Abstract: Functional stimulus equivalence has been demonstrated using a transfer of training design with matching-to-sample training in which two sample stimuli are associated with the same comparison stimulus (A-B, C-B; many-to-one matching). Equivalence is shown by training a new association (A-D) and demonstrating the presence of an emergent relation (C-D). In the present experiment, we show that symmetry training, in which a bidirectional association is trained between two stimuli (A-B, B-A, using successive stimulus presentations followed by reinforcement), can also produce functional equivalence using a transfer of training design (i.e., train B-C, test A-C). The results suggest that training pigeons in the substitutability of two stimuli may be sufficient to produce functional stimulus equivalence between them. The results also have implications for the development of an emergent transitive relation, because training on A-B and B-C relations results in the emergence of an untrained A-C relation, if B-A training also is provided.

Abstract: OBJECTIVE: To describe clinical findings, ultrasonographic features and outcome of injury to the branches of insertion of the superficial digital flexor (SDF) tendon in horses. DESIGN: Retrospective study of 14 cases. PROCEDURE: Fourteen Thoroughbred horses with tendonitis affecting the branches of insertion of the SDF tendon were examined for lameness, location and amount of swelling, and the presence of other musculoskeletal abnormalities. The flexor tendons were assessed by ultrasonographic examination, and recommendations were made for management of the cases. Outcome was assessed by re-examination of some horses, direct communication with the owner or trainer, and examination of race records. RESULTS: The lateral SDF branch was affected in 10 horses; the medial branch in three, and both branches in one horse. Two horses had concurrent injuries to the SDF tendon in the metacarpal region of the contralateral limb. Ultrasonographic findings included swelling of the affected SDF branch, peritendinous fluid accumulation, disruption of normal fibre alignment on sagittal scan, and variable loss of echogenicity. As healing occurred, there was return of normal echogenicity, but normal fibre alignment did not return completely and apparent adhesions formed between the affected SDF branch and adjacent structures. Seven of 10 horses which returned to their previous use were able to compete without further tendon injury. Recurrence of injury occurred in one case, and another two horses developed tendonitis in the metacarpal region. One horse was retired from racing but was able to compete at dressage without recurrence of injury. Two horses were retired for breeding without returning to training, and one horse was sold and lost to follow up but did not race. CONCLUSION: The prognosis is fair for return to previous use following injury to the branches of insertion of the SDF tendon in athletic horses.

Abstract: The objective of this study was to compare the stress response of horses suffering from laminitis after short- and long-term treatment with the intent to evaluate power spectral analysis of heart rate variability (HRV) for pain monitoring. Data were collected from 19 horses with acute or chronic exacerbating laminitis without known primary disease before and after treatment with non-steroidal anti-inflammatory drugs (NSAID). Recordings were carried out the day after admission to the equine hospital. Measurements were repeated on day 7 of the treatment. The recorded parameters included a clinical orthopaedic index (OLPI: Obel-grade plus hoof tester score), frequency of weight-shifting between contralateral limbs, mean beat-to-beat interval (R-R) duration, standard deviation of continuous R-R intervals, low- (LF) and high-frequency (HF) components of HRV, sympatho-vagal balance (LF/HF), and plasma concentration of cortisol, adrenalin and noradrenalin. The LF represents mainly sympathetic influences on the heart whereas HF is mediated by the parasympathetic tone. Weight-shifting and OLPI decreased significantly with treatment. The LF normalized units (n.u.) decreased after NSAID from 60.41 +/- 21.42 to 51.12 +/- 19.81 and was 49.33 +/- 22.64 on day 7, whereas HF n.u. increased from 35.07 +/- 20.02 to 43.14 +/- 18.30 and was 45.98 +/- 23.00 on day 7. Hormone levels showed no tendency to change with treatment. The OLPI was only correlated with LF/HF, LF and HF (R = 0.57, 0.55 and -0.54 respectively). Significant negative correlations existed between HFn.u. and weight-shifting frequency (R = -0.37), HFn.u. and adrenalin (R = -0.47), and HFn.u. and noradrenalin (R = 0.33). The LFn.u. only correlated positively with adrenalin. Cortisol levels were poorly associated with the other parameters. Determination of the sympatho-vagal influences on cardiac function may offer complementary information for reliable assessment of pain and may represent a valuable alternative method to catecholamine measurements.

Abstract: The objective of this study was to investigate the effect of routine dental occlusal equilibration treatment on dressage horse performance. Sixteen horses (11 treated; 5 untreated) ridden by a single rider performed a standardized dressage test twice and were scored by two experienced dressage judges according to recognized movements and rider cues. All horses were sedated and a full-mouth speculum was used to facilitate a complete oral examination. Treated horses had dental equilibration performed using a motorized dental instrument. The horses performed a second test 48-hours after dental equilibration, exactly as the baseline test, with the judges and rider blinded as to treatment group. The total test score as well as the individual movement scores were evaluated for equality of variance and statistical tests were applied to determine the influence of treatment. There was no significant improvement in the test score of horses that had received occlusal equilibration.

Abstract: The purpose of this study was to evaluate the effects of speed and slope on the activity of trunk muscles. The electromyographic (EMG) activity of the splenius (Sp), longissimus dorsi (LD) and rectus abdominis (RA) muscles was recorded with surface electrodes during treadmill locomotion at trot for different combinations of speed (3.5 to 6 m/s) and slope (0 to 6%). Raw EMG signals were processed to determine activity duration, onset and end and integrated EMG (IEMG). For the 3 muscles investigated, onset and end of activity were obtained earlier in the stride cycle when speed increased. A longer duration of activity for the LD, a shorter duration for the RA and an unchanged duration for the Sp were also observed. The IEMG of the latter was poorly affected by speed, whereas it increased linearly with speed for the 2 other muscles. When treadmill inclination changed from 0 to 6%, EMG activity of the LD and RA began and ended later; a longer activity duration was noted. Temporal parameters for Sp did not change with slope. A significant and progressive increase in the IEMG of the 3 muscles was observed with increasing slope. This evaluation of the activity of trunk muscles provides objective data for the use of speed or slope in training programmes.