In 1968, I wrote an article entitled, "Anesthesia for Great Pyrenees." It appeared in the Pyriodical a Great Pyrenees newsletter. It seems that 21 years later an update is needed. While some things have not changed, improvements in the drugs utilized have been great.
After all of these years, the Great Pyrenees still has a lower basal metabolic rate than some other dogs of comparable size and mass. The tendency toward hypothyroidism should be noted and may play a part in anesthesia dosage and choice. Cautious use of some drugs such as chloramphenicol with barbiturate anesthesia have been documented over the years. When possible, try to provide your veterinarian with a patient that is not wearing a flea collar or currently taking the antibotic chloramphenicol.
Problems with Great Pyrenees anesthesia stem from over estimation of weight. This is not as great a problem as it was 20 years ago since many veterinary clinics provide accurate weight information for large dogs. However, if your veterinarian does not have a method of weighing your Pyr accurately, err on the light side in guessing the weight. Better yet, find a feed store or a truck company with a walk-on scale and ask them to weigh your Great Pyrenees.
The safest anesthetic type for general anesthesia remain inhalant gas. Over the years several new gas anesthetics have been introduced - enflurane and isoflurane. At this time however, halothane and methoxyflurane remain the most popular choices in veterinary medicine for all dogs including Great Pyrenees. Both of these a very well tolerated by Pyrs and are indicated in any long surgical procedure.
For short procedures such as wound suturing, dental care, and radiographs a number of newer drugs can be considered. In all of these situations, I prefer to give the Pyr a pre-anesthetic or sedative. This drug combination does two things. It alleviates any apprehension on the part of the dog (not the owner), and it allows me to cut down even further on the amount of intravenous anesthesia that I need to use. My preferred pre-anesthetic for Great Pyrenees is a mixture (in the same syringe) of xylazine and atropine. Xylazine is feared by many veterinarians because it has the potential side effect of drastically slowing the heart rate. However, concurrent use of atopine controls this side effect.
I have used this combination in all ages. The oldest Pyr was eleven years; the youngest three weeks. In my practice the oldest dog of any breed was fourteen years when receiving this sedative. Common sense dictates that this combination not be used in any Pyr with clinical heart disease. For a 100 pound Pyr, I would give 50mg. of xylazine and 1.25 mg of atropine intramuscularly. After 15 minutes, the desired level of relaxation is achieved, and ultrashort duration intravenous anesthesia with Surital can be initiated.
I am now using a 4% Surital solution and would expect to give that 100 pound Pyr 2cc. over a 30 second period and followup with the amount necessary to perform the x-ray, suturing, or dental procedure. The followup is generally 3 cc. to 5cc. given over 2 to 3 minutes. This procedure will allow a Great Pyrenees to be able to walk under its own power within 30 minutes of the time we take an x-ray. Atropine is available under many generic lables. Xylazine is available under the names Rompun and Gemini.
Physical changes in the Great Pyrenees can alter the amount and type of anesthesia used significantly. Older Pyrs will need less sedation and less of whichever anesthesia is being utilized. Overweight Pyrs may actually absorb some anesthetic agents in the fat layer. They appear to require more anesthesia and awake much more slowly when barbiturate anesthetics are used.
Any long surgical procedure should be accompanied by the use of intravenous fluids to maintain cardiovascular function. This is necessary with any form of anesthesia. Unfortunately, Great Pyrenees cesarean sections are becoming more common place. Because some Pyr section candidates have primary uterine inertia and large amounts of intrauterine fluid, intravenous fluid therapy support is absolutely necessary during the surgery.
Because of the legal ramifications, it is necessary for me to issue a
disclaimer - something that was not necessary 21 years ago. These
recommendations are only guidelines, and your veterinarian will use his or
her expertise when giving anesthesia. This article is not to be construed as
the only or best method of providing anesthesia for Great Pyrenees.