SUMMARY1. In chloralose-anaesthetized cats, the impulse activity of single afferent units conducting at less than 30 m sol and having receptive fields in the triceps surae muscle or the calcaneal tendon, was recorded from thin filaments of the dorsal roots L7 and SI. The receptive fields of the units were tested with a variety of graded natural stimuli (local pressure, stretch, contractions, temperature changes). In addition, the algesic agent bradykinin was injected into the receptive fields, but the sensitivity of the receptors to this substance was not used for classification purposes.2. Four types of receptors could be distinguished using the strongest response to innocuous natural stimulation as the criterion for characterizing a given ending: (a) nociceptors showing no response to innocuous forms of stimulation and requiring noxious (tissue-threatening) stimuli to be clearly activated; (b) low-threshold pressuresensitive receptors responding to innocuous indentation of the tissue but being relatively insensitive to stretch and contractions; (c) contraction-sensitive receptors reaching high discharge frequencies during active contractions of moderate force and innocuous stretch, but being relatively insensitive to local pressure stimulation; (d) thermosensitive receptors responding strongly to small changes in temperature without reacting to innocuous mechanical stimulation.3. The possible involvement of the different receptor types in central nervous functions (nociception, mechanoreception, ergoreception, thermoregulation) is discussed.

Despite technical advances in implant material, design, and instrumentation, plate fixation of metacarpal fractures remains fraught with complications and unsatisfactory results.

SUMMARYPortosystemic shunts were ligated over a gauged stainless steel rod in 160 dogs and 15 cats, using a midline celiotomy. The diameter of the rod varied with the size of the shunt and the diameter of the portal vein cranial to the shunt. Shunts were narrowed to the smallest diameter that did not cause signs of portal hypertension such as cyanosis of the stomach, pancreas, and small intestine. A slight discoloration was accepted only if the heart rate, end-expiratory CO2%, or arterial blood pressure (if available) did not deviate more than 15% from the values that were recorded at the beginning of the surgical procedure. The perioperative mortality (0-30 days) was 29%. The most common cause of death was euthanasia because of hypoplasia of the portal vein cranial to the shunt. Animals with intrahepatic shunts had a significantly lower probability of survival than animals with extrahepatic portocaval or portoazygos shunts. In dogs, large breed and a high body weight were also significant risk factors for non-survival. Age had a significant effect on risk of non-survival, with an increased risk for older dogs, irrespective of the breed of the dog (large breed vs. small breed). The probability of survival without recurrence of hepatoencephalopathy (HE) after 1 and 4 years was 61.3% and 55.7%, respectively. The only variable that was significantly associated with non-recurrence of HE was the breed of the dog, there being a lower probability for large breeds. Among the animals that survived surgery for more than 30 days, there was a significant higher probability of recurrence of HE in cats than in dogs.

This study provides quantitative data on the effect of head/neck positions on thoracolumbar motion and may help in discussions on the ethical acceptability of some training methods.

Summary Reasons for performing study: Little is known in quantitative terms about the influence of different head‐neck positions (HNPs) on the loading pattern of the locomotor apparatus. Therefore it is difficult to predict whether a specific riding technique is beneficial for the horse or if it may increase the risk for injury. Objective: To improve the understanding of forelimb‐hindlimb balance and its underlying temporal changes in relation to different head and neck positions. Methods: Vertical ground reaction force and time parameters of each limb were measured in 7 high level dressage horses while being ridden at walk and trot on an instrumented treadmill in 6 predetermined HNPs: HNP1 ‐ free, unrestrained with loose reins; HNP2 ‐ neck raised, bridge of the nose in front of the vertical; HNP3 ‐ neck raised, bridge of the nose behind the vertical; HNP4 ‐ neck lowered and flexed, bridge of the nose considerably behind the vertical; HNP5 ‐ neck extremely elevated and bridge of the nose considerably in front of the vertical; HNP6 ‐ neck and head extended forward and downward. Positions were judged by a qualified dressage judge. HNPs were assessed by comparing the data to a velocity‐matched reference HNP (HNP2). Differences were tested using paired t test or Wilcoxon signed rank test (P<0.05). Results: At the walk, stride duration and overreach distance increased in HNP1, but decreased in HNP3 and HNP5. Stride impulse was shifted to the forehand in HNP1 and HNP6, but shifted to the hindquarters in HNP5. At the trot, stride duration increased in HNP4 and HNP5. Overreach distance was shorter in HNP4. Stride impulse shifted to the hindquarters in HNP5. In HNP1 peak forces decreased in the forelimbs; in HNP5 peak forces increased in fore‐ and hindlimbs. Conclusions: HNP5 had the biggest impact on limb timing and load distribution and behaved inversely to HNP1 and HNP6. Shortening of forelimb stance duration in HNP5 increased peak forces although the percentage of stride impulse carried by the forelimbs decreased. Potential relevance: An extremely high HNP affects functionality much more than an extremely low neck.