Pug Has Rash-red Spots On Belly And Underams And Hairloss. What Do We Do?

These red rash can be due to following reasons.

1. Allergy to irritant and environment
2. Allergy with chemicals
3. Allergy to inhalation of pollens
4. Allergies to diet
5. Parasites like mites and fleas.
6. Bacterial or fungal infection
7. All types of mange infection cause itching and hair loss.

These rashes cause itching and continuous scratching can lead to hair loss.
It will be good to take your dog to vet and get differential diagnosis and treatment.