What Should Be Considered When Anesthetizing Cats?

What should be considered during anesthesia and monitoring, how can the patient and owner be optimally prepared and how should complications be dealt with?

Cats differ from dogs in many ways, not only because they don’t happily trot into the doctor’s office next to their masters. There are some anatomical and physiological differences: compared to dogs, cats have a smaller lung volume and a smaller blood volume about body weight. The body surface, on the other hand, is relatively large in comparison, so the temperature can drop more quickly.

Statistically, cat patients unfortunately have a higher risk of anesthesia than dog patients. This is especially true for sick cats. What’s the best way to deal with this? Should we therefore rather not anesthetize our cat patients and z. B. do without the extraction of painful teeth? No! On the contrary, we have to exercise special caution and prudence and can also make use of some technology for this purpose.

Assess risk factors

The classification of every anesthetic patient in the so-called ASA classification (see PDF) is part of every anesthetic protocol.

For cats there are primarily the following risk factors – that is, these patients have an increased risk of dying:

  • poor health (ASA classification, comorbidities)
  • increasing age (see PDF)
  • Weight extremes (underweight/overweight)
  • high urgency and high degree of difficulty of the measure carried out

The most important chronic diseases in cats in connection with anesthesia are also the most common:

  • Thyroid disease (almost always hyperthyroidism/overactive in cats)
  • hypertension/high blood pressure
  • Kidney disease (chronic renal failure)

However, respiratory diseases (e.g. feline asthma), liver diseases, neurological diseases, blood diseases, electrolyte abnormalities, and infectious diseases also play a role in anesthesia.

The following applies to all age groups: stress reduction and temperature control are very important for risk minimization.

How do we best prepare?

Gather as much information as possible: The medical history is particularly important for cat patients. The following risk factors can be briefly queried over the phone: age, race, known illnesses, medication, changes in thirst/appetite, and special observations. This does not replace the anamnesis interview or the examination by the veterinarian at the preliminary appointment and on the day of the operation, but it helps immensely with planning. In addition, owners are already made aware of important aspects.

Preliminary examination and consultation: These are essential for an optimal assessment of the state of health. In addition to a thorough clinical examination, a blood pressure measurement and a blood test are often indicated. ITooptimally plans an anesthetic, the preliminary examinations (e.g. before tooth restoration) should take place at a separate appointment in advance. This has the advantage for the owner that questions can be discussed in peace. It usually requires some persuasion, but with the above arguments, it is possible to convince a large majority of owners that the preliminary visit makes sense. The measures of cat-friendly practice then additionally improve the experience for the owner and cat.

Take stress and anxiety seriously: Stress and anxiety impair the cardiovascular system, the effects of anesthetics, and the immune system. Anxiety and stress can also cause massive increases in blood pressure. This means that even a healthy patient can suddenly have high blood pressure. Our goal should therefore always be a cat that is as relaxed as possible. The best way to achieve this is in a calm, stress-free environment and with the working methods of cat-friendly handling.

Fall asleep and snooze gently

Rest and routine procedures are also essential for premedication, induction of anesthesia, and surgical preparation as well as maintenance of the anesthesia.

Professional monitoring lowers the risk

The most important indicators of both the depth of anesthesia and the integrity of our patients are the vital parameters: respiration (respiratory rate and oxygen saturation), cardiovascular (heart rate, pulse rate, blood pressure), temperature and reflexes.

Reflexes are primarily useful for assessing the depth of anesthesia, while the other parameters are essential for anesthesia monitoring. To be able to carry out professional monitoring, we must both know our instruments well and have internalized the normal values: the so-called target parameters.


Complications can occur before (preoperative), during (perioperative) and after (postoperative) an operation. How to deal with this?

Preoperative Complications

Stress and fear: usually always lead to a longer induction time and thus to a longer anesthesia time.

Vomiting: We must avoid vomiting before and during the anesthetic as well as the so-called oesophageal reflux (gastric juice gets into the esophagus and burns the mucous membrane) during and after the anesthetic.

Data on optimal fasting times for cats are still lacking. The length of the fasting period is highly dependent on the surgery or treatment and the patient’s health. Twelve hours and more should be strictly observed for certain blood tests and also for operations on the gastrointestinal tract. For other measures, shorter intervals (3-4 hours after a light, moist meal) may be sufficient. A very individual assessment should be made here. In the case of young or diabetic animals, fasting management should be discussed with the team.

Perioperative Complications

1. Oxygen saturation

  • Check pulse, alternatively heartbeat or Doppler signal
  • if not available: cardiopulmonary resuscitation
  • ventilate manually to check the airflow (obstructed airways, formation of mucus, crackling/crackling, …?) – if noticeable, rectify the cause
  • Check the oxygen supply to the patient (leak check)
  • Check the seat of the sensor

2. Temperature drop (hypothermia)

  • Increase room temperature, ensure active and direct heat supply from the start, and additional passive measures (blanket, socks)
  • Keep patient dry, dry
  • Supply of warmed infusion solution
  • Hypothermia may lead to hyperthermia during the waking phase, so keep checking the temperature after it has normalized!

3. Heart rate drops too far:

  • Check medication (narcosis/premedication), could it be a side effect?
  • Check blood pressure – if it is too low, infusion/medication if necessary (in consultation)
  • ECG – if different, medication may be necessary (in consultation)
  • Check the depth of anesthesia – reduce it if necessary
  • Check the temperature – warm

4. Blood pressure drops (hypotension)

  • Check the depth of anesthesia, if possible reduce the anesthetic (reduce gas when inhaling, partially antagonize when injecting)
  • Agree with the surgeon whether an infusion or medication is necessary to stabilize the circulatory system.

