Flea Control in Dogs

How can my dog get fleas?

Fleas can spread directly from an animal with fleas to your dog. However, most dogs get fleas from their environment.

Fleas live, feed, and mate on many animals, including cats, dogs, rabbits, ferrets, opossums, rodents, and raccoons. Flea eggs fall off these animals and into the environment, where they hatch into larvae. The larvae eat organic debris until they mature into pupae (the stage within a cocoon). The pupae may lie dormant for weeks to months, waiting for the right environmental conditions before hatching into adults.

Newly emerged adult fleas jump onto a host animal to complete their life cycle. Within two days of feeding on blood from the host and mating, the female flea begins to lay eggs. The eggs drop off the animal and into the environment, where the cycle starts again, spreading fleas to more animals. 

Under ideal conditions, the flea can complete its entire life cycle in as little as two weeks. In less favorable conditions, the cycle can take as much as a year. Homes with carpets and central heating provide ideal conditions for the year-round growth of fleas. The highest numbers of flea eggs, larvae, and pupae are found in areas of the house where pets spend the most time, such as their beds and furniture. 

Even if fleas are in your house, you probably will not see them. The eggs are tiny, white specks the size of dust particles. The larvae are somewhat larger, with dark heads and lighter bodies. They move deep down into carpets, furniture, or cracks in floors, away from the light.

How do fleas affect my dog?

Many dogs are sensitive to flea bites, which can cause excessive scratching, hair loss, and scabbing, especially at the base of the tail. This reaction can lead to skin infections. You may notice small bits of black material within your dog’s coat. These black specks are flea droppings (“flea dirt”), which contain digested blood. A single adult flea consumes many times its weight in blood over its lifetime. If a puppy, an older dog, or a dog in poor health has a lot of fleas, the blood loss can be severe, resulting in anemia (too few red blood cells).

In addition, fleas can carry several diseases, including plague, and one of the most common tapeworms known to infect dogs and cats. Any dog with fleas is likely to also have a tapeworm infestation. Less commonly, fleas can also transmit infections between animals, including several types of Bartonella bacteria. This bacteria can cause fever, swollen lymph nodes, and eye inflammation (uveitis).

Can fleas affect people?

Fleas that infest dogs and cats do not usually live on people, but may bite them if given the opportunity. Flea bites are often found below the knees. They can be itchy, and the bite may swell and develop a discolored ring around it. Severe reactions to flea bites include hives, swelling, and difficulty breathing.

Rarely, fleas can also spread infection, including plague (Yersinia pestis), cat scratch disease (Bartonella henselae), and murine typhus (Rickettsia typhi). These infections can cause symptoms including fever, swollen lymph nodes, headache, nausea, weight loss, and weakness.

How are fleas treated in dogs?

Ask your veterinarian what they recommend for treating fleas on your dog. There are many factors to consider, including your dog’s health, medical history, environment, and exposure to other pets and children. Many flea-control products are available, such as products given by mouth or applied to the skin, shampoos, sprays, and powders. However, each product works differently and some are more effective than others.

• Flea shampoos, powders, and most sprays kill fleas when they are applied or repel them for a few hours, but have little lasting effect, so your dog may have fleas again the next day. 
• Some flea collars can be effective and convenient, but some may cause side effects, such as a skin reaction or rash. 

There are very effective products designed to be given once a month or once every three months. Some of these products are conveniently combined with medications to prevent ticks, heartworm, and intestinal worms, and are available through your veterinarian. 

Some products contain ingredients called adulticides, which kill adult fleas and remain active between scheduled doses (e.g., imidacloprid, fipronil, isoxazolines). Others contain insect growth regulators (IGRs) that prevent larvae from developing into adults (e.g., pyriproxyfen, methoprene, lufenuron). Some products combine adulticides and IGRs. 

Safety considerations:

• Always read the label carefully. Any product, whether natural or pharmaceutical, can have side effects, especially when used incorrectly.
• Apply the product as instructed and repeat at the intervals stated.
• Use with care around other pets, as some flea control products for dogs are poisonous to cats. 
• Watch for counterfeit or improperly imported products that do not meet your country’s standards
• Consult your veterinarian for the most effective and safe flea control products for your home and pets, and let them know if you have any concerns.
• Report any suspected reaction to your veterinarian or local veterinary emergency clinic right away.

Can I treat my dog with home remedies?

