Hair loss and scratching are common symptoms in dogs and cats. There are many diseases that can cause these symptoms and many of them will appear similar to one another. These are some of the most common causes.
Allergies Can Cause Hair Loss and Scratching in Dogs and Cats
Allergies are the most common cause of hair loss and scratching in dogs and cats. The three most common canine and feline allergies are:
- allergies to fleas
- atopy (an allergy to substances in the environment, such as grasses, plant pollens and dust mites)
- food allergy
Parasites and Fungal Infections that Cause Hair Loss and Scratching in Pets
There are several different parasitic diseases that can cause hair loss and scratching for your dog or cat.
- Demodectic mange is caused by a mite, a small insect. It is most commonly seen in dogs but can be seen in cats also. Some dogs (and cats) seem to be more likely to show symptoms of demodectic mange than others and some pets may be genetically predisposed to infection.
- Sarcoptic mange is also caused by a mite but it is a different mite than the one that causes demodectic mange. Sarcoptic mange can affect people as well as pets.
- Otodectic mange is caused by ear mites. Though most commonly found in the ear canals, ear mites can also live on the hair and skin outside of the ear canals. They can be responsible for causing hair loss and scratching, particularly in and around the ears. Ear mites are contagious to both dogs and cats, but generally do not bother people.
- Ringworm is caused by a fungal infection. It is contagious to pets and people both.
Skin Infections and Their Role in Hair Loss and Itchiness in Dogs and Cats
Both canine and feline skin can become infected with various types of bacteria and yeast. The most common yeast infection seen is caused by Malassezia. Both yeast and bacterial infections can make a dog or cat extremely itchy, causing scratching and hair loss.
Skin infections in dogs and cats rarely occur on their own, without an underlying factor. Usually, there is another skin disease or skin problem which causes changes in your pet's skin allowing the bacterial or yeast infection to occur. It is important to locate and treat the underlying cause in addition to the skin infection. Otherwise, the skin infection is likely to recur.
Canine and Feline Skin Diseases Caused by Autoimmune Disorders
There are several autoimmune disorders that can cause skin disease in dogs and cats. They are reasonably rare but the most commonly seen are:
- pemphigus
- discoid lupus erythematosis (DLE)
- bullous pemphigoid
- systemic lupus erythematosis (SLE)
In an autoimmune disease, essentially the body's immune system mistakenly recognizes a part of the body as a foreign object and mounts an immune attack against that part of the body.
Endocrine Diseases that Cause Skin Problems in Dogs and Cats
Endocrine diseases can sometimes cause hair loss, particularly in dogs. However, normally skin problems resulting from endocrine disorders are not itchy and do not cause scratching, unless the skin has become infected with bacteria or yeast.
The two most common endocrine causes of hair loss in dogs are hypothyroidism and hyperadrenocorticism.
- Hypothyroidism occurs when the thyroid gland does not secrete sufficient amounts of thyroid hormone.
- Hyperadrenocorticism is also called Cushing's disease. It is a disorder of the adrenal gland in which adrenal hormones are secreted in abnormally high levels.
These are some of the most commonly encountered causes of hair loss in dogs or cats. Other causes include nutritional deficiencies or imbalances. Disorders of keratin production and seborrhea are also possible.
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