Flea and Tick Prevention for Dogs and Cats: A Safe Guide

Fleas and ticks are more than an itchy nuisance. Fleas can cause skin allergies, tapeworms and anaemia, and ticks can carry serious diseases. The good news is that prevention is far easier than treating an infestation or an illness.

The catch is that parasite products are medicines, and the wrong one can be dangerous. Some products made for dogs can seriously harm cats. This guide covers how fleas and ticks affect pets, the main types of prevention, how to avoid dangerous mistakes, how to remove a tick, and how to deal with fleas in your home. It’s general information, and your vet should choose the product for your pet.

The short answer

• Use a product made for your pet’s species, weight and age, ideally one your vet recommends.
• Never use a dog flea product on a cat. Some contain permethrin, which can be life-threatening to cats.
• Follow the label exactly. Don’t split doses, double up or mix products without your vet’s advice.
• Prevent year-round if your vet advises it. Fleas can live indoors in any season, and tick risk depends on where you live.
• If fleas are found, treat every pet in the home and the environment, not just the pet you can see them on.
• Check your pet for ticks after time outdoors in risk areas, and remove them promptly and correctly.

Why it matters

Fleas can cause:

• Itching and skin damage
• Flea allergy dermatitis, a strong allergic reaction to flea saliva, where even a few bites cause intense itching and sore skin
• Tapeworms, if a pet swallows an infected flea while grooming
• Anaemia, from heavy infestations, which is particularly dangerous for puppies, kittens and small or sick pets
• Other infections, depending on the region

Ticks can cause:

• Local skin irritation and infection at the bite site
• Tick-borne diseases, which vary by region and tick species. In dogs, examples include Lyme disease, ehrlichiosis, anaplasmosis and babesiosis. Cats can be affected by tick-borne illnesses too, though they’re diagnosed less often.
• In rare cases, tick paralysis in some regions

Which diseases are a risk depends on where you live and travel, so ask your vet about your area. Some diseases can also affect people, which is another reason to check pets and yourself.

Know your enemy: the flea life cycle

When you see fleas on your pet, they’re only a small part of the problem. A commonly cited estimate is that adult fleas on the animal make up a minority of the total population, while eggs, larvae and pupae live in carpets, bedding, cracks and soil.

• Adult fleas feed on your pet and lay eggs, which fall off into the environment.
• Eggs and larvae develop in bedding, carpets and furniture.
• Pupae can stay dormant in a protective cocoon for weeks or months, then hatch when they sense a host. That’s why fleas can seem to come back after you thought they were gone.

This is why effective flea control means treating the pet and the home, and why it often takes weeks to clear an infestation.

Types of prevention

There are several kinds, and different products suit different pets. Your vet can recommend one based on species, age, weight, health, lifestyle and region.

• Spot-on treatments applied to the skin, usually between the shoulder blades. Must be species-specific. Some contain ingredients that are harmful to cats.
• Oral treatments (chewables or tablets) given by mouth, often monthly or less often. Some prevent only fleas, some fleas and ticks. Ask your vet about your pet’s health history, since regulators have issued notices about possible neurological side effects, such as seizures, in a small number of pets given certain oral products, particularly those with a history of seizures or neurological disease.
• Collars, which release active ingredients over months. Check the species, size and age on the label, and follow the instructions for fitting. Keep them away from children and don’t let pets chew each other’s collars.
• Sprays, which can be useful for some pets, but may be disliked, and need careful use.
• Shampoos and dips, which usually give short-term relief and shouldn’t be your only prevention.
• Prescription products, often stronger or more specific. Ask your vet.
• Combination products that also cover worms or heartworm. Heartworm is spread by mosquitoes in some regions, and prevention should come from your vet.

Natural and home remedies. Essential oils, garlic, apple cider vinegar, and “natural” sprays and collars aren’t reliably effective, and some are harmful. Tea tree oil and many other essential oils can be toxic to cats and dogs. Garlic is toxic to both. If you’re interested in a natural approach, ask your vet before using it. See our guide to foods toxic to dogs and foods toxic to cats.

The most important safety rule: dogs and cats are different

Many dog flea and tick products contain permethrin or related ingredients that are very toxic to cats. Even small amounts can cause severe reactions, including tremors and seizures, and sometimes death.

