black throat monitor, 15 years old, losing weight fast

Question
Hi my name is vanessa. I have a reptile education and rescue inn Northern California. I have about 15 years experience and was an emergency vet tech. I am only telling you his to let you know that I have cared for reptiles for a long time and nothing is working. My 15 year old monitor is in a 9 foot long and 5 foot wide by 4 foot tall enclosure. He has multiple sources of heat and uv lighting. clean water and a clean cage. Substrate is crushed walnut shell. He has not been holding down food. off and on for almost two months. He eats rats, mice, baby chicken (for thanks giving), baby rabbit, and a frozen dog food his previous owner used to feed him. I think the frozen dog food was old and contaminated with salmonella or bacteria. I have been had feeding him chicken, in hopes that he will retain the food if its small. He is drinking and staying hydrated. I was thinking about treating him with panacure. I am worried about antibiotics, as i know he will not want to eat. He is about 5-10 lbs. I do not know how much to give him. (i could look it up). Any ideas...should i go with parasites or antibiotics. The vets here are not knowledgeable and fix everything with betryil. help? Could he have gotten sick from bad frozen dog food? It is not that I have not seen them crash so fast...but...it is strange.

Answer
It sounds like Salmonella to me personally which is probably from the dog food. As far as dosages are concerned I would have you look that up as I never self treated a reptile as I am not a qualified vet. I would quit feeding the dog food all together as well.