Why Is My Dog So Itchy? Top 5 Causes Of Itching In Dogs

by Lorie Huston, DVM  

Dogs can become itchy and begin to scratch for many different reasons. However, allergies of various types are among the most common causes.

Canine Flea Allergy Dermatitis

An allergy to fleas is one of the most common reasons dogs become itchy. When a flea bites a dog, it injects a substance into the dog’s skin which causes the allergic response.

For a sensitive dog, one flea bite can make the dog extremely itchy. 

One of the most difficult things to understand is that often no overt evidence of fleas is present even though a flea allergy is the reason for the dog’s discomfort. This inability to find evidence of fleas stems from the fact that only one flea need be present and bite the dog in order for the allergic reaction to occur.

In addition, dogs frequently groom themselves and remove the evidence of the fleas through their grooming behavior. Therefore, not being able to find fleas does not rule out a flea allergy as a cause of itching in a dog.

Canine Atopy

Canine atopy is a type of allergy that causes a hypersensitivity reaction to environmental stimuli, such as dust mites or pollens. It is a common disorder in dogs and typically causes scratching and itching. Finding the source of the allergy in these cases can be challenging.

Food Allergies in Dogs

Food allergies are another common cause of itching in the dog. Food allergies can result from reactions to any ingredient within the food but beef, chicken and wheat are some of the most common culprits.

Bacterial Skin Infections in Dogs

Bacterial infections in the skin, commonly called bacterial dermatitis, are another common cause of itchiness in dogs. Bacterial skin infections frequently occur as complications to canine allergic skin disease and are usually a secondary disease.

Bacterial dermatitis must be successfully treated with antibiotics in order to evaluate and control the underlying allergic skin condition.

Canine Yeast (Malassezia) Skin Infections

Yeast skin infections most commonly involve a specific type of yeast known as Malassezia. Like bacterial skin infections, yeast infections are generally secondary to another underlying disease, often allergic in origin. Antifungal medications, such as ketoconazole, are needed to treat canine yeast infections.

Most Common Causes of Itching in Dogs

The three most common causes of itching in dogs are flea dermatitis, atopy and food allergies.

Any of these three types of allergies can be complicated with secondary bacterial or yeast invaders resulting in bacterial and/or yeast skin infections in affected dogs. These skin infections can become quite itchy in their own right and cause extreme discomfort and distress for the infected dog.

Less commonly, other causes, such as canine ringworm (dermatophytosis) or sarcoptic mange may cause itchiness and discomfort as well.

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Lorie Huston has been practicing veterinary medicine for over 20 years. Besides a successful career in a busy small animal hospital in Providence, RI, Lorie is also a successful freelance writer specializing in pet care and pet health topics. 

Currently, she is the feature writer for the Pet Care section at Suite101.com and the National Pet Health Examiner at Examiner.com. Lorie also publishes her own blog, The Pet Health Care Gazette and manages an increasingly popular facebook page, The Voice of Pet Care. 

Articles by Dr. Huston:
Lyme Is Lame (Pun Intended)
The Ticking Bomb
Don’t Let Heartworm Become A Heartbreak!
Summer Perils: Blue-green Algae
Your Dog And Leptospirosis
Canine Parvovirus
Canine Distemper Virus