Breeders obsess about a lot of things, one of which is sheltie size. The breed standard calls for the Sheltie to stand between 13” and 16” at the withers (shoulders). If not in that range the Sheltie is disqualified from the show ring.
It certainly doesn’t affect their health in any way. It’s just something that was agreed upon in the standard. Considering the breed originally stood a mere 12”, the increase in agreed upon size over the years makes for a different Shetland Sheepdog for sure.
I personally like the smaller Shetland Sheepdogs, but it is difficult to breed a good, “typey” specimen in the smaller package. As a fellow breeder once said, “Just one of God’s little jokes. You can’t have it all in one dog.”
While most breeders will sell a Sheltie not within the standard rather than use them for breeding, I’m not willing to throw the baby out with the bathwater.
For example, Ditto has everything that I need in a Sheltie EXCEPT his size is too big. Considering he came from a small dam and a moderate sized sire, I’m hopeful that maybe he will throw some moderate sized pups just like him.
Show breeders will keep a promising puppy and “grow them out” (i.e., keep them and watch them grow) to see if they will develop into the specimen they want for their breeding program.
One task is to measure the pup’s height weekly, starting at 6 weeks old.
We have a Growth Chart also known as the Nobel Growth Chart that gives us a general idea of how big the pup will get. It’s based on old time breeder’s records.
The pup’s height is plotted and if the height exceeds the safe area, there is a good chance the dog will go oversized.
Click on the Nobel Growth Chart above to get an 8x11" chart that you can copy and use for your sheltie!! Plot his size weekly and see how he compares and get an estimate of where he will end up.
Of course just to make things interesting, some pups hit a growth spurt and scares the bejabers out of the breeder and then just as suddenly stops growing. So nothing is for certain.
The whole issue of size stems from the outcrossings with other breeds, most notably, the rough coated collie. That gave us all those nice “big” size genes that we are still to this day fighting to retain the correct Sheltie size.
Have them stand squarely and measure from the top of the shoulders down to the ground. Kinda the same way your mom may have measured your height as a kid, by using a ruler held horizontally on top of your head over to the wall. Then she'd scratch a line on the wall.
It can be tricky with a squirmy pup, but do it enough and they settle down.
You can buy a wicket like most breeders use, but it isn't cheap. But at least then you don't have to mark up your walls.