Summary The anatomical basis of gas exchange impairment in the anaesthetised horse was studied by computerised tomography (CT; three Shetland ponies) and morphological analysis (one pony and three horses). By means of CT, densities were seen in dependent lung regions early during anaesthesia, both with spontaneous breathing and with mechanical ventilation. The densities remained for some time where they had initially been created when the animal was turned from dorsal to sternal recumbency. Deep insufflation of the lungs reduced the dense area. Gas exchange was impaired roughly in proportion to the dense area. On histological analysis, the densities were atelectatic and congested with blood. Gravimetry showed no more extravascular water per unit lung tissue in the atelectatic than in the ‘normal’ regions, and the blood content was increased only slightly. It is concluded that the horse develops atelectasis in dependent lung regions early during anaesthesia in dorsal recumbency, and that atelectasis is the most likely explanation for the large shunt and impaired arterial oxygenation regularly seen during anaesthesia.

Six hunting dogs were investigated after showing signs of diffuse back pain. In three of the dogs, prodromal signs included coughing. Swelling in the dorsal lumbar region was noted in four of the dogs, but in two there was no visible or palpable swelling. Initial radiographs of the lumbar region were normal in two of the dogs and showed mild to moderate ventral periosteal reactions in the L1 to L4 region in the remaining four. On ultrasonography and magnetic resonance imaging, changes were seen in the sublumbar muscles (e.g., abnormal echogenicity and increased signal intensity) in five dogs examined. Exploratory surgery revealed plant material foreign bodies in the sublumbar muscles in the L1 to L4 region in five of the six dogs. The concurrent infections were caused predominantly by anaerobic bacteria common to the mucous membranes of the oropharyngeal and respiratory tracts. All dogs recovered, with restored hunting ability. The mean follow-up period was five years (range 1.3 to 7.8 years). It is proposed that the plant parts were inhaled, and then migrated along either diaphragmatic crus to lodge in the sublumbar muscles.

Early decompressive laminectomy according to the method previously described (Funkquist, 1962b) has been performed during the period 1963‐66 on a large number of cases of thoraco‐lumbar disc protrusion with paraplegia at the Department of Surgery of the Royal Veterinary College, Stockholm, Sweden. In the author's own cases, twenty‐six of the twenty‐seven dogs operated on (96%) regained their ability to walk. Corresponding figures for the total number of cases operated on (including those of the author) by specially trained surgeons are seventy‐three of eighty‐two or 89%. In control cases treated conservatively twenty‐one of forty‐one dogs (51%) regained walking ability. In the cases operated on as emergencies by operators with mainly a general surgical training, operation results are conspicuously worse (thirty‐one of forty‐nine dogs or 63% regained walking ability). Relapse incidence was at least as high after laminectomy as conservative treatment, the former, as a rule, should be followed by a prophylactic disc evacuation in a subsequent operation. Zusammenfassung. Frühzeitige dekompressive Laminektomie nach der früher beschriebenen Methode (Funkquist, 1962) wurde wahrend der Periode 1963–1966 an einer grossen Zahl Fälle von thoracolumbarem Bandscheibenvorfall mit Paraplegie in der Chirurgischen Abteilung der Königlichen Tierärztlichen Akademie in Stockholm, Schweden, durchgeführt. In den Fällen des Autors erlangten 26 der 27 operierten Hunde (96%) ihre Gehfähigkeit wieder. Die entsprechenden Zahlen (einschliesslich der des Autors) für die Gesamtzahl der von Chirurgen mit Spezialausbildung durchgeführten Operationen sind 73 von 82 oder 89%. In den konservativ behandelten Kontrollfällen erhielten 21 von 41 Hunden (51%) ihre Gehfähigkeit zurück. Bei solchen Fällen, die als Notoperationen von Chirurgen hauptsächlich mit allgemeiner chirurgischer Ausbildung behandelt wurden, waren die Operationsergebnisse auffallig schlechter (31 von 49 Hunden oder 63% erhielten die Gehfähigkeit zurück). Da die Rückfallhäufigkeit nach Laminektomie mindestens so hoch ist wie nach konservativer Behandlung, sollte sich an die erstere in der Regel eine prophylaktische Bandscheibenevakuation in einrr späteren Operation anschliessen. Résumé. Une laminectomie précoce de décompression d'après la technique décrite antérieurement (Funkquist, 1962b), a été effectuée au cows de la période de 1963 à 1966 dans un grand nombre de cas de protrusion des disques thoraco‐lombaires avec paraplégie au Département de Chirurgie, Veterinary College de Stockholm (Suède). Parmi les cas personnels de l'auteur 26 chiens sur 27 (soit 96%) ont pu remarcher. Le nombre correspondant pour la totalité des cas opérés (y compris ceux de l'auteur) par des chirurgiens entraînés était de 73 sur 82 chiens, soit 89% des cas. Pour les cas témoins la proportion des animaux traités conservativement et ayant pu remarcher, était de 21 sur 41 (51%). Dans les cas opérés en urgence par des opérateurs entraînés surtout en chirurgie générale, les résultats de l'opération...

