I really recommend people look on the ARAV website (Association of Reptile and Amphibian Veterinarians) to find a local vet who can help diagnose and treat their frogs. If nothing else, taking the body in after the frog has passed to have it examined can help find a cause of death. There are many specialists who look at tissue samples of exotic animals for this purpose. Of course, there is going to be an expense to this, but it can often be well worth it if you have more than one amphibian (and, well, who of us doesn't!) to save others in the group or to keep us from transmitting things to future pets. If you can't find a vet close enough who will treat frogs, any vet can send in tissue samples on deceased frogs to a lab for you. Bring the frog in cold (not frozen), describe the signs (even if it is acute death) and ask for the frog to be sent to their lab for necropsy. Especially with ranavirus and chytrid hanging over our heads, we need to be proactive. If they ask you for what tissues you want (and to save costs), tell them kidney, liver, heart, and lung.

Another option, if you do not have a vet close enough, is if you have a zoo that is close by. Get in touch with the veterinarian for that zoo (smaller zoos often have a vet that comes in 1-2 days a week, sometimes a local vet, sometimes from farther away) and establish a relationship. They will often be more than willing to help you if you explain your situation- you have frogs and no one to treat them.

I hope this can help. There are not many, but there are vets out there who truly love these animals like we do and want to try and do what is right for them.