Pelvic limb movement disorders in horses are, commonly, not well defined leading to confusion and inconsistencies regarding their diagnoses. A standardized web-based survey (n=305) was used to collect epidemiological data and videos. A standardized video (n=70) was requested from owners. Literature review and video analysis produced a definition of Shivers being hyper-flexion (Shivers-HF n=21) or -extension (Shivers-HE n=6) of the pelvic limbs during backwards walking and manual hoof lifting. Subjective and kinematic video analysis provided differences between Shivers, Stringhalt (n=7) and more advanced Shivers cases (Shivers-FHF n=4) where hyperflexion during forwards walking was seen. For the epidemiological survey diagnosis was confirmed either by video submission [v+ n=27], or by reported clinical signs alone [v- n=67]. Fifty matched case-controls were obtained. V+ had significantly more WBs, TBs and Draft breeds, taller horses (>17hh) and males compared to the controls. Height was the only significant predictor variable however. Signs frequently began at <10 yrs of age (V+ and V-). Both groups reported an improved with increased turnout, exercise and a low carbohydrate diets. No therapies were helpful or curative. More V+ horses showed progression of signs signs over time (80+%) than v- horses (50+%).