It is possible to carry out cardiopulmonary resuscitation (CPR) on animals. There are various sources of information about CPR for animals, including the Blue Cross website:
Oxygen can be provided via oxygen masks designed for people. However, oxygen masks designed for animals are available in various sizes to cater for small pets through to equines.
To protect emergency responders, the animal should be appropriately restrained prior to providing CPR or oxygen. 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.