Lyme disease (borreliosis) — caused by Borrelia burgdorferi transmitted by Ixodes (deer) ticks — affects dogs in tick-endemic regions. While most infected dogs remain asymptomatic, a minority develop clinically significant disease affecting joints, kidneys, and occasionally heart or nervous system. Prevention through effective tick control is far preferable to treatment.
Transmission and Distribution
Ixodes ricinus (sheep tick) in the UK and Europe, and I. scapularis in North America, transmit Borrelia when attached for >24–36 hours. Tick activity peaks in spring (March–June) and autumn (August–October). High-risk habitats include woodland with bracken, long grass, heath, and areas with deer or rodent populations. UK Lyme disease risk is concentrated in the Scottish Highlands, New Forest, Lake District, and parts of Wales.
Clinical Signs in Dogs
- Shifting lameness — intermittent lameness affecting different joints is characteristic; caused by immune-mediated polyarthritis
- Fever, lethargy, and anorexia
- Lymphadenopathy (swollen lymph nodes)
- Lyme nephritis — a severe immune complex-mediated kidney disease; particularly common in Labrador and Golden Retrievers; causes acute kidney failure and carries a grave prognosis
- Cardiac and neurological involvement rare in dogs
Diagnosis
Serology (C6 antibody ELISA, Quant C6 quantitative test) detects exposure. A positive result indicates exposure, not necessarily active disease — many seropositive dogs remain well. Western blot testing confirms equivocal ELISA results. Urinalysis and renal panel essential in any seropositive dog to screen for Lyme nephritis.
Treatment
Doxycycline (10mg/kg once daily for 28–30 days) is first-line treatment for clinical Lyme disease. Response is usually excellent for arthritis — fever, lethargy, and lameness typically resolve within 24–48 hours. Lyme nephritis requires aggressive fluid therapy and immunosuppression alongside antibiotics; prognosis guarded to poor.
Prevention
Regular tick prevention is the cornerstone of Lyme disease prevention in dogs:
- Tick-repellent products: isoxazolines (fluralaner, afoxolaner, sarolaner) provide excellent tick kill and prevention when used consistently
- Daily tick checks after walks in tick habitat — prompt manual removal within 24 hours prevents transmission
- Vaccination: a canine Lyme disease vaccine (Nobivac Lyme) is available in the UK and provides additional protection in high-risk areas
- Avoiding peak tick habitat during high-risk seasons is impractical for most working and active dogs — pharmacological prevention is essential