Experimental treatment of dog lice infestation in interior Alaska wolf packs

Biting dog lice (Trichodectes canis) were first detected on wolves (Canis lupus) in Southcentral
Alaska (USA) in 1981 introduced via domestic dogs. Lice infestation expanded north via wolf dispersal to the
Tanana Flats of Interior Alaska in December 2003. Effects of this ectoparasite on wolves were persistent with
moderate to severe clinical signs of pediculosis lasting multiple generations. Our objectives were to evaluate
the extent of lice infestation on wolves within the Tanana Flats and develop a management program that
limited further transmission. We implemented a treatment method that consisted of multiple applications of
oral antiparasitic ivermectin-injected baits aerially distributed at den and rendezvous sites during mid-May
through August. During 2005–2010, we evaluated 12–19 packs annually as part of a treatment group and
3 infested packs as a control. Infestation rates of treatment packs prior to treatment varied from 15% in 2005
(2 of 13), 50% in 2006 (7 of 14), 24% in 2007 (4 of 17), 5% in 2008 (1 of 19), and 0% in 2009–2010 (0 of 19).
We treated 50%, 71%, and 75% of the infested treatment packs during 2005–2007, respectively. All treated
packs were lice-free the winter following treatment, whereas all 3 control packs remained infested. The
combination of treatment and harvest successfully eliminated the local source population of lice within 3 years
and we found no evidence of lice infestation within the treatment area during the last 3 years of the study. By
using this treatment method, managers can eliminate dog lice infestations of wolves in areas 13,000 km2
.
By initiating treatment promptly after detection, transmission to unexposed nearby packs can be postponed
and the local source population of lice on wolves eradicated.