Preferred Anesthesia Procedures (courtesy of a vet student via a discussion on safe dentals)

See also: Choosing the Safest Anethesia

The American Animal Hospital Association put together a task force to make dentals as safe as possible for cats. Their recommendations are explained below. You should be able to use this as a guide for discussion with your vet especially in regards to prescreening and monitoring during any procedure involving anesthesia.

PRESCREENING: The scariest part of any procedure is anesthesia but cats need to be anesthetized for dentals for their safety, comfort, and so that the problematic areas under the gum where plaque accumulates can be reached.

Anesthesia is an unnatural state and problems do occur occasionally. The AAHA recommends that most complications can be avoided if the following prescreening tests are always done -- even in young healthy cats:

1. Thorough physical exam 2. 12 panel CBC/Chemistry Profile (RBC, Hematocrit, Hemoglobin, WBC, BUN, Creatinine, Glucose, ALT, Total Protein (and/or Albumin, Globulin), Sodium, Potassium, Phosphorus)* 3. Urinalysis (UA)

*At this time, many vets do not require CBC or UA for cats until they reach a certain age (typically 5 or 6). The AAHA strongly recommends that this be done in all cats, regardless of their age. If your vet doesn't require these tests, you may want to ask for them anyway. I doubt your vet will say no! He/she is probably just considering your budget.

My anesthesia class instructor strongly feels that NO anesthesia should ever be done without a hematocrit or packed cell volume level. If the cat is already borderline anemic and bleeds during the procedure, precautions need to be taken immediately to save the cat's life.

She also believes that a CBC, creatinine, BUN, ALT, glucose and the electrolytes (sodium, potassium, phosphorus, chloride) should be tested along with a UA.

In geriatric cats, and cats with known or suspected health issues, the following should always be done:

1. Thorough physical exam 2. 12 panel CBC Profile with Superchemistry and Thyroid Function* 3. Urinalysis** 4. If any heart abnormalities are suspected, ECG or cardiac ultrasound should be done** 5. Chest radiographs (especially if cancer is suspected)** 6. If any organ dysfunction is suspected, an abdominal ultrasound should be done**

**If anything is in doubt from the tests above or presents a greater risk, consultation with a specialist is highly recommended.

ANTIOBIOTICS: Cats that have bleeding gums, foul-smelling breath, and/or obvious infection, should be pre-treated with antibiotics for 3-5 beforehand to minimize infection.

EYE PROTECTION: Protection (lubricants) should be used to ensure the eyes do not dry out during the procedure.

PREMEDICATION/INDUCTION: Pre-medication using sedation and pain relief drugs are now strongly recommended in all cases -- even for geriatric cats. Sedating the animal reduces stress and calms the patient. Remember, this is all very scary for cats! If you've ever undergone anesthesia yourself, you'll know that humans are usually premedicated.

Premedication allows the use of much lighter anesthesia (and this does include inhalant gases such as Isoflurane and Sevoflurane). The lightest anesthesia possible is always the best and recovery time is quicker when premedications are used.

Drugs that cannot be quickly withdrawn or reversed should always be avoided and most especially in senior cats.

It's difficult to select the appropriate premedication drug(s) for a geriatric cat with or without pre-existing health conditions and there are several considerations. I could spend about a week talking about them alone. Senior cats are assumed to have reduced kidney, liver and heart function. This occurs naturally because of the aging process. They also often have a loss of lean body mass and some have an increase in body fat. For all these reasons, drugs and inhalant gases are metabolized differently than in young cats.

For pain relief Butorphanol is the most commonly used and considered safest even though it can cause some minimal and usually reversible side effects.

Midazolam or Diazepam (valium) is often used to calm and sedate. Propofol is the safest agent and really has no side effect if used correctly. But it's expensive and has a very short life after opening. Many vets don't carry it for this reason because they believe their clients won't bear the added expense and their profits will be lower. It must be administered slowly to avoid a drop in blood pressure. However, it is extremely short-acting and is metabolized very quickly resulting in a really fast recovery. Thiopental is another drug that is considered safe and cheaper than Propofol. It can result in a blood pressure decrease and recovery times are slightly longer than with Propofol, but it is a good choice for geriatric cats. Many vets still use a combination of Ketamine/Valium or Midazolam, or Ketamine/Acepromazine mixtures. Personally, I don't like Ketamine being used in any cat, regardless of age. In geriatric cats, my biggest fear is in regards to the way it is excreted which is entirely through the kidneys. Several cats with unknown borderline kidney function have deteriorated following anesthesia with Ketamine. In addition, recovery after Ketamine use is a minimum of 2 hours, and generally 6 hours. For an old cat, that's a very long time and too many complications can occur during that time. Acepromazine has to be used with extreme caution in geriatrics or cats with kidney/liver issues and I don't believe it's worth the risk it presents to the older cat.

