Reptiles and amphibians – commonly referred to together as herptiles – are two distinct families of ectothermic animals. Herptiles present unique challenges within the veterinary environment due to their comparatively “alien” nature of internal functions. Indeed, one area of particular concern, and commonly queried, is analgesia. How do you know if an animal is in pain if it cannot express itself in the same manner that we relate to? This is an ongoing and often misunderstood question, which veterinary professionals are duty-bound to alleviate to the best of their abilities.
What are herptiles?
Herptiles is a broad definition that encompasses the reptile and amphibian classes. It derives from the Greek language and was used to encompass animals that are “crawling things”. Due to this, and the nature of their internal body temperature control, they are commonly grouped under the term “herp” in the private sector.
However, the reality is that reptiles and amphibians are two anatomically distinct lineages. Reptiles have existed for over 320 million years, while amphibians date back over 350 million years, meaning that amphibians are generally accepted as precursors to reptiles (Ridley, 2003). To consider them “primitive” is a gross misdemeanour for classes of species that have thrived long before the mammal lineage even existed.
Reptiles are classified into four main categories. It is important to note here that some argue the case for five due to birds’ evolutionary lineage; however, the author believes that birds are distinctly birds for the purposes of this article. The four categories are:
- Chelonians: tortoises and turtles
- Squamates: lizards and snakes
- Crocodilians: crocodiles
- Tuatara: a distinct reptile, endemic to New Zealand, which resembles a lizard but is not a squamate
Comparatively, amphibians are divided into three main categories which are:
- Anura: frogs and toads
- Urodela: newts and salamanders
- Gymnophiona: caecilians, which are elongated, worm-like amphibians
Pain assessment in herptiles
Species identification
When assessing any animal for potential signs of pain, it is essential to know what species the individual animal belongs to. While most correctly sourced animal species will be known and presented by hopefully knowledgeable owners, this is not always the case, and identification will be needed.
Some chelonians, for instance, can have very subtle differences which means an owner may assume it to be one species when in fact it is another. Further, with six native species of reptile and seven native amphibians in the UK, wild animals are frequently presented in clinic, resulting in identification issues (Figure 1). In turn, there are often reports of escaped animals, stowaways or pets released into the wild in the UK. Indeed, some species are doing comparatively well, such as the now-banned red-eared slider terrapins or Aesculapian snakes. There are many excellent resources online and textbooks available to guide species identification, including some identification apps that are showing positive results.
Identifying pain in herptiles
Pain is defined by the International Association for the Study of Pain (IASP) as: “An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage”(The British Pain Society, 2025).A key line for veterinary care identifies that an “inability to communicate does not negate the possibility that a human or a nonhuman animal experiences pain”, which is particularly important for reptiles and amphibians who are not considered overly communicative (The British Pain Society, 2025).
An inability to communicate pain means veterinary professionals must monitor other factors in herptiles, and these largely focus on behavioural aspects. Pain is often subjective, and individuals react differently; however, stoicism of one patient should not be taken as indicative of an entire species. It is better to provide appropriate analgesia and reassess than leave an individual suffering.
Common behaviour patterns
While pain scores do not exist for herptiles in the same manner as other species, the basic principles can be extracted and utilised
Once the herptile has been identified, then its behaviour can be considered and reviewed. Is the animal naturally nocturnal, which could explain lethargy during the day? Or is the animal normally a feast and famine predator, which could explain its reported anorexia for a period? Knowledge of “normal” behaviour is essential when assessing any animal’s potential pain, and while pain scores do not exist for herptiles in the same manner as other species, the basic principles can be extracted and utilised.
In turn, common sense also assists us; for example, if an animal has an open wound (Figure 2) or traumatic fracture (Figure 3), then it will be in pain, regardless of whether it doesn’t express it in the same way we as humans would do, or as we see in our more traditional companion animals.
Contrary to many still upheld, but outdated, beliefs, reptiles and amphibians do express preferences and routine behaviours in their captive environment. It may be that a lizard expects a certain feeding routine or enjoys one “treat” item over another, and therefore a deviation from this “routine” behaviour could indicate a potential issue causing pain. A thorough background history and environmental review should always be taken in any herptile consultation, much as you would ask for background information on a traditional companion animal. The main difference is that the “owners” control the environments of their herptile companions to a higher degree than that of traditional companion animals in that a herptile’s environment, if managed correctly, should be different from our own with regard to temperature, UV provision, humidity and so forth.
An animal’s demeanour can also be indicative of pain, for example if it is spending time hiding or isolated, or is reactive to certain pressure, especially if appearing alongside changes in routine behaviours. Typical pain signs in reptiles and amphibians can include many common-sense responses: an animal may move away from painful stimuli, it may react to an area being assessed that it finds painful and it may attempt to bite if the pain persists. Further, it may self-traumatise or position itself abnormally to alleviate the symptoms as much as it can. It may have its mouth open and appear to be “gasping” or it may be rubbing itself on objects to put pressure on painful areas.
It is always important to remember that herptiles have not been domesticated to the same degree as our traditional companion animals and will retain many innate behavioural responses
In addition, most herptile species are prey to something else, and will attempt to hide away so as not to draw attention to themselves and show weakness to would-be predators. While hopefully captive-bred, it is always important to remember that herptiles have not been domesticated to the same degree as our traditional companion animals and will retain many innate behavioural responses, which have been honed through evolution over millennia. As such, many signs of pain are generalised, which can make locating the source challenging and necessitate appropriate diagnostics (Figure 4).
Pain management in herptiles
If pain has been identified or is suspected, then the appropriate analgesia methods must be used. Intravenous or intraosseous access for some species is possible, but not for all. Indeed, certain groups are excluded due to their anatomy, ie snakes. Moreover, it is important to consider the species in question as many herptiles are significantly smaller than traditional companion animals, thus making access more challenging. The ability to achieve prolonged access may be simply impossible, and so alternatives should be considered (Figure 5). Intramuscular access is a suitable choice for many; however, species specificity must be considered. For example, in a sea turtle who doesn’t require dry docking but does require analgesia, how do you access that patient frequently enough to provide analgesia, and is the stress of doing so worth it? Oral pain management is very commonly used; however, it is dependent on the animal eating, otherwise medicating must be done by “force”.
The research into herptile pain often centres on a small number of species types when compared to the diversity of these families
The research into herptile pain often centres on a small number of species types when compared to the diversity of these families. As such we can only review, assess and make judgement calls on the data we have available, alongside patient monitoring and review. Often, differing options can be complicated in that different species, sometimes within the same families, have markedly different reactions. Generally, it is accepted that μ-opioid agonist drugs are considered best for reptile analgesia (Sladky, 2023). Morphine is good for most lizards and chelonians, but causes pronounced respiratory depression in turtles, so tramadol is often used as both an oral and injectable option (MSD, 2025). Anti-inflammatories are often used, and while their actual analgesic properties are debated, the reduction of inflammation can reduce pain. Local anaesthetics can also be used; as with all species, a multimodal approach is considered best practice.
Final thoughts
The belief that herptiles don’t perceive pain is false and misleading. They have the ability and anatomical adaptations to perceive pain, and it is our duty in the veterinary profession to alleviate suffering regardless of species or comparative work. The provision of their correct environmental needs, appropriate supportive care and analgesia are all essential to alleviate pain.
