Hot spots on dogs: why they appear so fast and what to do

A hot spot can appear almost overnight: your dog scratches or licks one spot, the skin breaks, bacteria move in, and by the next morning there’s a raw, oozing, painful patch under the fur — so the key is to see your vet early and, above all, find and treat the itch that started it.

What a hot spot is

VCA Animal Hospitals describes hot spots — also called pyotraumatic dermatitis or acute moist dermatitis — as red, inflamed, oozing skin lesions that form quickly, are often painful and smelly, and can hide under matted fur. They usually start with self-trauma: an itch makes the dog scratch or lick until the skin breaks, setting up what VCA calls a lick-itch-lick cycle.

In a prospective study of 44 dogs with hot spots, Holm, Rest and Seewald (2004) found that males outnumbered females and that lesions were more common in dogs aged four or under. The cheek, neck and outer thigh were the most common sites, and Rottweilers, German Shepherd Dogs and Golden Retrievers were the most common breeds. A possible underlying cause was found or suspected in 31 of the 44 dogs, and bacteria (staphylococci) grew from almost every lesion cultured.

Are hot spots seasonal?

Many owners see more hot spots in summer, and several common triggers peak then: fleas, seasonal allergies, swimming and coats that stay damp. In UK veterinary records, Farrell and colleagues (2023) found flea cases peaking between July and October, and in Portugal, Pereira and colleagues (2025) found dogs more likely to carry fleas in spring, summer and fall than in winter. Interestingly, Holm’s study — carried out in an area without endemic fleas — found no significant seasonal pattern, which suggests the trigger matters more than the calendar.

VCA lists these common triggers:

• food or environmental allergies
• fleas, mites and insect bites
• ear infections
• bacterial or yeast skin infections
• matted coats that trap moisture
• boredom-related licking
• arthritis or back pain
• anal gland problems

What treatment involves

VCA describes treatment as stopping the self-trauma (an Elizabethan collar, a sock or bandage, or medication for the itch from your vet), clipping the hair around the lesion — never with scissors, because it’s easy to cut the skin — cleaning it with an antiseptic, and applying topical treatment. Clipping often needs sedation because hot spots are painful.

Do hot spots need antibiotics? The 2025 antimicrobial guidelines for canine pyoderma from the International Society for Companion Animal Infectious Diseases, summarised by Loeffler and colleagues, recommend that topical antimicrobial therapy alone is the treatment of choice for surface and superficial skin infections, with antibiotics by mouth reserved for deeper infections or when topical treatment doesn’t work. The guidelines also cover meticillin-resistant staphylococci, which is one reason responsible use matters.

Newer options exist too: in a small case series, Luciani and Marchegiani (2025) treated eight dogs with fluorescent light energy alone and saw all hot spots resolve within two weekly sessions, but this was a small study without a comparison group.

Prevention

• Keep up flea control for every pet in the home.
• Groom regularly to prevent mats, especially in thick or long coats.
• Dry your dog thoroughly after swimming or bathing.
• Get itchy ears and skin checked early, and work with your vet on allergies.
• Provide enough exercise and enrichment for dogs that lick from boredom.

When to call your veterinarian

• Any red, wet, oozing or smelly patch of skin, especially if it is spreading.
• Your dog won’t let you touch the area.
• Repeated hot spots, or hot spots in several places.
• Head shaking, ear scratching or chewing at the paws as well.
• If in doubt, call — your vet would rather hear from you early.

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Sources & further reading

1. Weir M, Williams K, Llera R, Ward E, VCA Animal Hospitals — Hot Spots in Dogs. vcahospitals.com
2. Holm BR, Rest JR, Seewald W (2004) — A prospective study of the clinical findings, treatment and histopathology of 44 cases of pyotraumatic dermatitis. Veterinary Dermatology 15:369–376. doi.org
3. Loeffler A, Cain CL, Ferrer L, et al. (2025) — Synopsis of the antimicrobial use guidelines for canine pyoderma by the International Society for Companion Animal Infectious Diseases (ISCAID). Veterinary Dermatology 36:552–565. doi.org
4. Luciani L, Marchegiani A (2025) — Photobiomodulation with fluorescent light energy as a sole treatment of pyotraumatic dermatitis (hot spot): a case series. Journal of the American Veterinary Medical Association 263:1–6. doi.org
5. Farrell S, McGarry J, Noble PM, et al. (2023) — Seasonality and other risk factors for fleas infestations in domestic dogs and cats. Medical and Veterinary Entomology 37:359–370. doi.org
6. Pereira A, Cruz A, Novo T, FleaPT group, Maia C (2025) — Epidemiological and molecular characterisation of flea infestations in dogs and cats in mainland Portugal. Parasites & Vectors 18:263. doi.org

Where evidence is limited, recommendations rest on established practice and expert judgment, and may be updated as knowledge develops. This is general information and does not replace advice from your veterinarian.

Next steps

• Read next: Fleas on dogs.
• Related: Seasonal allergies in dogs · Water safety for dogs.
• Return to the guide: For your puppy buyers.