Fleas and Your Pet

Fleas are the most common ectoparasites, or parasite found on the skin, veterinarians treat on a daily basis.  Fleas can infection dogs, cats, rabbits, and humans with over 2000 species.  The most common species found in pets is Ctenocephalides felis, or commonly known as the cat flea.

First, we need to get to know the flea in how to identify and why fleas can become such a nuisance to your pet and in a household. 

Flea Morphology

Fleas are a small wingless insect and area typically less than five millimeters in length.  These insects have a distinct flattened body.  Females will have a downward sloping body while a male will have an upward pointed abdomen.

Flea coloration can vary from light yellow to almost black.  The exoskeleton will be shiny.  The body and legs have bristles that vary in number allowing the insect to keep itself on an animal’s feathers or fur.  These bristles also make it difficult to remove through preening or grooming. 

Flea Biology

After the female takes the first blood meal from your dog, they will lay eggs within 24 hours.  Female fleas can lay up to 40 to 50 eggs per day with a typical life span of a month.  She will lay eggs in the hair coat of your pet.  The eggs will then roll off of the coat and into the environment.

The flea eggs will hatch to a larval form within a two-to-five-day time period if the conditions are suitable of warm temperatures and high humidity.  Larvae will have a maggot-like appearance at approximately 2mm long and pale.  The larvae will move away from the light and look for dark areas including carpet, crevices between floorboards, or corners of rooms.

While in the dark, larvae will feed off of flea feces, or flea dirt, other animal waste, and vegetative matter.  The larvae will undergo two molt cycles to develop into the next stage called pupa.  The progression from larvae to pupa takes five to eleven days to complete. 

The pupa stage has the flea larva spinning a whitish cocoon from a silky, sticky gossamer.  The pupa becomes difficult the vacuum and remove from the environment.  The sticky cocoon will attract dust, dirt, and flea feces to provide camouflage and harden the shell.

The pupal stage, in ideal conditions, will last for eight to twelve days but can remain dormant for up to six months to a year.  Stimulation to the pupa including warmth, vibration, and exhaled carbon dioxide cause hatching from the cocoon of an adult flea. 

Now that we know our enemy, why is it so important to control fleas in the environment? Fleas can cause serious health problems for your dog and yourself!  In your dog fleas can cause:

  • Hair loss
  • Skin infection
  • Transmit the intestinal parasite Diplidium caninum, or tapeworms
  • Transmit bacterial infection called Bartonella
  • Anemia, or low red blood cell count
  • Death

In the United States, fleas can transmit a number of diseases to people include:

  • Plague – The plague in people is caused by a bacterium called Yersinia pestis which life cycle involves a rodent flea.  In the United States, human cases range from 1 to 17 per year.  The most common regions in which plaque cases are seen include the southwestern states of New Mexico, Arizona, and Colorado or the western states of California, Oregon, and Nevada.
  • Flea-borne (murine) typhus – Flea borne typus is caused by a bacterium called Rickettsia typhi and is spread through contact with infected cat fleas.  Infections from these bacteria occur in tropical or sub-tropical regions and include California, Hawaii, and Texas.  Although this is rare disease in the United States
  • Cat scratch disease – Cat scratch disease is caused by the bacterium Bartonella henselae.  The spread of the disease is from scratches by a cat infested with fleas who has flea feces under their nails. 
  • Tapeworms – Humans can accidentally swallow a flea infected with tapeworms.  The ingestion will allow the person to develop a tapeworm infection.  Small children are at a higher risk of developing an infection due to them spending more time close to the floor. 

How to Control Fleas?

The best course of control is prevention in your dog.  Veterinarians have many options available for year-round flea prevention and will tailor the best option for your pet.  All animals in the household will need to be on prevent even if you have an indoor only cat.  Fleas can be tracked in and an unprotected pet can create a source of infestation.

What if I have a Flea Infestation Currently?

If you are currently having a flea infestation problem, realize treatment will not result in immediate resolution.  Fleas can persist in the environment even with treatment for up to three months.  With persistent environmental and pet control, flea infestations can be resolved.

1. Flea Prevention: Put all animals in the household on flea prevention. Many flea preventions are available. I recommend speaking with your veterinarian about the best product for your pet.

2. Flea Hot Spots:  Identify all the areas in the household that are flea hot spots.  Flea hot spots will be your dog’s favorite resting or sleeping area.  The flea hot spots areas will be the main focus of cleaning efforts.

3. Clean Thoroughly: The areas that you have identified as flea hot spots will need to be cleaned two to three times a week.  Vacuum furniture with making sure to remove cushions and reach all of the dark crevices since the larvae want a dark place to hide.  After vacuuming, remove the contents obtained immediately from the house. 

Wash bedding that can go into the washing machine on a hot water cycle.  You can also add a small amount of bleach to the wash to help destroy the immature stages of the flea. 

4. Treat the Environment: The first environment to treat is indoors.  All rooms of the house need two treatments one month apart with an adulticide and insect growth regulator product. If using bombs, only use one per room and ensure all pets are evacuated from this area until completely dry.

The next environment is outside.  When treating the outside environment, concentrate on kennel areas, your dog’s favorite sleeping spot, or shaded areas.  Thankfully flea eggs and larvae do not survive extended periods of full sun especially in the summer. 


Fleas are the most common parasite seen in veterinarian medicine and can pack a punch with infection and disease spread. Management and prevention of fleas can be accomplished but may take some time to achieve when an infestation occurs. Don’t be discouraged as the problem is manageable and ensure to employ the help of your veterinarian.

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