Spaying your cat should be safe and simple, and it generally is. One risk, though, is your cat eating or drinking too close to the start of surgery. A night of hungry cries can be hard to take, but it's worth it for the safety of your cat.
General Guidelines
Your veterinarian should tell you how long your cat needs to fast before surgery, but there are some general guidelines. For cats younger than 4 months old, withhold food should be withheld starting about four hours before the spay surgery. Cats older than 4 months old should not eat overnight before surgery. Some veterinarians will recommend removing food at midnight, others recommend 9 p.m., and others will advise you to restrict food whenever you go to bed. Many times the difference in times depends on the time surgery is scheduled. Food restrictions vary by age because young cats could experience a dangerous drop in blood sugar if they go without food for too long. Withhold water the morning of the surgery for both younger and older cats unless otherwise recommended by your veterinarian.
Reason for Fasting
Cats must be under anesthesia for spay surgery. The anesthesia makes the cat temporarily unable to swallow, and it relaxes the epiglottis that prevents food and liquids from getting into the lungs. If a cat vomits during surgery, it is possible for the food and liquid from its stomach to get into the lungs. An empty stomach prevents this from happening.
Aspiration Pneumonia
If food or liquid gets into a cat's lungs during spay surgery, it becomes very susceptible to aspiration pneumonia. The acid from the stomach can burn the lining of the lungs, and the food in the lungs can lead to an additional bacterial infection. Signs of aspiration pneumonia include coughing, nasal discharge, difficulty breathing and loss of appetite. The condition requires immediate intervention; it can be life-threatening. It's much safer for a cat to spend one night hungry before surgery than to risk a lung infection.
Other Considerations
Elderly cats or those with health conditions such as diabetes may not be healthy enough to go without food for up to 12 hours. If your cat has a special condition, be sure your veterinarian is aware, and ask for special recommendations on how long to withhold food before spay surgery. In addition, make sure all sources of potential meals are eliminated. Lock up trash cans, keep the cat indoors away from birds and mice, and secure any kitchen cupboards that a hungry cat might explore.
Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.