In the past decade reports of canine subcutaneous dirofilariosis, caused by the mosquito-transmitted nematode Dirofilaria repens, increased in number in several countries in Europe, along with a rise of human cases. Given the merit to the new approaches for the control and treatment of this
infection, the present study evaluated the efficacy of a single application of the spot-on formulation containing
imidacloprid 10%/
moxidectin 2.5% (Advocate(®), Bayer Animal Health) in the elimination of D. repens microfilariaemia in naturally infected dogs. In September 2009, 18 dogs with a natural
infection by D. repens were enrolled in the study. In October 2009 all the dogs were treated once with Advocate(®) and the presence/absence of circulating MF and skin lesions
after treatment was evaluated monthly until April 2010. From November 2009 to April 2010 15 dogs scored negative for D. repens while one dog remained negative till March 2010 when it died. Two dogs had a recurrence of microfilariaemia in December 2009 and January 2010 respectively. Nine infected dogs showed skin lesions at the beginning of the trial, which disappeared
after treatment in 7 dogs, whereas the other two symptomatic dogs did not show any dermatological improvement until the end of the trial even though they scored negative for D. repens microfilariae. This study demonstrated that a single
dermal administration of Advocate(®) is effective in eliminating microfilariae of D. repens and likely has a certain degree of activity in killing subcutaneous adult worms as well. This study demonstrates the efficacy of Advocate(®) in the treatment of
dermatitis caused by D. repens. Also, these results are of importance towards further control programs aiming to reduce the number of
bites infectious for mosquitoes and the risk of
infection for both humans and dogs.