ASA Status

Scoring System

This is where ASA classification can help. An ASA risk is a 1-to-5 score adapted for animals from human medicine’s American Society of Anesthesiologists. The system is based on the patient’s overall health, not the procedure being performed.

The ASA scoring system is NOT an assessment of total perianesthetic or perioperative risk, since many things, including the surgical procedure planned, the skill & training of the anesthetist and the surgeon, as well as the the resources at hand, contribute to the entirety of operative risk. If you EVER have any questions or concerns regarding your pet and any upcoming procedure they may be having talk to your veterinarian/veterinary support staff immediately!

The pre-anesthestic phase includes NOT only the choice of preanesthetic sedatives & analgesics but also a full preanesthetic evaluation & stabilization of the patient, if necessary. Categorization of patients using the American Society of Anesthesiologists (ASA) provides a framework for evaluation of patient health & determination of stabilization requirements prior to anesthesia.

STATUSASA CLASSIFICATIONEXAMPLES
IHealthy Pet, No DiseaseElective Spay/Neuter
IIMild systemic disease or localized diseaseHealthy geriatric pet, mild anemia or obesity
III (Fair)Moderate systemic disease limiting activity but NOT life-threateningMitral valve insufficiency, collapsing trachea, poorly controlled diabetes
IV (Poor)Severe systemic disease, incapacitating; life-threatening; not expected to live without surgeryHemoabdomen from splenic rupture, severe traumatic pneumothorax, organ failure
V (Grave)Moribound; not expected to live >24 hours, with or without surgeryMulti-organ failure, severe shock, terminal malignancy

Common Veterinary Anesthetic Medications Chart

DISCLAIMER: These are COMMON medications/adverse reactions to veterinary anesthetic medications, just like humans, pets also can have a variety of symptoms/reactions that are not listed or documented.

If you have any questions or concerns always speak to your veterinarian about the kinds of medications utilized and the potential side effects that may occur.

Anesthetic/Analgesic DrugCommon Adverse Effects
Dexmedetomidine Medetomidine XylazineBradycardiaCardiac Output ReductionHypertension/HypotensionVasoconstriction
NSAIDs SteroidsBleeding DisorderDiarrhea/VomitingGastrointestinal UlcerationLethargyRenal/Liver Failure
Diazepam MidazolamMinimal Cardiorespiratory EffectsParadoxical Excitement of Patients
Halothane Isofurane SevofuraneDecreased Cardiac OutputDecreased Myocardial Contractility Hypothermia/HyperthermiaMay result in hypotensionVasodilation
Diazepam/Ketamine Propofol Tiletamine/ZolazepamCyanosisOccasional Muscle Twitches/SeizuresProfuse Salivation/Airway SecretionsRespiratory Depression Transient TachycardiaVasodilation
Bupivacaine Lidocaine MepivacaineBradycardiaHyperthermia in some animals; hypothermia more likelyCardiac ArrestHypotensionSeizure
Buprenorphine Butorphanol Fentanyl Hydromorphone MorphineBradycardiaMydriasis/MiosisRespiratory Depression (hypoventilation, apnea)Vomiting

Dr. Cary Craig – Weighing in on CH & Anesthesia!

Cary Craig
Health Science Associate Clinical Professor
Surgical & Radiological Sciences UC Davis Veterinary School

PART 1

     There are no medical contraindications to any anesthetic technique in CH. However, I think there are considerations, particularly with respect to recovery from general anesthesia. My preference would be to use short acting or reversible techniques. Inhalant anesthetics such as isoflurane have the advantage of being very short acting and recovery is rapid once the inhalant is discontinued. My own CH kitties I have induced anesthesia either with propofol (a short acting injectable anesthetic) or isoflurane or sevoflurane by mask. For anesthetic maintenance gas anesthesia is best, maintaining anesthesia with injectable anesthetics for a spay would require doses that would prolong the recovery period. The gas should be delivered by an endotracheal tube rather than a facemask. Anesthetized animals, with or without CH, cannot protect their airways and are at risk for aspiration and/or airway obstruction. I would also recommend the use of an analgesic (pain control medication) and it is best used as a premedication, i.e., given prior to the surgical procedure. Usually this is a narcotic. The doses used for pain control are safe. Occasionally, some cats have some behavioral changes when they are given narcotics which can be sedation, euphoria or dysphoria. These are temporary; they go away as the drug wears off. If the drug effects are unacceptable the narcotic can be reversed.