It is understandable to want a gentle, safe option for your dog. Vacuuming, washing bedding, and using a flea comb can help, but they usually are not enough to eliminate an infestation. Do not apply essential oils or home remedies without the advice of a veterinary professional who knows your dog and their medical history. 

If you are worried about medications, share your concern with your veterinarian and their team. They can help you choose flea control options and discuss the likelihood of side effects and how they can be managed.

How do I treat my home environment?

Start with regular cleaning and effective flea treatment for your pets. Your veterinarian may also recommend products to treat your home, especially for a heavy infestation. These include:

• Household sprays that kill adult fleas (adulticides)
• Household sprays containing IGRs
• Insecticides applied by professional pest control companies

Sprays should be used in places where the flea eggs, larvae, and pupae are likely to be. Treat the entire household first and then concentrate on the hot spots — your dog’s favorite napping spots, such as soft furniture, beds, and carpets. Once larvae hatch from eggs, they move away from the light and burrow deep into carpets and small spaces where they are difficult to reach. Move cushions, furniture, and beds to spray under them. Larvae are also likely to live along baseboards and in gaps between floor seams or floorboards.

Flea eggs and pupae are extremely tough and resistant to insecticides. To remove eggs, as well as dead fleas, wash your pet’s bedding in hot water or replace it. Regular and thorough vacuuming of your carpets, floors, and soft furnishings can remove many flea eggs, larvae, and pupae.

Seal used vacuum bags in a garbage bag and dispose of them outside. If your vacuum is bagless, empty its contents into a bag, seal it, and dispose of it outside. 

It is helpful to vacuum before using a spray for the house because the vibrations can encourage newly developed fleas to emerge from pupae and be killed by the insecticide.

Should I treat outdoor areas where my dog spends a lot of time?

Flea exposure is inevitable when your pet goes outside, so ensure you are using a veterinary-recommended flea preventive. Another way to reduce flea exposure is to discourage other animals, like raccoons and opossums, from spending time in your yard. Reducing damp, shady areas in your yard can also minimize fleas:

• Keep grass cut short
• Trim overhanging trees and shrubs to let in more sunlight
• Prevent access under porches where animals may prefer to spend time

If necessary, you can consider spraying a product containing an IGR and repeating every 14 to 21 days for three to five applications. Concentrate on dark, shaded areas, and any sleeping spots, including bedding. Try not to use sprays that may have a negative effect on other insect populations outdoors.

Biological flea controls, such as nematodes, may be an effective way to reduce fleas in the environment around your home. Outdoor insecticides are not generally needed when your pets are on modern veterinary-recommended flea preventives.

Are insecticides safe for my dog and my family?

Approved flea control products are tested for safety when used according to label directions, but side effects may occur. Possible reactions include skin irritation, hair loss, drooling, and vomiting. Isoxazoline-based medications have been associated with neurological side effects, including seizures, in dogs and cats, although the risk is very low.

Work with your veterinarian to choose the safest and most effective flea product for your cat. Always mention any products used on or around your cat, as combining products can increase the risk of side effects. When used as directed, flea control products are generally safe and side effects are uncommon. Some products may also affect birds, fish, amphibians, reptiles, and invertebrates, so consult your veterinarian before using them around these pets.

My dog had fleas after returning from boarding. Did he get fleas there?

Not necessarily. Pre-adult fleas (pupae) can survive for many months in their protective cocoons. When you or your pets are away from home, these pupae remain in cocoons because no host is available. As soon as you or your pet returns home, vibrations (from walking) or increased carbon dioxide (from breathing) can trigger the fleas to emerge from their cocoons. Adult fleas may emerge in large numbers and jump onto cats, dogs, and even people to feed on blood.

Why does my dog still have fleas after treating them and the environment?

Seeing fleas after treatment doesn’t mean the product has failed. Fleas continue to emerge for weeks to months and will continue to be a problem if a treatment is missed or delayed, if another pet in the house is not treated, or if your pet picks up fleas again. It is important to continue to administer flea control to all pets in the house for 3 to 6 months after an infestation to allow time for remaining flea life stages to develop into adults and then be killed when they jump on your pet.

Although fleas have developed resistance to older products like organophosphates, pyrethroids, and carbamates, there is no evidence of fleas developing resistance to more modern insecticides, especially once-a-month flea preventives that contain a sterilizing agent or IGR in addition to the adulticide. Most flea problems can be overcome by using a veterinarian-recommended flea preventive product on your dog along with appropriate cleaning and environmental treatment when needed.