My dog's bald spot is dark & irritated after a month. What's wrong?

Skin darkening can occur due to natural aging, low level irritation from infection or allergies, a healed wound or changes in hormone levels from hypothyroidism. Your veterinarian may be able to determine the exact cause after a thorough physical exam. I hope this helps and please feel free to post any additional questions.

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to see that Bingo is having this problem. Hair loss and a darkening of the skin are often signs of dermatitis or inflammation/infection of the skin in that area. Not sure where the area is from the pictures. Reasons for this include external parasites (fleas, ticks, mites), allergies, thyroid problems, bacterial infections, etc. The best option is to take Bingo to your veterinarian and let them evaluate him. They can either advise treatment at that point or advise some skin tests (skin scrape, fungal culture, Woods lamp exam, etc) to determine the cause. The location of the area is important as well as what is noticed upon examining the area. Good luck with Bingo and I hope this gives you some direction to getting him over this.

Hello and thank you for contacting Petco Pet Education Center, formerly Petcoach. It could be a ringworm or superficial bacterial skin infection. If it has been getting bigger over the last few weeks, you should really take Milo to your local vets to get the bald patch examined and start treatment. Most likely, the treatment will be in form of antibacterial/antifungal cream or ointment.

Thanks for posting on the forum! Focal alopecia (local hair loss) can be a sign associated to different skin diseases. The most common are: Demodicosis (parasitic infection), dermatophytosis (fungal infection), scars, medication application site, alopecia areata (uncommon). I would suggest to have Maya checked by your veterinarian as further test are needed to make a diagnosis and prescribe the correct treatment, if needed. Your vet might perform a skin scrape to check for parasite and collect a sample to exclude a fungal infection; further test might be needed depending on the results of the ones mentioned. If those basic tests are negative, a biopsy and a allergy testing under general anaesthetic/sedation might need to be performed. 
Do not hesitate to post again on the forum or request a consultation if you would like to discuss it any further.

Those spots on Bailey could be several things including allergies to fleas, allergies to something in the environment, food allergy or endocrine disease. Skin mites and ringworm (which humans can get) will also look like this. Each one of these problems is detected and addressed differently and I recommend to discuss with your veterinarian which one to start hunting down first. The veterinarian can preform a few simple diagnostics to start figuring out the problem. Best of luck and please feel free to post any additional questions.

Hi and thanks for your request. One of the most important reasons for darkening of the skin is a chronic type of inflammation. This is usually combined with more clinical signs (like other skin lesions, itch or alopecia). If no other signs are present then a metabolic or endocrine disease can be suspected. Please repost your question and give us more informations and ideally some pictures so we can give you more specific answers.

This could be caused by an allergy or also endocrine condition. Hypothyroidism can cause hyperpigmentation, as can Cushing's disease or a liver condition amongst others. All of those disease can easily be diagnosed via a clinical exam by your veterinarian and blood work. Hypothyroidism can easily be treated with medication containing thyroid hormone. Treatment of Cushing's disease (overproduction of cortisone by the adrenal glands) is usually treated with medication that destroys part of the adrenal glands so they do not produce so many glucocorticoids. Liver conditions are treated according to their cause. And then there always is the possibility that this is just harmless hyperpigmentation without disease. Best schedule an appointment with your veterinarian for an exam.