     To dispel any myths- gas anesthesia is not safer than injectable anesthesia but it does offer a number of advantages in many circumstances. In CH kitties the rapid recovery is the primary advantage. It is not dangerous to use ketamine in CH kitties but I expect recovery from ketamine to be a very unpleasant experience for a kitty that has difficulty with balance and coordinated movement. Ketamine has a fairly long duration which gets very long if it is used intramuscularly as an anesthetic.

 Acceptable medications for CH cats are; Dormitor/Antisedan, Dormitor (medetomidine), is a sedative/analgesic that can provide profound sedation and short term analgesia. It is reversible with Antisedan (atipamizole) which makes it very useful for short procedures. It is not really an anesthetic so I would not recommend it for a spay which is an abdominal surgery. I think it is suitable for castrations in young, healthy animals.

PART 2

Neurologic injury from anesthesia is caused by a period of inadequate oxygen delivery to the brain. The severity of the neurologic damage is proportional to the length of time the brain is oxygen deprived. The part of the brain involved in vision is particularly sensitive to lack of oxygen so blindness is the most common symptom, more severe deficits are certainly possible.

There are basically two reasons why the brain would not get enough oxygen during anesthesia in all patients (normal or otherwise) and with all anesthetics (there are no safe anesthetics, only safe anesthetists):

  1.  Not enough oxygen gets into the blood – this would occur if there is a problem at the breathing level. Almost all anesthetics depress breathing in a dose dependent manner, the deeper the level of anesthesia the more depressed breathing is. A kitty breathing room air (21% oxygen) probably will not get enough oxygen into his/her lungs if breathing is depressed. This is why anesthetized patients should always be provided supplemental oxygen. Another thing that can prevent enough oxygen from reaching the lungs is an obstruction of the airway. Anesthetized kitties cannot protect their own airways reliably and are at an increased risk for airway obstruction. This why a fully anesthetized (as opposed to sedated) kitty should have an endotracheal tube placed. It keeps the airway open and helps prevent any fluid (saliva, blood, mucous, vomit, etc.) from being aspirated into the lungs. One caveat, in the hands of someone not experienced intubating cats, intubation itself can be associated with complications (tube accidentally placed in the esophagus, traumatic intubation, spasm of the larynx)
  2. Not enough blood gets to the brain. Even if there is plenty of oxygen in the blood if blood flow to the brain is inadequate the brain will become hypoxic (oxygen deprived). This can happen if blood pressure gets very low. Most anesthetics decrease blood pressure in a dose dependent manner. It is impossible to predict how much blood pressure will decrease in any given patient by any given dose of any anesthetic. Cats are particularly sensitive to the blood pressure lowering effects of commonly used anesthetics so blood pressure should be routinely measured in cats that are under general anesthesia. That way, a drop in blood pressure will be detected and appropriate action can be taken to restore it to normal.

     I think one of the most common causes for a cat to wake up with neurologic problems is a prolonged period of very low blood pressure. If not enough oxygen gets to the lungs so that there is not enough in the blood the gums and pink skin will turn bluish purple (cyanotic) and if anyone is looking at the cat they should see this. If there is enough oxygen in the blood but not enough is getting to the brain you have no way of knowing this unless you are measuring blood pressure. It can even happen sometimes when blood pressure seems ok – blood flow is extremely important and we infer blood flow from blood pressure. So it is important that the person monitoring the anesthesia can interpret the blood pressure numbers in the context of the cat’s clinical signs of adequate blood flow.

  There are still too many practices that do not routinely measure blood pressure in their anesthetized patients with the assumption that standard drug protocols and dosages won’t cause a problem. But normal doses in normal patients can, and often do, cause problems. If the problems are detected and addressed they are not serious. If not detected there may have serious consequences.

