September 26, 2018

Combined Use of Frontline Tri-Act and NexGard Spectra

A recent study evaluated efficacy of the 2 drugs in an endemic region for canine Leishmania and Dirofilaria immitis infections.
By Natalie Stilwell, DVM, MS, PhD
ticksResearchers in Italy recently examined safety and efficacy associated with combined use of 2 new antiparasitic products (Frontline Tri-Act and NexGard Spectra, both manufactured by Merial, now part of Boehringer Ingelheim) in client-owned dogs. The authors aimed to determine an effective prophylactic regimen against ectoparasites, endoparasites, and vector-borne diseases in endemic regions. Intestinal nematode infection is common in Italy, and canine leishmaniasis and dirofilariasis have overlapping distributions.

Study Design
Apparently healthy, client-owned dogs in endemic regions of southern Italy underwent initial screening for internal and external parasites and vector-borne diseases.

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Assessment included:
  • physical examination
  • fecal examination
  • CBC
  • Modified Knott’s test for D immitis
  • Rapid ELISA for Leishmania, Anaplasma, Borrelia, Ehrlichia, and D immitis 

Frontline Tri-Act (fipronil/permethrin) and NexGard Spectra (afoxolaner/milbemycin oxime) were then administered every 28 days for 6 months, and diagnostic tests were repeated throughout the study to re-evaluate parasite burdens.

Results
Thirty-seven dogs with a mean age of 3.6 years and weight range of 3.4 to 32 kg completed the study. All dogs either lived in single-pet households or in 1 of 3 kennels consisting of multiple hunting dogs.

No adverse events were observed from concurrent administration of Frontline Tri-Act and NexGard Spectra, and all biological parameters, including weight, body condition, and hematological parameters, remained within physiological limits throughout the study.

At the beginning of the study, 19% and 84% of pet and hunting dogs, respectively, were infected with gastrointestinal nematodes, mostly consisting of Trichuris vulpis and Ancylostomatidae. Fourteen days after the first administration of Frontline Tri-Act and NexGard Spectra, 40% of hunting dogs continued to shed eggs. All pet dogs remained nematode-free from Day 14 until the end of the study, while several hunting dogs continued to shed hookworm eggs for the study’s duration.  

Nineteen percent of pet dogs and 84% of hunting dogs were infested with fleas at the beginning of the study, while 98% of all dogs were flea-negative 1 day after Frontline Tri-Act and NexGard Spectra administration. Four weeks later, 28% of hunting dogs again had flea burdens, but the authors noted most fleas were dead or moribund.

Ticks were initially observed on 6% and 12% of pet and hunting dogs, respectively, but dogs were all tick-free from Day 14 until the end of the study. While 6 hunting dogs were serologically positive for Leishmania at the beginning and end of the study, all other dogs tested negative for Leishmania, Anaplasma, Borrelia, Ehrlichia, and D immitis.

Final Thoughts
The study’s authors deemed that combined use of Frontline Tri-Act and NexGard Spectra for 6 months was safe and effective against endo- and ecoparasite infections in client-owned dogs. Although all dogs appeared clinically healthy, many were infected with intestinal parasites on initial examination. Also, hookworm infections were particularly persistent in kennel-housed dogs, which may necessitate milbemycin oxime dosing every 2 weeks for initial control, according to the authors.

 
Dr. Stilwell received her DVM from Auburn University, followed by a MS in fisheries and aquatic sciences and a PhD in veterinary medical sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.

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