Contrary to what some of our competitors claim, CatWalk XT is by far the most cited gait analysis system. In the past 10 years, CatWalk XT has been cited at least 2 to 3 times more often than the most cited competing system (Google scholar search.)
Very detailed print measurements
The parameters CatWalk XT measures are based on the actual footprints of the animal. So to get reliable data, it is of extreme importance that these prints are measured accurately. A problem many other print-measuring systems (recording from below a translucent stepping surface) face is that the software detects the paws during the entire gait cycle. In other words, every part of the paw (and sometimes additional body parts) is taken into consideration, even though part of this paw might not be touching the floor and is not part of the actual print at that moment in time. These systems rely on advanced algorithms based on simple assumptions to determine if the paw is in swing or stance. With this method, the stepping surface is also overestimated, causing errors in the results and preventing important gait impairments from being detected.
CatWalk XT solves this problem by using Illuminated Footprints Technology™. In short, this technology captures the light that is reflected only where the paw is physically touching the floor, thus ensuring that the actual print is measured. An added benefit is that you do not have to mark (black out) any body parts, such as the knees If a knee does happen to touch the walkway, you have the option to add it to your quantitative analysis as a factor in the animal’s gait.
Read more about Illuminated Footprints here.
Rats and mice are photophobic prey animals and easily become stressed in brightly lit environments. Interestingly, some gait analysis systems are equipped with a bright overhead light. CatWalk XT however, utilizes a dim red light that minimizes stress for the test animal, thus reducing the side-effects of the testing method.
In gait analysis, velocity is a heavily discussed parameter, not only as a research result, but also as a factor that can cause considerable variability in the test results. So, several ways to adjust your results for speed are used. The most obvious is the researcher-induced regulation of speed: a treadmill or treadwheel. The assumption here is that all animals will walk or run at the same speed, but this introduces at least two problems.
Firstly, forced movement does not reflect the actual intrinsic speed of the animal, and forcing a walk or run is extremely stressful for the animal. Since rodents are prey animals and thus not keen on showing potential predators their weakness, a treadmill or wheel may actually disguise the gait abnormality you are investigating. Secondly, animals in a test group might have the same average movement speed, but they typically reach this average by constantly varying their speed on the treadmill. They will have different strategies to keep up, such as jumping or limping.
So we believe in another solution: letting the animals walk freely while measuring real footprints, motivate and guide them, giving them a relatively stress-free environment, and using sophisticated software to correct for speed differences.
Read more about the issue of speed in gait testing in this blog post.
The added value of an efficient workflow in testing and software
When it comes to processing data, gait analysis can be cumbersome. Even if you have said goodbye to the old-fashioned ink-and-paper method, you might still be working with software that makes you work harder, or rather longer, than you need to.
Software is, of course, designed to be accurate, but also efficient. What’s the point of using an automated system if analyzing a couple of seconds of a run takes hours? Or if you have to manually select the ‘good’ parts of a run and classify each print? Those days are long gone with the use of CatWalk XT.
The CatWalk XT system takes into account a stress-free environment, voluntary movement, and motivation to achieve good throughput. Feedback from our customers tells us that animals quickly learn to walk across the corridor in a consistent manner, so it is easy to extract a lot of data from the run videos. Classifying the footprints is done automatically and – at least as importantly – quickly and efficiently. It literally only takes seconds.