Have you ever looked at the ‘large dog’ sized flea control product and wondered whether you could just buy it and split it between your three small dogs? Or have you run out flea treatment product for your cat and been tempted to give it a leftover from your dog?  This is a bad idea! I recommend that you stick to the manufacturer’s guidelines and save yourself a lot of trouble.

While it may seem more economical or convenient to share flea control products between your pets, there are good reasons for the manufacturer’s guidelines printed on your packet. They aren’t there to rip you off. The dosages listed on the flea treatment products are there because they have been tested and found to be safe for use at that dose. If you use products contrary to the directions on the packaging you will potentially end up wasting your money, or worse, losing a pet.

Sharing between pets of the same species is bad because it is too easy to get the dosage wrong. Most top-spot flea control products are administered in very small volume doses. This means that it is easier and less messy to apply, but it also means that the products are more concentrated. Small differences in volume given can mean big differences in amounts of medication given. Also, the active ingredients may not be well mixed, and different parts of the dose may have different concentrations. Getting the dose wrong is bad either way: give too little and the product won’t have its intended effect and you have wasted your money. Give too much and you risk poisoning which could cost you a lot of money and heartache.

Sharing between dogs and cats is a really bad idea! Cats are very sensitive to some flea control products, for example permethrin. This drug is registered for use in dogs as a flea control product, and works fine for them. If you put the same product on a cat, you will likely cause permethrin poisoning in the cat, which leads to tremors, seizures, hyperthermia and even death. Cats are so sensitive to this product that they can even show signs of poisoning from licking the area where the medication was applied.  

All in all, it is simply not worth it to share flea treatment products between your pets. On the surface, it seems like you might be saving money. However, if you take into account the money wasted on ineffective treatments and in the worst case, a trip to the vet, then the savings you might make seem a lot less attractive.