Fleas: How to Identify, Treat and Prevent Them from Infesting Your Dog


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Fleas. They are one of the most annoying and dreaded pests for dog owners. Preventing an outbreak of fleas on your dog can save you a lot of headaches and hassle, as fleas are not only an annoyance, but they can also transmit disease. If fleas begin to infest your dog, they can spread to other pets and to people. If they start to spread in your home, getting rid of them is a major undertaking.

Unlike some pests that can be found around the home, fleas cause discomfort and irritation to both pets and people. Some dogs and people will suffer allergic reactions to flea saliva that can result in rashes.

Flea bites create a small, hard, red, itchy spot, slightly-raised and swollen with a single puncture point at the center. The bites often appear in clusters or lines, and can remain itchy and inflamed for up to several weeks. Fleas can also lead to hair loss as a result of frequent scratching and biting by an infested dog, and can cause anemia in extreme cases.

Besides these problems, fleas can also transmit disease. For example, fleas transmitted the bubonic plague between rodents and humans in the Middle Ages by carrying the bacteria. Although not common, endemic typhus fever, and in some cases, tapeworm can also be transmitted by fleas.

Flea Life Cycle

Fleas have four stages of development: egg, larval, pupal and adult. It takes from 2 weeks to several months to go from egg to adult depending on the species, temperature, humidity and food availability. After each blood meal, females lay 4 to 8 smooth, round, light-colored, sticky eggs. She can lay 25 eggs per day, and roughly 800 in her life.

Eggs hatch into very small, hairy, wormlike larvae that are whitish with brownish heads. The larvae are from 1.5 mm to 5 mm long. They feed on organic debris, their own cast skins and dried blood in adult flea excrement. Larvae can survive up to 200 days even in unfavorable conditions and travel up to 30 cm per minute. They will spin silken cocoons covered with particles of dust, fibres, sand and organic debris and later emerge as an adult flea.

Fleas may remain in the cocoon for several months until favorable conditions arise, such as a rise in temperature and carbon dioxide levels. Vibrations created by the presence of humans and pets will also stimulate their emergence and activity.

Fleas usually feed several times a day, but can survive several weeks without a meal. Adult fleas usually leave the host after feeding; however, flea eggs, larvae or pupae may be found on pets.

The peak season for flea infestations outdoors in regions with colder winters (like Canada) is from early August to early October, although they can be present earlier and later in the year. In areas with mild climates, fleas survive all year round. They can also live inside homes at any time of year.

Fleas live in the grass, woodlands and on animal hosts. In excessively dry, hot summers fleas tend to dehydrate and die.

As fleas reproduce very quickly, when you discover any on your dog they should be dealt with immediately.

A flea.

Identifying if your dog has fleas

One of the best ways to prevent your dog getting fleas is to inspect your pet regularly, especially once spring arrives. Here’s what to look for:

  • Fleas are small insects (one to four millimeters long) with dark brown or reddish brown flattened bodies. Though wingless, they have powerful back legs that allow them to leap up to 200 times their body length.
  • Bits of black the size of ground pepper. These bits of debris are flea feces – dried blood waste that fleas produce. You will often find it on the skin near the tail on the back of your dog or in areas where the skin is more exposed (thin) such as the underbelly, ears, rear end. These black bits are tell-tale signs that they may have fleas.
  • You notice your dog is scratching regularly and vigorously, especially around his/her ears and underbelly, or is biting at his tail. If you notice this behavior it’s time for an inspection.

Flea dirt

Managing a flea infestation

Use a flea control product once an infestation has occurred. Before using a product, consult with a veterinarian to determine the best treatment for your pet and to limit the amount and combination of chemical exposures. Be sure to use flea products only on the animal specified on the product label – dog products for dogs and cat products for cats. It is equally important to keep the amount and combination of different chemical exposures to a minimum, especially if pets are already taking some form of medication.

