Flea Infestation in Dogs

Written by Small Door's medical experts

Fleas are parasitic, wingless insects that feed off the blood of their hosts. There are approximately 2,200 types of fleas worldwide, but in North America there are only a few that commonly infect animals: Ctenocephalides felis (the cat flea) and Ctenocephalides canis (the dog flea). Oddly enough, the most common fleas found on dogs are cat fleas, which can cause not only itching and irritation but transmit infection as well.

In This Article

What are fleas on dogs

Fleas are parasites that feed on dogs, cats, and other mammals. These pests can create a lot of discomfort and itchiness by repeatedly biting and feeding off your dog.   

Fleas go through four life cycle stages, meaning they can live on your dog for a long time if not properly treated. Fleas mate after feeding, with the females laying their eggs 1 to 2 days after their first feeding. Relatively soon after emerging from their cocoon, adult fleas must find a blood meal; otherwise, they will not survive in order to mate.

After a flea egg hatches, it turns into larva, which proceeds to feed on “flea dirt,” or digested blood excretions that the adult fleas have left behind. After the larva has fed for some time, it will encase itself in a cocoon and start developing into a full-grown flea, which takes around 7 to 19 days. However, the larva can remain dormant in this protective casing for up to five months until a host is nearby.

Signs and symptoms of fleas on dogs

You may be able to see fleas on your dog, but if there aren’t many, or if your dog has been biting at his skin, they may be hard to detect. Many animals are allergic to flea saliva, which can cause an intense allergic reaction and prompt constant biting/chewing at their skin. Even those that aren’t allergic may still scratch themselves due to the annoyance of these tiny insects.

Telltale signs that your pet is dealing with fleas include:

  • Restlessness and discomfort

  • Scratching, licking, rubbing, chewing, or nibbling at the skin

  • Crusted skin in areas including the base of the tail, over the hips, and the thighs

  • Hair loss

  • Scabbing

  • Thickened or darkened skin as the condition becomes chronic

Additionally, if there’s a heavy infestation (especially for young puppies), blood loss can lead to anemia.

While you may not always find actual fleas on your pet’s body, it can be easier to see “flea dirt.” Flea dirt, which looks like black dandruff, is actually digested blood that the fleas have excreted. The best way to determine whether the dandruff is flea dirt is to brush it onto a white cloth and add a drop of water; if it turns reddish brown, that’s confirmation that fleas were present on your dog at some point.

What is the life cycle of a flea

Understanding the life cycle of a flea is useful for treating fleas on your dog. Fleas have four life cycle stages including: egg, larvae, pupae, and adult that can last from weeks to months depending on the climate and temperature they’re in.

1. Flea eggs

All fleas begin as eggs. The cycle starts when a flea feeds on its host (a.k.a your dog). The female flea then immediately lays eggs on your dog, which then take anywhere from a few days to weeks to hatch depending on temperature. Flea eggs hatch fastest in warm, humid conditions, typically around 75-80°F. While the eggs are first laid in your dog’s fur, many will fall off as your dog shakes and walks around, dispersing eggs around your home and areas your pet frequents. 

2. Flea larvae

When fleas hatch from the egg stage, they become larvae. These larvae take several weeks to develop as they feed off of pre-digested blood that the adult flea has passed along and left behind in the environment that is your dog’s fur. 

Flea larvae are a light white color, almost see through — unlike the brown color of adult fleas — and don’t have any legs. They also avoid sunlight and hide in dark areas like your pets fur, carpet, under furniture, or other dark areas of your home.  

3. Flea pupae

Flea larvae move onto the next stage of the life cycle by becoming flea pupae. They do this by creating a cocoon for themselves where they incubate for several weeks before emerging as an adult flea. The cocoons of flea pupae have a sticky coating that allows them to stick in your dog’s fur or to other household spaces like carpet and furniture — flea pupae can live anywhere, even up to several months, until conditions are right for them to emerge and find a host.

4. Adult fleas

When a flea pupae emerges from its cocoon, it becomes an adult flea that will begin to feed on a host within a few hours. The flea cycle then continues as once an adult flea has its first meal, it will begin to lay eggs. Adult fleas will continue to feed off a host, breed, and lay eggs, living up to several months. 

Adult fleas are small but still visible to the naked eye and are typically dark brown in color, have a flat shape and legs, making them much easier to spot than eggs, larvae, or pupae.

How did my dog get fleas?

Your dog can pick up fleas in numerous ways, both from other animals as well as humans, inside or outside of the home.

  • Exposure to other flea-infested animals. Fleas can easily jump onto your pet from a carrier animal in close range, whether that’s outside or inside your home.

  • Mice. These common flea-carriers can bring fleas into your household from outdoors.

  • Humans. Animals aren’t the only ones who can bring fleas indoors—humans can, too! Fleas and flea eggs can stick to shoes or clothing from outdoors and drop onto the floors of your home. They can also be found in bedding, rugs, blankets, and plush toys, so if you receive any of these secondhand, thoroughly check them for fleas before bringing them into your home, and immediately wash them in hot water.

  • Pet daycare, boarding facilities, or even the groomer.

  • From the outdoors. Fleas can survive outdoors for a long period of time, especially during warm, humid weather. Check your dog after he’s been to places like the dog park, a backyard, or out for a long walk, especially in grassy or wooded areas.

Diagnosing flea infestations on dogs

The diagnosis of a flea infestation is usually visual. If your pet is itching or scratching and looking generally uncomfortable, check certain areas of the body for fleas: the base of the neck and tail and the insides of the hindlimbs are good places to start. Your veterinarian can provide a closer look for flea bites and any skin irritation. They may also use a flea comb to check for flea dirt.

