Objective—To evaluate the safety of moxidectin
administration at doses of 30, 60, and 90 µg/kg of
body weight (10, 20, and 30 times the manufacturer's
recommended dose) in avermectin-sensitive Collies.
Procedure—Collies with mild to severe reactions to
ivermectin challenge (120 mg/kg; 20 times the recommended
dose for heartworm prevention) were used.
Six replicates of 4 dogs each were formed on the basis
of body weight and severity of reaction to ivermectin
test dose. Within replicates, each dog was randomly
allocated to treatment with oral administration of 30,
60, or 90 µg of moxidectin/kg or was given a comparable
volume of placebo tablet formulation. Dogs were
observed hourly for the first 8 hours and twice daily
thereafter for 1 month for signs of toxicosis.
Results—Signs of toxicosis were not observed in any
control group dog throughout the treatment observation
period. Likewise, signs of toxicosis were not
observed in any dog receiving moxidectin at 30, 60, or
Conclusions and Clinical Relevance—The moxidectin
formulation used in the study reported here
appears to have a wider margin of safety than ivermectin
or milbemycin in avermectin-sensitive Collies.
(Am J Vet Res 2000;61:482–483)
Objective—To evaluate the safety of dermal application
of 10.0% imidacloprid-0.08% ivermectin in ivermectin-
sensitive Collies at dose rates of 3 to 5 times
the proposed maximum therapeutic dose.
Animals—15 Collies (5 males and 10 females) that
were confirmed as ivermectin-sensitive dogs.
Procedure—Dogs were assigned to 3 treatment
groups (control, 3×, or 5× group) in a randomized
block design on the basis of the maximal ivermectinsensitivity
score obtained during preliminary screening.
Dogs in groups 3× and 5× were treated at 3 and
5 times the maximum label dose, respectively.
Control dogs received an application of an equal volume
of a nonmedicated solution. Observation and
scoring on all days were conducted to specifically
include neurologic signs typical of ivermectin toxicosis,
including lethargy, ataxia, abnormal mydriasis, and
Results—None of the dogs had clinical abnormalities
during the study period.
Conclusions and Clinical Relevance—Analysis of
results of this study indicates that dermal application
of 10.0% imidacloprid-0.08% ivermectin is safe for
use in ivermectin-sensitive Collies at dose rates of 3
or 5 times the proposed maximum therapeutic dose.
( Am J Vet Res 2004;65:277–278)