October 06, 2016

Efficacy of Afoxolaner and Fluralaner Against Sarcoptes scabiei Infestations in Dogs

In two recently published studies, afoxolaner and fluralaner eliminated Sarcoptes scabiei infestations and improved clinical signs of sarcoptic mange in dogs.
By Laurie Anne Walden, DVM, ELS
In two recently published studies, afoxolaner and fluralaner eliminated Sarcoptes scabiei infestations and improved clinical signs of sarcoptic mange in dogs. The afoxolaner trial was published in Parasite and the fluralaner trial was published in Parasites & Vectors.
 
The trial of afoxolaner (NexGard; Merial Inc, Duluth, GA) included 20 client-owned dogs with naturally occurring infestations of S scabiei var. canis. Ten dogs received oral afoxolaner on days 0 and 28 at the label dose. Ten control dogs received no treatment. Researchers performed skin scrapes and assessed pruritus, crusts, and alopecia on days −1/0, 28, and 56. All dogs in the treatment group and one dog in the control group were completely free of mites on days 28 and 56. In the treatment group, pruritus, crusts, and hair loss were significantly improved at day 56 compared with baseline. At the end of the study, afoxolaner was offered to owners of the control dogs, and five of these dogs were re-evaluated 28 days later. A single mite was found on one dog.
 
Fluralaner (Bravecto; Merck Animal Health, Madison, NJ) is available as oral and topical formulations. The fluralaner trial included 29 client-owned dogs with natural S scabiei infestations. Dogs living in the same household were also treated but were not included in efficacy calculations. Nine dogs received a single oral dose of fluralaner (minimum dose, 25 mg/kg). Eleven dogs received a single topical dose of fluralaner solution (25 mg/kg). Nine control dogs received topical saline. Skin scrapings and clinical assessments were performed four weeks later. After four weeks, mite counts were reduced by 100% in all dogs in the treatment groups and in three control dogs. Most clinical signs of S scabies infestation improved to some degree in both treatment groups, but scales increased. The authors attributed the variability in clinical sign resolution to local irritation caused by dead mites.
 
Authors of the afoxolaner trial concluded that oral afoxolaner cured S scabies infestation in one month and resolved clinical signs in most dogs by two months. Because a single mite was found in one of the control dogs treated with afoxolaner at the end of the study, they suggest that “a second treatment is probably needed to reach complete antiparasitic efficacy in any case.”
 
“Fluralaner administered either orally or topically to naturally infested dogs eliminates Sarcoptes scabiei var. canis mites and improves clinical signs over a 4 week observation period,” write the authors of the fluralaner trial, adding that the study period may have been too short to document resolution of all clinical signs. They suggest that a single dose of fluralaner may provide longer control of scabies, given that it is effective against fleas and ticks for up to 12 weeks.
 
Both trials were conducted by ClinVet, a South African contract research organization, and were sponsored by the product manufacturers. All authors of both studies are employees of either ClinVet or the product manufacturers.
 
 
Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC.
 

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