Fleas are tiny, but they can become a big problem quickly. As temperatures climb in spring, flea activity picks up in many regions, and a few fleas picked up on a walk can turn into an infestation in your home. Understanding how fleas develop explains why veterinarians focus on prevention rather than waiting until you see fleas.
The four stages
Fleas go through four life stages: egg, larva, pupa and adult.
- Eggs: adult female fleas lay eggs on the animal after feeding. The eggs are not sticky, so they fall off into bedding, carpets, furniture and the yard.
- Larvae: eggs hatch into tiny larvae that avoid light and burrow down into carpet fibers, cracks and shady soil. They feed on organic debris, including flea droppings.
- Pupae: larvae spin cocoons and develop into adults inside. The cocoon protects them, and pupae can wait for a long time until they sense a host nearby through warmth, vibration or carbon dioxide.
- Adults: newly emerged fleas jump onto a passing animal, begin feeding and soon start laying eggs, continuing the cycle.
Why what you see is only part of the problem
The adult fleas you might spot on your dog are only a small part of the total population. Most of an infestation is in the environment, in the form of eggs, larvae and pupae. That is why removing fleas from your dog alone often does not solve the problem, and why fleas seem to come back weeks later as new adults emerge.
Signs your dog may have fleas
- Scratching, biting or licking, especially near the base of the tail
- Small dark specks in the coat, often called flea dirt, that turn reddish when placed on a damp white paper towel
- Red, irritated skin or small bumps
- Hair loss or scabs
Some dogs are allergic to flea saliva and can react strongly to just a few bites. Fleas can also carry tapeworms and, in heavy infestations, cause anemia, particularly in puppies and small dogs.
Prevention and treatment: ask your vet
There are many flea control products for dogs, and they work in different ways. Some kill adult fleas, some interrupt development of eggs and larvae, and some do both. Your veterinarian can recommend a product suited to your dog’s age, weight and health, and advise whether year-round prevention makes sense where you live. Treat all pets in the household as your vet recommends, and use only products labeled for the species you are treating. Some dog products can be dangerous to cats.
Helping at home
Regular vacuuming of floors, furniture and the spots where your pets rest helps remove eggs and larvae. Empty or dispose of the vacuum contents afterward. Wash pet bedding often in hot water. If you are dealing with an active infestation, your veterinarian can help you build a plan for your pets and your home.
