This indicates that your dog has developed an acute moist dermatitis, a condition more commonly known as a hotspot. A hotspot is often a localised area of inflammation of the skin that can have several underlying causes, including allergic disease. 

Hotspots are most often discovered in the head or neck region when the dog is scratching more than usual in one specific area. The fur is often visibly wet or greasy and sometimes hair is missing or coming out. 

A characteristic of the "hot spot" is that it is moist, oozing and that it can quickly grow in circumference and sometimes even spread to other skin areas.
For hotspots smaller than 3-5 cm in diameter, you can try to treat at home. If the eczema is larger or in multiple areas, the dog is in pain or if the eczema worsens despite treatment, the dog should be examined as soon as possible by a veterinarian.

Treatment at home:

- Put a Elizabethan collar on the dog so that it cannot bite or scratch the wound.

- Keep the wound clean and dry. Carefully cut or shave the fur above the wound and at least 2 cm around the wound where the skin is healthy.

- Please pour cooled boiled water over the skin to get rid of any discharge and dissolve scabs. Thick scabs must not be allowed to form over the wound, as these prevent healing.

- Wash the wound with dilute chlorhexidine solution (0,05%). Soak a cotton ball in the solution and press gently against the wound for a few minutes. Chlorhexidine is bactericidal and drying. Do not rub against the wound, as the inflamed skin is often painful.

- Repeat the treatment 2-3 times a day until the wound is healed. Allow the wound to air dry or dry the area with a hair dryer at a cool temperature.

- You can help the wound to heal with e.g. Manuka honey, Vetericyn wound spray/wound gel or other antibacterial wound spray. Apply the ointment or gel when the wound is clean and dry.

If the wound does not appear to be healing satisfactorily within 1-2 days, or if your pet develops a fever, pain or swelling, I recommend that you consult a veterinarian, request a physical examination and further treatment plan for your dog.

Sometimes anaesthesia is necessary in order to be able to effectively examine the wound and to be able to clean the wound completely. In addition, there may be a need for antibiotic treatment and other prescription medication.

Also think about your own hygiene when handling the animals' wounds; wash your hands before and after cleaning and preferably use disposable gloves.

It is also a good idea to ensure that the animal has clean surfaces in its basket and other resting areas.