Lyme disease is one of the most common tick-borne illnesses that affects dogs—and people—around the world, but it only causes signs in 5% to 10% of dogs. So, your dog may have Lyme disease and you will never know it, unless your pet receives an annual heartworm and tick-borne disease test. Since its origination in Lyme, Connecticut, this nasty disease has begun to spread across the United States as the tick population has expanded. Most prevalent in the upper Midwestern states, the Atlantic seaboard, and the states along the Pacific coast states, areas with sizable deer populations—a necessary host in the tick life cycle—are most at risk for being classified as a Lyme endemic area.
What Ticks Cause Lyme Disease in Pets?
While Lyme disease is a serious and growing threat, only one type of tick carries the bacteria responsible for this illness—the black-legged, or deer, tick. Two tick species fall into this category: Ixodes scapularis in the midwestern and eastern United States, and Ixodes pacificus along the west coast.
The black-legged tick is a hardy pest, with a life cycle lasting about two years as the tick evolves through four life stages. Each life stage must come with a new host to provide a meal for the tick to grow and mature. The larvae’s favorite meal is a white-footed mouse, while the nymph chooses larger prey, such as birds, squirrels, raccoons, dogs, and people. The adult tick is known for feasting on white-tailed deer, but your pet or yourself can also become a meal if no deer are nearby. Ideally, a tick will have three different host species over the course of its life cycle.
Preparation for feeding can take from 10 minutes to 2 hours. When the tick finds a feeding spot, it grasps the skin and cuts into the surface, inserting its feeding tube. Ticks can secrete small amounts of saliva with anesthetic properties so that the animal or person can't feel that the tick has attached itself, plus it can go unnoticed if it discovers a sheltered spot.
A black-legged tick will attach to its host and feed slowly for several days, either ingesting or transmitting a potential pathogen, such as the bacterium responsible for Lyme disease. After feeding, the tick drops off and prepares for the next life stage. At its next feeding, it can then transmit the infection to the new host. Once infected, a tick can transmit infection throughout its life. However, if you remove a black-legged tick quickly from you or your pet, you can greatly reduce the chance of Lyme disease transmission. A tick must be attached for about 48 hours for disease to spread, so finding the tick quickly and removing it properly is key for halting the infection.
What are the Signs of Lyme Disease in Pets?
If your dog is one of the unfortunate ones who has an infected tick attached for a full 48 hours and develops signs, they can appear as transient, mild signs, or the disease can develop into a severe case of illness. Signs of Lyme disease among dogs vary, but may include:
- Intermittent, recurrent lameness due to joint inflammation
- General depression and lethargy
- Swollen lymph nodes
The most common sign of Lyme disease in dogs is “shifting-leg lameness,” which occurs when painful joint inflammation flares up in a different leg every few days or weeks. This lameness often lasts for only a few days, then will voluntarily resolve, only to reappear in the same or a different leg at a later date. Although this condition is chronic and frustrating to manage, it is not generally fatal or very serious.
Another issue caused by Lyme disease is fortunately rare, as it is often fatal. In uncommon instances, the Lyme bacterium can travel to your pet’s kidneys and cause Lyme nephritis, leading to renal failure. As the Lyme bacterium attacks your dog’s kidneys, renal function and filtration is diminished, allowing toxins to build up in the bloodstream. If your dog is affected by this form of Lyme disease, you may notice vomiting, anorexia, weight loss, depression, and increased thirst and urination.
How is Lyme Disease in Pets Diagnosed and Treated?
Lyme disease in pets can be challenging to diagnose, as the incubation period is lengthy and few dogs present with clinical signs. The best way to help your veterinarian diagnose the cause of your pet’s lameness or lethargy is to provide a complete history, along with known tick exposure. Your veterinarian will likely perform a specific test to check for Lyme antibodies, which can take two to five months after exposure to appear. However, a positive antibody test does not always mean an active infection is occurring, or that the antibodies did not develop after vaccination. Multi-step testing is necessary for a confirmed Lyme disease diagnosis.
Once your pet has been properly diagnosed with Lyme disease, treatment is generally an outpatient process, unless severe kidney disease is an issue. The most common treatment is a month-long course of antibiotic therapy, although longer courses may be necessary. Anti-inflammatories may be indicated if your dog is uncomfortable or lame.
Unfortunately, antibiotic treatment does not always completely eliminate the Lyme bacterium, which may instead harbor in the kidneys to recur at a later date. Signs of the disease may dissipate or completely disappear, only to reappear later, with the threat of kidney disease always a lingering possibility.
How Can I Protect My Pet from Lyme Disease?
With the potentially severe effects Lyme disease may wreak upon your beloved companion, prevention is critical to keep your pet healthy. Follow these steps to protect your pet from the threat Lyme disease poses:
- Administer tick prevention on a regular schedule.
- Vaccinate your pet as recommended for Lyme disease.
- Check your pet for ticks as soon as you return indoors. Search under the collar, in the armpits, in the groin, and under the ear flaps, although ticks can attach anywhere, even the eyelids and gum tissue.
- Keep your pet away from thick brush and heavily wooded areas that can harbor high tick populations.
Speak to your veterinarian about the best tick preventive option to keep your furry pal safe and to discuss a vaccination schedule. Fortunately, cats rarely develop Lyme disease and become ill from the pathogen even less frequently. However, prevention is still important for your feline friend to keep blood-sucking parasites at bay.
By keeping your four-legged friend on proper tick prevention and checking carefully for ticks after a day outdoors, you and your pooch can enjoy a wonderful summer full of adventure and free from the threat of Lyme disease.