Creepy Crawlies Part 1

In veterinary medicine, two of the creepy crawlies we concern ourselves with most are fleas and ticks. The other two are flies and mosquitos, which will be discussed in Creepy Crawlies Part 2.

Most people are familiar with Lyme disease and understand that it is one of several bacterial diseases spread by ticks. Caused by the bacteria Borrelia burgdorferi, Lyme disease is an inflammatory condition that is characterized by joint swelling and pain, lameness that shifts from one limb to another, fever, swollen lymph nodes and lethargy. Symptomatic dogs are usually screened in clinic using the SNAP 4DX test, which also screens for two other tick borne bacteria and heartworms. Cats appear to be less susceptible to developing Lyme disease and rarely show symptoms. Dogs who are symptomatic and test positive for one of the tick borne bacteria are treated with antibiotics and pain medications. The antibiotic of choice is Doxycycline prescribed for one month. The symptoms usually clear up within a few days of starting treatment. However, the antibiotics do NOT clear the bacteria from body tissues so the symptoms can reappear, becoming a potentially chronic problem.

Rarely, some dogs develop a severe kidney disease called Lyme Nephritis. These dogs will display symptoms like a significant increase in water consumption and urination, dehydration and fluid building up in body tissues, particularly in the limbs. Even with hospitalization and aggressive supportive care, 90% of these dogs will die. Some success has been reported treating these dogs with hemodialysis. However, veterinary hemodialysis is not a commonly offered service and is very expensive.

Every article I have read about Lyme disease states it is far better to prevent exposure than to try to treat the disease. Even if you find a tick attached to your pet's skin, prompt removal may still avoid exposure. Studies have shown that it takes 24-48 hours for the embedded tick to transmit the Borrelia bacteria to the host, your pet. If you and your dog live in an area with large tick populations, daily inspection of your pet is your best defense, regardless of which product you use.

Fleas carry a few diseases that are life threatening to humans, namely cat scratch disease, typhus and the plague. Each disease is caused by a different strain of bacteria that is transmitted to people via fleas. For our pets, fleas become life threatening when the infestation is so severe it results in profound anemia. Flea allergy dermatitis and tapeworms are commonly seen with chronic infestations but are not generally considered life threatening. Clearly, controlling flea and tick infestation is as important to humans as it it is for our pets.

When I first started working in veterinary medicine, flea and tick control products were derived from insecticides used in agriculture. Insecticides only kill adult fleas so environmental control required frequently repeated applications of product. Exposure to some insecticides will cause neurologic symptoms like tremors and seizures in pets and people. One class of insecticides called organophosphate was frequently responsible for neurologic toxicities in pets. Only one early insecticide, pyrethrin, is still commonly used in flea/tick control products. Naturally derived from chrysanthemums, it's considered to be generally safe. However, pyrethroids are synthetic pyrethrins and have been shown to be extremely toxic to cats. Read that label carefully!

Parasitologists continued to research safer and more effective ways to control fleas and ticks. In 1994, lufeneron was released, representing a new approach to insect control. The first of a class of products called Insect Growth Regulators, they disrupt the development of the larva so it can't mature into a blood sucking adult. Lufeneron is combined with milbemycin in Sentinel, protecting pets from heartworms, intestinal worms and fleas.

In 1996, imidacloprid (Advantage) and fipronil (Frontline) were released as the first topical spot on products for flea control on our pets. Finally. flea control products that are easy to apply, effective and appear to be almost non toxic! Primarily effective against adult fleas, these two insecticides are typically combined with an insect growth regulator for more complete flea control.

Imidacloprid and fipronil are now two of over a dozen insecticides developed in the last couple decades to control fleas on our pets. Some of these new insecticides are labeled for dogs only. In order to be effective against ticks, many of these products include other ingredients, like permethrin, that are toxic to cats. When choosing a product for your pet, consult your veterinarian and carefully read label directions before applying.

While researching this article, I saw a number of alternative products that attempt to control fleas on your pet with combinations of essential oils. My own experience with these products has shown me two things. One, some pets will have an allergic reaction to certain essential oils, even if they are considered safe for use around dogs and cats. Two, these formulations don't seem to be as effective as the recently developed veterinary products available today.

On the other hand, environmental control can be obtained through the use of beneficial nematodes applied to your yard. When correctly applied, these nematodes hatch and eat all the flea larvae they can find. Once the flea larvae are gone the nematodes die off, posing no threat to you or your pet.

Fleas are hardy, tenacious and very difficult to eradicate once they establish themselves in your home. The product I prefer for indoor use is Mycodex Plus Environmental Spray but it's meant to be more of a spot treatment for furniture and bedding. As with Lyme disease, prevention is the key to keeping fleas out of your home. Consistently using effective flea control products on our pets greatly reduces the likelihood of those menaces getting into our homes.