At the Animal Clinic at Thorndale, we are concerned about flea control product safety as well as product efficacy. All flea products have certain risks and benefits associated with them. We carry a variety of flea control products in our hospital. A flea infestation usually requires more aggressive treatment than continuing year round control. We will design your flea control program with the specific needs of your pets and household members in mind. Please feel free to discuss your specific concerns with our veterinary staff. We are here to help. Successful flea control has two aspects. Fleas must be controlled on your dog, and fleas must be controlled in your dog’s environment. Since cats and dogs share the same fleas, the presence of a cat in your dog’s environment can make flea control much more difficult.
Diagnosis of Flea Infestation
When a dog is heavily infested with fleas, it is easy to find them. If the numbers are small, it is best to turn your dog over and look on its belly. If you do not find them there, look on the back just in front of the tail. Be sure to part the hair and look at the level of the skin. When the numbers are very small, look for “flea dirt.” Flea dirt is digested blood left behind by the fleas. Flea dirt is actually fecal matter from the flea. Finding flea dirt is a sure indication that fleas are present or have been present recently.
The easiest way to catch fleas or obtain some flea dirt is to comb your dog, especially just above the tail base, with a fine toothed flea comb, collecting the hair and debris on a white paper towel. Flea dirt looks like pepper. It varies from tiny black dots to tubular structures about 1/32″ (1/2 mm) long. If you are not sure it is flea dirt, add one or two drops of water, and wait about 30 seconds. If it is flea dirt, the water will turn reddish brown as the blood residue goes into solution. A red stain will become apparent if you gently wipe the material across the surface of the paper towel.
Many people find tiny drops of blood in a dog’s bedding or where the dog sleeps. This is usually flea dirt that was moistened, then dried. It leaves a reddish stain on the bedding material and is another sign that fleas are present.
Life Cycle of the Flea
To appreciate the complex issue of flea control, you must understand something about the flea’s life cycle.
Although you are only able to see the adult flea, there are actually 4 stages of the life cycle. The adult flea constitutes only about 5% of the entire flea population if you take into account all four stages of the life cycle. Flea eggs are pearly white and about 1/32″ (1/2 mm) in length. They are too small to see without magnification. Fleas lay their eggs on the dog, but the eggs do not stick to the dog’s hair. Instead, they fall off into the dog’s environment. The eggs make up 50% of the flea population. They hatch into larvae in 1 to 10 days, depending on temperature and humidity. High humidity and temperature favor rapid hatching.
Flea larvae are slender and about 1/8-1/4″ (2 to 5 mm) in length. They feed on organic debris found in their environment and on adult flea feces, which is essential for successful development. They avoid direct sunlight and actively move deep into carpet fibers or sofa cushions or under organic debris (grass, branches, leaves, or soil.) They live for 5 to 11 days before becoming pupae.
Moisture is essential for flea larvae survival; flea larvae are killed by drying. Therefore, it is unlikely that they survive outdoors in shade-free areas. Outdoor larval development occurs only where the ground is shaded and moist and where flea-infested pets spend a significant amount of time. This allows flea feces to be deposited in the environment. In an indoor environment, larvae survive best in the protected environment of carpet or in cracks between hardwood floors. They also thrive in humid climates.
Following complete development, the mature larvae produce a silk-like cocoon in which the next step of development, the pupa, resides. The cocoon is sticky, so it quickly becomes coated with debris from the environment. This serves to camouflage it. In warm, humid conditions, pupae become adult fleas in 5-10 days. However, the adults do not emerge from the cocoon unless stimulated by physical pressure, carbon dioxide, or heat.
Pre-emerged adult fleas can survive up to 140 days within the cocoon. During this time, they are resistant to insecticides applied to their environment. Because of this, adult fleas may continue to emerge into the environment for up to 3 weeks following insecticide application. This is very important when you consider your flea control efforts!
When the adult flea emerges from its cocoon, it immediately seeks a host because it must have a blood meal within a few days to survive. It is attracted to people and pets by body heat, movement, and exhaled carbon dioxide. It seeks light, which means that it migrates to the surface of the carpet so that it can encounter a passing host. Following the first blood meal, female fleas begin egg production within 36 to 48 hours. Egg production can continue for as long as 100 days, which means that a single flea can produce thousands of eggs.
This entire life cycle (adult flea >>> egg >>> larvae >>> pupa >>> adult) can be completed in 14-21 days with the proper temperature and humidity conditions but can last 3 months or longer. This adds to the problem of flea control.
If untreated, the female flea will continue to take blood for several weeks. During that time, she will consume about 15 times her body weight in blood. Although the male fleas do not take as much blood, they, too, contribute to significant blood loss. This can lead to the dog having an insufficient number of red blood cells, which is known as anemia. In young or debilitated dogs, the flea bite anemia may be severe enough to cause death.
