The most violent storm will not damage tamed creatures in the slightest. A single globule of resin is most definitely the remains of a Greyling your boar killed. Keeping your boar/s behind earthen walls with full antispawn items such as workbenches can definitely increase your animals' security. Two star boar can kill Greylings with little or no loss of health, and keeping tamed wolves and boars together is another extremely beneficial option.