OBJECTIVES

The aim of this study was to determine the prevalence of demodectic otitis in dogs with generalized demodicosis and evaluate the efficacy of moxidectin and ivermectin in the treatment of Demodex canis infestation in ears of dogs with generalized demodicosis.

MATERIALS

At the Veterinary Teaching Hospital (HOVET) of FMVZ/USP, Demodicosis is the most common canine parasitic skin disease. 114 cases of canine demodicosis were diagnosed in HOVET between August 1999 and January 2002. Demodex mites were found in the ears of 57 (50%) dogs with generalized demodicosis (GD). The dogs age varies from 3 to 160 months and the weight ranged between 1,5 to 57kg. Moxidectin was administered, orally (0,5mg/kg) every 72 hours to 14 dogs with GD and concurrent demodectic otitis.

On other hand, Ivermectin was administered orally (0,6mg/kg) every 24 hours to 11 dogs with GD and also a concurrent demodectic otitis.

Five days before the initiation of the two therapeutic schedules, a ceruminolytic agent was administered topically in the external ear canal, three times a day for five days.

RESULTS

The average treatment duration was 49,5 days for dogs treated with moxidectin, meaning that no parasites were found in the external ear canal after this time. Three (21%) dogs had side effects: emesis (21%), salivation (7%), tremors (7%).

In the group of dogs treated with ivermectin, the mean treatment duration was 56,6 days, after this period Demodex mites were not observed in the ear canal. Only one dog (9%) showed adverse reactions including sedation, lethargy, salivation and lameness in the right limb.

The treatment for generalized demodicosis with moxidectin and ivermectin were maintained until three negative skin scrapings.

No statistical differences in the average duration Demodectic otitis treatment between moxidectin and ivermectin (p>0,381).

CONCLUSION

Both drugs, moxidectin and ivermectin, were effective and safe to treat demodectic otitis in dogs with generalized demodicosis. However, the moxidectin caused 21% of side effects. It's important note the occurrence of demodectic otitis observed in 50% of the dogs with (GD), because if not treated properly it will result in a chronic otitis externa.

There was no difference in the average treatment duration between moxidectin and ivermectin treatment for demodectic otitis in these animals.