Minimising Risk by Pre-anesthesia Check | Sharing by Dr. Tsui Weizhi

Dr. Tsui Weizhi

Chief Veterinarian of Joy and Smile Animal Hospital 

“Anesthesia is indispensable for veterinary daily practice.”

As a primary care veterinarian, Dr. Tsui Weizhi commented that veterinarians are different from the human doctors in terms of clinical practice, there is no clear system for veterinary speciality. Veterinarians need to deal with different types of animal diseases. We are responsible for both medical and surgical treatments including but not limited to physical examination, dental cleaning, and disease diagnosis. However, animal patients usually are not as calm and cooperative as humans. Veterinarians are often required to perform anesthesia on the patient to ensure a smooth treatment procedure. 

“Just like humans, there is always a risk when anesthetic drugs are administrated. All patients should be given a complete pre-anesthetic check to minimise the associated risk.”

Dr. Tsui stressed the importance of the pre-anesthesia check. Animals cannot speak, plus there is no dedicated anesthesiologist at primary care animal hospital. In addition, as the level of anesthsia-related risk for every patient varies, customized anesthesia plans and procedure are required. With the challenges mentioned, Dr. Tsui suggested using ASA Risk Classification as a standard reference. It is the most common anesthesia classification to evaluate the anesthesia-related risk associated with that particular patient and facilitate the communication with the pet owner. Dr. Tsui emphasized that it is crucial to have such communication with the pet owner prior to pet anesthesia. The ASA risk classification is a helpful communication tool he often used.

In order to attribute an ASA score to the patient, it is necessary to first understand the patient’s overall health by a complete physical examination. Safe and effective anesthesia of animal relies on pre-anesthetic assessment and preparation. In the following paragraphs, Dr. Tsui shared with us the common practice at Joy and Smile Animal Hospital regarding pre-anesthetic check.  

Medical History and Conditions 

It is necessary to communicate with the pet owner prior to anesthesia. Understanding the medical history and conditions of the animal patients helps veterinarians to identify risk factors. Information such as animal responses to previous anesthetic events, known medical conditions, and change in physical conditions or lifestyle are some important indicators of the health status.  

Basic Physiological Parameters

Blood pressure, heart rate, pulse, respiratory rate and body temperature are important measures. Measuring and monitoring patient’s basic physiological parameters are necessary to take place before, during and after anesthesia. During pre-anesthetic check, abnormal physiological parameters indicate a need for special attention. It is important to distinguish whether the change in vital signs during anesthesia is caused by anesthetics or the patient is encountering medical complications. It provides direction for the veterinarian’s corresponding actions. 

Electrocardiogram & Thoracic Radiography

Anesthetics suppress the body’s normal automatic functions. It even affects the cardiorespiratory function of the pet patient and being the most common causes of anesthesia-related death. According to an observational cohort study, pets with good health (ASA classification 1 or 2) are associated with a lower mortality rate of 0.12%. While patients with severe, systemic or life-threatening diseases (ASA 3 or above), have a much higher death rate of 4.77%. Therefore, cardiorespiratory function is of cricual importance. Electrocardiogram, the gold standard for heart rhythm and conduction; Thoracic Radiography, which provides preliminary information of the lungs condition are important pre-anesthesia tests to be conducted. 

Blood Test

Pre-anesthesia blood work consists of Complete Blood Count (CBC) and biochemistry test shall be done. According to the test result, physiological parameters indicate if the animal is in anaemia. In some cases, adjustment such as infusion plan should be considered. In addition, the hepatic and renal functions reflected by the test indicates the level of drug metabolism. These findings not only affect the veterinary operation procedure but also the key to predicting the patient recovery speed from anesthesia.

Other Examinations

When the animal comes with known medical conditions, further investigations such as abdominal ultrasound and echocardiogram are required. The findings provide support to disease diagnosis and assess risk of anesthetics. 

Lastly, Dr. Tsui highlighted that a continuum of care should start before anesthesia is administered, and continue during and after the surgery. It is recommended to assess the overall anesthesia risk by a complete pre-anesthesia check to minimise the associated risk. Regular health check-ups provide veterinarian with an overview of patient’s health status to reduce adverse anesthetic events.

In addition, veterinarian should communicate with pet owner the anesthesia-related risk possible situation and post-anesthesia care. Together, we join force to give the animal the best protection against anesthesia risk.


Interview with Dr. Tsui Weizhi :

Futher Readings

What is pre-anesthesia check? New release: The 2020 AAHA Anesthesia and Monitoring Guideline has the answer!

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