The Royal Society for the Prevention of Cruelty to Animals (RSPCA) has warned that snakes and lizards bred for rare markings and unusual patterns are "suffering silently" from debilitating physical problems caused by extreme selective breeding.
The charity's report describes a snake whose head wobbles constantly, leaving him permanently dizzy, a python who has to eat in the dark because of his poor eyesight, and a gecko with such bad eyesight that he bumps into the sides of his enclosure.
Lead author Ashleigh Brown, RSPCA scientific and policy manager, said the very features that make reptiles appealing as exotic pets, their unique needs, unusual colours and patterns and often other-worldly appearance, have also made them vulnerable to experimental breeding for novel and rare traits, such as scalelessness or colour morphs linked to harmful genetic conditions.
"Unfortunately, in many cases, this leads to them suffering in silence," she said.
Culture of rarity driving demand
The RSPCA said a culture of "the more unique, the more they sell for" has worsened the problem across the exotic pet trade. Alongside the report, the charity released a documentary showing the conditions some of these reptiles now live with.
The film follows a team visiting Brighton Reptile Rescue in Sussex to meet animals in its care, including a royal python called Donnie, who has been intentionally bred for the "spider" colour morph. The trait produces pale, web-like markings on his scales but also causes what has become known as spider wobble syndrome, a severe neurological condition affecting the inner ear.
The syndrome disrupts Donnie's balance and coordination, causing him to wobble, sway or "star-gaze", an abnormal upward tilting of the head. He struggles to catch and eat his food and has difficulty finding his way around his environment. His keepers had to replace his water bowl with a shallower one after finding he was unable to move away from it safely, to stop him accidentally drowning.
All spider morph pythons affected
Fred Bark, head of reptiles at the rescue centre, said morph pythons became popular in the 1990s because of their distinctive markings. "The more unique, the more they sell for," he said.
"But they later discovered that, after years of selective breeding and inbreeding, every single spider morph, that's 100 per cent of the snakes, now have the genetic disorder causing the wobble. These morph snakes are now banned from all major UK expos."
The RSPCA report lists several reptile varieties bred for colouration abnormalities, including the enigma leopard gecko, jaguar carpet python, lemon frost leopard gecko, spider morph royal python, super champagne royal python, super jungle boa and super motley boa.
Gecko and python also affected
Snakes are not the only reptiles harmed by these traits. Cletus, a leopard gecko, has been bred to be completely white, a condition known as leucism, leaving him with very sensitive eyes and skin that cannot tolerate the lighting levels a typical leopard gecko needs.
"Leopard geckos generally require low levels of light, but Cletus needs even weaker lighting to account for how sensitive his skin and eyes are, all issues caused by his genetics," Mr Bark said.
"His leucism has been caused by severe inbreeding, you can also see this through deformities such as his multiple tail-tips. He can't function like a normal leopard gecko would. He is also prone to prolapse because his abdominal muscles aren't properly developed, so if he gets stressed then prolapse can happen."
Oscar, an albino royal python with striking yellow markings, has extreme light sensitivity affecting both his skin and eyes. Not all albino pythons are as sensitive as Oscar, but the RSPCA recommends that all albino reptiles be kept under lower light levels than usual in captivity.
Mr Bark said Oscar's eyesight is so poor that he struggles to eat. "If he misses his prey twice in a row then he won't eat, and he'll be put off trying again for a month, a behaviour they utilise in the wild to conserve energy if hunting," he said.
"This obviously has potentially severe repercussions of malnutrition, but staff worked out that if we switch off the lights he's more likely to eat successfully, so now he has to eat in the dark. This is unnatural selection for the wrong reasons."
A wider pattern across pets
Ms Brown said most people are aware that dog breeds such as pugs and bulldogs have breathing problems because of their flat faces, and that dachshunds can suffer major spinal problems because of their short legs and long backs.
"But people don't always realise that this is an issue that affects a much wider range of pets, from flat-faced cats to lop-eared rabbits, tail-less rodents to bubble eye goldfish," she said.
"And, being less commonly-seen pets, reptiles are at risk of becoming the forgotten victims of breeding for looks over health."
