Fainting is the sudden loss of consciousness or a sudden and marked weakness. It may be associated with numerous medical conditions and can be caused by anything from low blood sugar and neurological diseases to heart disease. 

What to Do

• Immediately position the pet with the head down and the hind quarters elevated. This will improve brain blood flow. 
• Cover the pet with a blanket to preserve body heat. 
• If the pet vomits, make sure he does not inhale any of the vomitus into his lungs by keeping his head down. 
• Seek veterinary attention.

What NOT to Do

• Do not give anything by mouth. It can be aspirated into the lungs and cause serious problems. 
• Do not slap the pet or douse him with cold water trying to shock him into consciousness. 
• Do not fail to seek veterinary attention just because the animal recovered quickly and seems fine now. Several of the conditions that cause fainting or dizziness are serious and require diagnostic tests in order to determine the cause and prevent future episodes.