Isoxazolines in Small Animal Practice: Clinical Applications and Safety

Isoxazolines, including afoxolaner, fluralaner, lotilaner, and sarolaner, represent an important advancement in the control of ectoparasites in dogs. Available in multiple oral and topical formulations, these products may be combined with other active ingredients depending on regional licensure and prescribing guidelines. Isoxazolines have been used effectively in the management of demodicosis, sarcoptic mange, and lice infestations in clinical studies, though individual patient response may vary. 

Canine Demodicosis^1,2,3,4,5,6 

Demodicosis, caused by proliferation of Demodex mites, commonly presents with alopecia, erythema, and crusting. Clinical studies suggest the following outcomes: 

• Oral afoxolaner: In multiple studies involving 253 dogs, mite reduction ranged from 82–100%, with few adverse events reported. 

• Oral/topical fluralaner: In studies involving 373 dogs, oral or topical administration was associated with mite clearance in most cases, typically by Day 56–84, without significant adverse events. 

• Oral lotilaner: Case series indicate that dogs treated orally three times at 28-day intervals achieved mite-free status by Day 70, without reported adverse effects. 

• Oral sarolaner: Controlled and field studies suggest efficacy in clearing mites by Day 44–150. Comparisons with imidacloprid/moxidectin spot-on formulations generally favored sarolaner, with no major adverse events reported. 

Canine Sarcoptic Mange (Scabies)^1,7,8 

Saroptic mange is a highly pruritic and contagious condition caused by Sarcoptes scabiei var. canis. Isoxazolines have been associated with favorable clinical outcomes: 

• Oral afoxolaner: In controlled studies and case series, dogs treated once or twice were largely mite-free within 28–60 days, with no serious adverse effects reported. 

• Oral/topical fluralaner: Single-dose oral or topical treatments were associated with mite clearance in 14–56 days in the studies reviewed, with minimal adverse effects reported. 

• Oral lotilaner: Dogs treated orally three times, 30 days apart, were reported mite-free at Day 30 without adverse effects. 

• Oral sarolaner: Laboratory and field studies indicate clearance by Day 30–60. Sarolaner was generally non-inferior to imidacloprid/moxidectin spot-on treatments, with no major adverse effects. 

Canine Lice Infestation^1,9 

• Oral fluralaner: Single-dose treatment of dogs with Linognathus setosus infestation led to lice-free status by Day 28, reportedly outperforming permethrin spot-on. 

• Oral sarolaner: One case of Heterodoxus spiniger infestation was resolved 28 days after oral sarolaner administration, with no adverse effects reported. 

Dosage and Administration Considerations¹ 

• Fluralaner and lotilaner are recommended to be administered with food to optimize absorption. 

• Afoxolaner and sarolaner may be administered with or without food. 

• Follow label dosage recommendations for flea, tick, and mite control, and adhere to minimum age and body weight requirements. 

• Individual patient response should be monitored, and repeated or extra-label use should follow veterinary clinical judgment. 

Safety Profile¹ 

Isoxazolines are generally well-tolerated, though potential adverse effects have been reported, including: 

• Vomiting 

• Diarrhea 

• Anorexia 

• Lethargy 

• Seizures 

Use cautiously in patients with a history of neurological disorders or seizures. All treatments should be administered under veterinary supervision, with monitoring for potential adverse events. 

Medico-Legal Considerations 

• Adverse effects should be documented in patient records and reported to relevant regulatory authorities where applicable. 

• Clinicians should discuss potential risks, benefits, and alternative treatment options with clients. 

• Individual patient variability should always be emphasized, and therapeutic decisions should follow evidence-based guidelines and product labeling. 

Conclusion 

Isoxazolines have expanded therapeutic options for canine demodicosis, sarcoptic mange, and lice infestations, offering convenient dosing schedules and generally favorable safety profiles. While clinical studies report high efficacy and minimal adverse events, veterinarians should continue to assess patient suitability, monitor treatment response, and inform clients of potential risks, ensuring safe and responsible use. 

References  

1. Defalque VE. Isoxazolines for treating canine demodicosis, sarcoptic mange (scabies), and lice infestation. The Canadian Veterinary Journal. 2022 Nov;63(11):1159. https://pmc.ncbi.nlm.nih.gov/articles/PMC9558591/pdf/cvj_11_1159.pdf  

2. Beugnet F, Halos L, Larsen D, de Vos C. Efficacy of oral afoxolaner for the treatment of canine generalised demodicosis. Parasite. 2016 Mar 24;23:14. https://pmc.ncbi.nlm.nih.gov/articles/PMC4807374/pdf/parasite-23-14.pdf  

3. Chávez F. Case report of afoxolaner treatment for canine demodicosis in four dogs naturally infected with Demodex canis. International Journal of Applied Research in Veterinary Medicine. 2016 Jan 1;14(2):123-7. https://jarvm.com/articles/Vol14Iss2/Vol14%20Iss2%20Chavez.pdf  

4. Mueller R, Shipstone M. Update on the diagnosis and treatment of canine demodicosis. Advances in Veterinary Dermatology. 2017 Jun 12;8:206-9. https://onlinelibrary.wiley.com/doi/pdf/10.1002/9781119278368.ch7.4  

5. Lebon W, Beccati M, Bourdeau P, Brement T, Bruet V, Cekiera A, Crosaz O, Darmon C, Guillot J, Mosca M, Pin D. Efficacy of two formulations of afoxolaner (NexGard® and NexGard Spectra®) for the treatment of generalised demodicosis in dogs, in veterinary dermatology referral centers in Europe. Parasites & Vectors. 2018 Sep 10;11(1):506. https://link.springer.com/content/pdf/10.1186/s13071-018-3083-2.pdf  

6. Romero-Núñez C, Guiliana Bautista-Gómez L, Sheinberg G, Martín A, Romero A, Flores A, Heredia R, Miranda L. Efficacy of Afoxolaner Plus Milbemycin Oxime in the Treatment of Canine Demodicosis. International Journal of Applied Research in Veterinary Medicine. 2019 May 1;17(2). https://jarvm.com/articles/Vol17Iss1/Vol17%20Iss1%20Gomez.pdf  

7. Romero-Núñez C, Bautista-Gómez LG, Sheinberg G, Martín-Cordero A, Flores-Ortega A, Heredia-Cárdenas R. Efficacy of afoxolaner plus milbemycin oxime and afoxolaner alone as treatment for sarcoptic mange in naturally infested dogs. Canadian Journal of Veterinary Research. 2020 Jul 1;84(3):212-6. https://pmc.ncbi.nlm.nih.gov/articles/PMC7301669/  

8. Moog F, Brun J, Bourdeau P, Cadiergues MC. Clinical, parasitological, and serological follow‐up of dogs with sarcoptic mange treated orally with lotilaner. Case reports in veterinary medicine. 2021;2021(1):6639017. https://scholar.google.com/scholar?output=instlink&q=info:_WyOm23eLYIJ:scholar.google.com/&hl=en&as_sdt=0,5&scillfp=7052063869873067970&oi=lle  

9. Kohler-Aanesen H, Saari S, Armstrong R, Péré K, Taenzler J, Zschiesche E, Heckeroth AR. Efficacy of fluralaner (Bravecto™ chewable tablets) for the treatment of naturally acquired Linognathus setosus infestations on dogs. Parasites & Vectors. 2017 Sep 18;10(1):426. https://link.springer.com/content/pdf/10.1186/s13071-017-2344-9.pdf