Pinnae is another word for ear flaps, basically the outer ears of the dog. When the pinna of the dog's ear has erythema, it just means that the skin of the outer ear is reddened or inflamed. Injuries from fighting with other animals also causes pinnae erythema that is made worse by infections from open wounds.
This condition is caused by immune deficiency and is characterized by T-cells in the blood stream attacking the skin. The affected skin turns bright red, swollen and itchy, causing the dog to rub his ears on objects, trying to relieve the itching. The rubbing can create painful ulcers in the skin. Canine parvovirus and staphylococcal dermatitis are both common causes of this condition as are ear margin seborrhea, chemical burns, food allergies and dermatitis.
Erythema From Biting or Scratching
The ears are easily injured in animal fights and the pinnae become inflamed from scratches or bites to the ears. Infection is a problem if the skin breaks and bacteria gets in, causing a more serious condition. If there is a wound of the skin that won't heal, call a veterinarian as the wound may require stitching, bandaging, or antibacterial treatment. The doctor will diagnose infection in the inner and middle ears at that time as well.
Erythema From Allergic Otitis
Ear allergies are a common cause of inflammation of the pinna. This is often seen in dogs with canine atopy, or skin hypersensitivity, and food hypersensitivity dermatitis. Ear allergies often result in loss of hair inside the pinna, crusty scabs, brown ear wax and moist, red inflammation. The longer the allergy goes on without medical treatment, the itchier and more red the ear becomes, resulting in near constant scratching and subsequent tearing of the skin.
Treatments for Erythema
Skin creams are often prescribed for the dog's ears, to treat dermatitis and seborrhea, both of which are itchy skin conditions. A change of diet is prescribed by the veterinarian if the diagnosis is food allergies, which can cause skin sensitivities and reddening. For chemical burns, contact a veterinarian and rinse the skin quickly, using vinegar and water for alkaline burns or baking soda and water for acidic burns. Antiviral medications may be prescribed for treatment of parvovirus, which is often fatal and requires immediate veterinarian care.