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The Vet’s Perspective with Dr. Joyce: Flea Control

Author: Joyce Heideman, DVM

It’s that time of year again when the weather is warm and humid, and the fleas are making our pets miserable. It has been said that with the past year’s weather conditions, this year will be pretty bad with the flea, tick and mosquito problem. To help you get control over this problem (and maybe even prevent it) here are a few facts and tips regarding flea control.

Flea Basics:

Fleas are tiny brown insects that live on mammals and suck blood from their tissues. They are most common external parasite of companion animals, and carry many diseases including tapeworms. Flea allergy dermatitis is the most common skin problem in pets, and fleas can make even non-allergic pets uncomfortable. However, just because your pet is not itching doesn’t mean it does not have fleas. If one pet in the household has fleas, they all have fleas. Some are just more sensitive to flea bites than others.

Fleas can infest squirrels, rabbits, mice and rats, and these hosts can be a source of fleas for our pets. Pets do not need to go outside to get fleas. We can transport fleas inside on our clothing, they can jump through open doors, and they can be brought in by mice or rodents.

Once in the house, fleas seek out our pets. They prefer pets to people, but will jump on and bite people if there are no pets present or if there is a very heavy infestation.

Just because you don’t see fleas doesn’t mean they are not there. It is unusual to be able to see fleas in a mild to moderate infestation. They burrow and run fast, and many pets groom them off and swallow them.

Female fleas lay a tremendous number of eggs which fall into the environment and hatch when conditions are right. This can be as short as 16 days or as long as 90 days. The pupated flea can be dormant in the yard over the winter and re-emerge when the weather warms. Fleas are at their worse during warm humid months, typically May to October in Michigan.

Lifecycle of the Flea:

Eggs are laid in the hair coat and are designed to fall off the host. They are resistant to insecticides, but susceptible to various insect growth regulators. Larvae develop in the host’s environment and feed on adult flea feces (blood) that fall out of the hair coat of the pet. Larvae are susceptible to traditional insecticides, borates and insect growth regulators. Larvae eventually spin cocoons (often within carpet fibers) for pupation. Pupae are resistant to freezing, desiccation, and insecticides. Pupae can lie dormant for many months; they are stimulated to ex-pupate as emergent adults by vibration, warming and increased carbon dioxide. Normally, ex-pupation occurs when a host is near and the new flea finds the pet within seconds of emergence. Emergent fleas are fairly mobile and can survive a few days without a host, if in a suitable environment. New fleas begin feeding within hours of finding a dog or cat. Once a blood meal has been taken, the flea can survive only a short time if it is dislodged from the host. New fleas experience very high mortality on healthy adult hosts. Most fleas do not survive 72 hours on an animal that is itching and able to groom itself

Flea control basics:

Effective flea control aims at breaking the flea lifecycle on the pet. This is done by using products that interfere with the flea’s reproduction, or growth of the juvenile forms. Many new products combine this ability with the ability to kill the adults as well. Products that just kill the adults like many over the counter sprays or collars are very ineffective.

Insecticides that have been around for a long time, are more likely to have some resistance with them. Over time, fleas have been exposed to pyrethrins so often, that they often no longer work. Newer products or non-insecticidal products are less likely to have resistance problems.

Most over the counter products are insecticides and many can have toxicity problems. Insecticides like permethrins are very toxic to cats and toxicity has been reported just from contact with a treated dog in the house. Make sure you read the label well and use the product properly if using over the counter insecticides.

Monthly applied flea control, that kills the adult and breaks the lifecycle, should be used monthly for at least 3 months to overcome an infestation. After that, products that simply break the lifecycle can often be used as a preventative. Remember that products that just break the lifecycle like Sentinel, do not kill adult fleas, and you may see fleas on your pet, but they will not lay viable eggs, and will die or be groomed off typically by 72 hours.

Helpful tips for picking the right flea control:

  1. Stay away from powders, sprays and shampoo that only kill the adult and don’t last very long (24-48 hours)
  2. Basic flea collars, like those made by Hartz or Sergeants are very ineffective and concentrate insecticide around the pet’s neck.
  3. Products that you get from your veterinarian usually are really better because they are made with safer and more effective ingredients, the company usually stands behind veterinary products, and you are getting the expertise of your veterinarian.
  4. Many fleas are resistant to over the counter products containing permethrins and pyrethrins. Check the ingredients list before you buy. There are some safe and effective over-the-counter products out there, particularly the ones that contain “fipronyl” found in “Front line”.
  5. Now-a-days, many flea products come combined with tick, heartworm and even intestinal parasite control. Be sure your pet has been heartworm tested before using combination products that prevent heartworms.
  6. Make sure you are using the right type and dose of medication for your pet. Never use a dog only product on a cat and vice versa.
  7. If you have an infestation problem, you will need to use a monthly product for at least 3 months to get the problem under control.
  8. If your pet swims or is groomed often, you may want to stay away from the topical insecticidal products. Even if they say they are water proof, swimming and bathing has been shown to decrease some of the efficacy.
  9. If your pet has been diagnosed with a food allergy, you will want to stay away from flavored oral pills.
  10. If you have any questions or concerns about flea control products, discuss them with your veterinarian.

About the Author: Dr. Joyce A Heideman is a graduate of the MSU College of Veterinary Medicine and has been a practicing veterinarian in the Lansing area for over 25 years. She is dedicated to the health and welfare of companion animals and is regularly donates her time to animal welfare and rescue efforts.

Southside Animal Hospital
5134 S ML King Jr Blvd
Lansing, Michigan 48911

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