Comparative assessment of computed tomography and magnetic resonance imaging of the spider morph of Python regius and wild type Python regius to evaluate the morphological correlate of the wobble syndrome

Abstract

There is general awareness of artificial selection and its potential implications on health and welfare of animals. Despite growing popularity and increasing numbers of breeds of atypical colour and pattern variants in reptiles, only few studies have investigated the appearance and cause of various diseases associated with colour morphs. Ball pythons (Python regius) are among the most frequently bred reptiles and breeders selected for a multitude of different colour and pattern morphs. Among those colour variants, the spider morph of the ball python is frequently associated with the wobble syndrome. The aim of this study was to determine, whether a morphological variant can be found and brought in association with the clinical occurrence of the wobble syndrome in spider ball pythons, using MRI and CT-imaging as intra-vitam diagnostic methods. Data from eight ball pythons including five spider ball pythons and three wild type ball pythons was assessed and evaluated comparatively. We were able to identify distinctive structural differences in inner ear morphology in spider ball pythons highly probable to relate to the wobble syndrome. To our knowledge, these anomalies are described for the first time and represent a basis for further anatomical and genetic studies and discussions regarding animal welfare in reptile breeding.

Malformations of the sacculus and the semicircular canals in spider morph pythons

“…We compare wildtype and spider morph individuals of Python regius . All wildtype individuals were healthy and showed no signs of wobble syndrome, while all spider morph individuals showed noticeable neurological problems that were described as “wobble syndrome” [ 5 ]. Sample size was primarily limited by access to material.…”

“…As reported above, the sacculus of spider morph snakes is distinctly smaller, deformed, and lacks a coherent macula. Because the sacculus and the ampullae of the semicircular canals are organs of equilibrium, it is not surprising that these morphological differences are associated with neurological symptoms including head tilt, tremor, corkscrewing, reduced striking accuracy, and reduced righting reflex (reported in detail in [ 5 ]). An independent study by [ 2 ] showed that all spider morph pythons were affected by the wobble condition, however, to some variable degree.…”

“…Three wildtype snakes were obtained from preserved material at LMU Munich; protocol notes describe them as healthy when killed for other research purpose. Clinical examination and health status including neurological symptoms in spider pythons have been described in detail in [ 5 ]. Animals were euthanized by intramuscular injection of ketamine hydrochloride (100 mg/kg; Ketamine 10%, Selectavet, Germany) combined with medetomidine (0.25 mg/kg; Domitor, Vetoquinol, Ismaning, Germany), then applying T61 (2 ml/kg, Intervet, Unterschließheim, Germany) intracardially.…”

“…showed noticeable neurological problems that were described as "wobble syndrome" [5]. Sample size was primarily limited by access to material.…”

“…Our study is descriptive and explorative in a sense that we investigate the morphology of individual spider morph pythons with an explicit anamnesis, and compare it to healthy wildtype animals. Details of the anamnesis, clinical examination and intra vitam diagnostics of the snakes studied here have been reported by [ 5 ].…”