Evil sorcerers are known for their meddling in the dark arts, and that includes the creation of new and novel dragon breeds. But not all of them made it into the dark army or evil fortress.
The lobster dragon tasted delicious on toast. They were slaughtered by the thousands.
The cow dragon could give no milk, and was pigeon-toed to boot. Plus it needed time to chew its cud.
The wiener dog dragon had speed and agility, but made opponents laugh with its strange yipping roar. It also had a tendency to lie down in a patch of sunlight with its belly exposed instead of fighting.
Of the horrible dragon crab, the less said, the better.
The dragon cat, like all cats, proved to be completely ungovernable. Some still exist today in wild, out-of-the-way places.