     This is scary stuff but it should not stop client’s from having their cat’s anesthetized for necessary procedures (e.g. spay, neuter). The incidence of cats that aren’t ill dying while anesthetized has been found to be about 0.3% (or 175 out 80,000). That figure goes up substantially if the cat is sick when it is anesthetized. This is much better than 10 or 15 years ago (but still ten times the mortality rate seen in people) and we are working very hard at finding ways to make it even better.

     I think the most important factors in improving the safety of anesthesia are experience with the drugs being used and in anesthetizing the species they are being used in, experience and skill with endotracheal intubation and vigilant monitoring. 

Eight Common Myths about Surgery & Cats

Dr. Phil Zeltzman, brought to you by IDEXX & Pet Health Network


There are many urban legends surrounding surgery and cats. Here I take a rational look at 8 stubborn myths I encounter regularly.

1. Myth: “My cat is too old for anesthesia”
You should think twice when your friend or the internet tells you that your cat is too old or sick for anesthesia, and don’t be afraid to seek out an expert about this concern. If your cat is that old, surgery is probably not being recommended just for fun. Your veterinarian is probably talking about performing surgery because of a serious reason or even a life or death situation.

A complete physical exam and blood work should always be performed before anesthesia. In older cats, it may be wise to also take chest and belly radiographs, as well as an ECG to be thorough. Some patients may need to be stabilized before anesthesia, which may mean correcting blood work imbalances, giving IV fluids or giving a blood transfusion prior to anesthesia and surgery.

2. Myth: “Surgery is painful”
This is actually a true statement. However, surgical pain should not be ignored in 2015. We have many safe pain medications to choose from to treat pain before, during and after surgery. We should also remember that depending on what your cat’s condition is, she is most likely already in pain, which will continue to stay the same or worsen without surgery. The goal of surgery is often to decrease pain.

3. Myth: “There is no point if there is no cure”
This mostly relates to cats with a tumor. It is a matter of opinion and expectations. And it’s a very personal decision.

Without the benefit of a biopsy, we don’t know whether a mass is cancerous or benign until it is removed and analyzed. Even when a mass is cancerous, it doesn’t necessarily mean that it’s the end of the road.

Ultimately, your decision should not be based only on quantity of life (or survival), but mostly on quality of life.

Ironically, sometimes, the situation doesn’t depend on whether a mass is benign or cancerous, but on where it is located. A perfectly benign mass blocking the windpipe, the esophagus (the tube between the mouth and the stomach) or the urethra (the tube between the bladder and the outside world) will have life-threatening consequences.

4. Myth: “My cat will not survive confinement”
Confinement is often required after surgery. The time required depends on the procedure. Confinement may be in a crate, an upside down baby/puppy play pen, a “cat tent,” a small room or part of a room. It may seem cruel to some, yet preventing jumping and running is critical to allow proper healing. Cats don’t know what is best for them. You should.
 
Interestingly, most cat guardians I deal with regularly tell me that in the end, confinement was easier than they expected.

5. Myth:  “I can’t keep a plastic cone on my cat”
Sure, a plastic cone can be a royal pain depending on how stubborn your cat is. But this “necessary evil,” worn for two weeks, is not nearly as bad as another surgery to stitch up a chewed incision. And it sure is cheaper than paying for this second surgery!

There are a few alternatives to the standard “lamp shade” or Elizabethan collar such as neck braces or inflatable “donuts.” Not all of these options will work, depending on where the incision is located, so alternative options must be discussed with your surgeon or family veterinarian.

6. Myth: “There’s always a cheaper way”
Sure, you can get to work in a beat-up truck or in a Ferrari. You can go to work in worn-up, second-hand clothes or in a tailor-made suit. But when it comes to surgery, the choices are suddenly much more important. Seeking the cheaper surgery may not be in your cat’s best interest. Which corner do you want to cut? Not give pain medications? Not give antibiotics? Not use sterile equipment? Unfortunately, good equipment, good staff and good skills cost money. And this is reflected in the cost of surgery. The good news is you can get an insurance plan for your dog to avoid this financial dilemma.

7. Myth: “I can just use medication instead”
I am very sorry to say that I have met cats with megacolon (a painful condition due to many months of severe constipation) and other long-term conditions that had been treated “medically” (i.e. with medications) for months to years. These cats suffer on medications, while surgery could have provided much better results. Initially, the medications only address the signs, until they don’t. Surgery addresses the cause of the condition.

