Journal Article

Efficacy of Credelio Quattro™ (lotilaner, moxidectin, pyrantel, praziquantel) and Credelio™ (lotilaner) against longhorned tick, Haemaphysalis longicornis,-induced infestations on dogs

Whitehead, Liezl, Wiseman, Scott, Momberg, Mandie, Maree, Riaan, Young, Lisa, Savadelis, Molly D.

2025

Overview

Background Haemaphysalis longicornis , the longhorned tick, is an invasive tick species that has been identified in increasing numbers and regions across the USA. This tick species is a competent vector for various pathogens to dogs, humans, and other species, with heavy infestations documented to lead to exsanguination. Therefore, determination of ectoparasiticides providing adequate treatment and control of H. longicornis is imperative to help reduce vector-borne disease transmission and protect against infestation in dogs. Methods Three laboratory studies were conducted to evaluate the efficacy of Credelio Quattro and Credelio for the treatment and control of H. longicornis. A total of 30 dogs per study were randomized to receive either placebo, Credelio Quattro, or Credelio on Day 0 according to a complete block design on the basis of pre-treatment live attached H. longicornis counts, infested on Day −7. To assess efficacy against preexisting infestations, enrolled dogs were infested with 50 unfed adult H. longicornis on Day −2 or −1 prior to treatment. Residual efficacy post-treatment was evaluated with subsequent infestations on Days 5, 12, 19, and 30. All ticks were collected and evaluated as live or dead and free or attached 48 h after treatment or infestation. Results Adequacy of infestation was achieved in at least two studies for every infestation time point evaluated. Both Credelio Quattro and Credelio provided 100% efficacy against H. longicornis from Day 2 through Day 32, with no live ticks observed on any dogs. A statistically significant number of dead ticks were recovered from both treated groups as compared with control on all assessment days. Post-treatment, treatment-related diarrhea was reported in six dogs receiving Credelio Quattro and one dog receiving Credelio on Day 0, with all dogs recovering on Day 1. Conclusions The laboratory studies described confirm the safety and effectiveness of a single dose of Credelio Quattro and Credelio, at the minimum effective dosage of 20 mg/kg lotilaner, 0.02 mg/kg moxidectin, 5 mg/kg praziquantel, 5 mg/kg pyrantel, and 20 mg/kg lotilaner, respectively, for the treatment and control of H. longicornis infestations in dogs for one month. Graphical abstract

• Publisher: BioMed Central,Springer Nature B.V,BMC
• Subject: Acaricides - administration & dosage / adults / Animals / Arachnids / Biomedical and Life Sciences / Biomedicine / Credelio / Credelio Quattro / Diarrhea / Disease transmission / Dog Diseases - drug therapy / Dog Diseases - parasitology / Dogs / ectoparasiticides / Effectiveness / Encephalitis / Entomology / Female / Haemaphysalis longicornis / Infectious Diseases / Infestation / Introduced species / Invasive species / Ixodidae / Ixodidae - drug effects / Longhorned tick / Lotilaner / Macrolides - administration & dosage / Macrolides - therapeutic use / Male / moxidectin / Oxazoles / Parasitology / placebos / Praziquantel / Praziquantel - administration & dosage / Praziquantel - therapeutic use / pyrantel / Pyrantel - administration & dosage / Pyrantel - therapeutic use / species / Statistical analysis / Thiophenes / Tick Infestations - drug therapy / Tick Infestations - parasitology / Tick Infestations - veterinary / Ticks / Treatment Outcome / Tropical Medicine / Vector-borne diseases / Vectors (Biology) / Veterinary Medicine/Veterinary Science / Virology / Zoonoses