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Fleas and your pet

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Fleas are the most common external parasite of companion animals. Flea allergy dermatitis is the most common skin disease of dogs and cats! Flea control has always been a challenge for veterinarians and pet owners because the adult fleas cause the clinical signs, yet the majority of the flea population (eggs, larvae and pupae) are to be found off the pet in and around the home.  The ideal flea control program utilizes products that target the various stages of the flea life cycle, not only the adult fleas on the pet. In order to help you to select the most appropriate products to achieve a flea-free existence for an allergic pet, we will start by telling you about the life cycle of the flea.
The Life Cycle of the Flea: Ctenocephalides felis

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 expupate as emergent adults by vibration, warming and increased carbon dioxide. Normally, expupation 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.

Unfortunately, limited egg production does occur even on allergic animals. The entire life cycle of C. felis can be completed in as few as 16 days!


Flea Control Recommendations

For the flea allergic patient, continuous excellent flea control is required to remain symptom free. Even very minimal exposure may be sufficient to perpetuate itching in a hypersensitive patient.
In Southern Ontario, a dog or cat who does not have flea allergies can achieve excellent flea control by using a monthly product from June through to November.

At Bay Cities Animal Hospital, we recommend the use of the following products:

Sentinel® (Lufenuron) from Novartis
This flea and heartworm preventive is available for dogs as a once a month flavored chewable (soy and pork) pill to be given with a full meal.  It is only available through prescription.   Sentinel also contains Mibelmycin oxime, the heartworm preventive drug that is used in the product Interceptor.  Female fleas that feed on pets treated with lufenuron produce sterile eggs. The product does not kill adult fleas. It is a very easy way to break the life cycle but pets remain fully susceptible to the emergence of any fleas from pupa already present in the environment. Therefore, 4 to 7 months may pass before the flea free state is reached. In order to stop the life cycle, every animal in the patient's environment must receive lufenuron or another insect growth regulator. Pets should be treated for fleas with an adult flea-killing product during the first few weeks of starting Sentinel.  Sentinel can be used on puppies as young as 2 weeks old, if they are greater than 1 kg body weight. 

Sentinel is our drug of choice for flea prevention in dogs.


Revolution® (selamectin) from Pfizer
This prescription drug is designed as a once-a-month heartworm preventive and flea preventive for dogs and cats as young as 6 weeks old.  It also kills adult fleas and can be used to treat sarcoptic mange, ear mites and ticks.  It also helps control roundworms and hookworms in cats. The product is placed on the skin at the back of the neck, but is absorbed into the body to have its effect when female fleas ingest it with a blood meal.  Adult fleas will die slowly, but more importantly, female fleas stop egg production as soon as they are exposed. It is most useful as a preventive for flea infestation and in the presence of a flea problem in an allergic pet, but it is an excellent flea control product for cats.


Advantage® (imidacloprid), K9 Advantix® (with permethrin), Advantage Multi® (with moxidectin) from Bayer
These products are available as a spot ons for either dogs or cats. Advantage Multi® is a prescription drug that also is a heartworm preventive. Advantage® seems to be very well tolerated by sensitive cats. It provides flea knockdown in about 8 hours. 100% killing can be maintained for at least two weeks. It is susceptible to wash off, therefore outdoor active dogs and dogs that swim or that must be bathed because of dermatitis must be re treated frequently. (Weekly re treatment is allowed with Advantage only®). Imidacloprid has no efficacy against ticks, but K-9Advantix®, with permethrin does. K9 Advantix is only labeled for once a month, and ONLY FOR DOGS.

Advantage Multi is our drug of choice for flea prevention in cats. 

Comfortis ®for Dogs (spinosad) from Elanco Animal Health Division of Eli Lilly
This monthly prescription tablet for fleas represents a completely new class of drugs in flea control.  It is available for use on puppies and dogs 14 weeks of age or older and is available in 5 different sized flavored (soy and pork) chewable tablets. It is meant to be used once a month and preliminary results show it will be very useful for flea allergic pets as it has a rapid kill rate. 
We recommend the use of Comfortis, in addition to a growth-regulator product such as Sentinel, for dogs that have flea allergies or are faced with more intense flea outbreaks.

Capstar® (nitenpyram) from Novartis
This is a prescription tablet for dogs and cats as young as 4 weeks of age.  It offers extremely rapid and complete killing of adult fleas on the pets after administration.  It is safe enough that the tablets may be used as needed, as often as once per day, whenever you see fleas on your pet.  This is designed to be used in combination with an insect growth regulator to knock out fleas when these slower products are being used for long-term control.  It can also be used when the pet has visited a flea-infested environment for rapid protection. When given every-other-day, it is a useful flea control for single cat households.

Article adapted from Veterinary Partner, www.veterinarypartner.com