protein/creatinine ratio or the more sensitive E.R.D. test
Is This An Autoimmune Disease ?
Some of the symptoms and pathological changes associated with Lyme disease are very similar to those found in autoimmune disease. In autoimmune disease, an invading bacteria can be the trigger – but the damage is caused by the body’s own immune system turning on itself. What we know about this regarding Lyme we know from studies designed to help humans.
These studies indicate that once the immune system is alerted to the presence of Lyme organisms, it produces cells and antibodies that attack normal tissues of the body as well as the Borrelia. This may explain the cause of joint inflammation seen in long standing cases of Lyme. (ref)
However, your pet’s immune system may not be chasing phantom objects as it does in autoimmune disease. Other studies have show that Lyme organisms are extremely clever at hanging around and avoiding detection. (ref)
Is Lyme Disease Becoming More Common ?
Lifestyle changes have brought Borrelia-carrying ticks closer into our home environments. Suburban residents are more likely to feed wildlife than they once were and these deer and other urban wildlife bring disease-carrying ticks close to home. Some authorities have even suggested that indoor house cats and fat pampered felines are less likely to keep wild mice populations down.
But increased availability of rapid tests that your veterinarian can perform in the office are certainly responsible for much of the increase in Lyme disease diagnosis.
Heightened public and veterinary awareness of Lyme also accounts for some of the increase in diagnoses.
Lyme disease is not a problem in all parts of the United States.
Dog, with tick exposure, in the Northeast are most at risk. Those
in Northern California are also at moderate risk, depending on their
life style and tick exposure. A belt of cases also meanders down
the Mississippi river drainage.
The CDC might be slow in recognizing the presence of lyme in some areas of the United States. For example, looking at their 2012 map, one might think that the risk of exposure to the lyme organism in Texas, my home, is quite low. However, a quarter of Texas deer ticks collected in a recently study apparently carried the lyme bacteria. (ref) The data I have access to is quite preliminary and needs to be confirmed. Perhaps other factors here in the Southwestern United States influence infection rates in humans and dogs besides the simple presence of infected ticks; or perhaps, veterinarians and physicians here just aren't looking out for it as much. It's just too early to judge the significance of this recent study.
How Will My Veterinarian Check For Lyme Disease ?
most commonly used check for Lyme disease in your pet is the Idexx
There has been some recent criticism of the accuracy of the current tests available to you veterinarian - in certain instances, the tests apparently miss positive dogs and report uninfected dogs as positive. (ref)
Do not panic if your veterinarian says your dog is positive for Lyme disease. In 2007, almost two dogs in ten in the Connecticut area had positive test results. In addition, previous Lyme disease vaccinations you pet may have received or exposure to other, similar organisms sometimes give false positives for Lyme disease.
If your pet tests positive for Lyme on the 3Dx test – particularly if it has health issues - you need to have a second test performed.
This second test looks for the amount of antibodies your pet produces against a particular component protein on the surface of the Borrelia bacteria. At the time of the writing of this article, this test was only available through Idexx Laboratories. It has largely replaced an older test called the western blot.
It is called their Quantitative C6 assay and it looks for the level of antibodies your dog has produced against this specific surface protein on the Borrelia (the C-terminus of Osp C). (ref)
Your veterinarian will send a blood sample out for this test. The beauty of this test is that it measures the level of a specific antibody that is only present when the Borrelia is still present. So dogs that have cured themselves or received prior vaccinations are not confused with pets that have an active Lyme infection. It is hoped that this test will also allow your veterinarian to monitor the success of antibiotic treatment of your pet.
My only concern with the Idexx Quantitative C6 test is that the only information available is distributed by the Marketing Department of Idexx themselves , or through marketing seminars that Idexx underwrites. (ref)
If your dog is positive on either test, your vet may suggest urine tests to check if kidney damage has occurred (the E.R.D and protein/creatinine tests I mentioned earlier).
The may also suggest blood work analysis to gauge your pet’s general health.
How Is Lyme Disease Treated ?
Treatment of early Lyme disease is straightforward. The American College Of Veterinary Internal Medicine recommends a 30-day treatment with doxycycline. If kidney function tests were abnormal they suggest the pet stay on the medication longer and that it receive a diet formulated to minimize kidney problems.
Other antibiotics are effective in treating early Lyme disease, but they are not as effective in treating the other disease organisms that ticks often carry and which may be in your pet’ system as well.
If your pet is experiencing joint pain, an anti-inflammatory NSAI such as Remadyl might be prescribed.
Dogs given antibiotics early in Lyme disease improve. But there is doubt that the organism is ever entirely eliminated from their body. Most veterinarians feel that it goes into remission but continues to lurk in the body in some sleeping, inactive form.
You veterinarian may want to run additional follow up blood and kidney tests subsequent to treatment. We are hopeful that repeat tests that show that your pet's C6 antibody level is dropping is evidence that the antibiotics and your pet's immune system are eliminating a large the number of Borillia from its body.
Why Are Treatment Decisions In Lyme Disease So Difficult ?
It appears that many more dogs have positive lyme tests than will ever show symptoms of the disease. The common tests only confirm the presence or recent exposure of your dog to the lyme organism. They do not tell us how successfully your dog will be in dealing with exposure. Recent studies at Harvard tell us that there are several strains of the lyme bacteria circulating in the United States. Some appear more likely to cause symptoms than others (RST1 strain). Some strains disseminate throughout he body faster than others. (ref) A single tick is even capable of transmitting more than one strain at a time. (ref) Compounding that in humans (and mice) are differences in our genetics that make the results of exposure to lyme organisms highly unpredictable. A similar situation might easily occur in dogs - as of 2012, veterinarians just do not know. You can read a human-oriented study on the known strains of lyme here.
