Herbie's guardian wrote me about the loss of her beloved cat following what was supposed to be routine anesthesia for an optional procedure. Herbie was an older cat with undiagnosed Hypertrophic Cardiomyopathy (HCM), which slipped past the routine blood screening, and by the time his post-operative symptoms were diagnosed by a veterinary cardiologist, it was too late.
Lisette fell victim to the same thing that affects all of us from time-to-time: she was asking some of the right questions, but not all of them; she didn't know that she was receiving the wrong answers in some respects; and she was not advised as to the risks of anesthesia, what could be done to minimize the risks, nor what potential problems or signs to be aware of.
This article is written to further that aim, and is dedicated to the memory of Herbie, and all other cats who have died before their time due to anesthesia-related events that might have been avoided.
A Necessary Evil
To experienced cat owners, nothing is quite as frightening as being told your cat needs to be anesthetized for a procedure. The definition of anesthesia is "loss of feeling or sensation," and in the lay person's mind, anesthesia is as close to death as a body can be without actually dying. Yet, the use of anesthetics is common in veterinary practices, and provides an essential tool for surgical or other painful procedures.
Certainly no one would ever expect their cat to be spayed or neutered without benefit of anesthesia, nor undergo dental surgery, nor fracture reduction. Therefore, a better understanding of some of the commonly-used types of anesthetics and analgesics (pain relievers), how they work, and their potential drawbacks, will help us make the best decisions when it comes to sedating our cats.
Cat are generally given sedatives or tranquilizers, either singly or in combination, prior to the induction of anesthesia, or as a first step to induction. These drugs sedate and calm the animal for introduction of the mask or tracheal tube required for an inhalant anesthesia; allow for a smaller amount of general anesthetic; help to minimize vomiting; and allow for a quicker recovery period. Sedating drugs are generally administered by injection, intravenously for the most part, although Ketamine can be given intramuscularly. Injectable anesthetics are also used for full anesthesia for relatively quick procedures, such as C-sections or spay/neutering.
Injectable anesthetic agents fall into three main groups: Barbiturates, Dissociative Anesthetics (DAs), and Nonbarbiturate Hypnotics. Acepromazine, the most commonly used sedative, is used in conjunction with an analgesic such as pethidine or buprenorphine to provide a reliable sedation.