Hi and welcome. Thanks for joining us. Your future posts won't need approval so post away. 

Tell us more about your dog. What's his name? Is he a Malamute? Looks like it from the pic but I can't really tell.

What is the reason why he might need the amputation? Also, have you seen an orthopedic surgeon for a second opinion?

Sorry for all the questions but the more information we have the better we can give you our own insight on what we've seen here.

Dogs have different challenges depending on which leg is removed and how old/young they were when the amputation happened. But it's nothing you can't overcome at any age. Now, I've never heard anywhere, or seen a study, that being three-legged shortens a life span. Perhaps your vet meant that a dog may have a a lower quality of life as a Tripawd due to pain and joint problems, which could lead to an earlier euthanasia decision? 

We have seen many dogs live a long time on three legs. Their quality of life depends on how well the parent handles things like weight management and exercise. 

Remember, no dog has an expiration date stamped on their rear end. With a good quality of life, any animal can live well into old age. 

Let us know more details so we can better help you OK? Thanks!