One of the most common problems affecting dogs and cats throughout their lives are skin issues like scratching, itching, and hair loss. Hair loss, or alopecia, can have a variety of causes, including parasites, hormone imbalance, food allergies, and infection. To effectively treat your pet’s skin problems, it’s important to understand what alopecia is and to properly identify the underlying cause.
Simply put, any type of hair loss—whether complete (affecting the entire coat) or partial (resulting in bald spots)—is considered alopecia. Signs of alopecia are usually obvious, and depending on the cause, may be accompanied by biting, scratching, or areas of irritation and broken skin.
The most common cause of alopecia in dogs and cats is fleas or other parasite infestations. It is estimated that for every flea you see on your pet, there are 5,000 more in the environment—so one flea can truly signify an infestation! Fleas bite your pet, causing itching and scratching. In severe cases, repeated scratching alone can lead to alopecia. More commonly, as your pet scratches and bites at their skin to remove the flea, they may damage or break the skin, introducing bacteria from their mouths or feet into the body. This bacteria then takes hold, leading to a skin infection.
Hot spots, or traumatic moist dermatitis, are the typical result of this cycle in dogs and can also occur in cats. As bacteria are introduced into the skin, swelling and discomfort follow, causing the pet to scratch and bite more aggressively—thus worsening the original problem. Hot spots can vary in size but are generally characterized by hair loss, severe reddening or bleeding of the skin, and signs of infection. Left untreated, hot spots can rapidly spread, and the infection will worsen.
Food Allergies
Food allergies in dogs and cats can also lead to itching, scratching, and alopecia. It can be difficult to differentiate between allergy-related alopecia and that caused by fleas, as both can result in scratching, skin irritation, and secondary skin infections like hot spots. In pets on a comprehensive flea prevention program who suffer from recurrent skin infections, hot spots, and alopecia, allergies might be the culprit.
Food allergies in pets typically develop over time, so it isn’t unusual for dogs and cats that have been eating the same food for years to begin showing symptoms. Studies show that the most common food allergens are beef, chicken, wheat, eggs, corn, and soy—and yes, these allergens are also the most common ingredients in commercially prepared pet foods. Pets suffering from food allergies may be allergic to one ingredient or several.
Symptoms of food allergies can vary greatly in both presentation and severity, making it difficult to diagnose the cause. In dogs, common symptoms include itchy skin, hot spots, alopecia, excessive chewing of the paws, and recurrent ear infections. In cats, alopecia and scratching may be present along with gastrointestinal symptoms like vomiting and diarrhea. While symptomatic treatments such as steroids and antibiotics may improve these conditions, they often return once treatment stops.
Unfortunately, there is no single test or quick fix for diagnosing and treating food allergies in pets. The best method is through a food trial, where many common allergens are eliminated from the pet’s diet. This ‘elimination diet’ consists of one novel source of protein (such as rabbit, venison, duck, or fish) and one novel source of carbohydrates (such as potato or rice) that the pet has never eaten before. This diet must be strictly followed for at least 12 weeks to determine if it reduces symptoms.
In older dogs with chronic thinning of the hair, thickened skin, and generalized alopecia, hypothyroidism may be to blame. The thyroid gland regulates metabolism, and as dogs age, it may produce insufficient thyroid hormones. This deficiency affects the metabolic function of all the dog’s major organs. Dogs with hypothyroidism may experience weight gain despite reduced food intake, lethargy, thickening and darkening of the skin, and thinning of the coat with alopecia.
A simple blood test can diagnose hypothyroidism in dogs, and most dogs with this condition can be treated with synthetic thyroid medication. Although lifelong treatment is usually necessary, dogs with regulated thyroid function can lead normal lives.
In contrast, older cats are at risk for developing hyperthyroidism, a disorder caused by an enlarged thyroid gland that overproduces thyroid hormone. This excess hormone production can have destructive effects on a cat’s body. Cats with hyperthyroidism may suffer from weight loss, vomiting, diarrhea, excessive thirst, high blood pressure, and areas of hair loss. A blood test can diagnose hyperthyroidism in cats, and medication is prescribed to regulate thyroid hormone production.
In some cases, cats may experience a compulsive disorder that leads to hair loss without any underlying medical condition. Psychogenic alopecia in cats is often caused by stress or anxiety, such as from changes in the environment, the introduction of a new person or animal, or other stressors. Cats may groom excessively, resulting in hair loss and bald spots. Reducing environmental stressors and providing behavior modification training can help resolve this issue. In severe cases, a veterinarian may prescribe medication to reduce anxiety.
Alopecia in dogs and cats can be a frustrating and recurring issue. Due to the range of potential causes for skin problems and hair loss, it is essential for your veterinarian to examine your pet, determine the cause of the alopecia, and recommend the best course of treatment.
