Acute Moist Dermatitis in Dogs - Causes and Treatment

Acute moist dermatitis is an inflammation of the skin which results in red lesions known as hot spots. As they are caused by the dog licking or scratching the skin and removing patches of fur, they can occur almost anywhere on the body. It is known as pyotraumatic dermatitis because it is often purulent (pyo-) and because it is the result of physical action by the dog (traumatic).

The lesions formed by acute moist dermatitis are usually circular in shape and known as hot spots. Although it is the trauma caused by the dog, it is believed there are other factors involved. This is because some dogs can lick a lot without developing a hot spot, whereas other can develop them with relatively minor intervention. This suggests a potential genetic factor, although little correlation in sex, breed, age and other factors has been determined^[1].

Hot spots in dogs will be well defined. Due to the loss of hair and top layers of skin, the underlying tissue will be exposed. For this reason, they are pink and wet to the touch. Since they can be quite irritating, the dog will often lick to relieve frustration, perpetuating a cycle of further skin damage.

Despite presenting almost anywhere on the dog, they are most common at the base of the tail, head, neck and ears. The incitement of the licking or scratching in one of these focal points is usually pain, itching or discomfort, although not always. We look at the cause of acute moist dermatitis in dogs to learn more.

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Despite the correlation between breeds and pyotraumatic dermatitis being poorly understood, there is some evidence to suggest that breeds with a dense undercoat are more likely to develop this condition. These include the Golden Retriever and St. Bernard^[2]. They are more disposed to developing wet dermatitis in the hotter and more humid months since this predisposes them to skin problems in general.

With these factors in mind, we can see the main causes of pyotraumatic dermatitis in dogs are the following:

• Parasites: various external parasites in dogs can cause the dog to feel itching in a part of their body. These include ticks and fleas. They bite the skin and cause agitation, leading to the dog licking the lesions and making them worse.
  
  
• Mites: a special mention has to be made of the parasites known as mites. Some mites can lead to mange and other skin conditions, but others have less obvious symptoms. Ear mites can cause irritation which leads to the dog scratching their ears a lot. This can be the cause of acute moist dermatitis.
  
  
• Allergies: if a dog has a sensitivity to a certain allergen, it can cause them to bite and scratch their skin. This can be to a parasite such as a flea bite allergy, but it can also be due to food or other allergens.
  
  
• Irritants: although allergens can cause itching which leads to wet dermatitis, any irritant substance can do the same. A common occurrence is the dog being exposed to household cleaners or other irritating chemicals.
  
  
• Anal gland disease: when a dog has impacted anal glands or an infection in their perianal area, they can try to lick to relive the discomfort. They may not be able to reach their actual anal glands, but will continue to scratch as close as they can.
  
  
• Infections: various skin infections can cause skin discomfort leading to acute moist dermatitis. These can be fungal such as ringworm or a yeast infection. Bacterial infections can occur when a wound or lesion is infected. Viral infections can also cause lesions or skin irritation which can cause them to develop pyotraumatic dermatitis as a result.
  
  
• Stress: while it is less common in pyotraumatic dermatitis, psychological stress can result in stereotypies such as licking or biting the same area. In these cases, hot spots can develop without a physical irritation to the skin.

In many of these cases, the moist dermatitis is a complication of the underlying disease. As we have already stated, some dogs may be more susceptible to developing the skin condition. This may be due to a compromised immune system, such as dogs with an immunosuppressive disease. Dogs which are provided with poor hygiene conditions are also more likely to develop parasitic disease or various infections.

Learn more about the types of localized and general fungal infections in dogs which can lead to acute moist dermatitis.

The main symptom of pyotraumatic dermatitis in dogs is the presence of hot spots. These are the hairless skin lesions which can have various levels of exudate. This can be in the form of a clear fluid from the lesion tissue or even purulent discharge in the form of pus. Patches of fresh blood can be seen with newly exposed tissue which will form into hard scabs as they attempt to heal. There may also be a bad odor from the lesion.

These hot spots can be of varying size, ranging from around 1-4" in diameter. They can develop quite rapidly, depending on the dog. This spread can be as little as a matter of hours. The dog's behaviors will be the fact they keep licking their paws or any other area where they feel agitation.

It is important to note the difference between a hot spot and acral lick granuloma in dogs. In the case of an acral lick granuloma, they are related to behavioral issues and result in hard lesion which is raised from the body. Hot spots are more acute, are usually caused by external factors and can resolve themselves more quickly.

Moist dermatitis produces a characteristic lesion that allows it to be diagnosed by direct visualization. To discover its cause, the veterinarian will perform an examination of the animal, perform a medical history and carry out the relevant diagnostic tests.

An example of a diagnostic test may include a skin scraping which is carried out to determine the type of bacteria are present. This is necessary to prescribe the most effective antibiotic against them. The important thing is to go to the veterinarian as soon as possible to prevent the dermatitis from getting worse. This is because the dog's continued biting and licking will complicate the condition.

The treatment will depend on the underlying cause. Veterinary diagnosis is necessary to determine this cause and provide the correct course of treatment. Some of these will include the following:

• Antibiotics for nacterial infection
• Deworming medication for parasitic infections
• Topical or oral antifungal medications
• Antihistamines and eradication of allergens
• Topical balms to relieve skin irritation

There is also some first aid for dogs when addressing the hot spots. This will involve trimming away some hair around the hot spot and disinfecting it with an antiseptic product such as chlorhexidine for dogs. Depending on the extent of the dermatitis and the pain the dog is experiencing, it may be necessary to sedate them in order to perform this thorough cleaning.

After hygiene, the veterinarian will prescribe the corresponding treatment as described above. They ay also use an astringent and antiseptic topical ointment. These may include antibiotics and/or corticosteroids. Two daily applications are usually scheduled for about 10-14 days. In some more serious cases, such as deep moist dermatitis, oral antibiotic treatment must also be prescribed.

An Elizabethan collar may need to be worn until the injury heals to prevent the dog from accessing the lesion. In more serious moist dermatitis, sedation of the animal for 1-2 days can even be considered. If the itching that the dog feels is very intense, the veterinarian can also prescribe corticosteroids during the first days of treatment.

Discover more about the types of skin lesions which can affect canines in our article on common dog nose skin conditions.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Acute Moist Dermatitis in Dogs - Causes and Treatment, we recommend you visit our Skin problems category.