Hot Spots (Pyotraumatic Dermatitis) in Dogs

Summary

A moist, inflamed, red, weepy, clearly defined spot on a dog’s skin is often referred to as a hot spot. This superficial skin infection (also called “acute moist dermatitis” or “pyotraumatic dermatitis”) is created when a dog obsessively licks, chews, scratches, and rubs an itchy spot so much it breaks the skin, creating a hot spot for bacterial growth. Once the bacteria have taken hold, the spot bleeds, oozes pus, and emits a noticeable odor. A crust of matted hair and dried pus often forms over the affected skin. Hot spots are often painful, and can be small or big, single or multiple. They can be obvious, or be hidden under matted fur.  They often pop up suddenly and grow quickly, and occur most commonly on the head, legs, and hips. In the majority of cases, the superficial infection resolves quickly once cared for and treated with appropriate antimicrobials. 

The itching and licking that creates hot spots is usually associated with an underlying condition. Hot spots are expected to recur if the underlying cause of the itch is not investigated and treated.

Risk Factors

Hot spots themselves are not life-threatening, nor are they symptoms of a life-threatening problem. They are painful and grow quickly, so prompt veterinary attention is indicated as soon as hot spots are detected on a dog’s skin.

More importantly, the underlying cause of the itch (pruritus) needs to be resolved or the hot spots will simply return. 30% of dogs who come to hospital because of hot spots have an underlying condition like allergies or fleas.

Possible Causes

Hot spots are caused by a dog excessively biting, licking, scratching, or rubbing their skin. This breaks the skin and allows bacteria to flourish, resulting in the infected wound. 

The excessive biting, licking, scratching, or rubbing can be caused by any irritant, including: 

• Insect bites from fleas, flies, mites, bees, lice, mosquitoes, etc. 

• Allergies to food or inhalants

• Topical irritants (i.e. new shampoo or topical medication)

• Ear or skin infections (bacterial or yeast otitis)

• Matted hair that traps moisture from rain or swim

• Skin scrapes or nicks 

• Boredom 

• Orthopedic problems - degenerating joints and itchy or sore abrasions that occur over pressure points like hips or ankles.  

• Anal gland inflammation

Main Symptoms

The main symptoms associated with hot spots are pruritus (itching), licking, and pain. Any area of skin that shows these symptoms is commonly referred to as a hot spot: 

• Well-defined patch of hair loss • Red, wet skin surface • Accumulation of pus in the surrounding fur

• Unpleasant odor coming from the spot

Detailed Characterization

Regardless of the underlying cause, the severity of a hot spot primarily depends on its size and how quickly it is growing. Some dogs show more distress with a hot spot than others.  

Hot, humid weather increases the likelihood of hot spots, but they can happen all year, depending on the underlying cause. Dense undercoats increase the likelihood of hot spots. 

Hot spots develop when the dog licks or bites the irritated spot, stimulating nerve endings in the skin, creating more itchiness, which in turn increases the dog’s licking and biting. The itch - lick - itch cycle quickly results in a messy oozing sore which can get dramatically bigger in a very short time.

Testing and Diagnosis

The presence of a hot spot is self-evident. Testing and diagnosis of the underlying cause of the itching (pruritus) may be recommended if the immediate cause of the licking and itching is not known or if it does not resolve on its own. This may include testing for allergies, parasites, and other skin conditions.

Steps to Recovery

The steps for treating a hot spot are: 

• Remove surrounding hair to prevent moisture from being trapped around or on the wound

• Gently clean with soap and water

• Pat the area dry

• Apply appropriate topical antimicrobials as indicated

• Break the itch - lick - itch cycle by using an e-collar or t-shirt to prevent licking

When these steps are followed, the hot spot is expected to improve right away and to dry out and scab over within 24-48 hours. If the hot spot does not improve quickly, oral antibiotics are a vet will prescribe oral antibiotics. If there is more than one hot spot, if the hot spot is painful, or if hot spots are a recurring problem, veterinary attention is advised.  Complicated hot spots often require additional treatment: 

• Sedation for clipping and cleaning the hot spot

• Bacterial culture and sensitivity to identify the pathogen and choose the best antibiotic

• Medications like antiinflammatories and steroids

By monitoring and treating underlying causes, future hot spots can be prevented. Grooming and regular bathing and brushing also help.

Prevention

Hot spots don’t spread from one pet directly to another, but it is possible for the bacteria present on the surface of the skin in a hot spot to infect an open sore or wound on another individual. Best practices for avoiding this include: 

• Wearing gloves • Washing hands • Preventing the pet from licking the hot spot

• Preventing other pets from licking the hot spot

If the hot spots are found to be associated with an underlying condition, their recurrence will be mitigated by treating the root cause.

Are Hot Spots Common in Dogs?

Hot spots are commonly reported in dogs as they are associated with a number of other common skin conditions.

Typical Treatment

Depending on the severity of the case and the root cause, typical treatment for hot spots may include some or all of the following:

• Clipping hair around the hot spot • Cleaning the wound and keeping it dry • Topical antimicrobials

• Oral antibiotics • Anti Inflammatories • Steroids