Hot Spots on Dogs

If you think your companion dog has hot spots and look it up on the internet, you will be bombarded with three different terms: superficial pyoderma, acute moist dermatitis, or pyotraumatic dermatitis.

Additional confusion may come about because your dog does not have a “hot spot” according to the veterinary world, but simply has red and inflamed skin.

Neither condition should be ignored.

So, what’s the difference? Hemopet breaks down the difference for you, but first let’s define the phrases.


Pyo – Pus; origin: Greek

Derma – Skin; origin: Modern Latin

Pyoderma – Pus-filled skin

Pyoderma is a very basic term that encompasses the more granular or exact diagnostic terms like impetigo, pyotraumatic dermatitis or superficial bacterial folliculitis.

Pyodermas can be bacterial, fungal or parasitic.

Superficial vs. Deep

A superficial pyoderma is limited to the epidermis (the top layer of skin) and hair follicles.

A deep pyoderma involves the dermis (lower layer of skin).

Acute Moist Dermatitis and Pyotraumatic Dermatitis

These two phrases are interchangeable, and they are the more exact diagnostic names for hot spots.

Basically, pyotraumatic dermatitis is a self-inflicted wound due to some irritant or underlying condition causing the dog to lick, scratch or bite.

What exactly are dog hot spots?

Hot spots are red, inflamed and moist to the touch areas on the skin. They are usually secondary or tertiary conditions to an underlying condition(s) or irritant(s).

Now, if a veterinarian says superficial pyoderma, he/she is probably referring to a hot spot. However, we suggest that you ask for clarification since the term is so broad and can also refer to other conditions, such as superficial bacterial folliculitis or impetigo. Additionally, some researchers argue that pyotraumatic dermatitis is a clinical manifestation of deep pyoderma.

When your veterinarian refers to hot spots, he/she is most likely talking about a bacterial infection. The bacterium is usually – but not always – Staphylococcus pseudintermedius.

Staphylococcus pseudintermedius is a commensal bacterium that resides on the mucosal and skin surfaces of dogs.

Commensal means that the bacterium is always there and lives in relationship to the organism. It derives food or other benefits from the body without hurting or helping it.

In the instance of hot spots, the bacterium becomes opportunistic and overpopulates, causing an infection.

Nowadays, many researchers are saying to do further testing for the fungi. In particular, the commensal yeast, Malassezia pachydermatis, because it can also be present and overly colonize like the bacteria.

Other Conditions That May Look Like Hot Spots

  • Atopic dermatitis (also known as allergic dermatitis)
  • Folliculitis (inflammation of the hair follicles) or pyotraumatic folliculitis – These conditions can also be Staph spp. or fungal infections like pyotraumatic dermatitis, but they present and are treated differently.
  • Acral lick granuloma (also known as acral lick dermatitis)

Underlying Causes of Hot Spots

  • Atopic dermatitis
  • Behavioral
  • Environmental allergens
  • Flea bites or other insect bites
  • Food sensitivities or intolerances
  • Hypothyroidism and thyroiditis
  • Orthopedic problems
  • Parasites
  • Poor grooming
  • Weather
  • Wet or dirty skin

Let’s look at atopic dermatitis as an example. Atopic dermatitis is red and inflamed skin caused by a dog’s reaction to an environmental allergen or food sensitivity. The dog may try to “self medicate” to relieve the itching sensation by scratching at it, thus causing skin trauma that becomes pus-filled, pyotraumatic dermatitis.


Testing is important to figure out which bacterial and/or fungal strain is infecting the hot spot. But, that testing only treats the current problem, not the potential underlying cause.

If fleas or other parasites are causing them, that’s fairly easy to diagnose and treat.

However, recurrent and problematic hot spots require further testing, which includes such conditions as thyroid and other endocrine dysfunction, food sensitivities, and environmental allergens.


The primary bacterium, Staphylococcus pseudintermedius, in hot spots has now acquired methicillin resistance, akin to methicillin-resistant Staphylococcus aureus in people. So, treatment has become more challenging and more expensive.

Remember, when you treat with an antibiotic, you are not only trying to kill or inhibit the bacterium causing the problem, but are also killing or inhibiting growth of beneficial bacteria.

On top of that, Staphylococcus pseudintermedius is commensal. So, it is always there.

What we want to do is to control and reduce it.

Definitely talk to your veterinarian about alternative treatments and protocols to antibiotics or antifungals to control the problem first, and only resort to antibiotics and antifungal medications for particularly bad infections.


Becker, Karen. “Getting to the Root Cause of Hot Spots”. Mercola Healthy Pets, 5 July 2015,

Clark, SM, et al. “Susceptibility in Vitro of Canine Methicillin-Resistant and -Susceptible Staphylococcal Isolates to Fusidic Acid, Chlorhexidine and Miconazole: Opportunities for Topical Therapy of Canine Superficial Pyoderma.” Journal of Antimicrobial Chemotherapy, vol. 70, no. 7, Jan. 2015, pp. 2048–2052., doi:10.1093/jac/dkv056.!po=70.8333.

Moriello, Karen A. “Overview of Pyoderma – Integumentary System”. Merck Veterinary Manual,

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