The Itchy Dog

itchy dogThere are many causes of pruritus (itchiness) in dogs. We all have an occasional itch that needs scratching, but when the itch persists or is associated with broken skin or hair-loss, it is time to see the doctor. In dogs, reasons for an incessant itch can include skin parasites; fungal, bacterial and yeast infections; food and inhalant allergies; and hormone related disorders that make the dog more susceptible to all of these. The longer an itch is scratched, the more likely that self-trauma will lead to secondary or deep-seated infections that can be difficult to clear.

Fleas are the number one cause of canine dermatitis in the world. They are easy to diagnose and easy to eliminate. Fleas cause an insatiable itch as their saliva is highly allergenic. Hair-loss, self-trauma, and secondary skin infection is very common with infestation. Fleas also spread tapeworms. Monthly topical products are available that kill and repel fleas, flea eggs, and flea larvae.

Inhalant allergy (atopy) is the second most common cause of skin itchiness in dogs. It can be difficult to eliminate, because the allergens are in the air we breathe. Atopy is a complicating and/or primary factor in many skin disorders. It responds to antihistamines and corticosteroids. Allergy testing and desensitization serum injections are recommended to reduce the need for oral medications which may have side effects.

Sarcoptic mange (scabies) is a microscopic mite that burrows under the skin causing severe itchiness. It can be hard to detect on skin samples under the microscope; however, it makes its presence well known. Often, it is treated as a rule out cause for itching before pursuing other diagnostics. Dips and extra-label use of injectable de-wormers are used to kill scabies mites.
Ringworm isn’t a worm at all. It is a fungal infection of the skin. It causes the hairs to break off and leaves a scaly red patch on the skin that may itch. Mild cases may respond to topical anti-fungal ointments; whereas, generalized infection requires the use of oral antifungal drugs concurrently with medicated shampoos or dips.

Yeast (Malassezia) infections of the skin are notoriously itchy. They also exude an offensive musty odor from the skin. Hyperpigmented and thickened skin (elephant skin) is a common appearance for dogs with Malassezia infections. They require the use of anti-fungal drugs and shampoos, and are almost always secondary to an underlying hormone disorder or primary allergic dermatitis.