The Parasite Killers Choices abound for owners searching for flea and tick remedies. By Mary K. McHale Today's pet owners have a wide choice of flea and tick remedies available through their veterinarian or pet stores. These products range from topical applications to orally administered pills and liquids, many of which are specifically formulated for cats only, for dogs only, or for both dogs and cats. To determine what products to use on your kitten or cat, read the labels and learn the basics about active ingredients in flea and tick products. Isabelle Francais These ingredients fall into two categories: insecticides, (also called adulticides), and insect growth regulators. Insecticides/adulticides kill adult fleas only and ticks. Insect growth regulators do just that — they prevent flea eggs from hatching and prohibit larvae from developing into adult fleas. Used in combination, these active ingredients provide full-range artillery against your pets' fight against fleas and ticks. Whether you're trying to decide to use a collar, shampoo, powder, topical "spot" application, a pill or liquid remedy, each flea and tick product contains differing active ingredient formulas and combinations for toxicity levels appropriate to kill fleas and ticks while guarding the safety of your cat. Product type and use recommendations for kittens and cats vary among products, as do length of effectiveness and kill rate. Always read the labels and follow directions carefully before using any flea and tick product on your kitten or cat. Products specially formulated for dogs only can be toxic, even fatal, to cats. Remember to consult your veterinarian or contact the product manufacturer if you have any questions or concerns regarding these common active ingredients and the types of flea and tick products that contain them. Insect Growth Regulators Lufenuron: This IGR inhibits the synthesis of chitin, a key component in the egg case of the flea and doesn't allow the egg or larva to develop into an adult. Lufenuron is administered by veterinarians only through oral administration or by injection. Methoprene: Once in contact with a cat's skin, this hormonelike IGR is stored in the sebaceous glands, providing protection against fleas, even after a bath. It appears in shampoos, collars, sprays and topical "spot" applications. Nylar: Imitating the hormone that regulates a flea's development, Nylar prevents flea eggs from hatching. It also kills ticks. You can find this ingredient in sprays/mists and topical "spot" applications. Selamectin: This IGR kills adult fleas and prevents eggs from hatching. It also helps protect cats from heartworm, ear mites, roundworm and hookworm. Insecticides/Adulticides Carbaryl: Some product labels list this insecticide by its brand name, Sevin. You'll find this active ingredient in flea and tick collars, powders and sprays/mists. Chlorpyrifos: Also called Dursban, this organophosphate attacks a flea's nervous system, causing certain death. It is commonly found in flea & tick collars. d-Limonene: This natural insecticide derives from citrus fruit. It works on contact by breaking down an adult flea's exterior coating. d-Limonene can be found in shampoos, dips and sprays/mists. Fipronil: Stored in the natural oils of a cat's skin and coat in the sebaceous gland, Fipronil spreads across a pet's skin, killing fleas and ticks on contact. It can be found in topical "spot" applications. Imidacloprid: Found in a topical "spot" solution, available exclusively through veterinarians, this insecticide kills fleas by attacking the nervous system. It spreads quickly over the skin killing adult fleas and reinfesting fleas rapidly. As a treated animal sheds its coat, the imidacloprid will kill fleas and flea larvae in the pet's environment. Pyrethrin: A natural extract of the chrysanthemum flower. This botanical insecticide kills fleas and ticks rapidly; it can be found in shampoos, dips, sprays/mists and powders. Permethrin: A synergized synthetic of pyrethrin. Found in collars, sprays/mists, powders, shampoos and topical "spot" applications. PBO: An acronym for piperonyl butoxide, a synergist that enhances the effectiveness of pyrethrin. You'll find it in some products containing pyrethrins. Nitenpyram: Interfering with a flea's normal nerve transmission, an encounter with nitenpyram follows with rapid death. Nitenpyram comes in a tablet flea remedy available through veterinarians.