Safety of a topically applied metaflumizone spot-on formulation for flea control in cats and kittens.

Four laboratory studies were conducted in cats of various ages to evaluate the safety of a novel low-volume topical spot-on containing 20% metaflumizone (ProMeris for Cats, Fort Dodge Animal Health, Overland Park, KS) when used in cats according to the recommended minimum dosage of 40mg metaflumizonekg(-1) delivered via fixed volume doses of 0.8ml for cats </=4.0kg and 1.6ml for cats >4.0kg. Study parameters included body weight, food consumption, clinical, physical and neurological examinations, and clinical pathology including complete hematology, coagulation, clinical chemistry and urinalysis. Exaggerated and repeated topical applications of metaflumizone at 1x, 3x and 5x the proposed recommended dose in adult cats and kittens 8 weeks of age had no effect on mortality, body weight, food consumption, clinical, physical or neurological examinations, or clinical pathology parameters. Transient salivation was sporadically noted following some, but not all treatment applications. It occurred and resolved within minutes of treatment application in all groups, including cats treated with placebo. Consequently, it was not considered a direct result of treatment with the active ingredient, metaflumizone. Cats orally administered 10% of the recommended topical dose exhibited considerable avoidance behaviors including spitting, head shaking, and salivation. Therefore, voluntary oral exposure is unlikely. No other adverse signs were observed. Repeated use of metaflumizone caused no adverse health effects when administered at 5x the recommended dose and is safe when used as directed, even on kittens as young as 8 weeks of age.