Stadig SM, Bergh KA. Gait and jump analysis in healthy cats using a pressure mat system. J Feline Med Surg. 2015 Jun;17(6):523-529.
In recent years, there are several publications showing osteoarthritis is common, but underdiagnosed, in older cats. Veterinarians are presented with a challenge in determining when cats are painful due to osteoarthritis. A large number of cats that have chronic pain do not exhibit visual signs of lameness upon physical examination and a gait analysis method has not been standardized yet for the species. There is a significant need to establish validated and reliable methods for objective gait analysis in cats.
The aims of this study were to determine the correct parameters for pressure mat analyses during a walk and a jump in cats, and to also determine the reference values for gait parameters in healthy cats. For the pressure mat to be a diagnostic tool, the authors needed to ensure that the data received from the cats is reproducible and reliable. They hypothesized that healthy cats have a symmetrical gait, a front/hindlimb asymmetry similar to health dogs and that their gait parameters peak vertical force (PVF) and vertical impulse (VI) have high intraclass correlation coefficients (ICCs) – used as a measure of the accuracy of gait parameters.
Fifty-eight clinically sound client-owned cats were enrolled in the study. Of the 58 cats, 74% were domestic shorthairs and 26% were purebred (such as Somalis, Burmese, Birmans, Ragdolls, and Norwegian Forest Cats). Each cat during data collection was filmed from the front, back and side. Videotaping enabled detailed studies of the nature of the walk and jump, while also allowing visualizing the possible influence of a non-centered head positioning (both eyes being visible from the side in video recordings) on weight distribution. In analyzing the jumps, sixteen cats produced 55 valid jumps. When looking at the front paws solely, the cats landed with both front paws simultaneously in 89% of the jumps. When looking at all four paws, the cats landed with the front paws simultaneously and the hind paws simultaneously in 65% of jumps. The difference in time between when the front paws and the hind paws hitting the ground was 0.12 ± 0.02 s.
The results showed that PVF (% BW) and VI (% BW*sec) are the most reliable gait parameters and healthy cats have similar gait symmetry to health dogs. Orthopedic disease is known to redistribute the body weight (BW) supported by the limbs in dogs and cats, but is considered usually hard to detect visually. There are no studies known on weight distribution within the paws of cats. This study’s results will help our ability to make the best use of diagnostics and monitor possible improvements of different therapies utilized. The majority of the cats (a healthy population) that jumped landed with both front paws horizontally, and that they landed with the hind paws symmetrically in relation to the front paws. In evaluating the distribution of vertical force within the paw demonstrated that the main weight during a (landing) strike is from the back (caudal) to the front-inside portion of the paw (craniomedial). Measuring the time between the front and hind paws touching the ground can offer additional indications for a diagnosis of painful osteoarthritis in affected cats.
A thorough orthopedic examination and detailed quality of life questionnaires are useful tools, but their sensitivity of being able to detect subclinical or undiagnosed osteoarthritis is very low. Radiography is also an important tool in the diagnosis of osteoarthritis, yet radiographically normal joints can still have pathological changes. The pressure mat appears to be a promising objective tool that aids in the diagnosis of osteoarthritis in cats. (VT)