## 1 Introduction  
Spinal cord injury (SCI), often caused by accidents, typically results in a series of severe physical and psychological health problems for the individual patient as well as in a huge social and economic burden for the society [1]. It is estimated that about three million people live with traumatic SCI worldwide, and up to 180,000 new cases are reported every year [2; 3; 4]. The cervical region (C1-4) is affected in about 55% of SCI cases, while the most common injury type is contusion and compression of the spinal cord [5; 6]. Respiratory complications, therefore, remain the primary cause of death after SCI, most likely being related to inadequate pulmonary clearance and subsequent infections [7; 8]. Other sequela of SCI such as deficits in motor, sensory, or autonomic function below the injury level are directly related to the primary disruption of the spinal cord. Furthermore, secondary complications including neuropathic pain, dysfunction of circulatory, respiratory, or bladder control, and loss of muscle tone affect patients in subacute and chronic stages [7; 8]. With a deeper understanding of biochemical and neuroanatomical features of pathological changes after SCI acquired in the recent decades, various therapeutic targets and approaches, including drug treatments, cell transplantation strategies, or even gene editing, have been comprehensively studied in preclinical models of SCI [9]. Thereby, severe confusion/compression injures to the cervical spine via e.g., modified aneurysm clips have repeatedly been identified to be clinically very relevant [10; 11; 12]. However, before new treatments could proceed to clinical trials, it is crucial that their effects on functional recovery can be validated in animal models and thus, stable and replicable systems of behavioral assessment are needed. To this end, the Basso, Beattie, and Bresnahan (BBB) open field rating scale was introduced in 1995 and is currently still the most widely used behavioral test for the assessment of the hindlimb motor function in rats. Compared to most single-task tests, the BBB open field rating scale is a more integrated system, including the assessment of joint movements, weight-bearing, coordination, and trunk stability, covering almost all the different levels of locomotion deficits [13]. However, beside the fact that the observations made during its assessment are subjective and should therefore be performed by at least two independent investigators, another major shortcoming of the BBB open field rating scale is its inability to assess the function of the forelimbs before the animal can support its weight or start stepping, which, in clinical practice, extensively affect the patients' quality of life after SCI. The CatWalk XT(r) gait analysis system is a more recent platform for the objective assessment of gait, coordination, and motor function in rodents. While the principle of the CatWalk XT(r) system is based on the classical ink footprint analysis test, its technological advancement allows an automatic analysis of more than 100 different gait locomotion, spatial, and dynamic parameters, providing a comprehensive understanding of functional impairment and recovery, including forelimb function [14]. Although it has been extensively used by many researchers to assess the functional recovery of rats in different SCI models, only limited numbers of its many parameters without a comprehensive consensus on which to use in a specific injury model have been published so far [15; 16; 17]. This makes it currently very difficult to determine the most suitable parameters of the CatWalk XT(r) system to best assess the recovery process induced by a certain treatment for a specific SCI model in preclinical studies. Therefore, our current analysis aims to describe the typical changes of the 30 major parameters of the CatWalk XT(r) system during the first six weeks of spontaneous recovery after a clinically relevant clip compression/contsion SCI of the cervical spine in rats.