To break the flea cycle successfully, the home, pet and often times, the yard must be treated all together. The manner in which these treatments are done can greatly influence the results. You must rely on a combination of sanitation and chemical treatments.

If you identify an infestation of fleas on your pet, here are a few things that are recommended:

Cleaning your home

  • Vacuum carpets and cushioned furniture daily. Be sure to replace your vacuum cleaner bags during this process as the fleas and larvae can live in the vacuum cleaner bags and re-infest the home.
  • Clean around cracks and crevices on floors and along baseboards and basement.
  • Steam cleaning carpets will kill fleas in all stages with the hot steam and soap.
  • Wash all pet bedding and family bedding in hot, soapy water every 2 to 3 weeks.
  • Lift blankets by all four corners to avoid scattering the eggs and larvae.
  • If an infestation is severe, replace old pet bedding..
  • If your dog travels regularly in your vehicle clean and vacuum it as well.
  • You may have to repeat this process for 1 to 3 months in and around the home to ensure eggs, larvae and adults have been removed.

Cleaning your dog

  • Get a flea comb. Flea combs can be used to remove some fleas, flea feces and dried blood. Focus combing where the most fleas congregate on the pet, usually the neck, tail or belly. When fleas are caught, kill them in hot soapy water. If you are not sure if it is a flea or a tick or another insect, preserve it in a sealed container and bring it to your vet for identification. Isopropyl alcohol will also kill the insect.
  • Check with your vet for his or her advice on an appropriate treatment. This is especially important if your dog is sick, aged, pregnant, nursing, is on medication or is exposed to other chemicals, as he/she may have additional sensitivity. As some flea preventatives also work to prevent ticks, worms and ear mites, we strongly recommend that you consult with your veterinarian prior to administering a preventative due to the potential for adverse drug reactions.
  • Wash your dog. Start cleaning from the head down, to avoid any fleas escaping to hide in your dog’s ears. Dog shampoo should be OK to use for cleaning unless the infestation is severe, in which case you may wish to use a special anti-flea shampoo. Once your dog is clean, comb him/her again. Note that flea control shampoos will kill fleas on direct contact but provide little residual control.
  • Use a flea control product. Flea control products are made from chemicals that kill fleas by either inhibiting their ability to reproduce or by poisoning them. However, not all flea products work the same or use the same chemicals. Some products only inhibit adult fleas and do not kill eggs or larvae. A number of flea control products can only be purchased directly from a veterinarian, while others are over-the-counter. Read more on flea control products below.

If you use a flea control product, be sure to always read the label before using it on your dog. Never apply garden pesticides and do not use cat products on dogs or dog products on cats. Do not use a product on puppies unless the product label specifically allows the treatment. Consult your veterinarian if you have any questions or concerns on administering any flea control product.

  • Follow the product instructions exactly.
  • Apply only the amount indicated for the size and weight of your dog to prevent overdose.
  • Observe your dog closely during and after the treatment and monitor for any signs of an adverse reaction, particularly when using flea products on your dog for the first time.
  • Do consult a veterinarian if your pet experiences an adverse effect. It is also important to report any adverse effects to the manufacturer, who is required by law to report them to the appropriate health authority. Manufacturer contact information can be found on the product label. Such incidents may also be reported directly to the FDA in the USA and Health Canada in Canada.

Selecting the appropriate Flea Control product

Before using a product, consult with a veterinarian to determine the best treatment for your pet and to limit the amount and combination of chemical exposures. Note that topical or spot on treatments may be extremely harmful to avermectin sensitive dogs (Dogs with a mutation in the MDR1 gene may develop signs of severe avermectin toxicity if they ingest certain medications). Collies and Collie crosses are the most common breed effected.)

Always follow the manufacturer instructions when using any pesticide product.