5. Heart rate increases too high: HR > 180 bpm (tachycardia)

  • Check the depth of anesthesia
  • Check the fit of the tube or venous access
  • hypoxemia.
  • hypotension
  • hypovolaemia/shock
  • hyperthermia

6. Rise in body temperature (hyperthermia)

  • Removal of all heat sources
  • actively cool with damp towels, fans, etc.
  • possibly renewed sedation

Postoperative Complications

1. Prolonged awakening/delayed awakening

  • Have 15-30 minutes passed after recovery?
  • Is temperature normal or possibly reduced? (see above)
  • Were all medications administered
    antagonized? (see anesthesia protocol)
  • breathing

2. Excessive arousal (dysphoria)

  • Is the cat responsive and manageable?
  • Is the cat in pain?
  • Is there hypoxia? (What is oxygen saturation?)
  • Which medications were used, and what side effects are to be expected?

Wake up gently

Our cat patients should be accommodated in a quiet, darkened environment with the possibility of retreat during the recovery phase and for further monitoring. They must continue to be monitored there, at least until all measured values ​​have normalized, ideally at least three to four hours.

Regular pain scoring is also very important. This should be done every 30 minutes and then, if necessary, an adjustment of the pain indication.

Think cat friendly

The measures of cat-friendly practice improve cat-owner compliance. This is particularly evident in the fact that the cat and owner are less stressed because the four-legged friends feel less threatened and the two-legged friends feel taken seriously. Owner surveys have shown that they perceive positively when their cats feel more comfortable and relaxed in the practice. This makes the owner willing to bring the cat in for check-ups more often and more regularly.

What does that look like in practice?

The entire vet visit should be as short and stress-free as possible. This already starts at home. The owner receives valuable tips for stress-free transport in advance (by telephone or at a prior appointment), starting with getting into the box, including boxing training if necessary, up to arrival at the practice.

Appointments are planned in such a way that ideally there are no waiting times for the patients and the practice is quiet. In practice, the cat is brought directly into a quiet environment. Special pheromones (cat face pheromone F3 fraction), raised parking spaces, darkening by covering the transport box, or dim light can help. In addition, work should be done calmly, patiently, and without violence at all times. The owner also brings snuggly blankets that bring the smell of the familiar into the unfamiliar surroundings. Owning food can improve the acceptance of food after anesthesia and help to activate the gastrointestinal tract.

Target parameters for anesthesia – what is normal?

  • Breathing: 8-20 breaths/minute

Count adspectorally – i.e. the visible breaths – and always assess them together with the oxygen saturation (do not put your hand on your chest, this makes breathing difficult!).

  • Oxygen saturation: 100%

In the case of spontaneous respiration, maximum fluctuations in the range of 90-100% should be tolerated. Monitoring with a pulse oximeter or a capnograph is best (make sure there is minimal dead space!).

  • Pulse rate and quality: strong, regular

This must be checked with the fingers or via the Doppler signal.

  • Blood pressure (systolic) > 90 mmHG and

A Doppler measuring device is best suited, as it measures very precisely and the pulse frequency and quality can also be assessed.

  • Temperature (normal range): 38-39 °C; in young animals up to 39.5 °C

The measurement is made with a rectal thermometer or temperature probe.

Frequently Asked Question

How dangerous is anesthesia in cats?

Serious complications are the result: death from suffocation or pneumonia can occur. So make sure that your animal does not get any food 12-15 hours before the operation in order to keep this risk as low as possible.

How long should cats not drink before being anesthetized?

Your animal must be fasting on the day of the anesthesia. In the best case, it shouldn’t have eaten anything twelve hours before the operation. You can offer him water up to two hours before the anesthesia.

Why can’t a cat eat after anesthesia?

As long as the anesthetic is still effective, there is a risk that the cat will vomit after eating. However, there are also operations after which the cat is not allowed to eat anything for a long time. Therefore, always ask your vet when he recommends the first feeding.

Why do cats under anesthesia have their eyes open?

The eyes remain open during the anesthesia. To prevent the cornea from drying out, artificial tear fluid in the form of a clear gel is placed in the eyes. As a result, the cornea can appear mottled and whitish crystals sometimes form on the edges of the eyelids.

What anesthesia is best for cats?

In cats, for example, veterinarians often choose injection anesthesia with ketamine and xylazine for castration. These drugs are injected into the muscles. After a few minutes, the cat has fallen asleep and is in a state where it can be operated on.

How long can a cat not jump after neutering?

After the end of the operation, she gets a wake-up injection and can soon go home again. Your cat should not be allowed to go outside for the next 24 hours so that the after-effects of the anesthetic can wear off.

How is a cat neutered?

Once the cat is under anesthesia, the vet shaves the hair on the animal’s scrotum and disinfects the area. Then the veterinarian makes two small incisions in the skin and ties off the vessels and vas deferens. Finally, he removes the testicles.

Do cats become more clingy after neutering?

Changes after neutering in cats

They stay more attached, play more, are less bitchy or aggressive, and don’t stray as far from home. By the way, castration has no effect on catching mice. If your cat has done this before, she will do it afterward.

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

Leave a Reply


Your email address will not be published. Required fields are marked *