mange and ivermec

Question
I have been trying to rescue a stray dog for some time.She has mange, lost all of her hair, is covered with scabs. After some time, some hair is beginning to grow back in sections and her whole tail is now covered with hair. A woman that runs a rescue offered me Ivermec, a  clear liquid to place in her food, I am not sure if this is the injectable or not or is even absorbed if given orally. She also gave me what looks like keflex capsules (dark and light green caps)Can ivermec be given by mouth and be effective and what if the dog has liver or kidney disease? Can I kill her by doing this? I want to help her but don't want to make her suffer anymore than she is. I was also wondering if she has heartworms, if giving this is dangerous. I cannot imagine that she does not have them. I live in Houston, Texas. Any advice will be appreciated.

Answer
Depending on the breed, Ivermectin can be dangerous.  Oral absorption is good (it is the major component of most heartworm preventatives) and at the doses needed to treat demodectic mange, it will definitely prevent heartworms.  The problem is that if it is not demodectic mange, it probably won't do much for the skin.  See your vet to make sure that it is mange and that this dog can take ivermectin.