• Never apply a dog product to a cat, and never cut down a dog dose “for a cat.”
• Read the label and check that it’s made for the right species.
• Be careful in homes with both. A cat can be exposed by grooming, cuddling or sleeping beside a dog that was recently treated with a permethrin product, or by licking the application site. Ask your vet how to keep them separate until the product dries, or whether to choose a different product.
• Don’t use a product labelled for a different weight range. Dosing by weight matters, particularly for small and young pets.
• Check age limits. Many products have minimum ages and weights, and puppies and kittens often need specific products.
• Don’t combine products (for example a collar and a spot-on) without asking your vet. Doubling up can be harmful.

If your cat is exposed to a dog product, or shows signs of poisoning, treat it as an emergency. Signs can include drooling, twitching, tremors, vomiting, unsteadiness, hiding and seizures. Contact a vet or an animal poison helpline straight away, and follow their instructions. In the US and Canada, the ASPCA Animal Poison Control Center (888-426-4435) and Pet Poison Helpline (855-764-7661) operate around the clock, and a fee may apply. [Add your local emergency and poison information if you serve readers elsewhere.]

Choosing a product with your vet

Ask your vet:

• Which product suits my pet’s species, age, weight and health?
• Do I need flea only, ticks too, or heartworm cover as well?
• How often, and how long should I protect my pet each year in our area?
• Is it safe with my pet’s other medications, or for pregnant or nursing pets?
• What side effects should I watch for?
• How should I handle multi-pet homes, especially with cats and dogs?

Tell your vet about your pet’s history of seizures, skin problems and any other conditions. Our guide to how to choose a vet can help you find one.

Be careful with online and unregulated products. Counterfeit and incorrectly labelled products exist. Buy from your vet or a reputable, licensed retailer.

How to check for fleas

• Look at your pet’s skin at the base of the tail, the lower back, belly and groin, where fleas congregate.
• Use a fine flea comb, and comb over a white towel or paper. Fleas are small and dark, and flea dirt (their droppings) looks like black specks. Put the specks on damp white paper. If they turn reddish-brown, it’s flea dirt.
• Watch for signs: scratching, biting or licking, hair loss, scabs, red skin, restlessness. Some cats groom away fleas, so you may see hair loss and itching but no fleas.
• Check bedding for flea dirt.

How to check for ticks

Run your hands over your pet’s body after walks in grassy, wooded or bushy places, and during tick season in your area. Check:

• Around the head, ears and neck
• Between the toes and under the legs
• Armpits and groin
• Under the collar, and around the tail

Ticks feel like small bumps, and can be anywhere from pinhead size to a grape when engorged.

How to remove a tick safely

Remove a tick as soon as you find it, because the risk of disease increases the longer it’s attached.

1. Use fine-tipped tweezers or a tick removal tool. Wear gloves if you can.
2. Grasp the tick as close to the skin as possible.
3. Pull straight out with steady, even pressure. Don’t twist, jerk or squeeze the body.
4. Clean the bite area and your hands with soap and water, or an antiseptic suitable for pets.
5. Dispose of the tick by sealing it in a container or bag. Some owners keep it in a labelled container so a vet can identify it if signs appear.
6. Watch the site and your pet over the following weeks.

Don’t use petroleum jelly, nail polish, alcohol, matches or other home methods. They don’t work and can make the tick release more saliva into your pet.

If the tick’s head stays in the skin, don’t dig for it. Clean the area and ask your vet. Call your vet if the area becomes red, swollen or discharges, or your pet seems unwell. Signs of tick-borne disease can appear days to weeks after a bite, and include fever, lethargy, loss of appetite, lameness, swollen joints, and bruising. Many vets recommend discussing tick prevention and testing with you based on your region.

Dealing with fleas in your home

If you find fleas, treat everything at once:

1. Treat all pets in the household with a vet-recommended product, including indoor-only cats.
2. Wash pet bedding and soft items in hot water, and dry on a hot setting.
3. Vacuum thoroughly and often, including carpets, rugs, furniture, cracks and under furniture. Empty or bin the vacuum contents straight away, outside.
4. Treat the environment if needed. Ask your vet about safe household flea products, and follow the label carefully. Keep pets and children away from treated areas as directed. Some household products are dangerous for pets, particularly cats and fish.
5. Be patient. Because pupae can lie dormant, it can take several weeks to clear an infestation, and you should keep treating your pets during that time.
6. Treat the garden and outdoor areas only with advice, since many products are harmful to wildlife and pets.

Don’t use “bug bombs” or foggers without careful consideration and your vet’s advice. They’re often ineffective and can be hazardous.

