After changing a tamed wolf's max health with the command:
/data merge entity @e[type=wolf,limit=1,sort=nearest] {Health:10.0f,Attributes:[{Base:10.0d,Name:generic.maxHealth}]}
stays at 20.0d when checking with data get command and also dies after getting 20 damage, not 10.
MC-165707 Taming wolf don't turn 20 health
MC-71977 Changing generic.attack_damage of tamed wolf has no effect / taming wolf removes custom generic.attack_damage