Saturday, October 29, 2011

Flea Allergies In Dogs and Cats

The Flea Factor

Some animals have many allergies. It would not be particularly unusual for an animal with a food or inhalant allergy to also be allergic to flea bites, especially considering that flea bite allergy is extremely common among pets. Because allergies add to each other, it is possible that a food-allergic dog will not itch if its fleas are controlled. Since new technology has made flea control safe and convenient, it is especially important (and no longer difficult) to see that fleas are not complicating a pet's itching problem. 

Ensure immaculate flea control for any itchy pet!
Fleas: Know your Enemy

Despite numerous technological advances, fleas continue to represent a potentially lethal plague upon our pets. Current products are effective so there is little reason for this; the problem seems to be one of understanding.

There are over 1900 flea species in the world but only one is species attacks your pets, commonly called the cat flea (but it also attacks dogs).

What Kind of Damage Can Fleas Cause?

It would be a grave mistake to think of the flea as simply a nuisance. A heavy flea burden is lethal, especially to smaller or younger animals. The cat flea is not at all selective about its host and has been known to kill dairy calves through heavy infestation. Conditions brought about via flea infestation include:

• Flea Allergic Dermatitis (fleas do not make animals itchy unless there a flea bite allergy)
• Flea Anemia. Puppies and kittens die daily in the United States from fleas sucking them dry.

• Feline Infectious Anemia (a life-threatening blood parasite carried by fleas)
• Cat Scratch Fever/Bartonellosis (does not make the cat sick but the infected cat can make a person sick)
• Common Tapeworm infection (not usually harmful but cosmetically unappealing)

Fleas can kill pets.  This is so important that we will say it again: Most people have no idea that fleas can kill. On some level, it is obvious that fleas are blood-sucking insects but most people never put it together that enough fleas can cause a slow but still life-threatening blood loss. This is especially a problem for elderly cats who are allowed to go outside. These animals do not groom well and are often debilitated by other diseases. The last thing a geriatric pet needs to worry about is a lethal flea infestation and it is important that these animals be well protected.

Flea Myths
• My pet cannot have fleas because he lives entirely indoors:  Fleas thrive particularly well in the well-regulated temperatures in the home.
• My pet cannot have fleas because if there were any fleas they would be biting (insert name of a person in the family reportedly sensitive to flea bites). Since this person is not being bitten, there must not be any fleas:  Despite Ctenocephalides felis’(the cat flea’s Latin name) ability to feed of a wide variety of hosts, this flea definitely does not prefer human blood and won’t eat it unless absolutely necessary. A newly emerged adult flea is hungry and may well take a blood meal from the first warm body it finds. An adult flea knocked off its normal host will also be desperate to find a new host and may feed on the nearest warm body it can find. In general, adult fleas regard human blood as a last choice and humans tend not to be bitten unless flea population numbers are high.

• We do not have fleas because we have only hard wood floors:  Fleas love to develop in the cracks between the boards of hard wood floors.

• My pet cannot have fleas because I would see them:  You cannot expect to see fleas as many animals, particularly cats, are adept at licking them away. Sometimes all that is seen is the characteristic skin disease.

The Flea Life Cycle

There are four life stages of the flea and it is important to know how to break this life cycle in more than one place. This two-step approach provides the most rapid control and the least resistance to flea control agents in future flea generations.

About one third of the flea population in someone’s home is in the egg stage. The adult female flea lays up to 40 eggs daily. The eggs are laid on the host where they fall off to hatch in the environment. Eggs incubate best in high humidity and temperatures of 65 to 80 degrees-in other words, just the environment people like to maintain in their homes all year long. 

Just over half of the fleas in someone’s home are in the larval stage. Larvae are like little caterpillars crawling around grazing on the flea dirt that is generally in their vicinity. Flea eggs and flea dirt both fall off the host. This is the stage that picks up tapeworm eggs, which are likely to be in the vicinity, as they graze.  As they get to a certain age and size, a molt occurs. After the third molt, the larva is capable of spinning a cocoon and pupating.

The time between hatching and pupating depends on environmental conditions. It can be as short as 9 days.

Note: Larvae are killed at 95 degrees. This means that they must live in some area where they are protected from summer heat. This means the shade of the yard or indoors.

