Robert Brown, DVM
Reprinted from the Bulletin of the Great Pyrenees Club of America
Copyright 1968,1989 Robert Brown, DVM

Reprinted for the Pyrenean Mountain Dog Club of South Australia with permission in 2000.

In 1968, I wrote an article entitled, "Anaesthesia for Great Pyrenees."  It appeared in the Periodical a Great Pyrenees Newsletter.  It seems that 21 years later an update is needed.  While some things have not changed, improvements in the drugs utilised 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 anaesthesia dosage and choice.  Cautious use of some drugs such as chloramphenicol with barbiturate anaesthesia has 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 antibiotic chloramphenicol.

Problems with Great Pyrenees anaesthesia 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 Pyrenean 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 anaesthetic type for general anaesthesia remains inhalant gas.  Over the years several new gas anaesthetics 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 Pyreneans and is 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 Pyrenean a pre-anaesthetic 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 anaesthesia that I need to use.  My preferred pre-anaesthetic for Great Pyrenees is a mixture (in the same syringe) of xylazine and atropine.  Many veterinarians fear Xylazine because it has the potential side effect of drastically slowing the heart rate. However, concurrent use of atropine controls this side effect.  I have used this combination in all ages.  The oldest Pyrenean 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 Pyrenean with clinical heart disease.  For a 100 pound Pyrenean, I would give 50mg. of xylazine and 1.25 mg. of atropine intramuscularly.  After 15 minutes, the desired level of relaxation is achieved, and ultra-short duration intravenous anaesthesia with Surital can be initiated.

I am now using a 4% Surital solution and would expect to give that 100-pound Pyrenean 2cc. over a 30 second period and follow-up with the amount necessary to perform the x-ray, suturing, or dental procedure.  The follow-up 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 labels.  Xylazine is available under the names Rompun and Gemini.

 Physical changes in the Great Pyrenees can alter the amount and type of anaesthesia used significantly.  Older Pyreneans will need less sedation and less of whichever anaesthesia is being utilised.  Overweight Pyreneans may actually absorb some anaesthetic agents in the fat layer.  They appear to require more anaesthesia and awake much more slowly when barbiturate anaesthetics 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 anaesthesia.  Unfortunately, Great Pyrenees Caesarean sections are becoming more common place.  Because some Pyrenean 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 anaesthesia.  This article is not to be construed as the only or best method of providing anaesthesia for Great Pyrenees.

 

 

The following comments on the above article were made by a veterinary surgeon from South Australia who has had much experience with Pyreneans.

 

“I think there are no problems with what the above author has said re anaesthetics and the risks. There are a couple of things I would like to add:

I would strongly recommend that no barbiturate anaesthesia is used at all, mainly because of the reflex bradycardia (slowing of heart rate) and the apnoea (breath holding) that results from its use when first administered. Apart from this there is the fat absorption and prolonged release from the fat, and this can be a real risk in overweight dogs.

I have always only masked down the Pyrenean's and we used Halothane, now a lot of vets are able to use Isoflourane or enflourane and that is much quicker to induce and a safer form of anaesthetic.  Would have to be my choice of anaesthetic for them.

For sedation I think now something like "domitor" (dormosedan) can be used, which can be reversed immediately with anti-sedan if there is a problem.”