Lyme Disease in Dogs: Symptoms, Diagnosis, and Treatment Options

TL;DR. Lyme disease is a tick-borne bacterial infection that primarily causes joint pain and lameness in dogs, but can occasionally trigger a severe, life-threatening kidney disorder.

Ticks thrive in tall grass and wooded areas, making active outdoor dogs prime targets for Lyme disease.

What is it?

Lyme disease, scientifically known as Borrelia burgdorferi infection or Lyme borreliosis, is an infectious disease transmitted to dogs through the bite of infected ticks. The culprit is a specialized, spiral-shaped bacterium called a spirochete. Unlike typical rod-shaped or spherical bacteria, spirochetes move in a distinctive corkscrew motion, which allows them to migrate efficiently through your dog's connective tissues, joints, and bodily fluids.

When an infected tick attaches to a dog, the bacteria migrate from the tick's salivary glands into the dog's skin. From there, the bacteria spread through the tissue, often settling in the joints. This migration triggers a localized immune response, which is why joint pain and swelling are the most common clinical signs seen in dogs.

While many dogs exposed to the bacteria never show outward signs of illness, those that do can experience significant discomfort. In some cases, the infection triggers a severe, abnormal immune response that targets the kidneys. This condition, known as Lyme nephritis, causes progressive damage to the kidney's filtration units and is a major concern for veterinarians and pet owners alike.

Causes & risk factors

Lyme disease is caused by the bacterium Borrelia burgdorferi. It is not contagious from dog to dog, or from dog to human; the infection can only be transmitted through the bite of an infected tick, primarily species of Ixodes (commonly known as blacklegged ticks or deer ticks).

For transmission to occur, an infected tick must typically remain attached to the dog for a significant period—often 24 to 48 hours—before the bacteria are successfully passed into the bloodstream. This makes regular tick checks and prompt tick removal highly effective preventive measures.

Risk factors for Lyme disease include:

• Geographic Location: Living in or visiting areas with high tick populations, particularly heavily wooded, tall-grass, or shrubby environments.
• Seasonal Activity: Ticks are most active during the spring, summer, and fall, though they can emerge anytime temperatures rise above freezing.
• Breed Susceptibility: While any dog exposed to ticks can contract Lyme disease, certain breeds, including Labrador Retrievers and Golden Retrievers, are suspected to have a higher genetic predisposition to developing the severe, renal (kidney) form of the disease.

Signs to watch for

In dogs, Lyme disease does not typically produce the classic "bullseye" rash seen in humans. Instead, the signs are often systemic and can sometimes be vague or mimic other arthritic conditions.

Common Signs

• Shifting Leg Lameness: This is a hallmark sign of Lyme disease. A dog may limp on one leg for a few days, appear to recover, and then begin limping on a completely different leg. This occurs as the bacteria move between different joints.
• Joint Swelling and Pain: One or more joints may feel warm to the touch, look swollen, and cause visible discomfort when manipulated.
• Fever: A sudden, unexplained spike in body temperature often accompanies the joint inflammation.
• Lymphadenopathy: Swollen lymph nodes, particularly those near the site of the tick bite or the affected limbs.
• Anorexia: A loss of appetite, often accompanied by general lethargy and depression, as the dog feels unwell.

Occasional Signs (Associated with Kidney Damage)

• Proteinuria: Excess protein in the urine, which is a key indicator of kidney damage.
• Peripheral Edema: Swelling in the limbs, face, or under the skin due to fluid retention.
• Body Cavity Effusions: Fluid buildup in the chest or abdomen.
• Uremia: A buildup of toxic waste products in the blood, leading to vomiting, weight loss, and a chemical odor to the breath.

Rare Signs

• Seizures: Neurological complications can occur if the infection or associated inflammation affects the central nervous system.
• Behavior Changes: Uncharacteristic irritability, confusion, or depression.

Swollen, painful joints and shifting leg lameness are classic signs of Lyme disease in dogs.

How vets diagnose it

Diagnosing Lyme disease is rarely as simple as running a single test. Because many healthy dogs in tick-endemic areas will test positive for Lyme antibodies without ever showing signs of illness, veterinarians must look at the whole clinical picture.

According to a leading veterinary internal medicine reference:

"Lyme disease polyarthritis should be diagnosed only if the animal has a history of recent potential exposure, the synovial fluid is confirmed to be inflammatory and sterile, serologic testing is positive, infection with other tick-borne diseases is eliminated, and a prompt and permanent response to appropriate antibiotic therapy is seen."

To build a complete diagnosis, your vet may recommend several of the following tests:

• Serologic Testing: These blood tests detect antibodies produced by the dog's immune system in response to the Borrelia burgdorferi bacteria. Common screening tests can distinguish between antibodies produced by natural infection and those produced by vaccination.
• Synovial Fluid Analysis: If your dog has swollen joints, your vet may perform a joint tap to collect synovial fluid. In Lyme disease, this fluid will show signs of inflammation (high white blood cell counts) but will be sterile, meaning no active bacterial colonies are easily grown from it, helping to rule out other joint infections.
• Polymerase Chain Reaction (PCR): This sensitive test looks for the actual DNA of the bacteria in joint fluid or tissue samples.
• Tissue Biopsy with Special Stains: In complex or atypical cases, a small tissue biopsy may be taken and treated with special stains or monoclonal antibodies to visualize the physical spirochetes under a microscope.
• Urine Testing: A urinalysis and a urine protein-to-creatinine (UPC) ratio are essential to screen for proteinuria, which helps catch early signs of Lyme nephritis.

