Halothane and halothane/succinylcholine induced malignant hyperthermia (porcine stress syndrome) in a population of Ontario boars.

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)     

Activities of some serum enzymes in halothane reacted and non-reacted pigs

Eight- and nine-week-old Hungarian Landrace pigs were tested with halothane as described by Laky et al. (1985). Immediately after the test blood samples were taken for determination of the activity of serum creatine kinase (CK), creatine kinase MB (CK-MB) isoenzyme, aldolase (ALD), lactate dehydrogenase (LDH) and alpha-hydroxybutyrate dehydrogenase (alpha-HBDH). Elevated creatine kinase, creatine kinase MB isoenzyme and aldolase activities indicating enhanced susceptibility to stressors were found in 92% of the halothane reacted and 16% of the halothane non-reacted animals. In these individuals the activities of lactate dehydrogenase and alpha-hydroxybutyrate dehydrogenase were also high. Data of the literature show a close relationship between enhanced susceptibility to stressors and halothane reaction in pigs. It was suggested, therefore, that determination of the activity of appropriate serum enzymes might be used for detecting this enhanced susceptibility.     

Porcine malignant hyperthermia susceptibility: erythrocytic osmotic fragility

Erythrocyte osmotic fragility was determined in 27 Pietrain swine which were susceptible to malignant hyperthermia (MH), 29 Yorkshire swine which were resistant to MH (controls), and 50 crossbred swine (Pietrain x Yorkshire), half of which were MH susceptible. Halothane challenge tests and blood creatine kinase activity were used as criteria for determining MH susceptibility. Mean values for osmotic fragility of erythrocytes in concentrations of NaCl between 60 and 120 mM were significantly different for the 3 groups (P less than 0.001). Hemolysis (50%) of erythrocytes occurred at NaCl concentrations of 90 mM for Pietrains, 85 mM for crossbreds, and 78 mM for controls. Increased fragility values occurred in 96% of the Pietrains, 3% of the controls, and 42% of crossbred swine that were halothane test-positive, and 58% of halothane test-negative crossbreds (P less than 0.05). The mean time of onset of signs of MH in response to halothane challenge testing was twice as long in the crossbreds as in Pietrains (P less than 0.01). Reticulocyte counts were moderately high in blood samples from both the Pietrains (P less than 0.001) and the crossbreds (P less than 0.05). Of the swine which were tested for erythrocyte selenium-dependent glutathione peroxidase activity, values were within acceptable laboratory limits in 18 of 20 Pietrains, 14 of 14 halothane test-negative crossbreds, and 8 of 8 halothane test-positive crossbreds. In 2 of 20 Pietrains, a 35% deficiency of this enzyme was found. Heinz bodies were not detected in erythrocytes examined from 21 Pietrains, 20 crossbred swine (8 halothane test positives), and 12 controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Canine malignant hyperthermia: diagnosis of susceptibility in a breeding colony

Fifteen related dogs were studied for susceptibility to malignant hyperthermia using halothane challenge and caffeine contracture tests. These dogs had hypertrophied muscles, were of a nervous temperament and had rectal temperatures at the upper limit of the normal range. Clinical pathology findings were mild elevations of serum aspartate transaminase and mean corpuscular hemoglobin. In vitro caffeine contracture tests were performed on muscle biopsies from five of these dogs. The concentration of caffeine required to increase resting tension by 1 g in biopsy specimens of these dogs was significantly lower than that required for control dogs: 7.6 ± 1.38 ( ± SEM) versus 15.5 ± 2.52 mM (P < 0.025), and in the presence of 1% halothane, 3.6 ± 1.44 versus 10.6 ± 2.19 mM (P < 0.05). Internal nuclei, fiber caliber variation and fiber hypertrophy were found in histological studies of muscle biopsies. Two other dogs possibly died of a canine stress syndrome analagous to the porcine stress syndrome which occurs in malignant hyperthermia susceptible swine. Eight others of this family were anesthetized with halothane or methoxyflurane. Methoxyflurane did not trigger the syndrome. The first exposure to halothane caused death from malignant hyperthermia in two dogs and a third died on the second exposure to halothane. Postmortem findings were nonspecific. The other three dogs exposed to halothane recovered uneventfully. Inheritance of the defect conforms to a multifactorial pattern, with gradations of susceptibility.     

Canine stress syndrome/malignant hyperthermia susceptibility: calcium-homeostasis defect in muscle and lymphocytes

This study provides the first comprehensive characterisation of the calcium (Ca) homeostasis defects found in muscle and lymphocytes of a malignant hyperthermia (MH)-susceptible dog. Novel findings regarding this dog are reported, compared to controls. First, a canine stress syndrome occurs, analogous to the porcine stress syndrome; susceptibility can be identified by exercise challenge testing. Secondly, caffeine causes Ca release from muscle sarcoplasmic reticulum in a greater amount and at a greater rate. Thirdly, there is a compensatory increase in Ca sequestration by sarcoplasmic reticulum. Fourthly, lymphocytes have lower cytosolic-free Ca and a greater ability to prevent Ca increase. Halothane increases Ca by a greater amount and rate. Fifthly, muscle is more resistant to the contracture-producing effects of caffeine, as occurs in the non-rigid variant of MH susceptibility in man. This resistance, despite increased caffeine-induced release through the Ca channel, may be attributable to increased Ca sequestration by sarcoplasmic reticulum. Finally, erythrocyte osmotic fragility and creatine kinase tests fail to distinguish between the MH-susceptible dog and controls.     

