Objective—To determine whether treatment with
selamectin would reduce clinical signs of flea allergy
dermatitis (FAD) in dogs and cats housed in flea-infested
Design—Randomized controlled trial.
Animals—22 dogs and 17 cats confirmed to have FAD.
Procedure—Animals were housed in carpeted pens
capable of supporting the flea life cycle and infested
with 100 fleas (Ctenocephalides felis) on days –13 and
–2 and on alternate weeks with 10 to 20 fleas. On day
0, 11 dogs and 8 cats were treated with selamectin (6
mg/kg [2.7 mg/lb]). Dogs were retreated on day 30;
cats were retreated on days 30 and 60. All animals
were examined periodically for clinical signs of FAD.
Flea counts were conducted at weekly intervals.
Results—Throughout the study, geometric mean flea
counts exceeded 100 for control animals and were ≤ 11
for selamectin-treated animals. Selamectin-treated
cats had significant improvements in the severity of
miliary lesions and scaling or crusting on days 42 and
84, compared with conditions on day –8, and in severity
of excoriation on day 42. In contrast, control cats did
not have any significant improvements in any of the
clinical signs of FAD. Selamectin-treated dogs had significant
improvements in all clinical signs on days 28
and 61, but in control dogs, severity of clinical signs of
FAD was not significantly different from baseline severity
at any time.
Conclusions and Clinical Relevance—Results suggest
that topical administration of selamectin, even without
the use of supplementary environmental control
measures and with minimal therapeutic intervention,
can reduce the severity of clinical signs of FAD in dogs
and cats. (J Am Vet Med Assoc 2003;223:639–644)