When typing 'spawn' into the search tab, or looking in the Miscellaneous tab, the spawn eggs for Stray Husk Donkey and Mule do not show up, however the Polar Bear does.
Linked issues
Comments
Removed the spawn eggs for 1.10.
Spawn eggs for Wither Skeleton, Mule, Skeleton Horse, Zombie Horse, Donkey, Cat, Elder Guardian, Stray, Husk and Polar bear were all added in update 16w20a. They were all removed except for Polar Bear in release 1.10 Pre2, as mentioned in the release notes.
This issue duplicates MC-103175.