Further testing may be done to rule out any other potential skin conditions and check whether your pet has flea allergy dermatitis, a condition that occurs when an animal develops a hypersensitivity (allergy) to flea saliva. When an allergic pet is bitten by fleas, the itching that results from the saliva is much more severe and prolonged than for a pet who is not allergic.

Flea treatment for dogs

If your pet is diagnosed with fleas, don’t panic! There are a number of treatment options. Your vet will tell you the best treatment for your pet’s specific situation.

  • Your vet can prescribe medications that will kill the adult fleas on your pet very quickly, and provide ongoing protection against re-infestation.

  • Anti-inflammatory medication will control skin irritation and soothe the itching.

  • If the skin has become infected, an antibiotic may be prescribed.

  • Environmental treatment: this is vital in the control of fleas on your pet and may include flea “bombs” (an aerosolized product that can help kill fleas and larvae in the home environment); washing all bedding, fabrics and items such as soft toys in hot water to remove and kill eggs and larvae; and meticulous vacuuming to remove eggs and larvae from the crevices they may be hiding in.

How long does it take to get rid of fleas on a dog

Getting rid of fleas on your dog is not just as simple as killing the adult fleas and by the time you spot fleas on your dog, there are likely several generations of fleas living in your home. As you now know, fleas have a life cycle which means that eggs, larvae, and pupae will need to be treated as well. 

While some medications and treatments can kill adult fleas within 24 hours, it can take anywhere from three to four months of treating your pet and home to get rid of an infestation and the various different life cycles of fleas. Bathing your pet may also give immediate relief in removing fleas, but this is only a short term solution.

Is there a cure for fleas on dogs?

Yes. There are plenty of products available to cure your pet’s flea infestation. It’s important to treat your home as well as your pet, to avoid reinfestation.

Are fleas on dogs contagious for humans or other pets?

Yes, fleas can be transmitted to other animals, as well as humans. However, it’s not the adult fleas that spread from host to host: flea infestations are spread via flea eggs. Adult fleas emerge from a cocoon and can survive between 1 and 2 weeks before finding a host on which to feed. Once attached to a host, fleas do not generally leave unless they are forced to, either by grooming or insecticides.

A dog infested with fleas can easily transmit them into your home, by depositing eggs that then hatch larvae that turn into adult fleas. So not only must you get rid of the live fleas, you must also protect your home from future infestations by destroying all the flea larvae and unhatched eggs.

While people can get flea bites, which can cause irritation similar to mosquito bites, they are not the preferred host for these tiny insects. So fleas are more problematic for our pets.

What is the cost of treating fleas on dogs?

With a number of different treatments available, the cost to treat fleas may vary. They include the following:

  • Vet office visit

  • Prescriptions for antibiotics/anti-itch medications

  • Preventative flea/tick medications to kill the fleas already on your pet and provide ongoing prevention

  • Flea bombs (costs vary, but usually range from $20-50)

As fleas can spread easily, eliminating them may be difficult and require spending additional money, since some of these treatments will need to be repeated more than once. As always, prevention is superior to treatment—and much more cost-effective in the long run!

Recovery and management of fleas on dogs

All it takes is one flea to start an infestation, since a female flea can produce between 40 to 50 eggs a day. Once the flea emerges from its cocoon, it can begin multiplying very quickly. Managing a flea infestation begins by addressing the problem at the first sign, administering some type of flea medication, and eliminating the fleas from your pet’s environment.

Monthly application of flea preventatives can do a lot to prevent future infestations and even kill fleas that may be lingering in your house: adult fleas will jump onto a dog that has been treated, then die before reproducing..

Preventing fleas on dogs

Luckily, it’s quite easy to prevent flea infestations.

Monthly preventative treatments, both oral and topical, are available to help protect your pet from getting fleas. These products range in cost depending on the brand and the weight of your dog but are typically around $16-20 per monthly treatment. Your vet can help determine which product is right for you and your dog.

It’s critical that you adhere to the monthly schedule. Missing even a single treatment – no matter what the season – could be the opening a flea needs to infest your dog.

How to get fleas out of your home

Getting rid of a flea infestation is no easy feat and requires a lot of patience and repetition to remove fleas of all life cycles.

Use the following steps to get fleas out of your home:

  1. Start by washing all dog bedding: this includes any blankets and plush toys as fleas like to hide in these spaces. Bedding should be washed in hot soapy water and may need to be repeated regularly until you’ve fully tackled an infestation. 

  2. Wash your own bedding: this includes sheets, duvet covers, blankets, rugs, bath mats, and couch cushions. 

  3. Vacuum carpets, hardwood floors, baseboards, and other hard household surfaces: once you’ve finished vacuuming, make sure to immediately throw away the vacuum bag or empty the contents of the vacuum into the trash. 

  4. Use a flea treatment on your home: pet stores carry liquid flea sprays, powder treatments for carpets and foggers that target the various cycles of fleas to help remove and prevent these pets in your home. Use these on various hard surfaces and carpet, ensuring that your pet is not in the room or exposed to the chemicals during the process. 

  5. Treat your vehicle: If your dog has ridden in your car lately, chances are there are fleas inside your vehicle as well. Vacuum the seats and use a flea spray around the car.

Is there a vaccine for fleas on dogs?

There is no vaccine available to prevent flea infestations. But monthly preventatives can keep your pet flea-free, as long as you don’t miss a single treatment.

Summary of fleas on dogs

Flea infestations can be extremely uncomfortable for your dog (and you!) and while there are thankfully plenty of treatments available, it can be tricky to totally eliminate fleas from your home after an infestation. Sticking to a strict monthly schedule of flea preventatives is the best, most cost-efficient way to avoid having to deal with fleas.

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