 I'm sure it's inflamed, and it could be skin fever, appetite. The most important thing is to get the dog to the vet, especially at four months old, so that the vet can really determine and assess exactly what type of infection it is. They're going to take urine samples, some skin swabs, and once they do that, they'll be able to treat it accordingly. So with a four-year-old fox terrier at this point, if it is a staph infection, was he to the vet already or not?