This could include applying pressure to a wound or cooling burns with water. There are various sources of information about first aid for animals, including the Blue Cross website:
To protect emergency responders, the animal should be appropriately restrained prior to providing first aid. The animal should be placed into the care of the owner, a suitable person, a veterinary surgeon, or an animal care specialist, at the earliest opportunity.
If fire and rescue services are called to an incident where there is a stranded marine mammal, they should contact the relevant animal welfare charity and request their attendance. While waiting for them to attend, and if appropriate, initial first aid for the animal may be provided as suggested on the British Divers Marine Life Rescue website. The fire and rescue service or the animal welfare charity may decide to request the assistance of local voluntary groups that deal with marine mammal rescue.