Amphotericin B-induced synovitis of the left tarsocrural joint was used to create a grade 3 of 4 lameness in 11 horses. Caudal epidural catheters were placed and advanced to the lumbosacral region. Baseline heart and respiratory rates were recorded and horses were videotaped at a walk and trot. Morphine sulphate (0.2 mg/kg) and detomidine hydrochloride (30 micrograms/kg) were administered to treated horses (n = 8) through the epidural catheter; an equivalent volume of physiologic saline solution was administered to control horses (n = 3) through the catheter. At hourly intervals after epidural injection for a total of 6 hours, heart and respiratory rates were recorded, and horses were videotaped walking and trotting. At the end of the observation period, video recordings were scrambled onto a master videotape. Lamenesses were scored by three investigators unaware of group assignment or treatment time. Lameness scores, heart rates, and respiratory rates were compared between groups using repeated measures analysis of variance. There was a significant decrease in lameness score after treatment with epidural morphine and detomidine (P = .0003); average lameness scores of treated horses were less than grade 1 at each hourly observation for 6 hours after drug administration. Early in the observation period, heart rates significantly increased in control horses and decreased in treated horses (P = .03). A similar trend occurred for respiratory rates (P = .07). Results of this study demonstrate that epidural administration of a combination of morphine and detomidine is capable of providing profound hindlimb analgesia in horses.

1. Histamine contracted the tracheal and major bronchial muscles of sheep and relaxed the muscles of the lesser bronchi and bronchioles. 2. The stimulant action of histamine on the trachea was antagonized by mepyramine, whereas the relaxant effect on the bronchial tree was not. 3. 5-Hydroxytryptamine contracted the musculature from all parts of the respiratory tract-an effect which was specifically antagonized by both methysergide and atropine. 4. Acetylcholine contracted all sheep tracheobronchial muscle and isoprenaline relaxed it. 5. Bradykinin had a very weak stimulant action. 6. It is concluded that histamine relaxes sheep bronchi by a direct excitation of histamine-sensitive receptors which are not blocked by mepyramine. No indirect components through autonomic nervous elements or by way of catecholamine release were evident. 5-Hydroxytryptamine seemed to have a dual mode of action in contracting sheep tracheobronchial muscle (a) directly on its own receptors and (b) indirectly through parasympathetic components.The pharmacological actions of histamine, 5-hydroxytryptamine (S-HT) and other agents on the tracheobronchial musculature have been described in many species. In most animals histamine causes contraction of the airway muscle.

The evolution of different colour morphs and how they are maintained in animal populations is poorly understood. We investigated the mechanisms maintaining yellow and brown morphs of a coral-reef fish, Pseudochromis fuscus, at Lizard Island, on the Great Barrier Reef. Histological examination of the gonads revealed that colour morphs were not sex-limited, therefore sexual selection does not appear to promote dichromatism in this species. The field distributions of the two colour morphs were spatially segregated, limiting the opportunity for negative frequency-dependent selection to operate. Our results support another ecological mechanism of coexistence. The yellow morph occurred in deeper areas, usually close to the reef edge, where there was a proportionally high cover of live branching corals. In contrast, the brown morph occurred in shallower areas, more distant from the reef edge, that were proportionally low in live branching corals. Within these habitats, each colour morph of P. fuscus displayed a close association with similar coloured damselfishes from the genus Pomacentrus. The yellow morph was associated with predominantly yellow damselfishes (P. moluccensis and P. amboinensis) and the brown morph with darker coloured species (P. adelus and P. chrysurus). Multiple-choice experiments in the laboratory revealed that: (1) each colour morph of P. fuscus preferentially selected habitat patches occupied by damselfishes with the same colouration; and (2) differences in microhabitat use between the two colour morphs of P. fuscus were due to the presence of different coloured damselfishes in these microhabitats. P. fuscus is a predator of newly recruited damselfishes and the striking resemblance between each morph of P. fuscus and the damselfish with which it was associated, suggests that aggressive mimicry may promote coexistence of P. fuscus colour morphs.

Vascular (pulmonary and hepatic blood vessels) and nonvascular (gastro-intestinal, reproductive and respiratory systems) smooth muscle preparations obtained from specifically sensitized animals of numerous species including man contract to specific antigen in vitro (Schultz-Dale phenomenon). This immunopharmacological technique is a useful tool to demonstrate immediate-type hypersensitivity in actively or passively sensitized tissues and may be used to investigate the nature of the principal pharmacological mediators involved in a particular tissue as well as to screen anti-anaphylactic (anti-allergic) drugs. However, much remains to be investigated on the complex mechanisms of action of antigen, desensitization and resensitization (recovery) of anaphylactic responsiveness.