Several skink species of the genus Plestiodon have blue tails as juveniles, leading people to call them blue-tail lizards. Some veterinarians, scientists and laypersons suspect these lizards are toxic to animals -- particularly cats -- but no direct evidence demonstrates that these skinks are toxic. Anecdotal reports of cats falling ill after being in close proximity to blue-tail skinks abound, though. Seek immediate veterinary assistance if your cat exhibits disorientation, a lack of coordination or other signs of illness, regardless of potential cause.
Five-lined (Plestiodon fasciatus), southeastern five-lined (P. inexpectatus) and broad-headed skinks (P. laticeps) are the three species most commonly called blue-tailed lizards. In addition to sharing similarly colored tails as juveniles, all three species have roughly similar biology, natural history and behavioral patterns. They are all quick-footed, diurnal lizards who eat invertebrates and small lizards. Despite their similarities, it is possible that the three species exhibit different levels of toxicity.
Many animals bear bright colors to indicate that they are venomous, poisonous or unpalatable. Using conspicuous colors to advertise noxious qualities is a strategy called aposematism. However, bright colors do not always indicate the presence of chemical defenses, as some animals use bold colors as a bluff. No published studies have examined the chemical composition of these Plestiodon skinks' tails.
A 2012 study published in "Zoology" demonstrated that whether or not the skinks' blue tail color is associated with toxic properties, the tails provide another benefit: They serve as decoys. During the study, researchers presented predatory birds with several skinklike clay models. The researchers painted various regions of the models' bodies with blue paint and found that the birds preferentially attacked these areas. By diverting the birds' attention away from the lizards' heads and vital organs -- and toward their tails, which the lizards can jettison and eventually regenerate -- the lizards may be able to escape from predators.
Different veterinarians, scientists and environmental educators interpret the issue of skink toxicity in different ways. For example, the Crowley Museum and Nature Center in Sarasota, Florida, states on its website that skinks may be poisonous to pets. Others, including University of Georgia professor and herpetologist Whit Gibbons, contend that the truth is not clear. The Glendale Animal Hospital website states that cats can suffer from a disease called lizard toxicosis after eating a skink, while veterinarian Robert Miller of Pine Island, Florida, asserts that he's unconvinced skinks are toxic to cats.
Diagnosis and Treatment
According to Dr. Miller, veterinarians often diagnose cats exhibiting illness after eating a skink with a condition called feline vestibular syndrome -- a disease that affects the inner ear. Afflicted cats may tilt their heads to the side, drool, cry out repeatedly, lean against objects for balance or exhibit darting eye movements. Other vets diagnose such cats as having idiopathic -- meaning "of unknown cause" -- vestibular syndrome, and treat the animal with supportive therapy such as fluids and rest.
The Merck Veterinary Manual suggests that a parasitic fluke -- Platynosomum concinnum -- may cause these types of symptoms. Normally, this parasite infects snails and roly-polies, but it can also infect lizards, who may pass the parasite on to cats who eat them. Antiparasitic medications may eradicate the flukes, but occasionally, surgery is required to remove the parasites from the bile duct.