Fleas, allergies, infections, and contact dermatitis are all common causes of rashes on dogs. Poor nutrition can also aggravate skin problems. Excessive scratching can break the skin, creating an opening for a secondary infection that can aggravate the ailment. Dogs that scratch excessively should be taken to a veterinarian for a diagnosis.
One common reason why a dog might be excessively scratching, creating red patches and a rash, is due to fleas. Fleas are highly contagious, easily passing to other pets. The fecal matter from the fleas act as the agent that causes rashes on dogs, as well as the actual biting from the fleas. Infected areas tend to be sore, red, and bare of hair due to the scratching. Fleas, however, can usually be easily managed with the help of medication.
Allergies are another cause for skin rashes on dogs. As a dog brushes against plants or grass, some of the pollen will stick onto the fur or skin. An allergic dog can experience skin irritation. Hives are another common symptom of an allergic response; the hives will usually be circular in shape, sometimes protruding from the skin. Dog shampoos formulated with oatmeal can help with skin irritation.
Broken skin due to the scratching can lead to bacterial infections, causing skin rashes. Internal infections can also cause external rashes on dogs. Scratching can spread the infection to other areas, worsening the problem. Bacterial infections tend to be more robust, and will usually require medication from a veterinarian to be controlled and cured.
Contact dermatitis is caused by surfactants, cleansers, and chemicals that can cause discomfort to the dog. Excessive shampooing, for example, can dry out the coat and skin, causing rashes on dogs. Canine dermatitis can also occur when the dog becomes irritated with material that it would normally not be reactive to, like bedding material. Monitoring the dog's lifestyle is important to eventually remove the substance or chemical that is causing the dermatitis.
Poor nutrition can lower the skin's defenses against skin disorders. Mineral deficiencies can alter the skin and fur as well, creating an environment for a skin ailment to develop. A dietary supplement formulated with essential fatty acids can help support healthy skin development and lower the chances of rashes on dogs from occurring.