Can you use frontline for cats on dogs?

Answer 1

Frontline for cats and dogs are chemically very similar. Frontline Plus for cats contains 100g/L fipronil and 120g/L methoprene. For dogs Frontline Plus contains 100g/L fipronil and 90g/L methoprene. As such, using the dog version on a cat would result in a higher dose of fipronil and lower dose of methoprene.

Fipronil is an insecticide which disrupts insects central nervous systems, and is the portion which kills adult insects. Methoprene is an insecticide which disrupts the reproductive process, preventing larvae from growing into adults. The reason for the variation between the formulas is not clear, and there is not sufficient unbiased and non-anecdotal data to say what effects such slight mis-dosing can cause to the pets.

Answer 2

Frontline, Revolution and Advantage can all be safely used on cats and dogs interchangeably, as the ingredients are identical, you just need to know the correct doses.

Frontline Plus for Dogs contains (fipronil 9.8% and S-methoprene 8.8%)

whereas

Frontline Plus for Cats contains (fipronil 9.8% and S-methoprene 11.8%)

Dogs are given a dose of 0.067ml of Frontline solution per kilogram of bodyweight.

So a 10.0kg dogs need a dose of 0.67ml

an 6.0kg dog only really needs 0.40ml

ALL cats are given a set dose of 0.50ml

The Frontline Plus for cats formula contains exactly the same concentration of Fipronil (the main ingredient which kills fleas, ticks, and lice) as the Frontline Plus for dogs formula.

The only difference is the cat version contains 3% MORE of the ingredient methoprene than the dog formula.

Giving your dog a tiny 3% more methoprene will not harm it. Look up the toxixity of methoprene online for yourself and see.

Methoprene simply acts as a juvenile hormone analogue in fleas, it keeps the fleas "young". The flea larvae are prevented from completing the metamorphosis into adults and subsequently die.

Other Answer:

Frontline for cats and dogs only differs in the concentration of S-methoprene - which cats need more of. The weight differences may impact on the effectiveness of frontline.