How to Verify Life (and Death) in Reptiles

Introduction

Although medical knowledge has answered many questions regarding animal life, there are still many mysteries that face us. And nowhere is the mystery of life and death more apparent than when dealing with reptiles (Fig 1).

Is this lizard dead?

Figure 1. This lizard appears to be dead, but is it? How can the veterinarian verify life (and death) in reptiles? Image by Eric Caballero.

Detecting the reptile heart rate

  • Stethoscope: Even in the active, healthy reptile the stethoscope is generally a useless piece of equipment. The presence of scales or the shell makes auscultation of the heart difficult, if not impossible, in many instances. Therefore ancillary testing such as ultrasonography or electrocardiography is required.
  • Doppler or ultrasound: A pediatric Doppler probe or ultrasound probe can be used to detect arterial blood flow. Place the Doppler probe directly over the apex beat or an accessible artery. Use Doppler gel to enhance contact between the probe and the skin.
  • Electrocardiogram (ECG): Alligator clips can be placed directly on the reptile’s leathery skin or scales, however recording potentials can be enhanced by attaching ECG clips to fine gauge hypodermic needles that have been placed in the appropriate locations. Loops of stainless steel suture can also be used as subcutaneous leads but this practice is most commonly elected for anesthetic monitoring.

Brain death versus cardiac arrest

Unfortunately ECG or Doppler readings can be misleading when verifying death in the reptile patient. Brain death can (apparently) precede asytole by many hours because the heart sometimes continues to beat and the body can continue to writhe for many hours after brain activity has ceased. Alternatively the heart rate can slow so dramatically that the “reptile’s heart rate can change from beats per minute to minutes per beat…” (Mader 2006).

All reptile vets have a story like this…

Checking heart rate is only ONE part of the picture when verifying reptile death. All reptile veterinarians have a story of a “dead” patient that wakes up 24 hours later—often with nothing more than time or supplemental heat provided.

…Last night on emergency I get a 6-year old 50-lb tortoise, which had been “basking” at the bottom of the pool for about 3 hours. Owners upset, ‘try everything’ kind of situation. So the tortoise is room temperature, not breathing, flaccid, no deep pain– hook up the ECG, no electrical activity. I pick up the tortoise; hold it upside down and about half a gallon of water comes pouring out. Not good.
…It gets busy, and about 2 hours later I hear this deep grunting sound. There’s a couple of critical animals in the hospital, so I get worried and look around – nothing. A few minutes later the same thing happens – and I look down to find the tortoise chewing on his ET tube!
…Now he’s getting pissed – poked and prodded quite a few times, and I can’t even contain him in a cage, he’s so restless. Call the owners – they pretty much fall over themselves when I tell them to pick the tortoise up. Makes me look like a champ, while honestly didn’t do much more than give it a good-natured whirl… goes to show, you never know how [a reptile will] turn out. —M.Dekker, DVM; EBVE, Antioch, CA

There’s no heart beat, now what…?

AFTER euthanizing a reptile or proclaiming a reptile (probably) dead, but BEFORE sending the patient home or performing a necropsy it is imperative to confirm (or ensure) that the animal is dead.

  • Reptile muscles go through all the same stages of death seen in other species: primary relaxation or flaccidity, rigor mortis or rigidity, followed by secondary relaxation. So if the animal appears to be in rigor it is likely dead (be sure to rule out tetany).
  • Another rule of thumb when dealing with euthanized or dying reptiles is to wait 12 or preferably 24 hours after euthanasia to send the animal home with the owners.
  • Adjunct procedures can also be performed to ensure death in a reptile AFTER euthanizing the animal and/or not detecting a heart rate.
    • Decapitation with transection of the cervical spinal cord or pithing the brain is often performed before necropsy (and AFTER euthanasia)
    • Some clinicians elect to place the reptile in the freezer AFTER euthanasia and not detecting a heart rate. Note: Freezing alone is NOT considered an acceptable method for euthanasia of ANY species (AVMA 2007).

Visit Reptile Wildlife Euthanasia Techniques for more detailed information.

Summary

In conclusion, there is no 100% reliable way to verify death in reptiles short of putrification or decapitation. For this reason, reptile veterinarians routinely wait 12 to 24 hours after declaring the animal deceased before releasing the body. Adjunct procedures, such as freezing, pithing, and decapitation, are also routinely performed as needed after euthanasia and after failure to detect a heartbeat.

References