The Bug:

The hitboxes of sniffers are not adjusted when they lay down.

When camels lay down, their hitboxes are adjusted accordingly. When polar bears stand up and kick, their hitboxes are adjusted accordingly. When horses rear, their hitboxes should be adjusted accordingly as stated in MC-195133. I'd expect similar behavior with sniffers; their hitboxes should be smaller when they lay down.

Steps to Reproduce:

1. Enable entity hitboxes by pressing "F3 + B".
2. Summon a sniffer and wait for it to lay down.
3. Summon another sniffer by the sniffer that's laying down and compare the sizes of their hitboxes.
4. Take note as to whether or not the hitboxes of sniffers are not adjusted when they lay down.

Observed Behavior:

The hitboxes of sniffers are not adjusted when they lay down.

Expected Behavior:

The hitboxes of sniffers would be adjusted when they lay down.