Dogs stop growing at different ages, depending on breed. Larger dogs stop growing later, smaller dogs earlier. For a Pointer, it will probably be around 1 year, or maybe a little more.
Don't you worry about him being a runt! Unless you intend to show him, it won't matter. As long as he is well-nourished through the growing period (and of course well cared-for after) he should grow to be perfectly fit and well. If he's a little smaller than his breed, does that matter?
At five foot 2 I'm a bit of a runt myself! But I certainly do throw a mean frisbee!
German Shorthaired Pointers are considered a medium-large breed and will grow until they are about 18 months old. They will reach their full height normally by the time they are about 12 months of age, but they will continue to broaden out, especially in the chest, until about 18 months of age.
Your dog sounds small for his age, but some of them hit a growth spurt at about 10 or 11 months and within a couple of months you'd never know it was the same dog, so don't give up yet and just figure he's going to be small for his breed. It COULD happen that way, but give him a chance.
If you have had him to the vet and the vet doesn't find anything wrong with him, then he's just on the small end of his breed. Did you buy him from a reputable breeder? You could check out the breeder by contacting the German Shorthaired Pointer Club of America to see how the person is thought of by his or her peers. That would at least give you some insight as to whether or not they know what they are doing as a breeder, and that the dogs they're breeding are healthy representatives of the breed. As long as your dog vets out well, I wouldn't worry too much about his size, however I wouldn't consider using him for breeding if he is that far under his breed's size standard.
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