As I always say, “the disease is the enemy. Surgery is your friend.”

8. Myth: “Things will get better on their own”
The difficulty is that you cannot tell if vomiting is a sign of something benign or something serious. Sometimes, vomiting is due to eating a bit too much or a bit too fast. And sometimes, vomiting is due to a foreign body which requires surgery to be removed. So don’t procrastinate; seek help from your family vet sooner rather than later. Waiting too long can have devastating consequences on your cat’s health.

These 8 myths are not meant to offend anyone. They are based on observations made over years of practice. Sure, there are complications, expected or not, during and after surgery. Fortunately, most of the time, surgery can make a world of difference for your cat.

Questions to ask your veterinarian about surgery:

  • What are the goals of the surgery you recommend?
  • What would happen if we didn’t do the surgery?
  • What can I do to ensure my cat’s comfort after surgery?

If you have any questions or concerns, you should always visit or call your veterinarian — they are your best resource to ensure the health and well-being of your pets.

What are the most common household toxins to pets?

Content Courtesy of AVMA;AVMA.org

As a pet owner, you want to keep your furry friend safe and healthy, but your pet’s curious nature sometimes can get him into trouble. Animals investigate the world with their mouths and they can ingest poisonous substances accidentally. The American Society for the Prevention of Cruelty to Animals (ASPCA) Animal Poison Control Center is open 24 hours a day, 365 days a year, to advise pet owners about potential pet toxicities. To help you take precautions and ensure your pet stays safe, the ASPCA has compiled a list of the most frequent offenders, many of which can be found in and around your home.

Pets and over-the-counter medications

In 2018, the ASPCA received 213,773 calls, almost 20% of which were related to ingestion of over-the-counter medications, such as ibuprofen, naproxen, cold medications, and herbal supplements. Even a medication that does not require a prescription can be extremely dangerous to your pet. Nonsteroidal anti-inflammatories such as ibuprofen and naproxen can cause acute kidney failure and should never be given to pets. Do not try to treat your pet’s medical problems without consulting an AAHA-accredited veterinarian, and never give him a medication that is not approved for veterinary use.

Human prescription medications and pets

ADHD medications, antidepressants, and heart medications were most commonly ingested by pets, although your pet can suffer significant side effects from any human medication he eats. Keep all medications, both prescription and over-the-counter, safely stored inside a medicine cabinet or cupboard or up high where your pet can’t reach them and ask your visitors to do the same.

What foods are toxic to pets?

Many foods that are safe for people can be deadly to pets. Keep the following toxic foods away from your beloved companion:

  • Chocolate
  • Xylitol (often found in sugar-free gum)
  • Macadamia nuts
  • Grapes and raisins
  • Onions
  • Garlic
  • Alcohol
  • Caffeinated drinks
  • Raw yeast dough
  • Raw or undercooked meat

Never leave food where your pet can reach it and keep pets out of the kitchen when children are eating to prevent them from gobbling up dropped food.

What about prescription veterinary products?

Prescription animal medications often are flavored to increase palatability, so pets may mistake them for treats and eat more than prescribed. Inquisitive pets may even eat pills that aren’t flavored, so keep all medications out of your pet’s reach. Remember, animals can chew through plastic bottles, so child-proof may not mean pet-proof.

What other household items are dangerous to my pet?

Products such as paint, glue, and cleaning chemicals often are left out on the assumption that pets won’t eat these bad-tasting substances. But sometimes pets lap up liquids because they feel good or have an interesting texture. Household products can contain dangerous chemicals and some household glues expand in the stomach, causing a life-threatening blockage.

Rodenticides

Products designed to kill rodents are particularly dangerous to pets, who may be tempted to eat the tasty bricks, granules, or pellets left out for mice and rats. Rodenticides kill rodents by causing internal bleeding, high calcium levels, brain swelling, or toxic gas production. Never put rat bait out where your pet can find it and keep your pet confined to your yard to prevent him from eating your neighbors’ rodenticides.

