Fleas: They cause a lot more than just itch

They cause a lot more than just itch

By Dr. Ed Mapes
Stonebridge Animal Hospital
McKinney, Tx

Veterinarians are expecting this to be a bad year for flea populations. The warm “winter” experienced in this area may well result in booming flea counts that threaten to infect our pets with a variety of diseases. We’re all aware that flea bites cause itch that results in skin irritation and scratching, but there are worse consequences to be aware of.

Fleas crawling over the skin surface and their bites can make the skin itch, but the situation is much worse when the animal is allergic to flea saliva injected into the bite wound. That allergic reaction (called flea bite dermatitis) causes inflammatory responses that make the itch sensation much worse than the bite alone.

Flea anemia is most often seen in very young animals or those with other debilitating medical conditions. Every time a flea bites the animal, more blood is stolen from the victim. This can lead to low red blood cell levels in susceptible animals, the condition known as anemia. Those animals will become listless, lethargic, and will have pale mucous membranes compared to the normal bright pink color.

Feline Infectious Anemia, or Feline Hemotropic Mycoplasmosis, is a disease that arises in cats that are infected by flea bites. The organism is known as mycoplasma, which is similar to bacteria but without a cell wall. Mycoplasmas are known to produce a number of diseases, but this particular species makes its way into the blood stream and coats the outer layer of red blood cells. The cat’s immune system eventually detects the foreign proteins on red blood cells and begins to produce antibodies to attack the organisms. These antibodies bind to the mycoplasma organisms, and mark the infected red blood cell for removal and destruction.

The marked red blood cells are destroyed in the animal’s spleen. The mycoplasma organisms are killed, but many red blood cells are also destroyed and removed from the circulation. The problem is that if many red blood cells are parasitized then so many red blood cells will be destroyed that the cat becomes anemic. Cats with concurrent feline leukemia virus infection tend to have more severe anemias as the virus does not permit the bone marrow to respond.
Bartonellosis is a syndrome of diseases in several mammals that is very familiar to readers of this column. We have discussed bartonella infection and the various diseases it causes in cats, as well as dogs and humans. The bits of fleas and ticks spread the bartonella organisms, and the fact that humans can also be infected by this potentially lethal bacterium from the simple scratch from an infected cat makes it particularly threatening.

The tapeworm known as Dipylidium caninum is spread to dogs and cats from fleas as well. These tapeworms develop in the animal’s stomach after the flea is eaten, and the larval tapeworms develop to an adult stage within the animal’s intestinal tract. There, they utilize specialized mouth parts to attach onto the intestinal wall, and the segments of their long bodies absorb nutrients and produce tapeworm eggs. The eggs are released within the tapeworm segments that de-attach from the worm as a whole, and are released to the outside world to infect another flea.

As you can see, fleas cause a lot more harm than just skin irritation. While they can be difficult to find on an infested animal, it is often easier to find “flea dirt”. This is actually flea droppings that resemble dark grains of sand. Fleas eat blood, so what they excrete is actually dried blood.

Figure 1

Figure 1

Figure 1 the dark, granular-appearing material is flea droppings. Fleas can be diagnosed by the presence of this material without – actually seeing a flea.

This can be distinguished from actual dirt by placing a drop of water on some of the collected particles. Flea droppings are identified if the granules dissolve and turn the water red.

There are several effective monthly medications to control flea infestations in our pets – see your veterinarian for recommendations. But if you find fleas on your pet or notice scratching, skin sores or hair loss, lethargy, vomiting, listlessness, oral lesions or redness of the gum line, see your veterinarian. What you thought was a simple flea infestation may actually be much more.

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