Does My Dog Have Fleas?

Image via Christian Buch/Shutterstock.com

By Jennifer Kvamme, DVM

In parts of the world where winter temperatures fall below 35°C for more than 40 hours per month, households and pets get a bit of a break from flea activity. But as the weather begins to warm in the springtime, you may be visited by some uninvited guests. Fleas become most active when temperatures are favorable (35°C with a relative humidity of 70 percent are ideal conditions for flea populations).

Fleas are very active insects, feeding on blood from dogs and people. They jump onto passing animals and burrow down into the fur to the skin, where they stay well hidden while biting and ingesting blood. This is irritating to the animal, and to humans as well, as the bites can cause severe itching and inflammation.

Behavioral Signs

In severe infestations, it’s easy to spot fleas jumping and moving on and off your dog’s body. In less obvious situations, you may notice that your dog is restless and is scratching, licking or chewing more than normal on certain areas of her body. Shaking the head often and scratching at the ears is another indication of a possible flea infestation in your dog.

Check the Skin and Haircoat

In order to see actual fleas on your dog, you may have to look fast. Fleas can jump very fast and very high, and even at their adult size they are very small (1/16-1/8 in.). They are flat-bodied and dark brown, almost black, in color. The more blood they ingest the lighter in color they may appear.

To inspect your dog, turn her onto her back and check the areas that allow fleas to hide best. The armpits and groin are two areas that tend to be warm and protected, making them preferred spots for large flea populations. Check the ears carefully for signs of scratching, redness, blood, or dirt. These can all be signs of fleas. The skin on the belly, groin, or base of the tail may appear red and bumpy, especially if your dog is doing a lot of scratching. Hair loss may occur in certain areas that are being scratched excessively, and there may be black spots on the skin along with scabbing.

Get a flea comb (a specially made comb with closely set teeth) and run it through the hair on your dog’s back and legs. The comb’s teeth are designed to catch and pull fleas out from under the haircoat where they are hiding. Make sure you get close to the skin when running the comb through the hair so you have a greater chance of getting to where the fleas are hiding out. Have a bowl of soapy water on hand to throw any live fleas into as you comb.

One trick that may help you if the fleas are hard to see is to place a white piece of paper or paper towel on the floor next to or beneath your dog while coming through her hair. Flea dirt (flea feces) will fall off of the dog’s skin and land on the paper.

One way to tell the difference between regular dirt and flea "dirt" is to wet any black specks that fall off the dog onto the white paper towel (using regular water sprinkled on the specks). If they turn a dark reddish-brown color, you are seeing the digested blood that the flea has passed through its body and excreted.

Check the Environment

Fleas don’t just stay on your dog. They can also be found all through your house, and especially in areas where your dog spends a lot of her time. Closely examine your dog’s feeding area, bedding, and her favorite locations for signs of flea dirt (black specks), or for the fleas themselves.

Another method you can use to search for flea dirt in the house is to wear white socks and walk through areas frequented by your dog. Fleas and/or flea dirt may be picked up by the fibers of the socks and will stand out on the white background.

Another method, called a "light trap," may also help detect the presence of fleas in the household. At night, before all the lights have been turned off, set a small bowl of water with dishwashing soap near a nightlight on the floor. Fleas will tend to jump toward the light and will fall into the bowl, where they will drown. In the morning, you may find several floating in the water.

Get a Veterinarian’s Advice

If you can’t find any signs of actual fleas on your dog or in your living environment, or if you have done the full flea eradication treatment on your dog and home but your dog is still scratching excessively, it’s time to ask your veterinarian for advice. He or she will help you determine the cause of your dog’s discomfort and suggest treatment options.