Luckily, pet parents have more choices than ever to treat parasites that harass their four-legged pals. When considering flea and tick protection for kittens and puppies, your first step should be a visit to your veterinarian to discuss options that are right for your situation.

Because many insecticide-based treatments are unsafe for animals 7-8 weeks and younger, Dr. Michael “Dr. Flea” Dryden, DVM, Ph.D., a veterinary parasitologist with Kansas State University in Manhattan, Kansas, recommends asking about non-chemical alternatives. 

Some chemical and non-chemical kitten and puppy flea treatments include:

• Flea combs
• Flea collars
• Pills and chews
• Gentle flea shampoos

Regardless of which one you pick, they all have one primary purpose: to repel, kill or remove adult fleas before they lay eggs on your pet or in your home.

A flea comb, like the Safari flea comb, might be your best bet if you have a dog or cat in your house who is too young (less than 7-8 weeks old or so) for other options. It enables you to manually check your pet’s coat for fleas and ticks and makes it easier for you to remove the pests from their skin, Dr. Dryden says.

“As soon as they’re old enough, place them on a veterinarian-recommended topical or oral flea and tick product, and never take them off,” Dr. Dryden says.

Cat and dog flea & tick collars, spot-ons and other insecticide-based treatments generally fall into two categories: topical and systemic.

• Topical treatments: “Topical treatments, like [some] spot-ons and collars, stay on the surface and distribute over the body, and then work when fleas or ticks contact or feed upon the surface,” says Dr. Dwight Bowman, Ph.D., professor of parasitology at Cornell University College of Veterinary Medicine in Ithaca, New York.
• Systemic treatments: Systemic treatments can be applied topically or taken orally and are absorbed into the dog’s blood stream. When a flea or tick feeds, it takes in the chemical.

How it works: The active ingredients in the topical and systemic treatments eradicate the insects in various ways, Dr. Dryden says. Some kill adult fleas and ticks. Others kill the larvae or sterilize the eggs. And still others prevent the insects from developing or growing. Some products contain multiple active ingredients to hit the parasites at several points in their lifecycles.

The bottom line: “The idea is either we’re going to kill the fleas before they lay eggs, or we’re going to kill their eggs,” Dr. Dryden says. “The products we’re using today have been designed to have pronounced residual activity, so when a flea or tick jumps on two to three weeks after you’ve treated the animal, the vast majority of them are going to die before they even lay an egg.”

Check the product’s label to make sure it’s formulated for use on your particular pet—including their species, age and weight. Also take a look at the active ingredients to be sure you’re targeting the right parasite. Of course, your vet can let you know which treatment and which product is best for your pet.

Below, you’ll find a list of the most common active ingredients in topical and systemic treatments that are available over the counter or through your veterinarian:

• Permethrin is a pyrethroid, a synthetic form of pyrethrin.
• Pyrethrins are natural flea, tick and parasite-repelling compounds found in certain types of flowers, like chrysanthemums. Pyrethrins can be quite safe, including for cats, but are not very effective, according to Jennifer Coates, DVM, a veterinarian in Fort Collins, Colorado.

Note that permethrin-based chemicals are only safe for dogs; they are toxic to cats of all ages. This is not to be confused with pyrethrins.

Always follow the label instructions on the product you are using. Formulations and instructions can change without notice.

Those little bloodsuckers can cause distress and anemia in young animals, not to mention skin irritation or worse, Dr. Dryden says.

“Fleas are the most common cause of flea allergy dermatitis in dogs and cats in North America,” he says. “The most common skin disease dogs and cats get is associated with the allergic conditions as a result of the fleas biting and feeding. So obviously, they’re bad. And they can transmit pathogens, too, to other dogs and cats, as well as to people. By the time you notice fleas on your pet, it’s too late. They’re just the tip of the iceberg.”