What Should I Do If My Dog Had A Positive Lyme Test But Looks Healthy ?
is where veterinarians have much disagreement. The 2005 position
paper of the ACVIM
This may be true, but doxycycline is an inexpensive drug that has been used safely for many years in pets and humans. If it were the pet I loved, I would put it on the medication - if only for peace of mind. The down side of not treating is just too great to worry about the very small chance of side effects or a treatment that was, perhaps, unnecessary. I would probably also extend the medication for an additional month if the pet tolerated it well.
There is also some evidence that just because your dog remains outwardly healthy is not a guarantee that undesirable tissue changes are not occurring due to the presence of Borrelia. It might be many years before these changes become evident. (ref)
What About Dogs That Have Had Lyme Disease For Long Periods Of Time – Chronic Lyme ?
When the Lyme organism has been in the body for extended periods, it does not respond to antibiotics as well as initially. (ref). That is why dogs with chronic Lyme disease are much more difficult to treat. They should receive antibiotics, just like acute or recent case, but they should be given for longer periods.
In some cases, ceftriaxone (Rocephin) antibiotic is added to the treatment as is done in humans with chronic Lyme disease.
Most of these dogs are suffering from joint or organ damage and these problems are usually not curable.
If your pet has painful joints and arthritis that are thought to be due to chronic Lyme disease, it needs to be managed the same way I suggest that other arthritic joint problems be managed. (ref).
If your veterinarian has detected kidney damage, it needs to be treated and managed in the same way I suggest for pets with damaged kidneys. (ref)
Can My Dog Ever Really Be Cured ?
The Lyme organism is extremely skillful at hiding and disguising itself from your pet’s body defenses. Because of that, we can never be sure that it is truly gone. With treatment, or with plain time, the number of Lyme organisms in the body decrease in number and symptoms of the disease dissipate. But we do not know if it is really ever gone.
Years ago, in the Middle East, I was infected with the Mediterranean cousin of Lyme disease - accompanied by near-fatal fevers of 106F and delirium. (ref) I was eventually “cured” with tetracycline. But for many, many years thereafter, I experienced repeated bouts of chills and weakness. I often thought that somewhere, on some infinitesimal microscopic level - this parasite never entirely left my body. Perhaps it still there somewhere – sleeping.
Can My Family Catch Lyme Disease From Our Dog ?
You can not catch Lyme Disease from your infected pet. However, if a tick bites your pet and then bites you, you can become infected. That is why eliminating ticks from your environment is so important.
What Can I Do To Prevent My Dog From Catching Lyme Disease ?
Eliminate Ticks From Your Pet And It’s Environment
Lime disease requires ticks to infect dogs. If you get rid of the ticks or keep your dog away from areas that are tick-infested, it will not catch Lyme Disease.
Here is what will help:
There are several vaccines approved to prevent Lyme disease in dogs. My preference is for Recombitek Lyme by Merial because it uses recombinant subunit technology to minimize vaccine side effects. The manufacturer states that this vaccine will reduce but not prevent infection. I suppose they mean it will reduce disease signs in dogs that become infected. Manufacturers suggest these vaccines be given every year.
I only suggest that dogs be vaccinated for Lyme disease when it is prevalent in your community and your dog’s lifestyle makes it highly at risk. That means you should consider vaccinating your dog if you see ticks on it or it roams in meadows, woods and parks that are tick-infested. The society of veterinary internists, the ACVIM, states in 2005: “The ACVIM diplomates believe the use of Lyme vaccines still is controversial and most do not administer them.”
There is another fact that brings the use of these vaccines into question. The safer subunit vaccines were developed to protect against a particular antigen protein of the Lyme organism called OSP- A. After these vaccines were already in production, it was found that other antigen proteins (OSP B & C) were important in developing immunity to Lyme. According to Dr. Bob Rogers , these vaccines do not contain these proteins. (ref)
Is There Risk In Giving This Vaccine ?
Yes. The vaccines contains potent foreign proteins meant to excite your pets immune system. Because of this, it has the potential of causing vaccine reactions and possibly even symptoms similar to the disease itself.
Some owners have reservations about using these vaccines because of problems that occurred when other Lyme vaccines were given to humans. I do not know how similar current canine vaccines are to the ones that were pulled from the human market. (ref)
Should My Lime-Positive Dog Be Vaccinated For Lyme Disease ?
I do not recommend that.
If your pet has already been exposed to Lyme organism proteins, its immune system has memory of that. Many of the kidney joint and neurological problems we associate with chronic Lyme disease are though to be due to chronic exposure to these proteins and the body’s reaction to them. I do not feel it would be wise to inject more of these proteins into your pet’s body.
If - for some reason - you cannot control your pet’s exposure to Lyme-carrying ticks, I would prefer it received tetracycline-class antibiotic intermittently. (Please do not do this without veterinary guidance)
What If I Discover that My Pregnant Dog Is Positive For Lyme Disease ?
If your pregnant dog shows no symptoms of Lyme disease and its C6 titer is not elevated, wait until it has delivered its puppies and then have it placed on an extended course of ammoxicillin. If the dog is ill and your veterinarian feels the symptoms are associated with an active case of Lyme disease (elevated C6 test, fever, etc.), I would begin the ammoxicillin immediately. There are veterinarians who disagree. They mention a condition known to occur in humans suffering from similar diseases in which symptoms temporarily get worse when antibiotics are given. It is called a herxheimer reaction. (ref) We do not even know if a similar situation occurs in dogs. In any case, to me, the health of the mother is a more important concern.
Can Our Cat Catch Lyme ?
It is very unlikely. In the laboratory, it is possible to infect cats with Lyme disease organisms. But I do not know of any cases that were reported by veterinarians as naturally occurring in pet cats. (ref)