OVERVIEW and DISEASE TRANSMISSION
In the Greater Madison Area, Lyme Disease is one of the most commonly diagnosed infections in dogs. Every week, we, unfortunately, diagnose several dogs with Lyme disease.
Lyme disease is the result of infection by a spirochete (bacteria-like organism), Borrelia burgdorferi, that is transmitted through the bite of an infected tick. Ticks bite in order to feed on blood. Although Lyme disease was named for the Connecticut town of Lyme in 1975, the disease itself has been around for at least 100 years.
Wisconsin is heavily endemic for Lyme and other tickborne diseases. In our area, Lyme is transmitted by the deer tick, Ixodes. An adult deer tick lays approximately 2000 eggs in the spring. These eggs hatch into tiny larvae, so small that they feed primarily on small prey such as the white-footed mouse. If the mouse is infected with Borrelia, the Lyme spirochete, the tick larva becomes infected. After feeding on the mouse, the larva drops off and lies dormant until the next spring when it molts into a nymph. The nymph is a bit bigger (about the size of a poppy seed - very difficult to spot) and therefore can reach bigger prey, such as deer, dogs, or humans. Nymphs are the most common transmitters of Borrelia. When the nymph has had its fill of blood, it drops off the animal, becoming dormant for a few months, and then molts into an adult in the fall. The adult tick will also seek prey to take a blood meal.
Infection with Borrelia can occur during any feeding if the larva, nymph, or adult takes a blood meal from an animal that is infected. Once the tick is infected with Borrelia, it can pass the infection along to any animal on which it feeds, however, a tick usually needs to be attached and feeding for at least 24 hours before it can transmit the Borrelia organism.
It is important to note that Lyme disease is not transmitted from mammal to mammal - rather, it must be passed through the bite of a tick.
SIGNS OF INFECTION
Signs of infection in dogs vary significantly from those seen in humans. THE MOST COMMON SIGN OF LYME DISEASE IN DOGS ARE NO SYMPTOMS AT ALL. Eighty percent of humans will develop a bulls-eye rash and flu-like symptoms after being bitten by an infected tick. This can then progress to joint pain, neurologic issues, or other symptoms within a few weeks. Dogs rarely experience this progression of events. In fact, dogs can be infected for weeks to months before any signs of infection become apparent, if signs become apparent at all. In dogs, the most common signs of Lyme disease are lethargy, poor appetite, lameness or joint pain (often inconsistent, or "shifting leg lameness"), and sometimes fever. Rarely, Lyme disease in dogs may lead to heart problems, neurological problems, or kidney dysfunction or failure.
The quickest way to test for Lyme and other tick-borne diseases (Ehrilichia and Anaplasma) is through the use of a 4Dx test. This test detects heartworm, Lyme disease, Ehrlichia, and anaplasmosis. Heartworm is transmitted by mosquitoes, while the other three diseases are transmitted by ticks. This test is run annually during your dog's physical examination or if there is suspicion of infection.
The 4Dx test is an antibody test, which means that it detects your dog's immune response to the Borrelia organism. A positive test means that your dog has been exposed to the Borrelia (bitten by an infected tick and invaded by the organisms) within the past few years. It does not necessarily mean that there is still Borrelia infection in your dog's body. Beyond keeping your pet healthy, it's important to know your dog's status as he/she may be a carrier of the disease which could be transmitted to human family members (for this to occur your pet would need to have an active infection, a tick would need to bite the dog, and then tick bites you).
At our practice, if your pet is positive for one of the tick-borne diseases we recommend two tests to determine if we need to treat your dog. We recommend a urinalysis (a urine sample) to make sure your dog isn't losing protein in his/her urine and to evaluate how well the kidneys are functioning along with a complete blood count. There is another test for Lyme positive dogs, called a Quant C6, however, there is a lot of controversy around the test and it's ability to determine if there is an active infection or not.
Fortunately, Lyme disease is more successfully treatable in dogs than in humans. Most dogs will be prescribed Doxycycline, an antibiotic, for one month. Although an infection relapse is possible, this treatment has proven effective in the majority of cases. Dogs that are already showing significant illness may require hospitalization and more aggressive treatment.
There are two ways to prevent Lyme disease - vaccination and tick prevention. No method works 100% of the time, so it's best to combine both types of prevention for the best protection of your dog.
The canine vaccinations available have been subjected to years of testing for safety and efficacy. Vaccination is recommended for most dogs, but each pet's age, health, and lifestyle will be evaluated individually by your veterinarian prior to receiving a vaccine recommendation. The first time your dog receives the Lyme vaccination he will need a booster in 3 to 4 weeks. After this initial series of 2 vaccines, annual re-vaccination is recommended.
Tick prevention is accomplished through the use of monthly topical products such as Frontline Plus.
Improved Lyme Test (IDEXX Snap® 4Dx Test) Showing Higher Incidence of Lyme Disease Exposure
With the use of the Snap® test, a routine heartworm test also tests for Lyme disease, Anaplasmosis, and Ehrlichiosis. The incidence of Lyme Disease exposure is much higher than previously thought.
Heartworm disease is caused by a parasite transmitted from dog to dog by mosquitoes. Lyme disease, Anaplasmosis, and Ehrlichiosis are caused by bacteria, and Ehrlichiosis is caused by a parasite, both of which can be transmitted by tick bites. All three diseases occur worldwide including in this area.
Clinical Signs of Lyme Disease:
- Fever of unknown origin
- Not eating
- Joint pain
- Intermittent lameness
Clinical Signs of Ehrlichiosis:
- Fever of unknown origin
- Difficult breathing
- Weight loss
- Skin Hemorrhages
- Bloody Nose
- Low platelet count
- Low white blood cell count
- High urinary protein
Clinical Signs of Anaplasmosis:
- Fever of unknown origin
- Swollen, painful joints