  • Topical or spot on treatments are by far the most effective in preventing a dog from catching fleas. Spot-on treatments are most often applied between the shoulder blades and near the back of the neck. Additional locations, such as on the back at base of tail, may be necessary for larger animals. But be sure to refer to the manufacturer’s packaging and consult your veterinarian if you have any questions about applying the treatment.Topical treatments provide longer term control of fleas for approximately one month. Note: some treatments are effective for also battling ticks and mosquitos. Once-a-month spot-on treatments include products such as Bayer Advantage (which contains the active ingredients imidacloprid and moxidectin), Revolution (which contains selamectin) or Frontline Plus. If spot on treatments are used effectively, insecticides, powders, shampoos and other preventatives are not necessary.Some spot-on products have the extra benefit of controlling intestinal worms and other parasites like heartworm (transmitted by mosquitos), tick-borne diseases and ear mites as well. If using spot-on treatments for the first time, consult with your veterinarian to confirm the proper dosage for your size of dog and what type of treatment is best for your climate and geographic area.
  • Flea collars will prevent fleas from biting your dog, but do not provide adequate control once an infestation has occurred. Some animals may develop a skin rash from flea collars. There is also a growing concern over the chemicals included in some flea collar products and in some countries flea collars have been declared poisonous and banned.
  • Flea powders are not as effective for pets with thick coats and are more often focused on treating carpets and bedding rather than the pet. Powders can be messy and are can accidentally be ingested if your dog licks it off his/her fur. If used on carpets and bedding it also exposes children and other pets in the home to the chemical, so proceed with caution.
  • Sprays, aerosols and foams. Foams may be preferable to sprays for nervous pets, especially cats.
  • Flea Control Shampoos will kill fleas on direct contact but will not kill eggs that may be in your home and dog’s bedding and therefore not have a lasting effect unless the home is also treated.

Naturopathic remedies include non-toxic solutions to ward off fleas.

  • Diatomaceous earth. Diatomaceous earth, a fine powder also known as silicon dioxide, consists of aquatic microorganisms. This powder is not applied on pets but rather used in the yard, garden, grass and home. It can be spread around window sills, baseboards, cracks and crevices around the home. As the insects crawl over the fine powder, their waxy outer protection is scratched, causing them to dehydrate and die. Diatomaceous earth is non-toxic to humans and pets and will remain active as long as it is kept dry. As with any powdered chemical, please follow instructions on the label for safe use and avoid inhalation.
  • Metal disks, amulets and tags are advertised as using ultrasonic waves or electromagnetic scalar waves to repel fleas. However, there have not been any scientific evidence that they are effective. Kansas State University conducted a study of CatanDog’s tags and evaluated the tags to see if they prevent flea infestations. The study concluded that the tags did not inhibit flea reproduction or repel existing fleas. The study was published by the US National Library of Medicine and National Institues of Health.
  • Garlic is often touted as a way to ward off fleas but DO NOT feed it to your dog. Garlic (in large quantities) can cause Heinz body anemia and be fatal. Read more about toxic foods for dogs here.
  • Cedar balls or chips and lavender are two natural ingredients that repel fleas. They won’t kill them, but sometimes dog owners use them in and around a dog’s bed.

Note: With any chemical (natural or otherwise) – flea powder, diatomaceous earth, pesticide, etc. – it should always be handled with extreme care, especially if individuals have asthma or other lung conditions. Some products warn of the risks of cancer, likely a caution for long term exposure or heavy inhalation. Only small amounts of chemical powders should be applied. We advise everyone to always read labels and instructions carefully before use and consult with your veterinarian if you have any questions or concerns.

Remember that you will need to treat your dog and your home together and consistently over a period of time in order to effectively rid your pet and home of a flea infestation.

Disclaimer: The content included in this article is not intended to be a substitute for professional medical or veterinarian advice, diagnosis or treatment. Always seek the advice of your veterinarian or other qualified professional health provider with any questions you may have regarding a dog’s medical condition. Do not disregard professional medical advice or delay in seeking it because of something you have read on this website.


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