My dog's anus is darker. Could it be a yeast infection or normal?

Unfortunately, it's impossible to be sure from a picture, but the area looks like normal pigmentation on the skin. Young dogs often develop darker areas on their bellies as they get older, so the area may continue to enlarge. If the area is irritated, red, bumpy, crusted, or appears different from the surrounding skin in any way other than color, I would have your veterinarian examine it, but I suspect that it is just a big ol' stomach freckle! I hope that was helpful. Thanks for using Petco Pet Education Center, formerly Petcoach.

I would monitor her for any diarrhea or straining to deviate or any itching or scratching or excessive licking in that area. If you rice that then I would have her anal sacs checked and possibly a thyroid test or checked for an infection around that area.

She may be coming into heat which could be causing her to feel irritated down there, making her scratch which damages tge skin barrier and can cause skin infection. Or alternatively she has simply got a skin infection. The skin does look inflamed and the dark pigment could just be natural colour change or it could caused by yeast. She looks sore so I would have the vet examine her and determine exactly what microbes ate present in the area and then decide how best to treat. She may just need an antinflammatory or antihistamine but I suspect she will also require an antimicrobial.

Sometimes it is normal change that will change back with no attention to it. Other times this can be a sign of an yeast infection or a low thyroid. Typically you do have other signs associated with these disease such as hair loss or itchy skin and lethargy. If none are nites then you can just monitor for any changes

It may be as the moisture from the diaper can create a skin infection and that pigment can be from a yeast infection. It may also be unrelated and due to changes due to the hormones. I would leave the diaper off and keep the area clean and dry. If you notice an odor or it seems to itch and bother her then I would get it checked

The dark area is likely just urine or saliva staining if she licks a lot. The area doesn’t look irritated but I would monitor her for signs of infection. Have her seen by a vet if she starts rubbing with more frequency or has urinary changes.

It may be a yeast infection and inflammation causing the skin to be thick and dark. This can also be caused by a low thyroid level. I would take her to your vet for a thyroid check and a skin sample to see if it can be resolved with medicines. If not and it gets larger then you would be looking at surgery