Q My precious 9-year-old golden was diagnosed with Lyme nephritis. I am devastated to learn that this disease is almost always fatal. I live in a wooded area on Johns Island, where ticks (and deer) are prevalent, but I always considered ticks more of a nuisance than a real danger.
My dogs live inside with me, but I occasionally find a tick on them and just pull it off. I use the Preventic collar on them during the summer. I now realize they should have worn it year-round. Since I have two other dogs, including another golden, which happens to be more susceptible to Lyme disease than other breeds, I want to do everything I can to prevent this from happening again. My vet is not in favor of giving them the vaccination. What do you suggest?
A. Once the kidneys are injured, whether from an infection like Lyme disease or a toxin like antifreeze, the injury is permanent and almost always progressive. So your questions about prevention are right on the mark. Understanding what you are dealing with always helps.
Lyme disease is caused by tiny spiral-shaped organisms called Borrelia burgdorferi. These spirochetes cannot live freely in the environment but must constantly be in a host to survive. This is how they are transmitted from animal to animal, as one of their hosts are various small, (less than 3mm) hard ticks.
The life cycle for many of these ticks lasts two years. In spring, the tick larvae emerge and feed one time, usually on birds or small mammals, and then over-winter. It is at this stage when the tick becomes infected with the Lyme organism. The next spring, the infected larvae molt into the next stage called a nymph. They look like tiny ticks and feed on mice, dogs, deer and even people. This stage is probably the most likely source of infection for canines and humans.
In the fall, they molt into larger adults that feed on large mammals like deer. The females lay eggs, die and the two-year life cycle is complete.
Lyme disease is found in areas where these ticks, and one of their primary hosts, deer, live. This is the Atlantic Coast, Gulf Coast, lake regions of the Midwest and the Pacific Coast. The dry areas in the middle of the country have few ticks and thus fewer infections. Of the areas where these ticks live, Lyme disease in dogs is primarily identified in the Northeast with much less incidence anywhere else (including South Carolina).
Despite the numerous dogs that are bitten, fortunately few develop Lyme disease. This is probably because most are removed before they can cause an infection, as they must be attached for 50 hours to transmit the disease. Also many dogs’ immune systems will fight the infection, preventing clinical symptoms from developing. In areas where up to 75 percent of dogs are exposed, only 5 percent to 10 percent will develop symptoms.
If they are going to exhibit symptoms, it is usually between two and six months after the tick bite. Once in the body, the organisms proliferate in the skin initially. They then can migrate and spread through the body to multiple areas. Fever, lameness that shifts from leg to leg, anorexia and enlarged lymph nodes are common symptoms.
Lyme nephritis is a sudden, progressive form of kidney failure. Excessive protein loss into their urine is often detected. Golden and Labrador retrievers are the most commonly affected breeds. It’s unknown if they are truly predisposed or just more likely to be exposed compared with other breeds. Unfortunately, as you correctly stated, most of these dogs die or are euthanized as a result of their renal failure.
Lyme disease can be difficult to diagnose and probably is overdiagnosed in dogs. This is because the most common test is to measure whether the dog has made antibodies against the organism. The problem is interpreting a positive result. It may be positive from an ongoing infection (indicative of disease), a dog that was infected but whose immune system fought off the infection or infection by a close relative of the Lyme organism.
The other problem with interpreting these antibody tests is a vaccinated dog will be positive, too. If vaccinated, further testing can be performed to differentiate a positive from vaccination or true exposure.
Dogs with fever and lameness generally respond within 24-48 hours of the start of antibiotics. This treatment is given for a minimum of 30 days. Chronic joint infections, if left untreated, may result in permanent joint damage and lameness. Once the kidneys are damaged, the renal failure usually is permanent and progressive.
The best prevention is to avoid infection by controlling tick exposure. Tick collars and the application of monthly topical solutions of insecticides may prevent infections. Since prolonged attachment is required, no prevention is as effective as daily combing to remove attached ticks. This is the same technique we use on ourselves after a day in the woods.
Reduction of deer and rodent populations also will decrease the chance of infection, as they carry the organism and infect the ticks that eventually may infect your dog.
Vaccinations to prevent Lyme disease are available for dogs and will lower the rate of infection compared with unvaccinated dogs. Annual vaccination is required to sustain adequate antibodies to prevent infection. Whether to vaccinate depends on the chance of exposure to Lyme disease weighed against any potential negative aspects of the vaccine. Even though vaccine side effects are low, you do not want to give your dog anything it does not need. The only way to decide is for you and your dog’s veterinarian to decide together.
Infected dogs do not excrete the organism in body fluid, so they are not a risk for infecting other dogs or people.
Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to firstname.lastname@example.org.