What about feeding and general anaesthesia?
Veterinarians perform procedures with animals under general anaesthesia on a daily basis. For many treatments, that can be performed without anaesthesia in humans, animals need to be under general anaesthesia. Communication between the owner of the animal and veterinarian before any anaesthetic procedure as well as thorough physical examination of the animal complemented by appropriate diagnostic procedures are of a great importance to avoid complications. Guidelines on how to best prepare an animal for anaesthesia are changing over the years with new research. If it was sometimes considered, that a patient needs to be fasted before anaesthesia (overnight), it is not so today. A recent study has shown, that with a shorter fasting we can reduce the possibility of gastroesophageal reflux (GER) (leaking of gastric contents into the esophagus) and, consequently, esophagitis (inflammation of the esophagus). It was found that GER appeared in 20% of dogs who received their last meal 10 hours before anesthesia, and only in 5% of dogs who received their last meal 3 hours before anaesthesia. The duration of anaesthesia did not have any effect, as GER appeared the first 30 minutes of anaesthesia.
At Animal Hospital Postojna, we advise 4-6 hour fasting before anaesthesia. The amount of food given before anaesthesia should be smaller, but access to water is fine until anaesthesia.
A small meal and free access to water should be offered to the animals as soon as possible after anaesthesia.
However, the same rules do not always apply for all patients - either due to illness or procedures requiring a special preparation for anaesthesia.
In diabetic patients, a thorough consultation with a veterinarian before an anaesthetic procedrue is even more important. The approaches in these patients currently vary. When the the procedure is planned in the morning, some owners will be advised to skip the morning meal and the morning dose of insulin. In other cases, the client will be advised to adjust the dose of insulin according to the measured blood glucose (if this is more than 15 mmol/L, a 100% dose of insulin is administered, if glucose is 8-15 mmol/L, 50% of the insulin dose is given, and if glucose is less than 8 mmol/L, insulin is not given). When the procedure is planned in the afternoon, the owner can administer a standard dose of insulin together with a normal meal, and the procedure is performed 6 hours later. When diabetes is well-controlled, there should be no major complications during anesthesia. Nevertheless, monitoring of glucose before, during and after the procedure (every 30-60 minutes) is of great importance. Some studies have shown, that the blood glucose level during anaesthesia and interventions can vary greatly, regardless of whether the patients have received 100% or 25% of the standard dose of insulin, and therefore careful monitoring of blood glucose levels is crucial. After the procedure, if possible, continue with the standard dose of insulin and the usual amount of the food.
Puppies and kittens (neonatal up to 6 weeks of age and pediatric up to 6 months of age) need shorter fasting time than adult animals, as their glycogen storage capability in the liver is smaller and hypoglycaemia (reduced blood glucose levels) can occur in cases of excessive fasting period, which can present a serious complication during anaesthesia. We do not fast puppies and kittens that are still suckling, and puppies and kittens aged 6 weeks to 6 months should not be fasted for more than 3-4 hours.
Patients scheduled for endoscopic diagnostics of the gastrointestinal tract are fasted longer than usual - otherwise, stomach and intestinal contents prevent us from performing a good endoscopic examination. The length of fasting depends on the part of the gastrointestinal tract that we want to examine. If we are interested only in the diagnosis of the stomach, it is recommended that the time of fasting is 12 hours. If we want to examine the entire gastrointestinal tract, including the colon, it is recommended that the time of fasting is 18 to 24 hours before the procedure.
If your animal is receiving any therapy, your veterinarian should be informed about this before anaesthesia and any procedures.
Anaesthetic protocols and perioperative procedures should be tailored to each patient individually, and good communication between the animal owner and the veterinarian is crucial for a good and safe anaesthetic procedure.
If you have noted any problems with your animal, please consult your veterinarian.
Article by Maja Bogataj