Fleas are tiny parasites that enjoy feasting on warm-blooded animals like cats and dogs. Unfortunately, if you see one flea, the odds are good that there are thousands more lurking in their fur—a female can lay up to 50 eggs per day. "Fleas are the most common external parasite for cats and dogs," says Dr. Carly Fox, an emergency and critical care staff doctor at New York City's Animal Medical Center. "Fleas can make your animals very uncomfortable." What's more, they can also be the cause of serious disease in our pets: Animals that ingest a flea, such as a cat when she is cleaning her fur, could become infected with a tapeworm. Tapeworms steal vital nutrients from our pets, and can prove life-threatening to young and elderly animals.
Even when temperatures fall too low for fleas to survive, they have a knack for seeking out more comfortable accommodations. "It's a common misconception that fleas and ticks are only prevalent during certain seasons or times of year," says Dr. Ari Zabell, a veterinarian with Banfield Pet Hospital. "Although we see flea and tick infestations decrease in parts of the country during the winter months, we continue to see issues persist even in the coldest regions." Banfield's 2018 State of Pet Health Report found that flea-allergy dermatitis has been on the rise over the past 10 years, with a 12 percent increase in dogs and a 67 percent increase in cats. Because of this, a visit to the veterinarian is in order. "We recommend twice-yearly comprehensive exams that include parasite screenings to look for fleas and any other visible external parasite or skin problem," Dr. Zabell says. They will look for signs that your pet is suffering such as biting, scratching, hair loss, red or irritated skin, and poor sleep.
Animals that are over four weeks old can generally be given flea medications like Frontline Plus, Revolution, or Capstar. As with any treatment, you should read the package instructions and consult your veterinarian when giving the medication to your cat or dog. "One of the things that we have seen in the emergency room is flea medication overdose on pets," Dr. Fox says. "An overdose, like applying a topical flea treatment meant for a dog onto your cat or one that's for a larger animal on your smaller dog, can cause twitching, seizures, and even death." So, it is extremely important to choose a medication designated for the weight and species of your pet.
Dr. Fox says that the most effective treatment for both cats and dogs are oral and topical flea medications. At her practice, they often prescribe Capstar to kill off all the adult fleas. Oral flea medications have a 99 percent effectiveness rate, while topical medications have an 88 percent effectiveness rate. "This could be because people are not applying the topical medication correctly or putting the right amount on, or their pet licks it off right away," she says. "Topical flea treatments are very effective at killing the entire life cycle of the flea, as well as killing ticks and lice. Topical treatments can repel fleas as well." Oral medications only target adult fleas and only kill them if they bite your animal.
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For dogs, most veterinarians recommend NexGard, K9 Advantix II, or Frontline Plus. For cats, most veterinarians recommend Frontline Plus, Revolution, Advantage II, or Seresto collars. Some flea treatments can be applied every seven days, while others must have 30 days between applications. The treatment plan that your veterinarian recommends will depend on your pet, the infestation, and your lifestyle (for instance, if your cat spends most of her time outdoors or indoors).
Most topical or oral medications are toxic for newborn kittens and puppies, explains Dr. Fox, but a flea bath can remove adult fleas. "Flea combing is also a great diagnostic tool for identifying if your pet has fleas," she says. You will also want to vacuum your home and wash any of their bedding and toys to prevent reinfestation. When it comes to treating our pets for fleas, it is important to be proactive. "The saying is that if you see one flea, there are bound to be thousands more in your environment," explains Dr. Fox. "You'll want to treat your animal for fleas but also where they sleep and play."