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A Dog Fight Against Infestation

Pet pest prevention

Pet parents all know that fleas can be a nuisance, but just how big of a problem they can actually become might surprise you. In fact, in just 30 days, 10 fleas can become an infestation of up to 250,000 on your pet and in your home. 

Your best defense when it comes to combating a flea infestation on your dog is knowledge — knowledge about where fleas come from, how to avoid them and the best treatments to use in case an infestation does occur. Luckily, you’ve come to the right place.

Where do dogs get fleas?

Unfortunately, there are a number of areas where your pet can contract fleas. Long grasses, woods and leaf piles in shaded areas are often high-profile spots. This means that your yard and other outdoor areas where you might walk your dog could be problematic. Other animals — especially wild, roaming ones — can also carry fleas, so the more stop-by visitors you have to your yard, the more likely you are to have an issue with fleas. Your pet’s items — like their doghouse, for example — could also be a hotbed for fleas, especially when they’re kept outdoors.

Outdoor areas aren’t the only problem spots, though. No matter how clean you keep it, your home is also a perfectly hospitable environment for fleas. Vacuuming and regularly cleaning all of your pet items can help stave off any unwelcome intruders.

When is flea season?

While fleas can survive in many climates, the worst time of year for these pesky critters is May through winter, with the seasonally worst months for flea infestations occurring in September, October and November.

However, since fleas thrive in humid, moist environments, if the weather in your area happens to feature more warm, rainy days, you may be apt to experience more fleas in the area than normal.

All about the flea lifecycle

When it comes to getting rid of fleas completely, it’s essential to understand the entire lifecycle of the flea in order to eradicate them at every stage. Fleas have four cycles:

After an adult female flea receives blood from a host (potentially your pet) and mates, she will lay small, white eggs, which is the beginning of the life phase for a flea. The average adult female flea can lay approximately 40 eggs a day. Eggs take between two days to two weeks to fully develop.

What hatches from the eggs are referred to as larvae, which are about 1/8-inch in length, white, legless and blind. These larvae go through three developmental stages themselves, and then, if the they survive, in approximately five to 20 days after hatching they will create cocoons for their next stage of life.

The final stage before adult flea is the pupae stage, wherein the flea develops within their cocoon for anywhere from several days to a couple months, or even years if the conditions aren’t optimal right away for hatching. The cocoon’s outer coating is sticky, which allows it to burrow and remain deep in carpets and furniture, as well as protects them from harmful irritants or chemicals. As such, this is the stage in which fleas are the hardest to eradicate. Once the environmental seems suitable and a host has made its presence known — maybe your dog walked by the couch, for example — the adult will emerge from the pupae phase.

Adult fleas are hatched from the cocoon ready to feed on a host within hours. Once a feeding occurs, the hatched fleas will breed, eggs will be hatched within a few days, and the entire cycle begins again. Adult fleas can only lay eggs after they’ve mated and fed.

How to identify a flea on your dog

Because they are so small — adult fleas are only and average of approximately 3 mm — and brown or red in color, fleas blend in well with their surroundings. Finding a flea outside or even within your dog’s fur can be very difficult. Because of this, determining whether or not your pet has fleas can be tricky, but some telltale signs that there could be a flea infestation on your dog include:

  • Physical discomfort: Excessive scratching, shaking and biting are all common signs that your dog is dealing with some sort of skin irritant, which could be a flea.
  • Red, bumpy skin, or patchy hair loss, especially near the tail or neck: Even if you don’t happen to catch your dog in the act of scratching or biting their skin, if you notice any red or bumpy areas, you’ll want to do a more thorough search for fleas.
  • Black Specks: Often referred to as flea “dirt,” these specks are essentially flea poop, and means there are adult fleas around. To test if a speck is flea “dirt” or actual dirt, place a few of the dirt pieces onto a paper towel and drop water on it. If the speck becomes red it is most likely flea poop – with your pet’s blood contained in it.
  • Actual fleas: While small, you can often find fleas roaming on your pet’s skin. Separate the fur and look for any fleas scuttling around. Adult fleas’ bodies are small, flat and covered with tiny hairs, and they have six legs. Flea eggs can also attach themselves in dog fur, but their small size and clear coloring makes them more difficult to detect. Using a flea comb can help.
  • Lethargy: In severe cases, a dog that’s dealing with fleas may appear lethargic and lack the energy to do the things they usually enjoy.
Fleas on dogs

What to do if you find a flea on your dog

When you spot a flea — in any form — don’t panic. Yes, dealing with a flea infestation on a dog is not ideal, but it is doable. Here’s how to handle it.

Obviously, your first coarse of action after discovering fleas is to treat your dog so they begin to feel more comfortable. A consultation with your veterinarian should be your first move, just to ensure that any treatments you use on your pet is in line with any additional health concerns. The best course of action will likely include shampoo treatments, which help kill off existing fleas in all of their forms, in conjunction with an ongoing preventative such flea pills, topical options, or flea collars. If you have multiple pets, it’s best to treat all of them at the same time, just in case the fleas have already managed to move around from host to host.

You’ll probably never know exactly how your pet came across the fleas, so it’s best to treat every possible area in your home as a potentially contaminated spot. Some things to consider doing include:

  • Vacuum all carpets, area rugs, hardwood floors, the bottoms of your furniture and your upholstered furniture.
  • Wash all your bedding, as well as your pet’s bedding and toys. Remember to do this frequently — especially things that your pet uses — to keep future flea infestations at bay. Change out your vacuum bags regularly as well, especially after an infestation.
  • Mow your yard and trim back hedges and bushes. To decrease the chances of having fleas, grass should always be kept short, and be sure to quickly remove any leaves or debris where they could hide out. Fleas thrive in the shade (they actually can’t survive in direct sunlight), so pay attention special attention to any shaded area on your property.
  • Spray your upholstery, carpet and yard with a flea-killing spray or powder.


Dealing with a flea infestation can be difficult, but luckily there are plenty of resources out there these days to help. By having your pet on a flea preventative treatment year-round you can also help protect them from any outbreaks that may occur in your area, keeping them happy and healthy.

Additional resources about pest prevention:

Reviewed by Petco’s Animal Care, Education and Compliance (ACE) Team

Petco’s ACE team is a passionate group of experienced pet care experts dedicated to supporting the overall health & wellness of pets. The ACE team works to develop animal care operations and standards across the organization and promote proper animal care and education for Pet Care Center partners and pet parents, while also ensuring regulatory compliance.