When you change the name of a Tamed wolf (dog) the entire NBT is reset to default.

What I expected to happen was...:
Only the name is changing and not entire NBT (Health for example)

What actually happened was...:
It change the name but reset the entire NBT

Steps to Reproduce:
1. Summon a tamed wolf / Tame of wolf

2. Hit him to decrease his HP

3. /data get entity [uuid of the dog] Health

4. See the amount of health

5. /data modify entity [uuid of the dog] CustomName set value '{"text":"Test"}'

6. /data get entity [uuid of the dog] Health and see that he went back to full HP.