Why does my dog have hair loss, bald patches, pus bumps, and swelling?
Hello and thank you for reaching out to PetCoach. I'm sorry to hear that Frisco is having these dermatologic issues. The most likely cause is the presence of ectoparasites, such as fleas, mites or lice. If he also has areas of raised pus-filled lesions, he also likely has a secondary bacterial infection. It sounds difficult to have Frisco seen by a veterinarian, but he would benefit greatly from an exam and a skin scrape, which is a test used to look for external parasites. Depending on what parasites are present, your vet can treat accordingly. Over-the-counter flea and tick medications are not safe or effective in dogs, and can sometimes be harmful. You may try to purchase chlorhexidine or other anti-bacterial/anti-fungal wipes online, which may help with any bacterial infection. https://www.chewy.com/douxo-chlorhexidine-3-ps-pads-dogs/dp/110823
However, if the underlying infection with mites, such as Demodex, is not addressed, the problem will continue. I hope this is helpful!
Updated on September 23rd, 2025