Objective—To determine pharmacokinetics, efficacy, and adverse effects of topically administered selamectin in flea-infested rabbits.
Animals—18 healthy 5-month-old New Zealand White rabbits.
Procedures—On day 0, rabbits (n = 6/group) received topically applied selamectin at doses of 10 or 20 mg/kg or received no treatment. Each rabbit was infested with 50 fleas (Ctenocephalides felis) on days −1, 7, and 14. Live and dead flea counts were performed on days 2, 9, and 16, and treatment efficacy was calculated. Blood samples were collected prior to drug administration and at 6 and 12 hours and 1, 2, 3, 5, 7, 10, 14, 21, and 28 days after treatment for determination of plasma selamectin concentrations via high-performance liquid chromatography with mass spectrometry. Pharmacokinetic parameters were determined.
Results—On day 2, efficacy of selamectin against flea populations of rabbits in the 10 and 20 mg/kg treatment groups was 91.3% and 97.1%, respectively, but by day 9, these values decreased to 37.7% and 74.2%, respectively. Mean terminal half-life and maximum plasma concentrations of selamectin were 0.93 days and 91.7 ng/mL, respectively, for rabbits in the 10 mg/kg group and 0.97 days and 304.2 ng/mL, respectively, for rabbits in the 20 mg/kg group. No adverse effects were detected.
Conclusions and Clinical Relevance—Selamectin was rapidly absorbed transdermally and was rapidly eliminated in rabbits. Results suggested that topical administration at a dosage of 20 mg/kg every 7 days is efficacious for treatment of flea infestation in rabbits. Further studies are needed to assess long-term safety in rabbits following repeated applications.
Objective—To determine efficacy of treatment with a
combination febantel-praziquantel-pyrantel product,
with or without vaccination with a commercial Giardia
vaccine, in dogs with naturally occurring giardiasis.
Animals—16 Beagles naturally infected with Giardia
Procedures—During phase 1, 6 dogs were treated
with the parasiticide for 3 days (4 were also vaccinated).
Four weeks later, all 6 dogs were treated with the
parasiticide again for 5 days and were bathed and
moved to clean cages after the last treatment (phase
2). Nine dogs were treated with the parasiticide for 3
(n = 4) or 5 (5) days and bathed and moved to clean
cages after the last treatment (phase 3). Fecal samples
were collected twice weekly for 24 days after
treatment and tested for cysts with a quantitative zinc
sulfate flotation technique and for Giardia antigen
with an immunoassay.
Results—Dogs in phase 1 were all shedding cysts
again by day 24. In phase 2, only 1 dog shed cysts
after treatment, and shedding was transient (day 17).
In phase 3, neither cysts nor antigen was detected in
fecal samples from 2 of 4 dogs treated for 3 days and
4 of 5 dogs treated for 5 days. In 18 of 57 (31.6%)
fecal samples, cysts were seen, but results of the
immunoassay were negative.
Conclusions and Clinical Relevance—Results suggest
that when a combination febantel-praziquantelpyrantel
product is used to treat dogs with giardiasis,
bathing and changing the environment after treatment
may be more important in preventing recurrence
than duration of treatment. (J Am Vet Med