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Identifying skin concerns in dogs

Bacterial and fungal skin infections in dogs can cause red, itchy, inflamed skin, and many other uncomfortable symptoms. This article outlines the different types of dermatitis you may find in your dog and how to recognize them.

What is dog dermatitis?

The skin is host to many bacteria and fungi. Usually, these organisms don’t cause dogs any problems and are kept under control by their immune system. However, if conditions on the skin change, or if the immune system is suppressed, these bacteria and fungi can multiply and cause infection.

There are two types of dermatitis. Yeast dermatitis is a fungal infection that takes place when the small amount of yeast present on dogs’ skin grows out of control and leads to inflammation. Fungal infections arise when a dog has inhaled or come into contact with fungal spores. If the fungal spores take over a large enough area of the dog's body, it can overwhelm the immune system and result in inflamed skin, crusting and hair loss.

Bacterial skin infections develop when a dog’s immune system has been weakened or compromised, creating an environment in which the natural bacteria can alter or multiply – for example, a flea infestation, an allergic reaction or a wound. Dogs that have recently been ill may be more susceptible to bacterial infections, as well as puppies and older dogs1.

Types of dermatitis in dogs

Although there are many types of infectious and bacterial dermatitis, some occur more often than others. Here are the most common conditions you might come across in your dog.

Ringworm

Dog ringworm is an infection caused by a fungus feeding on the skin cells. It grows and lives in the outermost layer of skin, hair follicles, and occasionally the nails of infected dogs. In most cases the infection only affects a few areas of the dog’s body, however dogs with existing skin conditions or weaker immune systems can sometimes suffer from more widespread ringworm infections2.

Hot spots

A hot spot is an area of inflamed, infected skin. Though the size and appearance can vary depending on the location, they are typically damp, red, sore, and sometimes raised with a scab on top. These spots can appear quickly, usually with some degree of hair loss, and can become much larger in a matter of days.

You can find out more about the differences between dog hot spot vs. ringworm in our article here.

Staph dermatitis

Staph is the most common type of bacterial infection and can affect any dog. It begins with a group of bacteria that normally live on your dog’s skin without causing any problem, but once the skin is inflamed – for example by a food allergy, parasites, environmental allergies or a wound – these bacteria can invade and rapidly multiply, seizing any opportunity to infect.

What are the common signs of dermatitis in dogs?

Although infectious and bacterial dermatitis have similar causes, they can vary in appearance. Here’s how to spot the most common signs.

Ringworm

Ringworm usually presents as circular areas of hair loss throughout the body. These lesions may start to heal in the center as they enlarge, creating a patchy appearance, and may become inflamed or scabbed. Generally, ringworm lesions appear on dogs’ paws, legs, head and ears3, but they can appear on any part of the body. For example, you may also see signs of early-stage ringworm on your dog’s belly.

Hot spots

Often a hot spot will begin as a small red area that owners may mistake for an insect bite, but as it develops, the skin will become very moist, swollen and inflamed, with some hair loss. The affected area may also discharge pus or fluid, which can lead to crusting and matting of the surrounding hair. Hot spots can occur anywhere, but are most commonly seen on the head, limbs, and hips4.

Remember, if you’d like to know more about the differences between dog hot spot vs. ringworm, you can read our article here.

Staph dermatitis

There are two typical types of staph lesions. One begins as a red area on the skin with a pimple-like pustule. The other is a circular, reddish area with a crusty edge and hair loss in the center. The latter can easily be confused with ringworm or yeast skin infection. However, finding either of these skin patterns in a dog that is also scratching highly suggests staph dermatitis.

Other common symptoms of a staph infection on your dog include pain, inflamed skin, excessive licking or chewing, patchy fur with peeling, and systemic infections in the ears, eyes, skin, or respiratory system.

If you’d like to know more about any other dermatology and skin issues in your dog, you can find more information here.

How to manage dermatitis in dogs

Your vet will be able to recommend reliable treatment and management options for both bacterial and fungal infections, which may include topical treatments, change in diet or antibiotics, depending on the dermatitis issue.

Ringworm

Because ringworm can be passed from pets to other pets and humans, it is important to seek veterinary attention if you think your dog starts to show symptoms. If your vet suspects dog ringworm, they will prescribe the appropriate medical treatment or recommend tailor-made nutritional solutions such as topical therapy, oral medications, or environmental decontamination.

Hot spots

Depending on the severity of the hot spot, most vets will treat the area with a combination of oral antibiotics, anti-itch medication, and an e-collar. They may also suggest additional cleaning at home with salt water or a medicated shampoo, or clipping the fur around your dog’s hot spot to allow air to reach it and speed up recovery.

Staph dermatitis

Since staph is caused by bacteria, it is usually sensitive to several antibiotics. Some infections may require three to six weeks of treatment before the infection is under control5. Antibacterial shampoos, sprays, and spot-ons can be helpful in bringing about rapid control of the infection. It’s also essential to stop the cycle of itching and scratching which may have contributed to the staph infection to begin with.

Your vet is likely to resolve staph first and then identify the cause, as other tests may be needed to determine what triggered the infection. Once the underlying cause has been identified it will help you to ensure your dog is on the correct long-term management.

Article References

1Hollinger. H, Bacterial Infection of the Skin in Dogs, Wag Walking, https://wagwalking.com/condition/bacterial-infection-of-the-skin, 2021

2Burke. A, Ringworm in Dogs: Symptoms, Treatment and Prevention, American Kennel Club, https://www.akc.org/expert-advice/health/ringworm-in-dogs/, 2021

3Ask your veterinarian how tailored nutrition may help address the underlying cause of skin problems, Royal Canin

4Racine. E, Treating and Preventing Hot Spots on Dogs, American Kennel Club, https://www.akc.org/expert-advice/health/treating-and-preventing-hot-spots-on-dogs/, 2021

5Hunter. T, Ward. E, Yeast Dermatitis in Dogs, VCA Animal Hospitals, https://vcahospitals.com/know-your-pet/yeast-dermatitis-in-dogs