Swaab, Megan E.2012-02-132012-02-132011-12https://hdl.handle.net/11299/120528University of Minnesota M.S. December 2011. Major: Veterinary Medicine. Advisors: Troy N. Trumble, DVM, PhD, DACVS. 1 computer file (PDF); viii, 59 pages.Reasons for Performing Study: Previous equine research has combined subjective analysis with kinematic or kinetic data to describe lameness, but has only shown evidence of compensatory mechanisms for only single forelimb and hindlimb lameness, not multiple limb lameness. Objectives: To create a consistent, controlled and immediately reversible lameness using a circumferential hoof clamp technique and measure the resultant changes in ground reaction forces. To compare the changes in ground reaction forces in both the limb(s) in which lameness was induced and in the sound limbs among a variety of individual and multiple-limb lameness scenarios to detect possible patterns in lameness and compensation in the sound limbs. Materials and Methods: Lameness was induced in 8 horses by tightening a circumferential hoof clamp, on an individual forelimb, or hindlimb, an ipsilaterally paired forelimb/hindlimb, a contralaterally paired forelimb/hindlimb, and bilateral forelimbs and hindlimbs. Kinetic analysis was performed with a fore plate prior to (baseline) and after lameness induction. The percent change in ground reaction forces (vertical and longitudinal) from baseline were calculated for all limbs for each lameness scenario. Changes were examined within each of four ground reaction forces (peak vertical force, vertical impulse, breaking impulse and propulsion impulse) to determine whether consistent patterns emerged in the lame limbs or the sound limbs that might indicate compensation. The magnitude of percent change from baseline was also compared between lame and sound limbs. Results: Using the circumferential hoof clamp technique, we were able to induce a consistent, controlled, and immediately reversible grade 2 out of 5 lameness in individual and multiple limbs. In general, peak vertical force, vertical impulse, and braking impulse decreased, and propulsion impulse increased in the lame limb(s). The forelimbs tended to decrease most consistently in the peak vertical force and vertical impulse, while hindlimbs tended decrease most consistently in the braking impulse. The majority of compensation seemed to come from the contralateral limb, directly opposite the lame limb (i.e. the sound forelimb compensated for a lame forelimb, and the sound hindlimb compensated for a lame hindlimb). Compensation tended to occur through increased vertical and braking impulses in the sound limb(s). The magnitude of percent change from baseline was small for the majority of forces, but was consistent and was associated with a visible lameness. Conclusions and Potential Relevance: Definite patterns were seen in ground reaction forces in both lameness and compensation. This information may help equine practitioners understand how horses alter their ground reaction forces in response to single and multiple limb lameness by determining primary versus compensatory change, and to clarify some of the complexities of multiple limb lameness.en-USVeterinary MedicineThesis or Dissertation