By this pupae or cocoon stage many young fleas have been killed off by an assortment of environmental factors. Less than 10% make it to the pupal stage but once they have spun their sticky cocoons they are nearly invincible. Inside the developing cocoon, the pupa is turning into the flea that we are familiar with. They are especially protected in the carpet, which is why carpet has developed such a reputation as a shelter for fleas.  The pupa can remain dormant in its cocoon for many months, maybe even up to a year as it waits for the right time to emerge.
After the pupa develops, it does not automatically emerge from its cocoon. Instead, it is able to remain in the cocoon until it detects a nearby host. The mature pupa is able to detect the vibrations of an approaching host, carbon dioxide gradients, and sound and light patterns. When the mature pupa feels the time is right, he emerges from the cocoon, hungry and eager to find a host.

Photo Credit: Trifexis

Here’s the story: a dog is boarded during the owner’s vacation. The owner picks up the dog from the boarding kennel and returns home. The mature pupae have been waiting for a host and when the dog enters the home, a huge number of adult fleas emerge at once and attack the dog creating a sudden, heavy infestation. Often the boarding kennel is blamed for giving the dog fleas. What really happened was that the pupae waited to emerge while there was no host present and then they all emerged suddenly when the host arrived.  An unfed flea is able to live for months without a blood meal.  Once it finds a host, it will never purposely leave the host.  After the adult flea finds a host and takes its first blood meal, the female flea begins to produce eggs within 24 to 48 hours of her meal and will lay eggs continually until she dies.  The average life span of the adult flea is 4 to 6 weeks, depending on the grooming abilities of the host. (For those of you who are grossed out by fleas:  40 eggs daily, 7 days a week, times 6 week life span=1,680 eggs.  Just under 10% of which reach adulthood, so say 160 adult fleas from every female! YIKES!)


Years ago, flea control meant foggers, shampoos, powders, collars, and sprays. While these products are still available, they have fallen largely aside in favor of the next generation products.

Photo Credit:
The next generation started in 1995 with the introduction of Program, an oral product that could be given once a month to a dog or cat and would sterilize - but not kill - any flea that bit the pet. The following year came Advantage and Frontline, topical products that could efficiently kill fleas for a month following an easy application. From there, Advantage has been modified to control additional parasites such as ticks and heartworm (Advantix, Advantage Multi), Frontline has been supplemented with flea sterilizers (Frontline Plus), and new insecticides (Revolution, Comfortis, Vectra, Promeris, Capstar) have been introduced.

Is Resistance Futile?
Photo Credit:
We learned long ago that insecticide use represents a selection factor in a flea population. The resistant individuals survive and pass their genes on to offspring. Eventually a resistant population is produced. We want to avoid creating a population of fleas who laugh at our best insecticides. There are two ways of doing this:

The First Way to Avoid Resistance: Change Products Periodically
Resistance is an important phenomenon and it should not be ignored. You may inadvertently be promoting resistance without realizing it.  If you want to make a resistant population, then keep exposing the population to the same insecticide and after enough generations your population will be resistant. If you switch to another insecticide, the group will be totally sensitive to the new insecticide. After a few more generations, change again.

Working against this method is the fact that advertisers encourage people to continue to use a product they like and this is, in fact, what people tend to do. The power of marketing is strong though, technically, it is better in the long run if a household alternates between two flea products each year.

The Second Way to Avoid Resistance: Use a Flea Sterilizer
A group of fleas that survives exposure to Frontline or Advantage cannot pass on their resistance genes if they have been sterilized by a second product. Program interferes with the production of chitin (the hard material making up the insect exoskeleton). The adult flea has already made its chitin but its off-spring need to develop a chitin egg-tooth to escape their eggs after development into larvae. A larva whose mother has had a big drink of lufenuron-laden blood will not be able to hatch.

Another such sterilizer is methoprene. Methoprene was developed as an additive to flea sprays used to treat the house, it is totally non-toxic, and represents a group of insect control agents called insect growth regulators.  This is a great way to break the flea life cycle before it reaches adulthood in your house; use a product containing an insect growth regulator.  Methoprene mimics a youth hormone of the flea so that larvae who consume it in flea dirt cannot mature and eggs laid by female fleas that have been topically treated with it cannot develop. Twenty years ago, this compound was a miracle in flea control. For the first time it enabled the life cycle to be broken in two places. Newer insect growth regulators have been released and are also in use.

By: Dr. Dana Lewis
Dr. Dana assists families in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties.)

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