General Anesthesia in Dogs

General anesthesia is a reversible, medically induced form of unconsciousness. During a general anesthetic the patient is temporarily immobile in a relaxed state, and unaware of pain or what is going on around them. 

General anesthesia is widely used in veterinary practice (both first opinion and specialist centers). It is used to facilitate any number of procedures from routine desexing to complex life-saving surgery or even to keep the patient still enough for an MRI scan. 

In first opinion practice, a state of anesthesia is induced by or under the direction of, a veterinary surgeon. During the procedure, a vet technician monitors and adjusts the depth of anesthesia. In referral centers, a specialist veterinary anesthetist is involved for complex or high-risk anesthetics. 

The method of general anesthesia is determined by the health of the animal, the procedure, and the experience of the surgeon/anesthetists. Within each method is a whole sweep of different options depending on which anesthetic drugs are chosen. The basic protocols are: 

1. Induction and maintenance with injectable agents
2. Induction with injectables, maintenance with anesthetic gas
3. Induction and maintenance with anesthetic gas

Of these, option #2 is the most widely used. 

In preparation for a general anesthetic, the patient (over 4 months of age) must not eat for at least 10 to 12 hours before hand so their stomach is empty. This is to prevent vomiting under anesthesia and the risk of inhaling food down into the lungs. 

Every dog undergoing anesthesia is carefully assessed with a physical exam and possibly blood work. This is to identify factors which need correction ahead of the anesthesia for maximum safety. 

Once the patient is stable, a premedication injection is given. This provides pain relief, minimizes the amount of inducing agent required, and makes for smoother maintenance. 

A catheter is placed in the foreleg and once the premed has taken effect, an induction agent is slowly injected into the bloodstream via the catheter, until the dog is asleep. A tube is then passed into the trachea (windpipe) and connected to a anesthetic machine. The dog is maintained under anesthesia by adjusting the gas flow and levels of anesthetic agent. 

Once the procedure is completed, the anesthetic gas is turned off, the system flushed with oxygen, and the patient monitored while they regain consciousness. 

Modern anesthetic agents and protocols are sophisticated and safe. The anesthetic agents are often short-acting and anesthesia is maintained by a steady low dose supply of them. This means there is less buildup ('hangover') in the body and less suppression of blood pressure of blood flow to major organs. All of this contributes to the safety and efficacy both during and after the anesthetic. 

Efficacy in terms of safety can be improved by careful pre-op assessment, including a detailed physical exam and blood tests. Careful selection of anesthetic drugs and the circuit used to maintain the anesthetic are also crucial. This allows the anesthetist to compensate for potential problems which could destabilize or endanger the patient. 

Alternatives to general anesthesia include heavy sedation and local anesthetic. This may be appropriate for minor surgical procedures on the skin, but does not give sufficient pain relief or immobility for abdominal or chest surgery.  

It is vital the patient is closely monitored during and after anesthetic. The period when the anesthetic is turned off and the dog regains consciousness is the recovery period. This is a time when the patient is at increased risk of vomiting and inhaling the vomitus, or extreme excitement, breathing difficulties, or injury to the incision. 

The full recovery time after an anesthetic (say for imaging) is relatively quick, with most dogs being back to normal the following day. For those patients undergoing surgery, the full recovery time depends on the operation they underwent. Typically, for neutering this is 10 to 14 days. 

The complexity of the anesthetic, the monitoring equipment involved, and the experience of the anesthetist all influence the cost of an anesthetic. In first opinion practice, the cost of the anesthetic for routine neutering is often discounted, because of the ethical importance of neutering, and performed at cost price. 

Thus the fee for an anesthetic can range widely from a basic $90 up to $1,000 for a high-risk patient with the most sophisticated monitoring and a fully qualified veterinary anesthetist in attendance. 

General anesthesia should never be undertaken lightly, and even for routine surgery the patient must be carefully assessed and monitored. 

Practice staff should be fully qualified and keep up to date with continuing education in the drugs and techniques available, along with handling unstable anesthetics. Your veterinary team should be happy to discuss to your satisfaction all aspects of your dog's care whilst under anesthesia and the risks involved, before proceeding. 

Anesthesia is usually induced in a pre-planned manner for either elective or essential surgical procedures. With this in mind, prevention is not really appropriate. 

The use of emergency anesthetics can be minimized by keeping your pet fit and healthy, and avoiding exercising deep-chested dogs immediately after eating (a predisposing factor for GDV). In addition, keeping a dog on leash near roads reduces the risk of traffic accidents, and careful consideration should be given to mating and breeding from female dogs.