Category Archives: Skin diseases of Dogs

The flea life cycle

Adult fleas are only 5% of the entire flea population. The eggs they lay on the dog fall off into the dog’s environment. Flea eggs are pearly white and too small to see without magnification. They hatch into larvae in 1 to 10 days depending on how humid and hot it is.

Flea larvae eat organic debris and adult flea faeces. They avoid direct sunlight and burrow into carpet fibres, grass, branches, leaves, or soil.

Dry conditions kill larvae. Outdoor larval development occurs where the ground is shaded and moist and where flea-infested pets spend a significant amount of time. Indoors, larvae survive best in the carpet or in cracks in the floor.

After 5 to 11 days larvae pupate. While in the cocoon pupae are resistant to insecticides and continue to emerge for 3 months despite insecticide application.

Pupae emerge as adult fleas in another 5-10 days if stimulated by the vibration of passing pets, physical pressure, carbon dioxide, or heat.

When the adult flea emerges it moves towards body heat, movement, and exhaled carbon dioxide. Following the first blood meal, female fleas begin egg production within 48 hours and continue for 100 days.

This entire life cycle (adult flea – egg – larva – pupa – adult) takes 7 – 21 days depending on temperature and humidity conditions.

Flea control depends on knowing this life cycle.

Flea allergy

What is flea allergy?

Some dogs are allergic to fleas and react with non-stop scratching and biting. Normal dogs are only mildly irritated by fleas. The flea allergic dog is allergic to flea saliva. Just one flea bite causes intense and long lasting itchiness.

The dog chews, licks, or scratches over the rump, on the belly and down the legs. This causes hair loss and damage to the skin. Breaks in the skin allow bacteria in and infection to develop.

What is the proper treatment?

We must eliminate all fleas on the dog and in the environment.

Capstar or Comfortis kill the fleas and paralyse flea mouthparts preventing deposition of saliva.

Every month treat your dog with Advantage, Advocate, Advantix, Frontline, Revolution, or Comfortis to keep flea numbers as low as possible.

Fleas spend most of their life cycle off the dog as larvae and pupae in bedding, carpet, dirt and leaves. Wash bedding in hot water and dry in the sun.  Vacuum carpets and furniture often. Rake up leaves in shady places and provide outside kennels or hidey holes off the ground.  Call a professional to fumigate your house.

Flea control depends on knowing the life cycle of fleas.

Cortisone products like prednisolone block the allergic reaction and give relief from the intense itching.

If your dog develops a bacterial infection in the skin, your vet will prescribe antibiotics.

Sarcoptic mange or scabies

Itchy dog?

Sarcoptic mange causes severe itching.  Dogs chew and scratch their skin constantly.  They lose hair and the skin is thick and red, especially on the ears, legs and belly.

What causes sarcoptic mange?

It is caused by a mite that lives on the skin of any age dog.  It’s also called fox mange. Many dogs catch it from foxes.

Is it contagious?

Sarcoptic mange is highly contagious to other dogs. Humans in close contact with their dog  can catch it, too.  Although the mites are not able to complete their life cycle on humans, they cause a rash and severe itching before they finally die.  Contact your family doctor or pharmacist for advice on treatment.

How is sarcoptic mange diagnosed?

Diagnosis is made by scraping the skin with the side of a scalpel blade and examining it under the microscope.  Despite severe itchiness there are often only a small number of mites present on the dog.  If all skin scrapings are negative and we are still suspicious we do a treatment trial.

How is it treated?

The spot on treatment Revolution applied weekly for 3 weeks is easy and effective.  Sometimes we inject or drench with ivermectin weekly. Ivermectin is not licensed for use in dogs and is dangerous for collie breeds.

All dogs in contact with the affected dog should be treated.

Discard the dog’s bedding before treatment.

If any member of the family develops an itchy skin rash, please tell your doctor that you have been exposed to a dog with sarcoptic mange, also known as scabies.