In the past, many vets used induction chambers to induce anesthesia, particularly in older cats. These are like fish tanks with inlets to deliver the inhalant (isoflurane or sevoflurane are commonly used). A mixture of oxygen and the gas is allowed to flow into the chamber. The cat will slowly lose his/her ability to stand over the course of 3-5 minutes, usually after rocking and fighting for a time. This method avoids the use of drugs but it can be traumatic for the cat. Also, there is no way to monitor the cat while the gas flows in. The blood pressure drops and there's no way to tell just how much. Low blood pressure can activate systems in the body that damage the kidneys and heart. If the cat vomits, aspiration may occur and there's no way to protect the airway. My instructor (a vet) said that cats are probably never as close to death as when they come out of that chamber.

With safe medications available to sedate a cat, current thinking is that the risk of using this method outweighs the benefits. Sedating the cat seems kinder especially with a short-acting method like propofol and then, intubating with oxygen and inahalant anesthesia once the cat is nice and relaxed.

IV CATHETERIZATION: One of the most important functions of an IV catheter is that it allows IV medication to be injected quickly and easily. This becomes very important if complications occur and the vet needs to administer emergency medications. All cats should be catheterized during even brief procedures.

ENDOTRACHEAL INTUBATION: All cats should be intubated with an endotracheal tube during every procedure -- regardless of its length. This is a step that many vets skip if the procedure is a short one. If cats vomit while under anesthesia, they cannot swallow. As a result, the vomitus can be aspirated (breathed) into their lungs causing an immediate airway obstruction -- and quite often death. If they do not die immediately, aspiration pneumonia often occurs later and that is a very serious condition. If the cat is intubated, there is protection against vomiting.

Also, oxygen can be delivered to the cat mixed with inhalant anesthesia (gas) to maintain the anesthetic state during the procedure.

SUCTION: Suction should be available to protect the airway from saliva, irrigation fluids and other debris. Suction can also be used to estimate blood loss.

HYPOTHERMIA: Warming devices should be available and used to prevent hypothermia (low body temperature) especially in lengthy procedures. An incubator to rewarm the cat is very helpful

MONITORING: Cats should be carefully monitored before, during and after the procedure, particularly during induction and recovery which are the riskiest times. Direct observation by someone appointed to do nothing else but monitor the patient is critical. This should not be the same person that is performing the procedure.

The following should be carefully monitored:

Blood pressure -- which is considered the best indicator of how the cat is doing; respiration rate; mucous membrane colour; capillary refill time; and peripheral pulse. The pulse quality and heart sounds should also be monitored periodically. Body temperature should be monitored carefully. Cats should be have urinary catheters to allow monitoring of renal function through output. Ocular signs and muscle tone should be observed to note the depth of anesthesia.

Helpful monitoring machines:

Pulse oximeters sense blood pulsing through capillaries (heart rate) and assess oxygen saturation in the blood. This can provide very helpful information and early warning that the heart has stopped.

Apnea monitors beep when the cat takes a breath.

Capnometers measure carbon dioxide build up and can be very useful in detecting any hypo- or hyperventilation.

Not all vets will have these machines and all of these can be monitored manually.

WHO DOES WHAT: Only vets should perform any extractions.

RECOVERY: During recovery, cats should be kept in a heated area or on a heating pad in close view of a tech until ambulatory. The endotracheal tube should not be removed until the cat begins to swallow. The urinary catheter should not be removed until the cat can stand up and keep his/her head up.

PAIN RELIEF: Pain usually occurs within 24-48 hours so pre-emptive pain relief should be given.

INFECTION CONTROL: All instruments used should be disposable, or have disposable heads, and should be autoclaved and sterilized after each use. Sharp instruments should be sharpened after each use.