One of the most common problems to affect dogs and cats throughout their lives are skin problems, scratching, itching and hair loss. Hair loss, or alopecia, can have a variety of causes, including parasites, hormone imbalance, food allergies and infection. In order to treat your pets skin problems, it is important to know what is alopecia, and properly identify the cause.

Simply put, any type of hair loss, whether complete (throughout the entire coat) or partial (a few bald spots), is considered alopecia. Signs of alopecia are obvious, and depending on the cause, may be accompanied by biting, scratching or areas of obvious irritation or broken skin.

The most common cause of alopecia in dogs and cats is fleas or other parasite infestations. It is estimated that for every single flea you see on your dog or cat, there are 5000 more in the environment- so one flea can truly be an infestation! Fleas bite your pet, causing itching and scratching. In severe cases, repeated scratching alone can cause alopecia. More commonly however, as your pet scratches and bites at their skin to try to remove the flea, they abrade or break the skin, introducing the bacteria from their mouths or feet into the body. This bacteria quickly takes hold, and a skin infection is born.

Hot Spots, or traumatic moist dermatitis, is the typical result of the above cycle in dogs, and can occur in cats as well. As bacteria are introduced into the skin, swelling and discomfort usually follow, causing the pet to become more aggressive in their scratching and biting- thus making the original problem worse. Hot spots can vary in size, but are characterized by hair loss, severe reddening or bleeding of skin, and signs of infection. Left untreated, hot spots will continue to spread rapidly, and the infection will spread throughout the skin.

Treatment of flea-related alopecias and hot spots is three-fold. First, the cause of the irritation must be removed- i.e., the pet and the pets’ environment must be treated for fleas. The affected areas of skin will be clipped of surrounding hair and cleaned with antibacterial solutions, in order to allow it to heal quickly. Finally, antibiotics will be prescribed to treat the underlying infection.

Food Allergies

Food allergies in dogs and cats can cause itching, scratching and alopecia. Often it can be hard to differentiate allergy-related alopecias and those caused by fleas. Both problems can cause scratching and skin irritation, as well as skin infections and hot spots due to the introduction of bacteria into the skin. In animals that are on a comprehensive flea-prevention program, and suffer from recurrent skin infections, hot spots, and alopecia, allergies may be to blame.

Because food allergies in pets tend to develop over time, it isn’t unusual for dogs and cats that have been eating the same diet for a long time to begin to develop symptoms of an allergy. Studies have shown that the most common culprits of food allergies are beef, chicken, wheat, eggs, corn and soy- and yes, these most common allergens are in fact the most common ingredients in commercially prepared pet foods. Pets who suffer from food allergies may be allergic to just one ingredient, or many of them.

Symptoms of food allergies can be varied in both presentation and severity, which makes diagnosing allergies as the culprit more difficult. The most common symptoms in dogs include itchy skin, hot spots and alopecia, excessive chewing of the paws and recurrent ear infections. In cats, alopecia and scratching may be present, as well as gastro-intestinal signs such as vomiting and diarrhea. All of these might respond to and improve with symptomatic treatment such as steroids and antibiotics, but often come right back as soon as the treatment is stopped.

Unfortunately, there is no one-stop test or trial to diagnose and treat food allergies in pets. The best way to diagnose a food allergy is through a food trial, where many of the most common allergens are eliminated from the pets diet. This ‘“elimination diet’” consists of one single, source of protein (such as rabbit, venison, duck, fish) and one single source of protein (potato, rice) that the pet has never eaten before. This diet must be strictly fed for at least 12 weeks in order to determine if the diet is causing a reduction in symptoms.

In older dogs suffering from chronic thinning of the hair, thickened skin, and generalized alopecia, hypothyroidism may be to blame. The thyroid gland is responsible for regulating metabolism, and as a dog ages, often not enough thyroid hormone is produced. The reduced amount of thyroid hormone in the system affects the metabolic function of all of the major organs in the dog. Dogs with hyperthyroidism may suffer from weight gain despite reduced food intake, obesity, lethargy, thickening and darkening of the skin, and thinning of the coat and alopecia.

A simple blood test can diagnose hypothyroidism in dogs, and most dogs suffering from this disease can be treated with a synthetic thyroid medication. Although treatment is generally required for the duration of the dogs’’ life, dogs suffering from hypothyroidism live normal lives once their thyroid function has been regulated.

While the thyroid gland in dogs often under produces the thyroid hormone, older cats are at risk for developing the opposite disorder. The enlargement of the thyroid gland causes hyperthyroidism in cats, as excess amounts of the thyroid hormone are produced. This over production of thyroid hormone is as destructive to the body of cats as the underproduction of the hormone is to the dogs’’ body. Cats with hyperthyroidism may suffer from weight loss, vomiting and diarrhea, excessive thirst, high blood pressure, and areas of hair loss. As in dogs, a blood test can diagnose hyperthyroidism, and medication can be prescribed to help regulate the thyroid.

In cats, a type of compulsive disorder may cause hair loss without an obvious underlying medical problem. Pyschogenic Alopecia in cats may develop when the cats’’ self-grooming behavior becomes over zealous, usually due to stress and anxiety. A new environment, a new person or cat in the household, and other major changes can cause cats to begin to groom themselves excessively causing hair loss and bald spots. Removing or reducing the stresses in the environment can help to solve this problem, and behavior modification training may be required. In severe cases, a veterinarian may prescribe medication to reduce the cats’’ anxiety.

Alopecia in dogs and cats can be a frustrating, and reoccurring problem throughout their lives. Due to the range of causes of skin problems and hair loss, it is important for your veterinarian to examine your pet and determine what the cause of the alopecia is, as well as the best treatment for your dog or cat.


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