Vetdrugs 2.0Fipronil is a phenylpyrazole ectoparasiticide used topically for fleas, ticks and biting lice in dogs and cats. Skin and hair-associated distribution supports residual parasite control. Sprays and spot-on products have different delivery characteristics, and combinations with insect growth regulators broaden flea-life-cycle coverage through separate active ingredients.
Group
Phenylpyrazole ectoparasiticide
Mechanism of Action
Fipronil inhibits arthropod GABA-gated and glutamate-gated chloride channels. Loss of inhibitory chloride signaling causes neural hyperexcitation, paralysis and parasite death. Deposition in surface lipids and associated skin structures sustains contact exposure after application. In combination products, immature-flea control may additionally result from an insect growth regulator rather than fipronil’s neurotoxic action alone.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Flea, tick and louse control | 7.5–15 mg/kg | TOPICAL | Once | Do not use in: Rabbits; For 2.5 mg/mL cutaneous spray only: equivalent to 3–6 mL/kg, chosen by coat length to wet down to skin. Do not use this regimen for concentrated spot-ons. |
| Trombicula infestation spray treatment | 7.5–15 mg/kg | TOPICAL | Once | For 0.25% w/v spray, equivalent to 3–6 mL/kg. Treat monthly through the season; selected cases require 14-day intervals. Thoroughly wet typical sites without eye exposure. |
| Historical ear-mite local procedure | Reference only | TOPICAL | A local procedure used 0.05 mL inside each ear canal plus 0.4 mL between the shoulder blades. The solution strength is unstated; do not choose a spot-on or spray concentration by assumption. Assess eardrum and product suitability before any otic treatment. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Flea, tick and louse control | 7.5–15 mg/kg | TOPICAL | Once | Do not use in: Rabbits; For 2.5 mg/mL cutaneous spray only: equivalent to 3–6 mL/kg, chosen by coat length to wet down to skin. Do not use this regimen for concentrated spot-ons. |
| Trombicula infestation spray treatment | 7.5–15 mg/kg | TOPICAL | Once | For 0.25% w/v spray, equivalent to 3–6 mL/kg. Treat monthly through the season; selected cases require 14-day intervals. Thoroughly wet typical sites without eye exposure. |
| Historical ear-mite local procedure | Reference only | TOPICAL | A local procedure used 0.05 mL inside each ear canal plus 0.4 mL between the shoulder blades. The solution strength is unstated; do not choose a spot-on or spray concentration by assumption. Assess eardrum and product suitability before any otic treatment. |
Indications
- Treatment and control of flea and susceptible tick infestations in dogs and cats.
- Treatment of biting-louse infestations with a corresponding canine or feline product.
- Extra-label treatment of selected harvest-mite infestations, cheyletiellosis or sarcoptic mange with a supported species-specific regimen.
Contraindications
- Rabbits
- Hypersensitivity
- Systemically ill or convalescent animals for the Frontline spray described
Interactions
- Avoid combining topical insecticides without a defined compatible regimen.
Adverse effects
- Transient salivation after licking
- Local irritation
- Rare neurologic signs
Toxicity
Accidental ingestion or excessive exposure may cause salivation, tremor and seizures; remove exposure and treat supportively.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Frontline spray 0.25% w/v Mechanical pump cutaneous spray. At 2.5 mg/mL, 3–6 mL/kg provides 7.5–15 mg/kg; pump output depends on pack size. | Other | 2.5 mg / mL | TOPICAL |
| Effipro spray 0.25% w/v Verified active concentration. Confirm this dispenser’s instructions; do not infer its pump output from Frontline bottle sizes. | Other | 2.5 mg / mL | TOPICAL |
Monitoring and Administration
For 0.25% spray, wet the coat to skin at 3–6 mL/kg, depending on coat length. Apply against hair growth from 10–20 cm away; use a gloved hand around the head. Let air-dry.
Pump delivery varies with bottle size. Do not transfer spray pump counts to a different brand or dispenser. Prevent licking until dry and keep away from flames until the coat is dry.
Spray and spot-on regimens are distinct. Combination products containing (S)-methoprene must follow their own complete-pipette instructions.
Other extralabel uses have included sarcoptic mange, cheyletiellosis and ear mites, but no complete regimen for each is supplied. Monthly flea/tick treatment and bathing restrictions are product-specific.
Age limits differ by territory and presentation; the older appendix uses 8 weeks, while separately verified spray labels may differ. Apply the exact product’s limit rather than a blanket rule for all fipronil.