So you thought you can will come home to a spick and span house after an out of town trip? You even boarded your dog in a kennel to make sure he doesn´t mess up. But alas, you return to find your house infested with fleas. How did this happen? More likely, there were quite a few flea eggs and larvae in your house before you left, but you probably did not realize your dog had adult fleas. The adult flea stays on your pet for most of its approximately six–week life span, and can produce up to 20 to 30 eggs per day. These tiny eggs fall off the pet into the carpet and small cracks in hardwood floors.

The complete flea life cycle (from egg to larva to pupa to adult) normally takes anywhere from 9 to 15 days. The eggs and larvae continued to develop to the pupa stages while you were gone. The pupa, however, can become dormant up to 200 days under the wrong conditions such as cold temperatures or lack of a host.

When the pupa senses vibrations, carbon dioxide from breath, or warmth that signals an animal host is near, it finishes developing into an adult and emerges from its cocoon. While you were gone, all of the immature fleas in your house developed to the pupae stage. When you came home, the dormant flea pupae rapidly finished developing into adults and emerged. Lacking an animal host, the hungry fleas attacked you.

To get the flea infestation under control, you need to use a premise treatment which will immediately kill adult fleas and leave a residual insect growth regulator (IGR) to stop the hatching phase. An oral flea medication can be given to immediately kill the fleas on the dog, but it stays in his system for only 24 hours. Follow it up with a topical spot–on flea treatment.

Sharon E. Anderson, DVM

Sharon E. Anderson, DVM, answers medically-related questions, but will not attempt to diagnose or recommend specific treatments. Her advice is not meant to replace professional care. If your pet is ill, contact your veterinarian immediately.