What I expected to happen was...:
That all mobs would have a consistent render view distance.

What actually happened was...:
That there is a significant difference in the render view distance of all mobs.

Steps to Reproduce:
1. Create an enclosed area where you can spawn a mob
2. Spawn a mob (any would do)
3. Walk away from mob
4. Stop once mob is no longer visible

My Results:
The following results are the distances before the mob are suddenly no longer visible:
-Chick: 14 blocks
-Baby Wolf: 22 blocks
-Baby Ocelot: 22 blocks
-Chicken: 28 blocks
-Baby Pig: 29 blocks
-Baby Villager: 33 blocks
-Baby Sheep: 34 blocks
-Baby Cow: 34 blocks
-Bat: 41 blocks
-Wolf: 43 blocks
-Ocelot: 43 blocks
-Baby Horse: 49 blocks
-Pig: 58 blocks
-Villager: 64 blocks
-Creeper, Skeleton, Zombie, Zombie Pigman, Blaze: 64 blocks
-Cow: 66 blocks
-Sheep: 66 blocks
-Horse: 79-85 blocks

Note:
My viewing distance is set to Far and Advanced OpenGL (On or Off) gives the same results