Impetigo is one form of bacterial skin infection, or pyoderma. It comes in two forms: a juvenile form in dogs under one year old, often called puppy pyoderma, and an adult form called bullous impetigo [1]. In puppies, the spots show up on skin with little hair, such as the groin, belly and armpits [1]. Pustules are small pimples filled with pus.
If you see pimples or pustules on your dog’s skin, see your vet. Other skin diseases can look the same.
For the wider picture of bacterial skin infections, see pyoderma in dogs.
What kind of infection it is
Impetigo belongs to the superficial pyodermas. In these infections the bacteria stay near the surface: mainly in the hair follicles, and also in the epidermis, the outer layer of the skin [1].
What you may notice in puppies
A puppy with impetigo may have pustules, small red bumps, honey-colored crusts and round scaly rings where a pustule has burst [1]. Some dogs itch [1]. Many affected puppies are otherwise healthy, but impetigo can also follow worms or external parasites, poor nutrition, a dirty environment or viral infection such as distemper [1].
Bullous impetigo in older dogs
The adult form shows up in middle-aged and older dogs as large, soft, floppy pustules and honey-colored crusts, often along the back [1]. It usually develops in dogs whose immune system is weakened by another illness, so finding and treating that illness matters [1]. Hormone diseases are one example. For hormone diseases that affect the skin and coat, see hair loss in dogs.
How vets diagnose it
Your vet will go over the history and look at the skin. A sample from a pustule looked at under the microscope can show the bacteria and the white blood cells fighting them [1]. Because mites (demodectic mange) and ringworm can also cause pustules and crusts, your vet may do skin scrapings or a ringworm culture to rule them out [1].
For a different skin disease of young puppies, see juvenile cellulitis (puppy strangles) in dogs.
Treatment
Your vet will advise on treatment for your dog. Mild puppy impetigo in an otherwise healthy dog may clear up by itself, and your vet will decide whether any treatment is needed [1].
At home, as directed by a vet:
- do not put human or leftover medicines or skin products on your dog unless your vet says so;
- give any treatment exactly as your vet prescribes, for as long as your vet says;
- go back for any recheck your vet books.
When to see your vet
See your vet if your dog has:
- pustules, red bumps or honey-colored crusts on the belly, groin or armpits [1];
- large, soft pustules, especially in an older dog [1];
- any skin change you are unsure about.
The bottom line
Impetigo is a surface bacterial skin infection. In puppies it is also called puppy pyoderma and shows up on skin with little hair. In older dogs it can point to another illness. Only a vet can tell it apart from other diseases that cause pustules.
This article is for general information only and does not replace advice from your veterinarian. If your dog has pustules or pimples on the skin, see your vet.
Sources
- Torres SMF. Canine Pyodermas (chapter 1.1). Small and Large Animal Dermatology Handbook, Vol. 1. University of Minnesota Libraries Publishing, 2025. Licensed CC BY 4.0. https://open.lib.umn.edu/animaldermatology/chapter/canine-pyodermas/