Just a quick question please...A friend has been looking after my dog whilst I have been away. To cut a long story short it needed vetinary treatment and she took him to her vets and registered him there, she is already a client.

She never explained the situation and never thought of the consequences. I now need to make a claim and need all the medical history..my vets no problem but her vets the medical papers are going to have the wrong addresss on. The vets say people often have different addresses...my gut feeling is the insurance will use this as a way to not pay....am I being overly critical of insurance companies ?

If you explain to the insurance company that your dog was being cared for when it required treatment there should not be a problem. You will need to list each vet that your dog has been registered with on the claim form. If necessary you may need a letter from the person caring for the dog to confirm the details.
My dog had an accident a few years ago and she was bleeding very badly I took off my sock and tied it round her foot as tightly as I could to stop the bleeding and got her to the nearest vet, it was too far to drive her to my usual vet. I put both vets details on the claim form and there was not a problem.
The same situation could occur if your dog was with a boarding kennels and needed to see a vet, the kennels would usually arrange for the dog to see their vet, some have a priviso to that effect on a form to sign when you leave your dog with them.
Hope your dog is now fit and well.
Just to add I now have a first aid kit in my car so I can make a temporary pressure bandage as it was so scary when my dog cut her paw so badly.

This should not be a problem - just be honest, put down her vet on the claim form, include all receipts and medical history from her vet, get her vet to fill out the form.  If your vet has also treated the dog, then it might be easier to then use another form for your vet - as 'continuation'.