Contrary to popular belief, most dogs have rather limited itching due to fleabites. However, many dogs become allergic to the saliva in the flea’s mouth. When these dogs are bitten, intense itching occurs, causing the dog to scratch and chew on its skin. In truly allergic dogs, the scratching is occurring even though the flea is no longer in the area where the bite occurred.
Flea Control
Successful flea control must rid the dog of fleas and it must rid the dog’s environment of fleas. In fact, environmental control ia as important as treatment of the dog. If your dog remains primarily indoors and you do not have other pets that come in from the outside, environmental control is relatively easy, especially with the advent of the new topical products (see below). However, the dog that goes outdoors frequently or stays outdoors presents a somewhat greater challenge and a few fleas may occasionally be seen indoors.
Many of the older insecticides (which had been the mainstay of flea control for years) have limited effectiveness against fleas because they are only effective for a few hours after application on the dog. Also, these are primarily geared to kill adult fleas. Flea powders, sprays, dips and shampoos may kill the fleas present on your dog at the time of application. However, most of these products have little or no residual effects, so the fleas that return to your dog from his environment are not affected. Thus, your dog may be covered with fleas within a day of having a flea bath or being sprayed or powdered. Worse, many dogs become allergic to these products as well.
Recommended Products
For Flea Control on Your Dog
There are many available topical treatments are applied to the nape of the neck on a monthly basis. At the Animal Clinic at Thorndale we are concerned about product safety as well as efficacy. The “gold standards” for flea control has been Frontline Plus and Frontline Gold. They are effective against fleas and also the least toxic to your pet because there is minimal absorption through your dogs skin. They have a growth regulator which will render any eggs sterile that are produced by a female flea that survives long enough to bite your dog. These products work when the flea comes in contact with them. They are designed to kill the fleas before the flea bites. Revolution is another flea product that has had good success against fleas. It is absorbed into your dogs system and has activity against some internal parasites, such as heartworm, as well. When fleas have reached overwhelming numbers, we have had good success with applying Frontline monthly and Revolution monthly offset by 15 days (e.g. Frontline on the first of the month and Revolution on the 15th). Products like Nexgard are oral medications that control fleas and ticks. Products like Revolution and Nexgard work when the flea bites your dog. If your dog is flea allergic, it will still be scratching until the flea population is depleted. Caution must be used with products containing permethrins, such as Advantix. These products can be very toxic to cats. They should not be applied to dogs who spend time around cats because the cats may ingest it while grooming the dog.
Oral Medications are also available which can give month long protection, such as Nexgard. Owners need to be aware that these by their very nature are internal toxins. The chemical ingredients are generally safe for dogs but are fatal to the fleas during a blood meal or when they contact the oils in the coat containing the product. Capstar can give a quick kill off of fleas on your pet at the time it is given, but does not have residual effects.
Environmental Control
If you have regained flea control through just treating your pets, you may not need environmental control other than routine housecleaning. When environmental flea control is indicated, it must be directed at your house and your yard.
House. Even though fleas may be in your house, most people never see them. Fleas tend to prefer cats and dogs to people; they only infest humans when there has not been a cat or dog in the house for several days. A professional exterminator may be called to treat your house or you may use a household spray, such as Siphotrol Area Treatment Spray. These sprays are very effective for adult fleas and also contain growth regulators, but they will not kill fleas that are still in their cocoon. In climates with extended warm temperatures and high humidity, it may be necessary to treat two or three times with a 30-day residual product before all stages of the fleas are removed from the house. The second treatment is most effective if it is done 2 weeks after the first.
Yard. Yard control may also be done by professional exterminators or with various insecticides you may use yourself. Be aware that many of these products may be toxic to fish and wildlife and are environmental hazards to you and your pets. It is best to keep the yard cleared of debris and the grass mowed. Keep pets from bedding down in shaded areas.
Re-emergence of Fleas
If you recall, pre-emerged adult fleas can survive up to 140 days within the cocoon. This is significant when your pets are gone from home for extended periods of time. During the time that the house is quiet and empty, pre-emerged adults remain in their cocoon. Even if the house was treated with an insecticide, their cocoon protects them. When people and pets return to the house, adults emerge from their cocoons and immediately begin to seek a blood meal. They jump on cats, dogs, and even people. Although it may appear that a dog just returned from boarding brought fleas to your home, it is also very possible that a sudden emergence of adult fleas may account for the fleas present. If large numbers of fleas are seen, they are almost certainly newly hatched fleas and have not been brought home with the pet.