Monitoring pet patients without ‘toys’

When technology fails, here’s how you can rely on your senses and skills to treat your pet patients

Doctors and veterinary technicians love toys. Is there anything more exciting than a new shiny multiparameter monitor with all the bells and whistles, including end-tidal CO2 and noninvasive blood pressure? Most newer models also feature an optional esophageal probe that provides a beautiful ECG and core body temperature. But wait—you can often select your favorite color for each parameter! Can it get any better?

Well, sadly, electronics can range from temperamental to downright frustrating. Sometimes, for no obvious reason, some or all parameters just won’t read. Murphy’s Law says this typically will happen at the worst possible moment.

Even if your monitor works, how would you take the patient’s temperature during perineal surgery? What do you do when an ECG lead falls off (or dries out) and rolls far under the drapes? Let’s review tips and tricks to succeed during surgery despite such possibilities.

Degrees of Control

Temperature is a basic but important parameter to monitor before, during and after surgery. It quickly drops after premedication and especially after induction. Add a cold X-ray table or a cool surgery room, and your patient quickly ends up hypothermic before surgery even begins, leaving you to play catch-up.

When taking a rectal temperature is impossible, a great option lies at the other end of the body: inserting the temperature probe or a dedicated digital thermometer into the cervical esophagus. But please only use that thermometer for that purpose! Don’t use it alternatively as a rectal thermometer.

Add long strips of tape to the end of the thermometer to make it easier to retrieve and read, and as a reminder to remove it at the procedure’s end.

Other locations have been tried—inside the ear, under the lip or inside the nose—but they aren’t as accurate. Besides, placing a thermometer into the nasal cavity might lead to a bloody nose and a very unhappy client, both during the car ride and at home.

The Heart of the Matter

Even though ECGs tend to be more reliable than other parameters, they still can be frustrating. They may stop working altogether; one lead may fall off or dry out or even break from corrosion.

Don’t panic. Simply grab your regular stethoscope and listen to the heart! If you auscultated the patient before surgery, you should know how the heart sounded and whether a murmur exists. Compare the heart rate to the pulse; hopefully both are in sync.

Another great option is an esophageal stethoscope, which is surprisingly affordable. Depending on size and brand, it costs between $5 and $15.

Take a Breath

Fortunately, you don’t need anything fancy to monitor respiration. Watch the bag or (ideally) the chest move, and count away. A good range for patients under anesthesia is 8 to 10 breaths per minute. If the patient is not breathing well, give a deep breath once or twice per minute, never exceeding 20 centimeters H2O. Change the soda lime regularly. Remember that each brand is different, and, amazingly, some pellets don’t change colors when saturated.

Keep the Beat

Multiple arteries all over the body can be used to feel a pulse. Some are classic, such as the femoral artery. Less common but very helpful options include:

  • palmar metacarpal artery in the front paw,
  • dorsal pedal or plantar metacarpal artery on the hind foot, and
  • medial coccygeal artery under the tail.

Another very useful site is the lingual artery. Yes, you easily can feel a pulse under the tongue of your patient!

Chin Up Under Pressure

When you lose your noninvasive blood pressure monitoring capabilities, or when they don’t register on a small or exotic patient, a Doppler (aka a sphygmomanometer) is a nice backup that is rather affordable at about $900 (new). However, it’s important to remember that it only measures systolic blood pressure.

There certainly is a learning curve to properly using a Doppler, but once you find a consistent pulse, you can tape it in place and use it regularly throughout the anesthesia episode.

Some say that if you can feel a peripheral pulse, the mean arterial pressure is at least 60 mm Hg. This number is important because that’s the minimum required to maintain perfusion of the kidneys and other vital organs.

Kurt Grimm, who is double board-certified in veterinary anesthesiology and veterinary clinical pharmacology in Conifer, Colo., believes this rule is a bit simplistic.

“The pressures at which the pulses are palpable depend on factors which are variable, including the size and conformation of the patient, the stroke volume, the vascular resistance and the pulse pressure,” he said.

So, rather than focusing on what the pulse feels like in a specific artery, he prefers to focus on how much digital pressure is required to occlude the pulse. Generally speaking, the higher the arterial pressure, the more digital pressure is required to make it disappear in a distal artery.

Other Assessments

You can assess other parameters without the use of monitoring equipment, including:

  • Eyeball position. The position of the eye is an easy way to assess the depth of anesthesia. It’s light (or deep) when the eye is central, and it’s medium when the eye is rotated ventro-medially.
  • Mucous membrane color, which is easy to assess in most patients (those without dark oral mucosa). Ideally, it’s nice and pink. Pale mucous membranes mean vasoconstriction (or anemia, or cardiogenic shock). Red mucous membranes mean vasodilatation (or other types of shock, or hyperthermia).
  • Capillary refill time (CRT). Again, when oral mucosa isn’t too dark, CRT is easy to assess. CRT should be less than 2 seconds.

Monitoring equipment is great, but there are multiple parameters you can track using your senses, your head and very basic equipment. When the situation arises, use them to your—and your patients’—advantage.

So Should You Not Buy a Monitor?

Of course, none of the information in this column means you shouldn’t have monitoring equipment. Safety has increased dramatically thanks to progress made in the electronic monitoring of anesthetized patients. Morbidity and mortality have decreased thanks to the accuracy and sensitivity of monitoring equipment.

As long as they work, machines are much more accurate than our physical and visual observations. How would you monitor CO2 without a machine? Could you tell the difference between an SPO2 of 100 and 90 based on mucus membrane color? How could you tell the origin and significance of an arrhythmia without studying an ECG?

“Improving patient safety is not done only by buying a monitor, but by training technicians to gather correct data from the monitor and their senses,” said Kurt Grimm, who is double board-certified in veterinary anesthesiology and veterinary clinical pharmacology in Conifer, Colo. “In addition, it is achieved by training veterinarians to correctly diagnose the problem and start the proper treatment to correct the problem.”

Monitoring equipment is considered standard of care in 2017—and for good reason.

Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling practice takes him all over eastern Pennsylvania and western New Jersey. Visit him at or follow him at

Kelly Serfas, a certified veterinary technician in Bethlehem, Pa., contributed to this article.

Originally published in the April 2017 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today! 

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