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Distal forelimb lameness is very common in horses around the world. The crucial part of a lameness examination is to localize the source of the pain. A practical and objective forelimb lameness evaluating tool without bias is needed to support clinical research study. Using a body-mounted inertial sensor system-based method in this clinical research study had two purposes: (1) to objectively assess the effect of different techniques of diagnostic anesthesia used in the feet of horses with forelimb lameness and (2) to compare these findings with the subjective assessment of veterinarians with different levels of experience.
A total of fifty-four horses with forelimb lameness were presented to the Equine Clinic, Free University Berlin, between March 2012 and June 2013. Complete standard lameness evaluations were performed for all horses; trotting the horse in a straight line was the method used for data collection. Owner permission for collection of body-mounted inertial data, video recording, and for its use in this study was obtained for every case. This clinical study was divided into two projects. The first project was Use of body-mounted inertial sensors to objectively evaluate the response to perineural analgesia of the distal limb and intra-articular analgesia of the distal interphalangeal joint in horses with forelimb lameness. It was published in Journal Equine Veterinary Science, 34 (2014) 972-977. There were six co-authors, of which was Porrakote Rungsri was the primary author.
Twenty-two horses (12 Warmbloods, 3 Standardbred Trotters, 3 Ponies, 1 Thoroughbred, 1 Friesian, 1 Fjord and 1 mixed Arabian) aged between 4-25 years old (mean = 14) were selected for the first project as follows: Each had (1) lameness in a forelimb when trotted on a straight line on a hard surface on both day 1 and day 2 of the study and (2) positive response to perineural analgesia of the foot. The Horses were divided into two groups. Horses with definitive decrease in lameness after only the PD block were designated as group 1. Horses with definitive decrease in lameness after only the AS block (after failure of the PD block to decrease lameness) were designated as group 2. Amplitude of lameness improvement after blocking was determined as a percentage decrease in VS from the baseline (before block) evaluation. Improvement in lameness after blocking was examined using the Friedman’s test with the percentage of improvement (dependent variable) and the blocking procedure (independent variable) (i.e. PD, AS, DIP2, DIP5, and DIP10).
The second project was Agreement between a body-mounted inertial sensors system and subjective observational analysis when evaluating lameness degree and diagnostic analgesia response in horses with forelimb lameness. It was published in Pferdeheilkunde, 30 (2014) 644-650. There were seven co-authors, of which was Porrakote Rungsri was also the primary authors. In the project study, 24 horses (12 Warmbloods, 5 Standardbred Trotters, 5 Ponies, 1 Thoroughbred, and 1 Appaloosa) aged between 4-24 years old (mean = 13.7) were used to assess lameness on a straight line before and after diagnostic anaesthesia by body-mounted inertial sensor systems and by two experienced veterinarians. For further study, video clip test units (n = 101) of all the trials were used. The lameness evaluators were blinded from the results of the BMISS. The inter-observers agreement and agreement of lameness evaluation between the BMISS and observers were classified into three categories: 1) right forelimb lameness or right forelimb lameness greater than left forelimb lameness, 2) left forelimb lameness or left forelimb lameness greater than right forelimb lameness, and 3) sound or equal right and left forelimb lameness. The Kappa statistic (κ), percentage of inter-observers agreement, and agreement between BMISS and subjective system (examiners opinion) were reported. The response of anaesthesia agreement was determined by six categories between body-mounted inertial sensors system and highly- experienced observers. This data was analyzed by calculation of the Kendall’s tau (Ƭβ) test.
For the conclusion of the first study, the results indicated that the intra-articular anaesthesia of the DIP joint using low volumes of local anaesthetic solution desensitizes a different region than the perineural analgesia of the digit. Moreover, the time-dependent gradual improvement of lameness observed in some patients suggests that the diffusion of the local anaesthetic plays an important role in the pain abolishment of the lameness in the foot; therefore, early re-evaluation of the lameness after 2 and 5 minutes is recommended to further differentiate the source of pain. Larger clinical studies with advanced imaging modalities should be performed to determine if there is a correlation between the time-dependent blocking pattern of the DIP joint and the pathological findings in the foot.
The second study indicated that the detection of mild to moderate lameness and response to regional or joint anaesthesia of horses obtained by use of a body-mounted inertial sensor system-based system did significantly agree with the subjective system, but variation of subjective lameness evaluation was based on experience. This study supports that the body-mounted inertial sensors system can be a practical tool for objective lameness detection and the effects of regional or joint anaesthesia in horses in clinical situation without bias.