Causes and Treatment of Hot Spots (Acute Moist Dermatitis) in Dogs

Skin & CoatQ&AMeongsiljang Veterinary Advisory Board

Hot spots in dogs are acute skin conditions caused by bacterial overgrowth when your pup repeatedly scratches or licks itchy skin. We’ve covered the causes, symptoms, treatments, and home care tips.

What Are Hot Spots in Dogs?

A veterinarian examining the skin condition of a Golden Retriever

Hot spots in dogs are a form of acute moist dermatitis (also known as pyotraumatic dermatitis) that occurs when bacteria rapidly multiply on skin damaged by self-trauma from repeated scratching or licking due to an itchy skin condition caused by fleas, allergies, or other factors. The most critical step is to break the itch-scratch cycle by immediately shaving the hair around the affected area, thoroughly cleaning the skin surface, and keeping it dry. If the itching is left unchecked, bacterial overgrowth can progress rapidly, causing the lesion to expand and the infection to deepen; therefore, the speed of initial intervention significantly influences the course of treatment.

Causes of Hot Spots

Hot spots can be triggered by a wider variety of causes than many pet owners realize. The most common culprit is flea allergy dermatitis: when a flea bite causes intense itching, your pet’s repeated scratching or licking compromises the skin barrier, leading to an acute moist dermatitis flare-up. Other potential triggers include atopic dermatitis, food allergies, ear infections, anal gland discomfort, and contact irritants—essentially any factor that repeatedly irritates the skin. Breeds with long, dense coats that trap moisture against the skin are at higher risk because the damp environment promotes bacterial growth. For these dogs, it’s especially important to ensure thorough drying after baths and to perform regular skin checks.

Superficial vs. Deep Hot Spots Comparison

Hot spots are classified into superficial and deep types, and because the treatment approaches differ, it is important to distinguish between them.

Type	Superficial Hot Spot	Deep Hot Spot
Appearance	Red, moist, single lesion	Accompanied by pus, papules, and satellite lesions
Main Cause	Flea or allergy irritation	Worsening underlying infection
Pain Level	Moderate	Severe (avoids touch, growls)
Treatment	Topical antibiotics + removal of cause	Systemic antibiotic administration required

Hot Spot Key Symptoms Checklist

Sudden hair loss: Acute hair shedding occurs, causing the affected area to expand rapidly.

Red, weeping skin: The affected area becomes red and swollen, with sticky discharge oozing from it.

Foul odor: Bacterial proliferation may produce a distinct fishy smell.

Intense itching: Continuous licking and scratching cause the lesions to gradually enlarge.

Pain response: Your pet may avoid touch or growl when the affected area is touched.

A concerned owner closely examining the skin condition of their Labrador Retriever.

When to Seek Immediate Veterinary Care

If the hot spot lesion spreads rapidly, or if pus is present along with a fever, it is likely a deep-seated hot spot. You should seek veterinary care without delay if you notice small satellite lesions, such as papules or pustules, around the affected area, or if your dog is lethargic and refusing food. Deep-seated hot spots may require systemic antibiotic treatment based on bacterial culture and sensitivity testing.

Veterinary Treatment Process

Clipping the affected area: The veterinarian will closely shave the fur around the lesion to allow air circulation.

Disinfection and cleansing: The affected area is gently cleaned to remove exudate and scabs using a disinfectant solution such as chlorhexidine.

Topical antibiotics: Superficial cases can often be treated with antibiotic ointments or sprays alone.

Systemic antibiotics: Deep-seated infections require systemic antibiotics. We recommend performing bacterial culture and susceptibility testing to select the most appropriate antibiotic, and in some cases, referral to a veterinary dermatologist may be necessary.

Itch control: Anti-pruritic medications are used to break the "scratch-worsen" cycle.

A veterinarian applying a topical medication to a dog's hot spot.

Home Care Tips

Wear an Elizabethan collar: Preventing your pet from licking or scratching is half the battle in treatment. Even if the collar seems uncomfortable, please keep it on until the affected area has fully healed.

Keep the affected area dry: Always ensure the lesion is completely dry after bathing or if it gets wet in the rain.

Apply prescribed ointment: Apply a thin layer to the affected area once or twice daily, as directed by your veterinarian.

Manage underlying causes: If fleas are the trigger, administer appropriate deworming medication. For allergies, eliminate the offending allergen from the diet to prevent recurrence.

A dog resting comfortably at home while wearing a neck collar

Preventing Recurrence Is Key

Hot spots are a condition prone to frequent recurrence. Relapses often stem from underlying primary causes that aren’t immediately visible, so once a hot spot develops, it’s essential to accurately identify and manage the root cause—such as fleas, atopy, or food allergies—to prevent it from recurring in the same spot. Regular deworming, thoroughly drying the affected area after bathing or swimming, and skin care practices that prevent moisture from becoming trapped on the skin can all help. In some cases, consistent, long-term management may be necessary for the pet’s entire life.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can hot spots be transmitted to humans or other animals?

Hot spots themselves are not contagious. They result from self-inflicted trauma caused by your dog scratching and licking, so they cannot spread to other animals or people.

Is there any first aid I can do at home before going to the vet?

Carefully trim the hair around the affected area to improve air circulation, and gently wipe away any discharge with lukewarm water. Put a cone collar on your pet to prevent licking, and visit an animal hospital as soon as possible.

How long does it take to treat a hot spot?

Superficial cases tend to improve relatively quickly with appropriate treatment. Deep-seated infections require systemic antibiotics, and it is important to select an effective antibiotic based on bacterial culture and susceptibility testing. The duration of treatment varies depending on the depth of the infection and underlying causes, so it is essential to follow your veterinarian’s instructions and complete the full course of therapy. In severe cases, referral to a veterinary dermatologist may be necessary. If the underlying cause is not addressed, recurrence is likely.

Do hot spots occur more frequently in the summer?

When moisture remains trapped against the skin for too long, it creates an ideal environment for bacteria to multiply rapidly on damaged skin surfaces. As a result, hot spots are more likely to develop in hot, humid conditions or if the fur isn’t thoroughly dried after swimming or bathing. It’s essential to completely dry both the affected area and the surrounding fur after any water exposure.

What should I do if hot spots keep coming back?

If the problem keeps coming back, it’s important to take a comprehensive look at flea control, potential allergies, and the condition of the skin barrier. Consulting with your veterinarian to accurately identify the underlying cause is the most crucial step.