[dottiesyrky]

I use a regular six inch diameter flat top approx kitchen scale, put a larger hard tray on the scale, zero it and it works well. Only hazard is that he might fall off. I always do it with a helper to steady the tray and dog. It is very important to do it with a helper as dogs can get wiggly.
Also put the scale on the floor so nothing can happen if he falls. Good idea to have a harness and leash on for further safety. A non slip mat on the tray also makes life safer and easier.
I know this may scare some, but it works for me with precautions mentioned above.
I am sure that a vet would be happy to weigh the pet when needed.