Lyme Disease in Cats

What Is Lyme Disease in Cats?

Lyme disease is a tick-borne disease caused by the bacterial spirochete Borrelia burgdorferi. Ticks do not cause Lyme disease, but they are a means to transport the bacteria. Ticks that transmit Lyme disease, mostly from the genus Ixodes (which includes deer ticks), acquire the disease as they feed off wildlife like deer, rabbits, and rodents. Lyme disease is common in many areas in North America, infecting up to half of the ticks in some areas. Lyme disease affects many mammals, including humans, dogs, and rarely cats.

Ticks infected with the Borrelia bacteria bite a cat and spread the parasite through their saliva. Once the tick is attached, it takes 24 to 48 hours for Borrelia to start transmitting through the saliva. In the rare case of cats having clinical signs of Lyme, it is similar to the disease in dogs and may be noticeable two to five months after a tick bite. However, most cats do not show any symptoms.

Borrelia species are highly specialized at invading the host’s immune system, and animals can have difficulty clearing the bacteria. Borrelia hides in the skin, joints, connective tissue, and nervous system.

Symptoms of Lyme Disease in Cats

Cats rarely have signs of Lyme disease. While humans commonly see a red “bull’s eye” rash around the bite, this is uncommon for dogs and cats. Black fly bites are commonly mistaken for a Lyme rash, and a veterinarian should carefully examine the pet.

The most common symptoms, when present, include:

• Lameness

• Fatigue

• Loss of appetite

• Fever

Animals with a more severe form of Lyme affecting their kidneys may show:

• Vomiting

• Weight loss

• Severe lethargy

• Edema (swelling caused by excess fluid) in the limbs

Severe cases may cause damage to the nervous system and heart.

Causes of Lyme Disease in Cats

Cats get Lyme disease after being bitten by a tick infected with the bacteria Borrelia burgdorferi. Immature ticks get the bacteria when they are feeding in the fall. The bacteria spreads to cats through the saliva in the tick’s bite, where the Borrelia quickly replicate on the skin and migrate through the cat’s tissues.

Ticks must be attached for 24 to 48 hours before Borrelia is transmitted. Therefore, tick preventatives have time to kill the tick before it can transmit the bacteria, which is why keeping all cats on flea and tick preventatives is so important. There are many options of tick control in cats.

How Veterinarians Diagnose Lyme Disease in Cats

Lyme disease is diagnosed mainly through history, signs of disease, laboratory tests, and ruling out other diseases with similar symptoms. Because Lyme disease is so uncommon in cats, other conditions—like fractures or abscesses—should be eliminated as potential reasons for limping and infection before Lyme disease is considered.

Testing for Lyme disease involves a positive result on a relatively inexpensive and quick blood test. Additional tests, such as blood work and radiographs, eliminate or diagnose other disorders that may cause similar symptoms. If a cat tests positive for Lyme, additional      tests will also help analyze the severity of the disease.                           

Cats exposed to Lyme disease may not test positive for Lyme disease for two to eight weeks after a bite, if at all. If you find a tick on your cat, you can consider sending it to one of many laboratories that will analyze the tick for any diseases it may be carrying. Cats aren’t routinely tested for tick-borne diseases, like Lyme, but your veterinarian can help you decide on the necessary tests or treatments if you find a tick on your cat.

Treatment of Lyme Disease in Cats

While veterinarians use a few medications to treat Lyme disease, the gold standard is the antibiotic doxycycline. However, not all cats can tolerate this antibiotic. Antibiotics are typically prescribed for 30 days, but cats may need more courses in the future to safeguard against flare-ups.

Pet parents should use caution when using doxycycline in cats. In the tablet form, it can cause esophageal strictures—or narrowing, scar-like formations in the esophagus—if it gets stuck. Many  veterinarians use liquid doxycycline or follow the tablet with a good amount of water.

Some cats may be helped by non-steroidal anti-inflammatories, or other pain relief medications while they are in acute pain from Lyme disease. Typically, animals start feeling better within one or two doses of antibiotics. If cats do not rapidly improve, other diagnoses should be considered.

While most cats can be treated on an outpatient basis, some may need IV fluid therapy, kidney medications, anti-nausea medications, and nutritional support during acute crises. They may require long-term hospitalization for severe cases affecting internal organs.

Recovery and Management of Lyme Disease in Cats

Most cats start feeling better within a day or two after receiving antibiotics. Even though they are feeling better, it is vital to finish the entire course of antibiotics, which is usually a month.

Because Borrelia is good at evading the immune system, it may never be fully cleared. It can hide in joints and other cells in the body, flaring up from time to time. These relapses may require more courses of antibiotics.

Lyme disease in cats is extremely rare. However, complications include arthritis and long-term kidney damage.

Prevention of Lyme Disease in Cats

While there is a Lyme vaccine for dogs, there is no vaccine for cats. Tick preventatives for cats are the best way to avoid and prevent Lyme disease in cats. There are a variety of tick preventatives on the market, and your veterinarian can help you decide the best choice for your pet. Remove any ticks you may find on your pet.

Lyme disease is zoonotic, which means it can infect humans. However, cats cannot transmit Lyme disease directly to pet parents. An infected tick would need to bite a human.