I have a 13 year old male golden that is one of the great ones, I have had trouble finding a suitable mate, what are the down falls of breading older dogs?
He runs and swims daily his health is great , he doesn't have the stamina he used to but the heart is still in the game.

Small litters. You'll only end up with one or two pup litters

Don’t know if that’s a universal truth. My farm manager just bred his bitch to a 9 or 10 year old male. Dogs tied only once and she had 11 pups.

I love to see Goldens in the field. Find a comparable mate and breed that boy!

If he is one of the great ones it is important to preserve those bloodlines. I would have no hesitation in using an old stud if he was in good health.

At about six years old I had my dogs sperm taken by a Vet and frozen....he said the sperm was good and I got like 6 tubes.

A13 year old dog sounds a little old the Vet can tell how virile he sperm is. I bought a female and a few years after his passing I had her artificially inseminated....I still miss my buddy and now I have a dog that is pretty much a clone of my dog with a little different personality.

what does that cost? Does the vet keep the sample until you need it?

Dog that age prob doesn't have a viable sperm count. Most often don't. But, never know.

Probably not as big a deal with studs as it can be with bitches. As mentioned above, less viable sperm may make for a smaller litter or none at all.

I tried to breed a 9 or 10 year old GSP bitch, who had been in great health, that I really wanted a pup out of. I had tried several time years earlier when I had found a stud with the bloodline that I liked but had been unsuccessful each time. The last time I tried, I thought we were successful but soon thereafter she became lethargic and drank incessantly prompting a visit to the vet. She had pyometra (infected uterus) and had to had to have an emergency spay. It was complicated by much more than usual bleeding and we just about lost her. Fortunately, she pulled through and I was able to wander the CRP fields with her for 2 more seasons before I had to have her put down.

Some things are not meant to be. Rosie was my "once in a lifetime" GSP... great hunting companion!

I was going to breed my 5 year old Griff. I spoke to a few experienced griff breeders and my vet who treats hunting dog s often. All advised too old to breed as hips were not pliable enough. Two other breeders advised it was ok. I opted not to breed

I'd find another vet. LOTs of dogs are bred past 5 yo

First breeding of a bitch past 5 years old is inherently more risky, to the point that my breed club (in the Netherlands) won’t approve such a breeding.

If it’s not the first breeding, they age out after 7 years of age.

Had a female Beagle that didn't start until 6yo, had 3 litters, last one at 10yo.

First two litters went great. 6 and 8. Last litter had 6, but one stillborn and two faded. (I don't believe in tube feeding sporting dogs, survival of only the fit and strong seems to make sense to me.) So only 3 lived.

Mamma was healthy and strong the whole time, but I'd say 10yo for the Dam is too old.

Used to raise English bulldogs, and we'd stop those girls at about 6yo... but that was a ridiculous breed... don't get me started! They're a happening!

I think it has very largely to do with the health of the dog in question. But as was said, far more for the dam than the sire.

If I was in your situation, I'd find a great female and try for it, without question.