Why amphibians respond differently to anesthesia and analgesia

Jb Minter, DVM, MS, DACZM, director of animal health and chief veterinarian at the North Carolina Zoo in Asheboro, discussed the unique physiological characteristics of amphibians that affect their response to anesthesia and analgesia in an interview tied to his lecture, “Navigating Amphibian Anesthesia and Analgesia,” originally presented at the recent Fetch dvm360 Conference in Charlotte, North Carolina (now available on Fetch On-Demand for CE credit).

Below is the video transcript, lightly edited for clarity:

Jb Minter, DVM, MS, DACZM: Amphibians have several unique...physiological characteristics that impact how they're going to respond to anesthesia and analgesia. One of those key characteristics is that amphibians are ectothermic, or cold-blooded, which means their body temperatures are very dependent on the external environment around them. This can result in lower metabolic rates compared to your endotherms, or warm-blooded animals, which can influence the dosing and duration of a lot of the anesthetic drugs that you may want to use for your patients.

They also have very permeable skin, so this plays a significant role in drug absorption and elimination. So, as you put drugs on them, they're going to be transdermally absorbed through the skin, which can sometimes lead to very unpredictable dosing and absorption rates.

They also have a pretty low metabolic capacity for detoxifying drugs, meaning anesthetic agents may stay in their system longer than some of our mammalian species that we deal with commonly.

Additionally, amphibians have a pretty unique respiratory system. In addition to their lung-based respiration that you and I would have, they also have cutaneous or skin respiration. This dual respiration means inhaled anesthetic agents must be carefully monitored to ensure that animals are receiving adequate oxygenation without causing respiratory depression.

They're pretty unique, but they're not as difficult as everybody makes them out to be. That's why...this talk that I'm going to be [giving] is making sure that the people [who] are not really comfortable seeing them have a general overview of what it is to anesthetize amphibians and potentially provide them some type of analgesic drugs.

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