TDK conference 2024

Shivering is a chronic degenerative neuromuscular disease of horses with characteristic intermittent muscle tremor and hyperflexion or hyperextension while walking backward and picking up the hindlegs. The disease has unknown etiology and can be seen in several breeds. Definitive diagnosis is made by histopathological evaluation of the peripheral and central nervous system and ante mortem diagnosis is based on the clinical signs and ruling out other potential causes such as stringhalt, upward fixation of the patella, and other orthopedic or neurologic causes. Our hypothesis is that since definitive diagnosis is not possible through imaging and/or specific laboratory tests, many horses may be misdiagnosed as shivers. Such false diagnosis of the disease may lead to inappropriate treatment and training strategies which might worsen the original disorder. Our aim was to evaluate how reliably diagnosis of shivers can be made based on specific clinical signs. We created a detailed questionnaire to Hungarian online platforms (including: nationale, medical history, diet and training regimens) to collect horses previously diagnosed with shivers. During the next step of our research, based on the studies conducted by Draper et al. (2014), we collected specific recordings of the horses when walking in a straight line, walking backwards, turning in sharp circles and picking up the hindlegs; as well as any other videos where the horse is demonstrating clinical signs. These videos were then evaluated by three independent board certified specialists blinded to any other data of horses and interrater reliability was tested by Fleiss kappa test. Altogether we collected 18 warmblood horses which included 3 mares, 15 geldings, of age between 5-20 years (SD: 4.7). The primary diagnosis of shivers was established by practitioners in 15, by farriers in 3 and by owners in 2 cases. In the secondary evaluation performed by the specialists, 3 horses were considered as shivers and 6 horses were considered as non-shivers by all three interpreters. In 9 cases there was disagreement between any of the interpreters. The interrater reliability showed a weak agreement with a kappa value of 0,318 when diagnosing shivers. In conclusion, the results demonstrated that the lack of reliable diagnostic methods causes many horses to be incorrectly diagnosed with shivers. The study showed that even board certified specialists evaluate clinical signs differently leading to a high subjectivity when establishing the final diagnosis. This inhomogeneity in diagnostic evaluation can lead to false conclusions when conducting research on the topic or to inappropriate treatments in clinical cases. Agreement might have been better with real-time onsite diagnostic observations. The study draws attention to the significance of excluding any other possible causes systematically, not just relying on clinical signs when diagnosing shivers.