Insecticides and pets

Ant baits, bug sprays, and foggers can be poisonous to your pet. Read labels to ensure proper use of these products and prevent pets from exposure during and after use. Store all insecticides on high shelves out of a pet’s reach.

Plants toxic to pets

Plants found in flower beds, vegetable gardens, and indoor planters and arrangements can be toxic to pets. Cats, who particularly like to munch on greenery, are sensitive to many plant types, but dogs also can be at risk. A complete list of toxic and nontoxic plants can be found on ASPCA’s website, but the most common toxic plants include:

  • Autumn crocus
  • Azalea
  • Cyclamen
  • Daffodils
  • Dieffenbachia
  • Hyacinth
  • Kalanchoe
  • Lily of the valley
  • Lilies
  • Oleander
  • Sago palm
  • Tulips

If your pet eats leaves, flowers, or stems, immediately take him and a plant sample to your AAHA-accredited veterinarian. Although toxicity signs may not be apparent, it is vital to remove poisonous material as soon as possible to prevent toxin absorption into the body.

Garden products and pets

Many products used on lawns, gardens, and flower beds can cause toxicity in pets. Fertilizers made from bone or blood meal are tempting to pets and can cause pancreatitis, or can clump in the intestines or stomach, causing a blockage. Other fertilizers and herbicides applied to lawns also may contain toxic chemicals.

Bloodwork & Your Cat

Bloodwork is recommended yearly to monitor for any changes/potential concerns as well as prior to any surgeries or procedures requiring anesthesia! Talk to your veterinarian about having bloodwork completed on your pet or if you have any questions about having bloodwork ran on your pet!

GLUCOSE is a blood sugar.  Elevated levels can indicate diabetes mellitus, but in cats, mildly elevated levels can also just indicate stress.  Low levels can happen with insulin shock or malabsorption syndromes and can cause weakness, seizures, or death.

SERUM UREA NITROGEN (also known as Blood Urea Nitrogen) generally indicates kidney function.  An increased level is called azotemia, and can be caused by kidney, liver, and heart disease, urethral obstruction, shock, and dehydration.

SERUM CREATININE is a more specific indicator of kidney function in cats, although it can also be affected by dehydration and urethral obstruction.  An increased level without dehydration or urethral obstruction generally indicates kidney disease.

URIC ACID is a nonspecific value in cats, and does not indicate any disease processes.

ALT (Alanine aminotransferase) is a sensitive indicator of active liver damage but doesn’t indicate the cause.

TOTAL BILIRUBIN elevations may indicate liver or hemolytic (red blood cell destruction)disease.  This test helps identify bile duct problems in the liver and certain types of anemia. 

DIRECT BILIRUBIN elevations are another indication of liver disease and hemolysis.

ALKALINE PHOSPHATASE elevations may indicate liver damage or can also be a result of active bone growth in young kittens.  In adult cats, this is especially significant for liver damage.

AST (Asparate aminotransferase) increases are also very nonspecific, and can indicate liver, heart, or skeletal muscle damage.

INDIRECT BILIRUBIN is calculated using the total bilirubin and the direct bilirubin, and is not significant as a diagnostic test.

BUN/CREAT RATIO is calculated using the serum urea nitrogen and the serum creatinine.  In some cases, this result can help indicate if azotemia is from dehydration or kidney disease.

CHOLESTEROL is used to supplement diagnosis of hypothyroidism, liver disease, Cushing’s disease, and diabetes mellitus.  This is not a prognostic factor for heart disease such as in people.

TRIGLYCERIDES are not a significant value in cats.  They can be elevated if the cat has eaten recently, or in some disease processes, but are not a significant diagnostic factor.

CALCIUM deviations can indicate a variety of diseases.  Tumors, hyperparathyroidism, kidney disease, and low albumin are just a few of the conditions that alter serum calcium.

PHOSPHORUS elevations are often associated with significant kidney disease, hyperthyroidism, and bleeding disorders.

SODIUM is an electrolyte lost with vomiting, diarrhea, and kidney and Addison’s disease.  This test helps indicate hydration status.

POTASSIUM is an electrolyte lost with vomiting, diarrhea, or excessive urination. Decreased levels can be an early indicator of kidney insufficiency.  Increased levels may indicate Addison’s disease, dehydration and urethral obstruction. High levels can lead to cardiac arrest.

