A new hope for defeating demodicosis?

A new foe for the agony of the feet (and other affected areas)? (Getty Images)Wouldn't it be handy if every time you saw a puppy with demodectic mange you could be the hero and say, “Here, just use this medication that you need for fleas and ticks anyway”?

Unfortunately, cutaneous demodicosis is still prevalent in general practice. This inflammatory parasitic disease in dogs is characterized by an increased number of Demodex species mites on the skin. These mites, in low numbers, are considered a normal resident of canine skin, but an overgrowth causes clinical dermatitis. Two types of clinical disease are recognized-localized and generalized-and the distinction between the two is somewhat subjective.

Veterinarians dream of an effective and convenient way to manage this disease because clients do not enjoy the long term daily medications, medicated dips or frequent rechecks employed in the past. Costly, messy and inconvenient are just not a recipe for compliance.

Sarolaner (Simparica-Zoetis), a new oral parasite medication, has recently come on the market and has been evaluated for efficacy against Demodex species and induced infestations of Otodectes cynotis (otodectic mange) in a study out of South Africa.

The opponent: Demodicosis

Sixteen dogs that tested positive for Demodex species mites and in which generalized demodicosis was diagnosed were randomly assigned to treatment groups. Group 1 was treated with sarolaner (2 mg/kg) orally on days 0, 30, and 60. Group 2 was treated with a topical product containing imidacloprid (dose greater than or equal to 10 mg/kg) and moxidectin (dose greater than or equal to 2.5 mg/kg) solution every seven days from day 0 to day 81.

In the dogs treated with sarolaner, pretreatment mite counts were reduced by 97.1% at 14 days and 99.8% by 29 days after the first dose. No live mites were detected after day 29.

The dogs treated with imidacloprid and moxidectin showed an 84.4 % reduction at 14 days and a 95.6% reduction at 29 days. No live mites were detected after day 59.

All treated dogs showed marked improvement in the clinical signs.

The opponent: Otodectic mange

A second study looked at otodectic mange. Thirty-two dogs with laboratory-induced infestations were randomly assigned to four groups. The first group received oral sarolaner at 2 mg/kg as a single treatment on day 0. The second group received a two-dose regimen on days 0 and 30 also at 2 mg/kg each dose, and there was a placebo group for each protocol. The single oral dose resulted in a 98.2% reduction in mite count at day 30, and the two-dose protocol (administered one month apart) resulted in a 99.5% reduction at day 60 when compared to placebo controls.

There were no treatment-related adverse events in either study.

Other isoxazolines work too!

In these studies, oral sarolaner at a dose of 2 mg/kg seems to be highly effective at reducing live demodectic and otodectic mite counts. A very similar study found that fluralaner (Bravecto-Merck), also in this class of compounds, showed similar efficacy in the treatment of demodicosis.1 And yet another study suggested that a similar efficacy might be expected when afoxolaner (NexGard-Merial) was used.2 However, experts agree that more studies are needed to confirm these observations.

Because young dogs are more often affected and consistent treatment with parasiticides should be recommended as a part of an overall health plan anyway, compliance would potentially be much improved with this drug. Although not approved for treatment of these mites at this time, it is possible that this new use of isoxazoline compounds could make treatment of demodectic mange much more convenient for owners to comply with treatment recommendations and procedures, thereby improving rates of improvement or cure.

Six RH, Becskei C, Mazaleski MM, et al. Efficacy of sarolaner, a novel oral isoxazoline, against two common mite infestations in dogs: Demodex spp. and Otodectes cynotis. Vet Parasitol 2016; epub ahead of print.

Link to article: http://www.sciencedirect.com/science/article/pii/S0304401716300504

References

1. Fourie JJ, Liebenberg JE, Horak IG, et al. Efficacy of orally administered fluralaner (Bravecto) or topically applied imidacloprid/moxidectin (Advocate) against generalized demodicosis. Parasit Vectors 2015;8:187. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394402/

2. Beugnet F, Halos L, Larsen D, et al. Efficacy of oral afoxolaner for the treatment of canine generalised demodicosis. Parasite 2016;23:14. Available at: http://www.ncbi.nlm.nih.gov/pubmed/27012161