Lizards can become intoxicated if they consume enough ethanol, the active component in alcoholic drinks. Intoxication occurs when the body absorbs ethanol faster than it can be metabolized, leading to a temporary state of poisoning that affects the central nervous system. This process is possible because lizards possess the same biological machinery for breaking down alcohol as mammals.
The Physiology of Ethanol Processing
A lizard’s ability to process alcohol depends on the enzyme Alcohol Dehydrogenase (ADH), which is primarily found in the liver. Research has confirmed that reptilian species, such as the spiny-tailed lizard (Uromastix hardwickii), possess an ethanol-active type of ADH. This allows them to initiate the breakdown of alcohol into acetaldehyde, a detoxification pathway found across many vertebrates, including humans.
However, the rate of metabolism is significantly slower than in mammals or birds due to their ectothermic nature. Lizards are cold-blooded; their body temperature and metabolic rate fluctuate with the surrounding environment. A lower body temperature drastically slows the enzymatic activity of ADH, causing the effects of ethanol to last much longer and making a small amount of alcohol more potent.
Natural Sources of Intoxication
In the wild, lizards do not seek out alcoholic beverages, and intoxication is almost always an accidental occurrence. The most common natural source of ethanol is overripe or fallen fruit. Natural yeast on the fruit skin begins to ferment the sugars inside, producing low levels of alcohol.
Species that include fruit in their diet, such as omnivorous or herbivorous lizards, are the most likely to ingest enough fermented pulp to become intoxicated. While lizards are sometimes found near discarded human alcohol containers, they are typically attracted to the container as a potential shelter or source of insects, not the drink itself. Although the ethanol concentration in naturally fermented fruit is low, it can still reach intoxicating levels for a small reptile.
Observable Effects and Risks of Alcohol Exposure
When a lizard becomes intoxicated, the physical symptoms are similar to those seen in other drunk animals, primarily affecting their motor control and balance. Observable signs include ataxia, which is a loss of coordination leading to an unsteady gait, and general lethargy. Intoxication also leads to impaired judgment, which is dangerous for a reptile that must remain alert to avoid predators and find food.
Scientific studies on the green anole lizard (Anolis carolinensis) show that alcohol consumption can affect complex behaviors like aggression and brain function. The lethal dose of ethanol is much lower for a small reptile relative to its body mass. Intoxicated lizards are also highly vulnerable to rapid dehydration, as they may become too disoriented or lethargic to seek out water or a temperature-appropriate microclimate. The combination of impaired function and slowed metabolism turns even mild intoxication into a serious survival threat.