Spinal Deformities in Wild Reptiles: A Systematic Review and Meta-Analysis

Spinal deformities-such as kyphosis, scoliosis, and lordosis-are observed across all major vertebrate groups. Reports in wild reptiles are increasing but are mainly published in natural history notes as curiosities, with little exploration of their aetiology, pathology, prevalence, or consideration of potential ecological, evolutionary, and life history implications. Addressing this gap, I compiled the most comprehensive database to date by reviewing the peer-reviewed and grey literature and collecting unpublished records via standardised social media inquiries. I identified 690 observations from 146 sources, covering 109 reptile species in 24 families across 37 countries. Spinal deformities appear across all major reptile clades, though Testudines are over-represented (78.6% of all observations and 42.2% of all species). A phylogenetic meta-analysis of 54 effect sizes from 37 species yielded a global prevalence estimate of 0.21%, with no significant effects of phylogeny, habitat use, or habitat type detected, possibly due to dataset limitations. However, kyphosis was more common in (semi)aquatic Testudines, whereas scoliosis was more frequent in terrestrial squamates. Although deformities may impair key life history traits, supporting evidence remains scarce. The findings highlight the understudied nature of spinal deformities in wild reptiles and underscore the need for standardised, ecologically informed reporting to better understand their causes and consequences.