What Causes Hot Spots in Dogs and How Are They Treated?

Hot spots (acute moist dermatitis) are painful, rapidly spreading skin sores. Quick home first aid helps, but vets often need to clip, clean and treat infections.

What is a hot spot (acute moist dermatitis)?

A "hot spot" — medically called pyotraumatic dermatitis or acute moist dermatitis — is a localized, red, often oozing and intensely itchy skin lesion. Hot spots usually start small but can enlarge quickly as a dog licks, chews or scratches the area. They are common in dogs with thick coats, long hair, or underlying irritation such as fleas, allergies or ear infections.

Hot spots can develop and become much worse in 24–48 hours, so early recognition and action are important to limit pain and secondary infection (Merck Veterinary Manual; VCA Hospitals).

Rapid progression warning

Hot spots are notorious for how fast they can expand. A tiny irritated patch can become a painful, hairless, weeping wound within a day or two if the dog continues to traumatize it. Because they can progress quickly, home measures should be started promptly and a veterinary appointment scheduled if there is no rapid improvement.

How to tell a hot spot from other skin problems

Common features of a hot spot:

• Very red, moist, raw-looking skin
• Rapid onset and fast enlargement
• Intense licking, chewing or scratching of the site
• Often painful when touched
• May smell foul if a secondary bacterial infection develops

Differential diagnosis (common causes ranked by likelihood)

A veterinarian will evaluate the lesion and the whole dog to determine the most likely trigger and rule out other causes (Merck Veterinary Manual).

When to see a vet immediately

Seek veterinary attention immediately if any of the following are present:

• The lesion is on or near the face, around the eyes, or inside the mouth or ear canal
• The wound is expanding very rapidly (hours) or multiple new lesions appear
• Your dog has fever, is lethargic, refuses to eat, or shows signs of systemic illness
• You suspect a bite wound or deep puncture (risk of deep infection)
• Severe pain or extreme distress

Red Flags — seek emergency care

These signs suggest a potentially serious or spreading infection and need emergency evaluation:

• High fever, collapse or obvious systemic illness
• Rapid swelling of the face or neck (airway compromise risk)
• Deep tissue involvement or severe bleeding
• Marked swelling, discharge with bad odor, or pus draining from multiple sites
• Signs of anaphylaxis (hives, vomiting, difficulty breathing) after exposure to an allergen or insect sting

Home first aid — what you can safely do right away

Important: home care can help control the lesion but should not replace veterinary assessment when the lesion is large, spreading, on the face, or accompanied by systemic signs. Do not use human steroid creams, antibiotics, or any prescription products without veterinary guidance.

Basic first-aid steps you can take at home:

When to avoid home trimming/cleanup: if the dog is highly painful, fractious, or the lesion is near the eyes or in the ear canal, wait for veterinary help — your dog may need sedation for safe, effective care.

What your veterinarian will likely do (treatment protocol)

At the clinic, the vet will perform a full physical exam and address both the lesion and underlying triggers. Typical treatment steps include:

• Sedation or light restraint as needed to safely clip and clean the area thoroughly. Removing hair and debris is essential.
• Careful cleansing of the wound with antiseptics (e.g., chlorhexidine) and removal of necrotic tissue.
• Short-term topical therapies: medicated sprays, creams or impregnated pads to control bacteria and soothe the skin.
• Systemic antibiotics if a secondary bacterial infection is present or likely. The vet decides based on the lesion, cytology and clinical signs.
• Short course systemic anti-inflammatory therapy (sometimes corticosteroids or other antipruritics) to reduce intense itching and allow healing, if appropriate.
• Pain relief if the lesion is painful.
• Treatment of the underlying cause: parasite control for fleas, allergy management, ear/anal sac disease treatment, or removal of a foreign body.
• Instructions for ongoing wound care at home and a recheck appointment to confirm healing.

Prevention strategies — reduce the chance of recurrence

Hot spots are usually a symptom of an underlying problem. Preventing recurrence means finding and managing triggers:

• Strict flea control year-round using veterinarian-recommended products.
• Address allergies: discuss food trials or environmental allergy management with your vet. Regular itch control reduces self-trauma.
• Regular grooming: keep coats clean and dry, especially after swimming or bathing. Shorter hair in long-haired breeds during warm months lowers risk.
• Promptly treat ear infections, anal sac problems, and interdigital dermatitis that create itch or discomfort.
• Behavioral modification: identify and address excessive licking due to boredom, anxiety or pain. Enrichment, training, and sometimes anxiolytic therapy are helpful.
• Use appropriate topical products: medicated shampoos and conditioners recommended by your vet can help control skin irritation.

Prognosis

With prompt treatment, most hot spots heal well within 1–3 weeks. The key is stopping the self-inflicted trauma, treating infection and identifying the trigger so new lesions don’t recur.

Key decision-support: Emergency vs Urgent vs Watchful waiting

• Emergency: facial/eye lesions, rapid spreading, systemic signs (fever, collapse), severe pain, airway compromise.
• Urgent: large or painful hot spot, no improvement after 24–48 hours of home care, signs of secondary infection (pus, foul smell), or lesions in difficult areas (ear canal, under tail).
• Watch-and-wait (with home first aid): small, superficial hot spot that you can clean, clip and protect; recheck in 24–48 hours and call your vet if not improving.

Sources and further reading

• Merck Veterinary Manual — Pyotraumatic dermatitis (hot spots): https://www.merckvetmanual.com/skin-and-mucous-membranes/skin-disorders-of-dogs/pyotraumatic-dermatitis
• VCA Hospitals — Hot Spots in Dogs: https://vcahospitals.com/know-your-pet/hot-spots-in-dogs

Key Takeaways

• Hot spots are common, rapidly progressive, intensely itchy and often painful skin lesions caused by self-trauma over an irritant.
• Early home care (keep dog from licking, clip hair, clean gently, use a cone) helps, but large, facial, rapidly spreading or systemically ill dogs need immediate veterinary care.
• Vet treatment typically includes clipping, cleansing, topical therapy, and often systemic antibiotics or anti-inflammatories plus treatment of underlying causes.
• Prevent recurrence by controlling fleas, managing allergies, grooming, and addressing behavioral causes.

Frequently Asked Questions