I rescued a colt with the same issue- he required leg casts, then splints, then special plastic shoes... Dam was over 16 hands, and sire was smaller than her.
Things like this can and will happen reguardless of mare size unfortunately
Yep! Was going to say the same thing... Worked in a barn where three 16 hh mares foaled and both foals had to be in splints to correct constricted tendons... The sires were roughly the same size maybe an inch or two taller than the mares.