My dog has a dark, crusty, painful lump on her head. What is it?

If this just appears to be a crusted area and is not raised, it is possible this was an insect bite that got irritated or a small scratch/wound. If the lesion is raised (I can't really tell from the appearance) then we sometimes get warty skin growths that can get traumatized and bleed/crust over. I would wash the area with a mild soap or Hibiclens (available at most drug stores) and apply a topical antibiotic like Polysporin or Neosporin a few times day. If she is scratching/rubbing at the area she may need an e-collar for a few days to stop self-trauma. If the lesions isn't improving after several days of this or it starts to get larger/other spots appear then these would be reasons to seek veterinary care.

This looks infected with either bacteria and/or yeast. I can't tell if anything else is going on like an abscess or tumor. Sophie needs to be re-examined and likely more tests done to determine what's going on.

According to the picture this looks like a wart that Lady scratched and now has a scab on it. Since she is bothering with it and seems uncomfortable I would take her to see your veterinarian. They can make sure it is nothing else like a scratch that got infected or a different type of growth that go infected and scabbed over. They also will be able to give her a topical ointment to place on the area to help with any type of infection. If this is something that continues to bother her or scab over I would recommend removing it so it does not continually get infected and bother her. If she is scratching at it I would put an e-collar on her so she does not make it worse. As dogs age it is very common for them to get more warts like these, some may bother them while others will not.

It could be a pyoderma (skin infection). See your veterinarian for an exam. He or she may diagnose bacterial or fungal skin infection and can prescribe the appropriate medication afterwards. Treatment may be topical, systemic or a combination. Consider adding an essential fatty acid supplement, such as DermCaps or EicosaCaps, to her diet to promote healthy skin and coat. Place an e-collar (cone) on your dog if she is licking or chewing excessively.

The picture makes it difficult to see. It's possible it may be a scab trying to heal, a minorly infected area of skin, or a wart/growth forming. It would be best to keep the area clean and dry and keep Belle from licking or chewing at the spot. If the area continues to change in appearance, is bothersome to Belle is hot to the touch, painful, or oozing debris, or doesn't seem to be healing, it is best to seek veterinary care in person. Your vet can take a look at and sample of the spot as needed and provide more tailored treatments depending on the cause.

I am sorry to hear about Daisy! Due to the size of this lesion and the fact that it isn't improving, I would recommend taking Daisy to the vet for examination of this swelling. I would be concerned that we could have a bacterial infection like an abscess, that this could be a spider bite or other insect bite, or possibly even a mass/tumor. The vet can examine the area and may try to aspirate the swelling (use a small needle to remove any fluid present or collect cells that may help identify the cause of the swelling and the best treatment). Best of luck with Daisy!

That lesion could be many things including an abrasion that is healing, a bacterial infection or something like ringworm (which humans can get). That's good that she is not scratching at it. You may monitor it at home. If it is not getting better after a week, if it starts looking worse or if she starts rubbing at it, have Bella examined by the veterinarian. I hope this helps and please feel free to post any additional questions.