Gastric Myoelectric and Motor Activity in Dogs After Isoflurane Anesthesia

To characterize the effects of isoflurane on gastric motility, gastric electrical and contractile activities were assessed in six healthy adult dogs before and after recovery from anesthesia. Baseline recordings (fasting and fed state) were obtained in unanesthetized dogs 8 days after implantation of serosal electrodes and strain-gauge force transducers. After an overnight fast, dogs were anesthetized with 1.3 minimum alveolar concentration (MAC) isoflurane for 4.5 hours (approximately 6 MAC hours). No other anesthetic or sedative drugs were administered. During anesthesia, ventilation was mechanically controlled to maintain arterial carbon dioxide tension at 36 ± 4 mm Hg. Gastric electrical and contractile activities (fasting and fed state) were recorded again 18 hours after recovery from isoflurane anesthesia. Recordings were analyzed to determine gastric slow-wave frequency, presence of slow-wave dysrhythmias, slow-wave propagation velocity, coupling of contractions to slow waves, a motility index based on relative contractile amplitudes, and onset and duration of contractions after a standardized meal. The only variable that was significantly decreased 18 hours after 6 MAC hours of isoflurane anesthesia was the gastric motility index during fasting-state phase III. This decrease was not apparent in the fed-state test periods. Our results suggest that, with the exception of gastric motility index during fasting-state phase III, variables for gastric electrical and contractile activities in dogs are unaffected by isoflurane 18 hours after anesthesia.     

A survey of neurological diseases in horses

SUMMARY: Case records of 450 horses with signs of neurological disease are reviewed. One hundred and nineteen horses with neurological disease due to trauma were examined, of which 60 were due to spinal cord trauma, 47 to brain or cranial nerve trauma and 12 to peripheral nerve trauma. Cervical vertebral fractures/trauma were the most common injury. Basisphenold/basloccipital bone fractures were the most common form of cranial trauma and facial nerve paralysis the most common cranial nerve injury. Eighty-nine horses with neurological disease due to malformation were examined. Cervical vertebral malformation occurred in 83 horses and congenital defects in 6 foals. Neurological disease due to inflammation or infection occurred in 30 horses. The most common disease of this type was meningitis, which occurred in 11 horses and foals. Neoplasms in the CNS caused neurological disease in 8 horses. The final category was miscellaneous neurological disease, which was diagnosed in 204 horses. Diseases in this category included neonatal (28 cases), toxic/metabolic (27 cases), idiopathic (133 cases), degenerative (3 cases) and other neurological diseases (13 cases). The most common condition was idiopathic laryngeal hemiplegia (116 cases).
Where possible, diagnosis relied on a thorough neurological examination with use of ancillary tests in selected cases including rhinolaryngoscopy, radiography, myelography, ophthalmoscopy and cerebrospinal fluid analysis when indicated. In many cases necropsy and histopathological confirmation or diagnosis was necessary.     

Effects of two large doses of equine recombinant growth hormone on clinical, haematological and serum biochemical variables in adult horses

Objective To evaluate the clinical, haematological, and serum biochemical effects of two large doses of recombinant equine growth hormone.
Design Duplicated Latin square.
Sample population
Three Thoroughbred and three Standardbred mares aged between 12 and 17 years.
Procedure Two horses were randomly assigned into one of three groups. On each of three successive days, each horse pair received one of two dosages of growth hormone or a saline placebo so that by the end of the experiment all three horse pairs had received both dosages and the saline placebo. Dose rates selected were 50 μg/kg, and 100 μg/kg. A clinical examination was performed and a venous blood sample drawn for a complete blood count and serum biochemical analysis before administration of growth hormone and at 1, 2, 3, 4, 6, 8 and 24 h after injection. Data were analysed by a repeated measures analysis of variance assessing the effects of dose and time.
Results There was an effect of time on a number of clinical, haematological, and serum biochemical variables. There were significant effects of growth hormone on heart rate and serum glucose concentration but values for both variables remained within the reference range.
Conclusion The results of the present study suggest that equine recombinant growth hormone has a wide margin of safety and show that the single administration of up to five times the recommended dose rate has no significant effects on clinical, haematological, or serum biochemical variables.     

Cardiopulmonary effects of ephedrine in halothane-anesthetized horses

The cardiopulmonary effects of intravenous (i.v.) administration of the sympathomimetic drug ephedrine during two different levels of halothane anesthesia [end-tidal concentration of 1.37% (light anesthesia) and 2.1% (deep anesthesia)] were studied in eight horses. Anesthesia was induced and maintained using only halothane in O2. Ventilation was controlled to maintain a Paco2 of 38-42 mmHg. Following instrumentation and stabilization of the horse at the halothane concentration being studied, baseline measurements of cardiac output (Q), arterial blood pressure (AP), pulmonary artery pressure, heart rate, Pao2, Paco2 and pH were made. Ephedrine was then administered (0.06 mg/kg i.v.) and these measurements repeated at 10, 20, 30, 45 and 60 min after injection. At both doses of halothane there was a significant (P less than 0.05) increase in Q, stroke volume (SV), and systolic AP following ephedrine administration. In addition, at 2.1% halothane, ephedrine administration resulted in a significant (P less than 0.05) increase in mean AP and Pao2 and a decrease in total peripheral resistance. The increase in systolic AP, Q, and SV was significantly (P less than 0.05) greater at 2.1% halothane than at 1.37% halothane. Ephedrine administration to horses during both light and deep halothane anesthesia results in an increase in AP that is due to an increase in Q and SV.     

Role of prokinetic drugs for treatment of postoperative ileus in the horse

All horses undergoing coeliotomy for an acute abdominal crisis are at risk of developing ileus and should receive therapy aimed at promoting gastrointestinal function by restoring fluid and electrolyte balance. Adequate analgesia and prevention against peritonitis, bacteraemia and endotoxaemia should be provided. Horses that at the time of surgery have a strangulating or non-strangulating small intestinal obstruction should be considered to be at greater risk of developing a persistent ileus that is refractory to treatment than those horses with lesions involving the large intestine. In horses considered to be at greater risk of developing a persistent ileus, the use of prokinetic agents should be considered. Agents that may be used to improve gastrointestinal motility include adrenergic receptor antagonists, cholinergic agonists, benzamides, dopamine antagonists, macrolide antimicrobials, opiate receptor agonists and antagonists, somatostatin analogues and local anaesthetics. There are limited studies into the use of these agents in the horse. Until further research provides more information on motility disorders following intestinal surgery and the efficacy of prokinetic agents in this species, only selective use of some of these drugs can be recommended.