My dog has a dark purple spot on her skin and losing hair. What is it?

Based on the photos, I am concerned that the purple area is some bleeding/bruising in the skin which we often see when a dog has low platelets. I'm not sure based on the photo, but I suspect the white area is a nipple that just looks really prominent due to the bruising around it. Low platelets are a very serious problem; even though he's otherwise acting fine, please take him to your vet to have him examined. They may recommend running some lab work to find our what his platelet count is. There are many causes of low platelets, some possible causes include an infectious tick-borne disease, an auto-immune disease where his body is destroying his platelets, or cancer. Because all of these are very serious, and because low platelets can lead to life threatening anemia, please take him to your vet. Thanks for asking Petco Pet Education Center, formerly Petcoach!

If your pup has been scratching or chewing at the spot, it could be getting red/purplish from irritation. Bruising may also cause a purplish color to appear. Since the site is changing in appearance, it is best to have it rechecked with your vet to make sure there aren't new problems, such as an infection or growth, causing the change. You may also want to use an Elizabethan (cone) collar or T-shirt on your pup to stop her from licking and chewing at it until you can get to the vet. If your pup seems very distressed, or the color is rapidly growing and changing, seeking vet care ASAP is best.

Unfortunately, without images or a physical exam, it is difficult to determine exactly what is going on with your dog. There are [multiple potential causes](https://www.petcoach.co/dog/condition/skin-ulcers-and-draining-lesions/) for the symptoms. That said, black or bluish discoloration of the skin may indicate necrosis (dying off of normal tissue) or a severe inflammatory reaction (if mainly black and also coarse to the touch). I would suspect a potential spider/centipede bite or severe yeast infection (if mainly black and coarse to the touch) or severe [vaginitis](https://www.petcoach.co/dog/condition/vaginitis/) are potential causes which should also be looked at by your vet ASAP. If this is a spider/centipede bite, it should be treated quickly with steroid therapy to stop the reaction from spreading and causing systemic (whole body) illness. Place an e-collar (cone) on her to prevent licking until she sees the vet.

I can't tell from the photo if that is a scab or an area of skin discoloration. I recommend to have him examined by the veterinarian to be safe. If that is something like a bruise, that is extremely worrisome. A scab could indicate something like an infection or a hot spot. Best to play it safe and have this checked out. I hope this helps.

Petra is very cute! I would recommend taking her to a vet for a skin scrape. This will make sure she does not have skin mites like demodex. IT is possible a small allergy,fungal disease, skin infection or even vasculitis from a rabies vaccine cause the hair loss. However due to breed I would make sure she does not have skin mites.

i am sorry to hear about your dog! It is very difficult to evaluate the skin by a photograph but it appears there is a defect/wound in the skin here? I would be concerned that this was an abscess that ruptures, a wound that isn't healing and is infected, or we could have something like a cuterebra (a fly larvae that lives in a hole in the skin- look closely and see if you see a tiny creature moving inside the hole!). I would recommend a visit to your vet- the area may need to be flushed/cleaned and have antibiotics prescribed. In the meantime, I would put an e-collar on your dog or a t-shirt if it would be covered by this to prevent your dog from licking/aggravating the skin. You can also clean the area with a mild soap or Hibiclens (available at the drug store) and apply an antibiotic ointment like polysporin to the area until your vet can see him.

It does look like potentially it could be a hot spot that has been going on for a while and that Honey has been scratching. Ideally you should prevent her from scratching the area and have a vet check up so that she can have either further tests done or she might get some antibiotic and pain relief treatment.