Tapeworms and other worms

Fleas can carry tapeworm eggs, and pets that swallow an infected flea can develop tapeworms. You might see small rice-like segments near the tail or in the stool. Flea treatment doesn’t remove existing worms, so ask your vet about worming, and about the right treatment for your pet. Many flea products do not cover worms. Heartworm, roundworm and other parasites each need their own prevention, which varies by region.

Puppies, kittens and special cases

• Puppies and kittens need products suited to their age and weight. Don’t use adult products. Heavy flea infestations can cause anaemia in very young animals, so contact your vet if you find fleas on a puppy or kitten. See our guides to new puppy care and kitten food and care.
• Pregnant or nursing pets: ask your vet which products are safe.
• Pets with seizures, skin disease, or other health conditions: ask your vet which product is appropriate.
• Senior pets: ask your vet, since older pets with health conditions may need adjusted choices. See our guide on senior pet food and care.
• Small pets, such as rabbits and ferrets, need their own products. Dog and cat treatments can be dangerous for them.
• Fish tanks and birds: some flea products are toxic to fish and birds, so take care when treating the home.

Skin problems and itching

Not every itch is fleas. Allergies, mites, infections and other conditions can look similar. If your pet is itching, licking or scratching, ask your vet. Don’t change your pet’s diet to treat itching without talking to your vet.

Handling products safely

• Wash your hands after applying treatments.
• Keep children away from treated areas of your pet until the product is dry, and follow label guidance on handling and cuddling.
• Store products safely, out of reach of children and pets.
• Dispose of used products as directed.
• Keep the packaging so you can tell your vet or a poison helpline exactly what your pet was given.

Mistakes to avoid

• Using a dog product on a cat
• Splitting or combining doses without vet advice
• Treating only one pet in a multi-pet home
• Treating only the pet, and ignoring the home
• Stopping treatment too early, while the environment is still infested
• Using “natural” remedies, essential oils or home treatments without checking they’re safe
• Pulling ticks off with home tricks
• Using the wrong weight or age range
• Buying unregulated or suspicious products
• Ignoring signs of illness after a tick bite

When to call your vet

Contact your vet if:

• Your pet has a flea or tick problem, or you’re not sure which product to use
• You find ticks, especially in an area with tick-borne disease
• Your pet is itching intensely, or has sore skin, scabs or hair loss
• A puppy or kitten has fleas, or your pet has pale gums or seems weak
• Your pet has signs of illness after a tick bite, such as fever, lethargy, loss of appetite, lameness or swollen joints
• You see tapeworm segments

Go to an emergency vet immediately if your pet, particularly a cat, shows tremors, twitching, drooling, seizures, collapse or severe vomiting after a flea or tick product, or if your cat has been exposed to a dog product.

Final thoughts

Keeping fleas and ticks away is one of the simplest ways to protect your pet’s health, and one of the easiest to get wrong. Choose a product made for your pet’s species, age and weight with your vet’s help, follow the label, never use dog products on cats, and treat the home as well as the pet. Check your pet regularly, remove ticks promptly, and call your vet if something doesn’t look right. For more on keeping your pet healthy, see how our reviews work.

Frequently asked questions

What is the best flea and tick prevention for dogs?
It depends on your dog’s age, weight, health and where you live. Ask your vet to recommend a product, and follow the label.

Can I use dog flea treatment on my cat?
No. Some dog products contain permethrin, which is very toxic to cats. Use only products made for cats, ideally recommended by your vet.

Do indoor cats need flea prevention?
Often, yes. Fleas can come in on people and other pets, and indoor cats can get them. Ask your vet.

How do I remove a tick from my dog or cat?
Use fine-tipped tweezers or a tick tool, grasp close to the skin, pull straight out with steady pressure, then clean the area and wash your hands. Don’t use petroleum jelly, alcohol or heat.

How long does it take to get rid of fleas?
Often several weeks, because eggs and pupae in the home keep hatching. Treat all pets and the environment, and keep going until your vet says to stop.

Are natural flea remedies safe?
Not necessarily. Many aren’t proven to work, and some, such as tea tree oil and other essential oils, can be toxic. Ask your vet.

Should I prevent fleas and ticks all year?
Many vets advise year-round prevention, because fleas can live indoors in winter and tick activity varies. Ask your vet about your area.

Can fleas and ticks affect people?
Yes. Fleas can bite people, and ticks can carry diseases that affect humans. Check yourself after being outdoors in tick areas, and ask a doctor if you have concerns.

What are signs of a bad reaction to a flea treatment?
Drooling, tremors, twitching, vomiting, unsteadiness, hiding or seizures. Treat it as an emergency, and contact a vet or poison helpline immediately.