Welcome to JustAnswer, this is Dr. Christie.
You certainly can try the 3 salves you mentioned. I would recommend placing an ecollar (lamp shade) on your dog so he will not lick them off and make the sore worse. The Green papaya and alow vera gel are both nontoxic, but I do not know what is in the black salve. Unfortunately, if the sore is cancerous, these salves will not get the cancer to go away, but might offer some comfort to the irritated skin. If the paw is painful, certainly doing warm water epsom salt soaks daily will help. You can also discuss pain medicine options with your vet, such as Rimadyl, Deramaxx, or Metacam.
Depending on the type of cancer it is, there may be some options, such as surgical removal, chemotherapy, or radiation. If you like, find out what type of cancer it is from your vet and we can discuss further options for your dog.
Thanks, XXXXX XXXXX have some Black Salve as I have used it on my own large basal cell carcinomas (nose, cheek, forehead etc.) and over a 3 week period they enlarged, pussed up, caved in and then disappeared so I'm a complete believer in topical treatments such as this. It comes from bloodroot but my concerns were: 1) black salve only attacks cancerous cells and if my dog licks it (despite the ecollar) will it affect him internally; 2) my cancers were not bleeding wounds whereas my dog's cancer is so, even though he is on Metacam for other reasons at the moment, would not the pain of the a salve on an open wound be unbearable for an animal? At 14 I don't think he should go through surgery. I think the cancer is a hemangiosarcoma or similar type of sc sarcoma.
Ah, black salve as in Sanguinaria candensis, the bloodroot escharotic. I would advise NOT using this on the sore. There is very little information on this type of salve and its use on animals. In humans, it has been used successfully for tumors that are located ONLY in the dermal (skin) layer, not the underlying subcutaneous, fat, and muscle layers. It has no known properties to treat underlying cancer and can actually destroy normal skin and leave significant scarring due to it's corrosive nature! Add in that it can definitely be painful too because it is corrosive. There are no known toxicity studies if it is ingested either. I would assume it would do some damage to the esophagus and stomach if ingested due to it's corrosive nature.
If it is a soft tissue sarcoma (such as hemangiosarcoma), then there are radiation and chemotherapy options. Certainly surgery is also an option. There are no known natural cures for this type of cancer. Unfortunately due to the nature of this type of cancer, it is likely that is has already spread somewhere else in the body.
Thank you, XXXXX XXXXX this might be the case with the black salve, just wishful thinking. My last contact now before I leave you in peace - I think the cancer my boy has is the dermal hemangiosarcoma type and I've had advice that something called Artemisinin has had some success. I don't know what is in this topical ointment but perhaps you have heard of this one? My 14 year old Ridgeback is my first and only child so I have to explore all "alternative" options - perhaps you may have heard only rumours of success with something outside of the chemo and radiotherapy options and if so I'd appreciate any suggestions.
I have heard of Artemisinin but am unfamiliar with it's use. I did, however, find an excellent article outlining it's use, side effects, and even three really well known oncologists who have done many trials with the medication. There are even contacts provided for these veterinarians. I think contacting one of these oncologists would be your best bet, as those of us in general practice will have no where near the experience as they will with Artemisinin. Dr. Cuoto at the Ohio State veterinary school is a wonderful man and excellent oncologist! I would highly recommend him, as I have worked with him before!
here is the article: http://www.bonecancerdogs.org/main/document/50
My best wishes to you and your Ridgeback!!