My dog's armpit skin is dark and licked. Is it an allergy or hot spot?

Thanks for using Petco Pet Education Center, formerly Petcoach! This is possibly due to allergies. It really comes down to figuring out what is causing his allergies so that they can be treated or the specific allergen avoided. A secondary infection is likely and also needs to be addressed. You can use chlorhexidine based pads to clean the affected area. There are many things that can cause allergies though in most cases they can be broken down into 3 big categories: flea, food and environmental allergies. Allergies are usually worked up in a stepwise fashion starting with flea allergies as this is the easiest and cheapest to take care of. If not on a flea preventative, then it would be a good idea to get started on one. If already on one then it would be a good idea to change to something else (there are many new products out in the market). If not improved in 1-3 months then it is time to move on and check for food allergies by switching to a novel diet (new protein and new carbohydrate). If that does not seem to be the issue then you are left out having to check for environmental allergies which require blood and/or skin tests. Allergies can be very frustrating to deal with at first but so rewarding at the end when we are able to treat them effectively!

This is a bit of inflammation usually caused by a mild allergy. If Izzy is otherwise not bothered by it or seen to excessively scratch or lick the area, then I would just recommend an over the counter shampoo or the Duoxo calm shampoo (my top pick for mild allergies) https://www.amazon.com/Douxo-Calm-Shampoo-Dogs-Cats/dp/B0010V5LNE/ref=sr_1_2?ie=UTF8

Any type of irritation/inflammation can cause the skin to be darker in color when it heals. You can see that in the second picture. It is not abnormal for the darker color in the skin to last for a while, but it almost appears that the skin in the last picture is darker than the second (which might just be an artifical aspect of the picture). The skin appears to have healed well, so if the dark area is just taking a while to resolve, it likely isn't anything worry about. If it appears to be enlarging or getting darker however, I would have your vet examine Addison. I hope that helps! Thanks for using Petco Pet Education Center, formerly Petcoach!

Thanks for using Petco Pet Education Center, formerly Petcoach! These are likely patches of hyperpigmentation. However, continue to monitor them closely because sometimes skin cancer such as melanoma can start like that. If these ever become raised or seem to bother him or appear to be spreading, have him evaluated by a veterinarian for further assessment and treatment. They would be able to check on it and sample to get a diagnosis. Best of luck!

Thanks for using Petco Pet Education Center, formerly Petcoach! Jack being an English Bulldog, this is possibly due to allergies if associated with itchiness or just a normal change in skin pigmentation which may be just transient. It really comes down to figuring out what is causing his allergies so that they can be treated or the specific allergen avoided. There are many things that can cause allergies though in most cases they can be broken down into 3 big categories: flea, food and environmental allergies. Allergies are usually worked up in a stepwise fashion starting with flea allergies as this is the easiest and cheapest to take care of. If not on a flea preventative, then it would be a good idea to get started on one. If already on one then it would be a good idea to change to something else (there are many new products out in the market). If not improved in 1-3 months then it is time to move on and check for food allergies by switching to a novel diet (new protein and new carbohydrate). If that does not seem to be the issue then you are left out having to check for environmental allergies which require blood and/or skin tests. Allergies can be very frustrating to deal with at first but so rewarding at the end when we are able to treat them effectively!

It's difficult to say based on pictures along. Your second picture almost looks like a nipple, but I'm assuming this is not the case if more and more have been noted. Sometimes a bacterial skin infection can cause darker skin and a raised lesion, and skin infections can be common secondary to allergies. It's also possible that these are normal areas of pigmentation. I would recommend having your vet examine Luna's skin.

Thanks for using Petco Pet Education Center, formerly Petcoach! It is hard to know for sure based on these pictures though this is likely a normal pigmentation change. If it is not associated with itchiness or discomfort, there is no need to be concerned about this. If you ever notice any discomfort or itchiness, have her evaluated by your veterinarian for further assessment and treatment. Good luck and have a great day!