Skin Infections in Dogs

By Dr. Rania Gollakner on Feb. 13, 2023

What Are Skin Infections in Dogs?

Skin infections are conditions that are caused by infectious organisms such as bacteria, fungi, or parasites. All areas of skin can be affected, including inside the ears and nose, as well as the hair and nails.

The severity of the disease depends on the type of infection and can vary from very mild to painful and itchy. Some organisms that cause skin infections are transmissible (or contagious), which means the infection can be passed to another mammal through direct contact or the environment. There are also infections that are caused by organisms that normally live on the skin and are not considered contagious.

Types of Skin Infections in Dogs

Bacterial
Fungal
Parasitic
Viral

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Symptoms of Skin Infections in Dogs

Redness
Bumps or raised areas of the skin
Itchiness (you may see your dog scratching, licking, and/or chewing the skin)
Scales or flakes
Crusts or scabs
Hair loss (alopecia)
Oozing or discharge (blood, pus, clear)
Skin color changes (darker or lighter)

Causes of Skin Infections in Dogs

There are many causes of skin infections in dogs. Some infections are primary infections—an infection directly caused by an infectious organism. Other infections are secondary infections and occur because of an underlying disease process that triggers an infection.

Primary Infection

Scabies is an example of a primary parasitic skin infection. Dogs acquire scabies by direct contact with an infected animal. The scabies mite then causes the clinical signs associated with the disease. Ringworm is an example of a primary fungal infection and is acquired due to contact with infected individuals or an infected environment, including soil.

Secondary Infection

A common example of a secondary skin infection is one due to skin allergies. The allergies cause inflammation of the skin, which then provides an environment favorable to organism growth. Bacteria or fungi that normally live on the skin are then able to multiply, leading to a bacterial or fungal skin infection.

How Veterinarians Diagnose Skin Infections in Dogs

There are several basic skin tests that are useful in diagnosing a majority of skin infections. The most common ones are:

Skin scrapes: A dull scalpel blade is used to scrape the top layer of the skin; effective for finding skin parasites like demodex.
Skin cytology: A sample is collected by pressing a microscope slide directly to the skin lesion or via a needle and syringe and then looked at under the microscope for bacteria, fungi, or abnormal skin cells.
Tape preps: Clear tape is used to collect a sample of hair or skin to find bacteria, fungi, or parasites when viewed under the microscope.
Cotton swabs: A cotton swab is used to collect a sample, most often from inside the ear, to diagnose bacterial, fungal, or parasitic infections.
Cultures: A sample of skin, hair, or discharge is collected onto a growth plate to look for bacterial or fungal growth over time. This test can also be used to learn which antimicrobial medication is best to treat the infection.

Treatment of Skin Infections in Dogs

The treatment of a skin infection depends on the type of infection, the location of the infection, and the condition of the dog. Bacterial skin infections are treated with oral (by mouth) antibiotics, and/or topical products such as medicated shampoos, conditioners, sprays, and ointments. Common products include:

Fungal infections are treated similarly, with antifungal medications, and parasites are treated with antiparasitic medications.

To help the skin heal and to prevent future infections, other treatments are used to support healthy skin. For example, when treating an ear infection, special ear cleaners are used in addition to the antimicrobial medication. Omega-3 fatty acid supplementation is another treatment used to help resolve and prevent infections. Prevention is often the best medicine and regular bathing and grooming can be helpful for not only treating skin infections but also preventing them from occurring in the first place.

For secondary skin infections, it is important to treat the primary cause of the secondary infection. Skin allergies, for example, frequently require medications to reduce inflammation and allergic reactions. Treating a skin infection without treating the allergy will likely lead to another infection. Food allergies require special diets to reduce skin inflammation. If a food allergy is suspected, your vet will work with you to determine an appropriate food trial, to slowly remove certain ingredients and introduce possible allergies to determine the culprit.

Recovery and Management of Skin Infections in Dogs

The time it takes to treat a skin infection depends on the type of infection, the ability to treat primary causes of the infection, and the severity of disease. Sometimes the most difficult part of the treatment is sticking with treatments for as long as needed.

Some skin infections can be difficult to treat because of antimicrobial resistance. Antimicrobial resistance occurs over time, when microbes develop defenses against our medications, making those medications ineffective. In those cases, treatment can take longer and may require further testing.

Infections can resurface, especially if the primary cause of the infection has not been treated or resolved. Dogs with chronic conditions such as allergies or other diseases are more likely to have repeat infections.

Managing skin infections successfully can be complicated, time consuming, and expensive. Following your veterinarian’s recommendations closely and being patient during the treatment period is important for resolving the infection and preventing recurrence in your pup.

Featured Image: iStock.com/Sergeeva