Tick-Borne Diseases in Dogs: Symptoms, Treatment & Prevention Guide 2026

Tick-borne diseases in dogs include Lyme disease, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, and babesiosis. These illnesses are transmitted by tick bites and can cause serious, even life-threatening illness if not caught and treated early.

This guide is for informational purposes. If you suspect your dog has been exposed to ticks or is showing illness symptoms, contact your veterinarian immediately.

Overview of Tick-Borne Diseases in Dogs

Ticks are external parasites that feed on the blood of animals and humans. During feeding, they can transmit bacteria, parasites, and viruses that cause a range of serious illnesses. In the United States, tick activity peaks in spring and summer but can occur year-round in warmer regions.

Source: CDC & AVMA tick disease data, 2025

Lyme Disease in Dogs

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted primarily by the black-legged (deer) tick. It’s one of the most common tick-borne diseases in the US, particularly in the Northeast and Midwest.

Symptoms

• Shifting lameness (limping that moves from leg to leg)
• Fever, lethargy, loss of appetite
• Swollen, painful joints
• Swollen lymph nodes
• Kidney disease (in severe or untreated cases)

Treatment

Lyme disease in dogs is treated with antibiotics (typically doxycycline or amoxicillin) for 4 weeks. Most dogs improve within 24–48 hours of starting treatment. A Lyme vaccine is available for dogs in high-risk areas.

Ehrlichiosis

Ehrlichiosis is caused by bacteria of the Ehrlichia genus and has three phases: acute (early), sub-clinical (no visible symptoms), and chronic (severe, potentially fatal). Dogs can remain in the sub-clinical phase for years before developing chronic disease.

Symptoms

• Fever and lethargy
• Unexplained bleeding or bruising
• Swollen lymph nodes
• Eye or nose discharge
• Weight loss, anemia (chronic phase)

Treatment

Doxycycline is the primary treatment, typically for 4 weeks. Early treatment leads to full recovery; chronic cases can be more difficult to treat and may result in lasting damage.

Anaplasmosis

Anaplasmosis is caused by Anaplasma phagocytophilum and is transmitted by the same ticks that carry Lyme disease, making co-infection common in some regions.

Symptoms

• Fever, lethargy, loss of appetite
• Painful or stiff joints
• Vomiting or diarrhea
• Neurological symptoms in severe cases

Treatment

Doxycycline for 2–4 weeks. Most dogs respond quickly. Dogs often test positive for both Lyme and anaplasmosis simultaneously — vets will typically treat for both.

Rocky Mountain Spotted Fever (RMSF)

Despite its name, RMSF occurs throughout the US and is one of the most serious tick-borne diseases. It’s caused by Rickettsia rickettsii and can be fatal if untreated.

Symptoms

• High fever (often above 104°F)
• Lethargy and loss of appetite
• Joint pain, reluctance to move
• Rash or skin discoloration (not always visible in dogs)
• Neurological signs (wobbling, seizures) in severe cases
• Swelling of face, legs, and abdomen

Treatment

Doxycycline — treatment should begin immediately if RMSF is suspected, even before test results. Delayed treatment significantly worsens outcomes. RMSF can be fatal within 2 weeks without treatment.

Tick Prevention for Dogs

Year-round tick prevention is the most effective way to protect your dog from tick-borne diseases:

• Prescription tick preventives — Oral (Nexgard, Simparica, Bravecto) and topical (Frontline, K9 Advantix) products kill ticks before they can transmit disease
• Lyme vaccine — Recommended for dogs in high-risk areas; given as a 2-shot initial series then annually
• Tick checks after outdoor activities — Run your hands through your dog’s coat after every outdoor trip, especially around ears, under collar, between toes, and around the tail
• Yard management — Keep grass mowed, clear leaf litter, and use yard treatments in tick-endemic areas
• Avoid high-risk environments — Leaf piles, tall grass, wooded edges — prime tick habitat
• Remove ticks promptly — Use fine-tipped tweezers to grasp the tick as close to the skin as possible and pull straight out; a tick must attach for 24–48 hours to transmit most diseases

Talk to your vet about the best tick prevention protocol for your dog’s lifestyle and region. Find veterinary clinics near you at HeiBob’s pet service directory.

Frequently Asked Questions About Tick-Borne Diseases in Dogs