Wolf's tail will spin 360 degrees if max health is increased

Confirm for 21w20a

You can also repeat the healing by also giving them regen with commands.

Can confirm in 1.17.

Can confirm in 1.17.1.

I can confirm this behavior in 1.18.1.

Here's a code analysis of this issue. The following is based on a decompiled version of Minecraft 1.18.1 using MCP-Reborn. Please note that I'm quite tentative about this analysis, although I'm persuaded to believe that this is likely the cause of the problem. 🙂

Code Analysis (tentative):

net.minecraft.world.entity.animal.Wolf.java

public class Wolf extends TamableAnimal implements NeutralMob {
   ...
   public float getTailAngle() {
      if (this.isAngry()) {
         return 1.5393804F;
      } else {
         return this.isTame() ? (0.55F - (this.getMaxHealth() - this.getHealth()) * 0.02F) * (float)Math.PI : ((float)Math.PI / 5F);
      }
   }

If we look at the above class, we can see that no checks are carried out to limit the angle of a tamed wolf's tail. The angle is simply determined by the wolf's maximum and current health, allowing it to be positioned illogically.

Simple fix would be to clamp the tail angle using Mth.clamp(...).

If we want the tail angle to represent the wolf's health ratio, from the lowest (0.15) meaning almost dead, and the highest (0.55) meaning fully healed, the formula should be

0.15 + 0.4 * (this.getHealth() / this.getMaxHealth())

This formula gives the same values for vanilla dogs as the current expression