Summary The multiple inert gas elimination technique was adapted for use in the conscious standing horse. The modifications included increased infusion rate of the inert gases (30 ml/min), extended infusion time (60 mins) in order to reach steady state, and construction of a nose mask mixing box system for collection of expired gas. Eight adult horses with a mean weight of 454 kg and a mean age of 6.1 years were studied while standing under resting conditions. Ventilation was 65.2 litres/min and cardiac output measured by thermodilution 40.2 litres/min. Systemic and pulmonary artery mean pressures were 114 and 26 mmHg, respectively. Three horses showed a unimodal V̇A/Q̇ distribution centred upon a mean V̇A/Q̇ of one. Five horses had a bimodal distribution with an additional high V̇A/Q̇ mode comprising 2 to 18 per cent of ventilation. The mean logarithmic standard deviation of perfusion was 0.41. There was no perfusion of Mow' V̇A/Q̇ regions, but minor shunting on an average of 1 per cent was noted. Inert gas dead space (minus apparatus dead space) averaged 38 per cent of total ventilation. Arterial oxygen tension varied from 11 to 14 kPa and the mean arterial CO2 tension was 5.7 kPa. It is concluded that the standing horse in general has a good match between ventilation and perfusion but that some individuals display high V̇A/Q̇ regions, possibly explained by poor perfusion of upper lung regions.

SUMMARY In dogs that had survived attacks of gastric torsion, X‐ray examination after subsidence of the acute symptoms usually disclosed retarded emptying of the stomach with normal or, in some cases, hyperactive motility, apparently due to pyloric sphincter dysfunction. On the basis of these findings it is hypothesized that torsion should be regarded as the final stage of a chronic dilatation of the stomach stemming from the deranged emptying mechanism. Intensive nonsurgical management of the acute phase, with evacuation of the stomach via trocarization and repeated introduction of a stout gastric tube, appears superior to primary surgical treatment insofar as the early results are concerned. The abovementioned roentgenologic observation has led the authors to try, in the hope of preventing recurrences, operative correction of the disordered emptying mechanism by means of gastrojejunostomy or pyloroplasty. As yet the series is too small and the follow‐up times too short for therapeutic evaluation of these surgical procedures.

The effect of selective mechanical ventilation of dependent lung regions were studied in anaesthetized horses (mean weight 486 kg) in dorsal recumbency. Blood-gas measurements were performed with the horse in the lateral position during spontaneous breathing (before selective intubation) and in dorsal recumbency during spontaneous breathing, general mechanical ventilation, and spontaneous breathing + selective mechanical ventilation. Arterial oxygen tension (PaO2) was 32.3 kPa in the lateral position during spontaneous breathing with a high inspired oxygen fraction (FlO2 greater than 92%). In dorsal recumbency PaO2 decreased to 10.9 kPa during spontaneous breathing and was not significantly affected by general mechanical ventilation (PaO2 12.6 kPa). The institution of selective mechanical ventilation with a selective positive end-expiratory pressure (PEEP) of 20 cm H2O caused a marked increase in PaO2 to an average of 35.3 kPa. It is concluded that selective intubation of dependent regions in the diaphragmatic lobes is a feasible procedure and that selective mechanical ventilation with PEEP markedly improves arterial oxygenation in the anaesthetized horse in dorsal recumbency.

No abstract

No abstract