Veterinarians use specialized blood tests to detect antibodies against the Lyme disease bacteria.

Treatment options

Treatment for Lyme disease focuses on eliminating the bacterial infection and managing the associated inflammation and pain.

First-Line Antibiotic Therapy

Antibiotics are the cornerstone of Lyme disease treatment. Because tick-borne infections can sometimes overlap, veterinarians often choose broad-spectrum options that target multiple potential pathogens simultaneously.

• Doxycycline (Tetracycline Antibiotic): This is the most common first-line treatment for Lyme disease and other tick-borne infections in dogs. As noted in a leading veterinary internal medicine reference:

  "Acute rickettsial infections causing polyarthritis are best treated with oral doxycycline... Empirical antibiotic treatment is warranted in all dogs with confirmed polyarthritis from endemic areas, especially if there is concurrent thrombocytopenia or other evidence to support rickettsial infection."

• Amoxicillin or Ampicillin (Aminopenicillin Antibiotics): These are highly effective alternatives, particularly for young puppies where tetracycline-class drugs might risk staining developing teeth.
• Amoxicillin/Clavulanate Potassium (Potentiated Aminopenicillin): A modified penicillin that provides robust antibacterial coverage.
• Cephalexin (First-Generation Cephalosporin): Another antibiotic option that may be utilized depending on the dog's specific health profile and tolerance.

Antibiotic courses for Lyme disease are typically prescribed for a minimum of four weeks. It is vital to complete the entire course, even if your dog's symptoms disappear within the first few days.

Supportive Therapies

For dogs experiencing severe joint pain, veterinarians may prescribe pain-relieving medications or temporary anti-inflammatory therapies to improve comfort while the antibiotics take effect. If a dog develops Lyme nephritis, treatment becomes much more intensive, requiring aggressive fluid therapy, blood pressure medications, dietary changes, and medications to reduce protein loss in the urine.

Prognosis

The prognosis for Lyme disease depends heavily on which form of the disease the dog develops.

• Acute Lyme Polyarthritis: The prognosis is excellent. Most dogs diagnosed early and treated with appropriate antibiotics show dramatic, rapid clinical improvement within 2 to 3 days.
• Lyme Nephritis: The prognosis for dogs that develop progressive, immune-mediated kidney disease is guarded to poor. This condition can lead to severe uremia, kidney failure, and death. Ongoing, long-term management and frequent veterinary monitoring are required for dogs with renal involvement.

Prevention

Preventing Lyme disease is far easier and more effective than treating it. A multi-layered prevention strategy is the best way to keep your dog safe:

1. Tick Preventatives: Use a veterinarian-recommended topical, collar, or oral tick preventative year-round. These products work by killing ticks shortly after they attach, preventing them from feeding long enough to transmit the bacteria.
2. Vaccination: A Lyme disease vaccine is available for dogs. Talk to your vet about whether this vaccine is appropriate for your dog based on your lifestyle and geographic location.
3. Daily Tick Checks: After walking in wooded or grassy areas, thoroughly check your dog's coat for ticks. Pay close attention to the ears, underarms, groin, and between the toes.
4. Environmental Management: Keep your lawn mowed short and clear away brush piles or leaf litter where ticks thrive.

When to call your vet

If you live in or have visited an area where ticks are common, you should monitor your dog closely for any changes in behavior or mobility. Contact your veterinarian if you notice shifting lameness, swollen joints, a warm-to-the-touch fever, or a sudden loss of appetite.

Seek immediate emergency veterinary care if your dog exhibits any of the following red-flag signs:

• Extreme lethargy or collapse
• Persistent vomiting or complete refusal to drink water
• Sudden, severe swelling of the limbs, face, or abdomen
• Difficulty breathing
• Seizures or sudden, severe behavior changes

For specific breeds

If you own a Labrador Retriever or a Golden Retriever, you should be extra vigilant. These breeds are suspected to have a higher risk of developing Lyme nephritis, the severe kidney-damaging form of the disease.

As noted in a leading veterinary internal medicine reference:

"There are numerous reports of dogs with Bb antibody developing a unique progressive renal disorder characterized by immune-mediated glomerulonephritis, tubular necrosis, and lymphocytic-plasmacytic interstitial nephritis. This disorder is most common in Labrador and G..."

If you own one of these breeds and they test positive for Lyme antibodies—even if they are not showing signs of joint pain—your veterinarian may recommend routine urine screening to check for protein loss, allowing you to catch and manage potential kidney issues as early as possible.

Sources

• Internal Medicine, 5th Edition, pages 1149, 1150.