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The incidence of post-anesthetic lameness in 655 horses undergoing 733 anesthetic episodes over a 3 year period was 6.4%. Nineteen factors previously reported or proposed to play a role in the development of post-anesthetic lameness were evaluated statistically. Only hypotension and the duration of the anesthetic period were significant factors.

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The porcine stress syndrome is a genetic disorder of swine which, like neuroleptic malignant syndrome, is characterized by hyperthermia, muscle rigidity, and autonomic dysfunction. We investigated the porcine stress syndrome as a possible animal model for neuroleptic malignant syndrome in two ways. First, we administered haloperidol and lithium carbonate, alone and in combination, to susceptible and resistant swine. Second, we attempted to prevent the syndrome by pretreating animals with bromocriptine. Porcine stress syndrome was induced in 2 of 3 susceptible and 1 of 3 resistant swine by combined treatment with lithium and haloperidol, but was not triggered by treatment with lithium or haloperidol alone. Pretreatment with bromocriptine conferred no protection against the syndrome.

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The pharmacokinetics of dantrolene sodium were investigated in horses following both intravenous (2 mg/kg) and intragastric (4 mg/kg) administration. Two ponies also received dantrolene sodium intravenously (2 mg/kg) in a pilot study to obtain preliminary kinetic data and to determine urinary and biliary excretion of the intact drug. Distribution and elimination of dantrolene was rapid, resulting in an elimination half-life of 129 +/- 8 (SEM) min and a whole body clearance of 4.16 +/- 0.52 ml/min/kg. Following intragastric administration, dantrolene rapidly acheived peak concentrations within 1.5 h, but was incompletely absorbed, with a bioavailability of 39 +/- 10%. Small amounts of intact drug were recovered in urine and bile. Based upon disposition kinetics of dantrolene in these studies, intravenous and intragastric dosage regimens were determined which would maintain blood dantrolene concentrations within the predicted clinically effective range.

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Two hundred and seven boars entering a Record of Performance Test Station at New Hamburg, Ontario were screened for susceptibility to malignant hyperthermia or the porcine stress syndrome. Screening tests included the determination of whole blood creatine kinase levels by a commercially available test using the method of bioluminescence and a halothane challenge. The validity of the bioluminescent or whole blood creatine kinase test as a screening mechanism for malignant hyperthermia was evaluated in boars in a field trial. The susceptibility of these animals to malignant hyperthermia or the porcine stress syndrome was unknown at the time of the study. It was determined in the initial field trial that 76.3% or 158 of the 207 boars tested by the bioluminescent creatine kinase screening test were stress susceptible. In contrast, only one boar (0.5%) reacted to a standard five minute halothane challenge. After further examination of the commercial screening test, little correlation was found to exist between the bioluminescent and Rosalki methods of creatine kinase determination. The coefficient of analytical variation for the bioluminescent method of creatine kinase determination ranged from 17.6% at a mean of 359 LU to 21.9% at a mean of 318 LU. Similarly, the coefficient for the Rosalki technique ranged from 7.1% at a mean of 324 U/L to 14.0% at a mean of 64 U/L. In addition, little correlation was found to exist between creatine kinase levels as determined by the bioluminescent method and outcome to the halothane or halothane/succinylcholine challenge, age of boars in weeks or percentage gain in weight.(ABSTRACT TRUNCATED AT 250 WORDS)

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In addition to receiving treatment for the primary disease, patients with advanced respiratory disorders may benefit from other forms of respiratory support. This article discusses three techniques of inhalation therapy that will aid in maintaining an optimal pulmonary environment and in normalizing arterial oxygenation. The role of aerosol therapy in direct intrapulmonary administration of pharmaceuticals is also discussed.

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This paper recounts a study of the prevalence of malignant hyperthermia in a population of boars entering the Record of Performance Test Station at New Hamburg, Ontario over a period of ten months. The literature is briefly reviewed and an account of the present status of malignant hyperthermia (porcine stress syndrome) in Ontario boars using the halothane or halothane/succinylcholine screening tests is presented. It was determined in this population of boars that there was a 1.5% prevalence rate of malignant hyperthermia susceptible boars. This was based on a five minute halothane challenge carried out on 786 boars from 107 herds. The halothane reactors came from a total of eight herds or 7.5% of the total number of herds. A majority of 58.3% of the animals reacted after the three minute mark of the halothane challenge. In contrast, an 18.0% prevalence rate was determined using halothane/succinylcholine challenge on 123 boars. This further identified an additional eight herds with the problem, bringing the total to 16 or 15% of the total number of herds. It is suggested that the prevalence of malignant hyperthermia in Ontario breeding herds is much higher than was originally thought and that the halothane challenge is an inadequate screening test for this trait if the intention is to remove the genetic trait from the breeding herd. At the same time halothane challenge testing will identify those animals which have a strong susceptibility to the trait and if used on key breeding stock will help to maintain some control on the condition until a more definitive test is readily available.(ABSTRACT TRUNCATED AT 250 WORDS)

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