Vet treating pigs

I am a qualified vet and generally treat farm animals.

Sometimes, the farmer asks me to treat a pig that is sick. I will need to examine the animal and administer the necessary medication or treatment to it. Naturally, this will involve some physical contact with the animal.

I was told that even a pig is deserving of treatment as it is the creation of Allah, and all creatures should be shown kindness. However, I want Islamic guidance in this regard.

Is this permissible? Will the money earned through this service be halaal?