The U.S. Food and Drug Administration has approved NexGard (afoxolaner), a chewable tablet administered once monthly to dogs, for the prevention of Borrelia burgdorferi (B. burgdorferi) infections by killing Black-legged ticks (Ixodes scapularis), which carry the bacterium. The FDA originally approved NexGard in 2013 to treat and prevent flea infestations and to kill Black-legged ticks, American Dog ticks, Lone Star ticks, and Brown Dog ticks.
The data presented by Merial, the manufacturer of NexGard, in the supplemental application measured the transmission of B. burgdorferi to dogs after exposure to infected ticks, and demonstrated that transmission was prevented as a direct result of killing the ticks. The study did not measure whether the product affected rates of illness from Lyme disease in dogs.
B. burgdorferi is the infective agent that causes Lyme disease. It is estimated that 5-10% of dogs exposed to B. burgdorferi develop Lyme disease.
Lyme disease can cause severe illness in both dogs and humans. In dogs, the disease may trigger fever, loss of appetite, lameness, joint swelling, and lethargy. In some cases, Lyme disease can lead to acute kidney disease. Dogs may not display the characteristic “bullseye rash” that is often seen in people with Lyme disease.
The Centers for Disease Control and Prevention (CDC) recommends preventing Lyme disease by minimizing exposure to ticks through various methods, including consulting your veterinarian about the most appropriate tick prevention product for your dogs and situation.