CHLORIDE is an electrolyte often lost with vomiting and Addison’s disease. Elevations often indicate dehydration.

SERUM PROTEIN indicates hydration status and provides additional information about the liver,kidneys, and infectious diseases.

SERUM ALBUMIN is a protein that helps evaluate hydration, hemorrhage, and intestinal, liver, and kidney disease.

GLOBULIN is calculated from serum total protein and serum albumin.  This is a blood protein that often increases with chronic inflammation and certain disease states.

OSMOLALITY CALCULATED is a calculated indicator of hydration status, and can help with interpretation of other blood values.

T4 (ANIMAL THYROXINE) is a thyroid hormone.  Decreased levels in cats do not signal hypothyroidism, rather, they can indicate an underlying disease process.  Elevated levels indicate hyperthyroidism.

Complete Blood Count (CBC)

WHITE BLOOD COUNT measures the body’s immune cells. Increases or decreases indicate certain diseases or infections.

RED BLOOD COUNT is the number of red blood cells per unit volume of blood.  Increases or decreases can indicate dehydration or anemia.

HEMOGLOBIN is the oxygen carrying pigment of red blood cells.  Increases or decreases in this number must be interpreted with other blood values.

HEMATOCRIT is probably the most important value of the red blood cells. This value measures the percentage of red blood cells in the blood to detect anemia, dehydration, and can help indicate some disease processes.

MCV (Mean cell volume) is the average red blood cell size. This value can help indicate some disease processes, but must be interpreted with other data.

MCH (Mean cell hemoglobin) is the average amount of hemoglobin per red blood cell.  This value can help indicate some disease processes, but must be interpreted with other data.

MCHC (Mean corpuscular hemoglobin concentration) is another value for interpreting hemoglobin concentrations in cells.

RDW (Red blood cell distribution width) elevations can indicate that there is an increased variety in red blood cell sizes.  This value should be interpreted along with other red blood cell values.

PLATELET COUNT measures cells that are used in blood clotting.

NEUTROPHILS are a type of white blood cells of the immune system.  An elevation or decrease in absolute or total neutrophil counts can indicate a variety of processes including stress, inflammation, infection, or other disease processes.

LYMPHOCYTES are another type of white blood cells of the immune system.  An elevation or decrease in absolute or total lymphocyte counts can indicate a variety of processes including stress, inflammation, infection, or other disease processes.

MONOCYTES are a less common type of white blood cells of the immune system that can indicate stress or chronic inflammation.

EOSINOPHILS are a type of white blood cells of the immune system.  An elevation in absolute or total eosinophils can indicate allergy disorders, parasitism,and some skin and intestinal disorders.

BASOPHILS are a less common type of white blood cells of the immune system. Elevations in these can indicate allergy disorders, parasitism, and neoplastic states.

Questions for the Veterinarian

The ongoing concern for “CH” parents is that they are afraid to have their special needs pet go for any procedures as they are concerned about anesthesia.

Currently there is NO studies that confirm nor deny the use (or avoidance) or certain anesthetic medications but there are certain medications to be cautious about as their side effects could affect even a non-CH pet! Here is a list of questions below to ask your veterinarian/veterinary staff prior to your pet’s “big day” (feel free to customize this template as you see appropriate!):

[   ] Are you aware of and/or ever cared for a cerebellar hypoplasia patient?

[   ] Do you have any reservations in caring for a CH pet?

[   ] Are pre-anesthetic physical examinations & pre-surgical bloodwork required/completed?

[   ] Can I request that pre-anesthetic bloodwork be completed on my pet PRIOR to surgery/procedure?

[   ] Premedication(s) – What type(s) are utilized?

[   ] Do you intubate anesthetized patients (this ensures that their airways stay open & they receive enough oxygen)?

[   ] Are IV catheters utilized? May I request that an IV catheter is utilized for my pet?

[   ] Do you monitor body functions under anesthesia (HR/RR/BP/ETCO2, SPO2, Temp)?

[   ] Documentation of patient parameters during anesthesia/recovery (anesthesia record)

[   ] Continued patient support & monitoring in recovery (post-anesthesia)?