What's this quarter-sized black blister on my dog's lower stomach?

It looks like Abby has some hyperpigmentation on her belly. This can be caused by any sort of inflammation, usually allergies. The blister looks like a pustule so she may have a mild skin infection. If she has been itchy I would take her to the vet so they can get her on an appropriate medication. You can also try a medicated shampoo to see if that helps as well. Good luck!

This is probably due to a severe allergy, although it could also be fleas or mites. First of all, in order to rule out skin parasites, you will need to treat Molly with a high quality flea treatment (e.g. Trifexis or Advantage), then get her to the vet to perform a skin scrape - this might reveal an infection or a mite infestation. If all of those came back negative, the next step is to treat the allergy symptomatically and try discovering the cause of the allergy. Some medications can be given by the vet in order to repair the skin lesions (steroids and antibiotics). simultaneously you should start her on a prescription hypoallergenic diet for at least 2 months. Hopefully you will see some results after all this, if not you and your vet should consider putting her on a long term allergy treatment (Atopica or Apoquel).

It may be a blood clot or blood blister. If you pop it you will likely get blood out and it will refill. It is best to have your vet remove it to make sure it is not a cancerous growth. This will be able to tell if there is an infection associated with it also

This looks potentially like a superficial skin infection. Skin infections like this can occur secondary to allergies, fleas, or sometimes to contact with an irritating substance. I would recommend having your veterinarian take a look. They might recommend topical treatment or an oral antibiotic, or they might want to do some testing as well.

This looks like a mild bacterial skin infection. Dogs can get this from laying on damp ground. Often it will go away on its own. You can bathe the area with antibacterial shampoo once or twice weekly to help it heal more quickly. Since she’s not bothered by it I’m not overly concerned. Should it worsen please take her in for an exam. She may need oral antibiotics if is gets bad. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Marley.

I'm glad to hear that Ivy doesn't seem to be bothered by this lesion, despite how inflamed and irritated it appears. While it's impossible to say definitively what the cause of this lesion is without further diagnostics, I can say that it's possible that this could be an irritated insect bite, or a benign or malignant mass. Given the irregular surface of this lesion, I think a bite/sting is unlikely, but the possibility shouldn't be ignored. Since it's so red and obvious, we have to assume that it popped up pretty quickly since you're just noticing it. As a result, I do think that you should have this checked out by your vet in person in the coming week. After an exam, your vet will likely want to perform a fine needle aspirate, where they'll use a needle to draw out a few cells for microscopic evaluation. That will help them to determine if this is more of an inflammatory/infectious issue rather than a more aggressive lesion. In the meantime, be sure to keep a close eye on Ivy. If she starts to lick this area at all, put an e-collar (cone) on her, as the licking will only cause further irritation. I hope that everything goes well!

Hi and thanks for posting on Petco Pet Education Center, formerly Petcoach! It is hard to say exactly what the cause of Lulu's skin lesions may be without an exam, but some possibilities may include a fungal infection, mites (scabies or demodex) a food or environmental allergy, or evidence of an underlying endocrine disorder such as Cushing's disease or a thyroid problem. Your veterinarian can diagnose these potential conditions with a fungal culture, skin scraping, and some blood work. I would recommend Lulu visit her vet soon to have the possibilities above ruled out so she can get appropriately treated.