Abstract
BACKGROUND: Borrelia burgdorferi, the causative agent of Lyme disease, is a zoonotic vector-borne pathogen transmitted by various Ixodes tick species. Lyme disease, while commonly asymptomatic, can induce fever and intermittent lameness in dogs. Highly effective acaricidal products with a rapid onset of action along with prompt removal of attached ticks are important aspects of successful Lyme disease prevention strategies. METHODS: Two studies were conducted with a total of 30 dogs each. Dogs were randomized to receive a control sham dose, Credelio Quattro, or Credelio. Treatment was administered on Day 0 in a fed state. On Day 28, all dogs were experimentally infested with wild-caught adult Ixodes scapularis. Blood samples for B. burgdorferi antibody analysis utilizing the SNAP 4Dx Plus and Lyme Quant C(6) tests were collected on Days 27, 49, 63, 77, 91, and 105. Skin biopsies were collected from four different areas of heavy tick attachment from each dog for polymerase chain reaction (PCR) detection of B. burgdorferi on Day 104 or 105. RESULTS: All control dogs demonstrated adequate I. scapularis infestation rates on Day 33 in both studies. In Study 2, on Day 27, one control dog tested positive for B. burgdorferi on the Lyme Quant C(6) test, prior to experimental tick infestation, and therefore was excluded from analysis. A total of eight out of 10 (Study 1) and nine out of nine (Study 2) control dogs tested positive for B. burgdorferi on at least one test after Day 27. One dog in the Credelio Quattro-treated group tested positive for B. burgdorferi on SNAP 4Dx Plus on Day 105 in Study 1 but was negative on all other tests and study days. None of the dogs treated with Credelio tested positive for B. burgdorferi at any point during either study. CONCLUSIONS: The laboratory studies described herein confirm that a single dose of lotilaner, at the minimum effective dosage of 20 mg/kg, administered as Credelio Quattro, in combination with moxidectin, praziquantel, and pyrantel or Credelio, is effective for the prevention of transmission of B. burgdorferi from infected I. scapularis for a full month in dogs.