Prescription Flea Medicine For Dogs & Cats | Comfortis (spinosad)

While most dogs can tolerate ivermectin, some breeds such as collies, shetland sheepdogs and other herding dogs, will have an adverse, even fatal, reaction to it. A recently introduced test makes it possible to assess whether ivermectin will be dangerous to your dog. Ask your vet for details on testing. There is also a caution related to using ivermectin simultaneously with Comfortis®, a relatively new flea control product. When used together, side effects are more likely to occur.

If necessary, you can administer Comfortis like you would other tablet medications.

Cats - In a margin of safety study, COMFORTIS was administered orally to 14-week-old kittens at 1X, 3X, and 5X the upper half (75-100 mg/kg) of the therapeutic dose band for six monthly dosing intervals 28 days apart. Vomiting was observed across all groups, but was seen with greater frequency in cats in the treated groups; it did not increase with increasing doses. Loose stool was observed in all but the 3X treatment group. Food consumption was decreased in the 5X female cats. COMFORTIS was not associated with clinically significant changes in hematology, clinical chemistry, coagulation, or urinalysis parameters. Minor elevations were seen in ALT, AST and cholesterol values in clinical chemistry but were not associated with any clinical signs. Cats demonstrated cytoplasmic vacuolation, consistent with phospholipidosis, in the liver, lung, and adrenal gland. The long term effects of phospholipidosis are unknown. One cat in the 3X group had an enlarged thyroid/parathyroid gland found at necropsy. Higher liver weights occurred in cats in the 3X and 5X group that correlated with hepatocellular vacuolation and hypertrophy. There was no indication of any detrimental effects based on clinical chemistries and anatomical changes. The administration of COMFORTIS was not associated with any clinically significant, gross necropsy or histopathological changes.

What Is Comfortis (spinosad) Flea Treatment?

The same regimen for Comfortis can be applied in administering Trifexis for dogs. In a margin of safety study, COMFORTIS was administered orally to 6-week-old Beagle puppies at average doses of 1.5, 4.4, and 7.4 times the maximum recommended dose at 28-day intervals over a 6-month period. Vomiting was observed across all groups, including the control. Increased vomiting was observed at elevated doses, usually within 1 hour following administration. Vomiting at all doses decreased over time and stabilized when puppies were 14 weeks of age. The average daily and total weight gains of treated dogs were smaller than control dogs and were dose dependent. COMFORTIS was not associated with clinically significant changes in hematology, clinical chemistry, coagulation or urinalysis parameters. Phospholipidosis (vacuolation) of the lymphoid tissue was seen in some dogs in the 4.4X group and all dogs in the 7.4X group. The long term effects of phospholipidosis are unknown. Treatment with COMFORTIS was not associated with any other clinically significant adverse clinical observations, gross necropsy or histopathological changes.

Frequently Asked Questions | Comfortis (spinosad)

In a dose tolerance study, COMFORTIS was administered orally to adult Beagle dogs at average doses of up to 100 mg/kg once daily for 10 consecutive days (16.7 times the maximum recommended monthly dose). Vomiting was seen in 5 of 6 treated dogs during the first 6 days of treatment, usually within 2.5 hours of dosing. Treated females lost weight early in the treatment period, but their weights were similar to control dogs by the end of the 24-day study. COMFORTIS was not associated with any clinically significant changes in hematology, blood coagulation or urinalysis parameters; however, mild elevations in ALT occurred in all dogs treated with COMFORTIS. By day 24, ALT values had returned to near baseline levels. Phospholipidosis (vacuolation) of the lymphoid tissue was seen in all dogs treated with COMFORTIS, the long-term effects of which are unknown.

For dogs: The most common adverse reaction reported is vomiting.