Anesthetic Drugs for Dogs
There has been many reports on Kangal’s “sensitivity” to anesthetic drugs, which is the case with some other large or ‘giant breeds’. Kangal dogs seem to require less of the sedative (a smaller dose per unit of body weight) than other dogs. The reason for this apparent difference is unclear. Partially, it may have to do with the ratio of body fat to lean muscle mass, breed differences in the hepatic (liver) metabolism, as well as individual differences. Some of the individual dogs within one breed responded differently to the same amount of anesthetic. Vigilant monitoring of vital signs during general anesthesia will enable the veterinarian to recognize and respond to life-threatening changes in heart and lung function.
Types of Anesthetic Drugs
There are several types of anesthetics used in all dogs. The drugs vary in route of administration and type or length of response. The main categories include:
1. Local or regional anesthetics
2. Tranquilizers Sedatives and
3. Inhalant “gas” anesthetics
Local anesthetics such are injected or infused into the skin at selected locations to numb the area and block the sensory pain response. These drugs are safe and overdosing is unlikely.
Tranquilizers, cause the dog to become relaxed or “tranquil” yet conscious. These drugs are often included in the pre-anesthetic plan, particularly in fearful or excited dogs prior to induction of general anesthesia. Sedatives vary in their mode of action, response and elimination by the dog, so the sedative selection is often made based on the amount of surgical pain anticipated and the dog’s temperament and physical condition (liver or kidney disease). These drugs are usually administered intravenously, just prior to general anesthesia. Depending on the dose and the dog, responses can vary from extremely relaxed to completely unconscious. Some sedatives have an added benefit of producing analgesia during, and shortly after painful procedures.
Inhaled anesthetic is delivered to the dog’s lungs via a tube that is inserted through the dog’s mouth deep into the wind pipe. It is impossible to place this tube in a conscious dog, so a very short acting injectable sedative must be administered prior to inserting it. The tube not only delivers the anesthetic, but also oxygen. In selected cases, even if anesthesia is being administered intravenously, the tube may be placed simply to deliver oxygen, especially in older or very ill dogs.
Most veterinarians use a combination of these drugs, depending on the type or complexity of the procedure that is to be performed.
How about anesthetic drugs for Kangal Dogs?
Propofol (a combination of diazepam and ketamine) is a pretty good choice for Kangal dogs, however it is somewhat expensive to use in large breed dogs (especially if it’s being used as a continuous infusion for a longer lasting surgery). Therefore, some veterinary hospitals use inhaled gas anesthetics for their surgical cases, and most of them are well tolerated. Isoflurane or sevoflurane are the two more popular ones; and some studies indicate the sevoflurane as the preferential choice.
Just like people, dogs respond differently to certain drugs, in particular the fat or lipid soluble drugs ( i.e. thiopental, pentobarbital, and halothane). Because lipid soluble drugs are absorbed by fat, once they are injected intravenously or inhaled, they move immediately from the blood to the brain and other tissues. As the fat absorbs these drugs, the concentration of drug in the brain and bloodstream is decreased and eventually eliminated. The general rule is that these drugs are not appropriate for Kangals. The drug concentrations can rise rapidly and remain high resulting in excessive sedation and prolonged recovery.
The majority of injected drugs are eliminated from the body by the liver, and in some cases, the kidneys. Though the mechanisms are not completely understood, there are differences in the liver at the cellular level as to how these drugs and by-products are metabolized.
Fortunately for us and our Kangal friends, we have a number of drug choices available today that have proven to be safe and predictable. The newer generation of inhalant anesthetics, such as already mentioned: isoflurane and sevoflurane are rapidly eliminated from the system. If properly administered, these drugs appear to have no adverse effects on Kangal dogs, and should not in any way extend or complicate recovery.
It is important to remember that most modern veterinary practices understand that there are inherent differences in the manner in which some large breeds respond to certain anesthetics. It is however our responsibility to discuss this with the vet prior to any procedure. We want to be certain the anesthetic methods are discussed and understood by both parties, especially in the parts of the world where Kangal dogs may not be overly popular, and the vet may have limited experience with the breed.