Erythrocyte osmotic fragility testing and the prediction of canine malignant hyperthermia susceptibility

A Doberman-German Shepherd cross-bred male dog, previously diagnosed as malignant hyperthermia susceptible, was mated to an unrelated nonsusceptible German Shepherd cross-bred female. The resultant litter was subjected to hematological, biochemical and erythrocyte osmotic fragility testing in an endeavor to predict the susceptibility of individuals to malignant hyperthermia. Laboratory evaluations were repeated at one year of age and the litter subjected to the halothane challenge test. No significant difference in erythrocyte osmotic fragility was found between malignant hyperthermia susceptible and nonsusceptible siblings at six weeks or at one year of age. Erythrocyte osmotic fragility, in both malignant hyperthermia susceptible and nonsusceptible animals, increased between six weeks and one year of age. Dantrolene sodium was an effective treatment for malignant hyperthermia in the dog when administered early in an episode and in adequate dosage. The initial sign of a malignant hyperthermia episode was a very rapid increase in end tidal partial pressure of carbon dioxide. This finding reinforces the value of capnographic monitoring in anesthesia.     

应用聚合酶链式反应(PCR)技术检测野猪的氟烷基因

猪应激综合征(Procine Stress Syndrome,PSS)是指猪在应激因子的作用下发生恶性高热综合症(Malignant Hyperthermia Syndrome，MHS)。试验随机选取18头纯种野猪提取基因组DNA进行聚合酶链式反应，扩增得到RYR。基因特异片段，经过HhaⅠ酶切阳性鉴定可断定这18头猪的RYR1基因都没有发生突变，因此不存在猪应激综合征问题。     

The effect of halothane anesthesia on the function of the adrenal cortex and some metabolites in the blood plasma of pigs not susceptible to malignant hyperthermia]

The effects were investigated of a 25-minute inhalation of halothane with oxygen on three to four months old pigs of the Large White breed. Symptoms of malignant hyperthermia did not occur. The actual total anesthesia, which causes slight hypoproteinemia, hypoglycemia and hypocholesterolemia without significant changes in the content of non-esterified fatty acids (NEFA) and urea, induced only a slight increase of circulating 11-hydroxycorticosteroids (11-OHCS). The combination of anesthesia with castration of gilts or barrows significantly increased the concentration of 11-OHCS but did not reach the level recorded after the application of ACTH. The higher levels of 11-OHCS were accompanied by higher concentrations of NEFA and glucose. The treatment of the animals lasting half an hour prior to inhalation of halothane at maximum doses or one hour in the control unanesthetized pigs produced an effect, mainly on the 11-OHCS concentration and on the activity of creatine kinase in the plasma. The results indicate that the adrenocortical response to the effect of halothane is not stronger than the response to simple handling connected with excitement and muscular activity of the animals. Therefore there is no reason of considering halothane anesthesia as a factor causing great stress and pigs which in its course do not respond with malignant hyperthermia as animals insensitive to stress. The aptness of denotation of clinical manifestations of genetically defective muscles in pigs is discussed.     

Postanesthetic equine myopathy suggestive of malignant hyperthermia. A case report

Signs of malignant hyperthermia, including progressive increases in PaCO2, skin temperature and heart rate, and elevated serum levels of potassium, inorganic phosphate, and creatine kinase, were identified in a halothane-anesthetized horse. Treatment was discontinuing halothane administration, applying ice and cold fluids, and hyperventilating with 100% oxygen. After an initial recovery, bilateral hindlimb myopathy and pigmenturia developed. The myopathy resolved after treatment with oral dantrolene, IV fluids, and hydrocortisone. Results of caffeine-halothane challenge, using semimembranosus muscle collected 2 weeks after the episode, were considered within normal limits for horses. The intraoperative abnormalities were evidently predictive of postanesthetic myopathy but the cause in this horse remained unclear.     

Postanesthetic Equine Myopathy Suggestive of Malignant Hyperthermia: A Case Report

Signs of malignant hyperthermia, including progressive increases in PaCO₂, skin temperature and heart rate, and elevated serum levels of potassium, inorganic phosphate, and creatine kinase, were identified in a halothane-anesthetized horse. Treatment was discontinuing halothane administration, applying ice and cold fluids, and hyperventilating with 100% oxygen. After an initial recovery, bilateral hindlimb myopathy and pigmenturia developed. The myopathy resolved after treatment with oral dantrolene, IV fluids, and hydrocortisone. Results of caffeine-halothane challenge, using semimembranosus muscle collected 2 weeks after the episode, were considered within normal limits for horses. The intraoperative abnormalities were evidently predictive of postanesthetic myopathy but the cause in this horse remained unclear.     

Halothane induced vasomotion of coronary, renal and iliac arterial rings in malignant hyperthermia susceptible swine.

Animals were identified as porcine malignant hyperthermia susceptible by halothane testing and were slaughtered at 90 kg of body weight. Coronary, renal and iliac arteries were isolated, dissected and 5 mm rings were mounted in 20 mL organ baths with modified Krebs solution maintained at 37 degrees C and oxygenated with 95% O2, 5% CO2. Halothane at 0%, 0.5%, 2% and 5% concentration was bubbled in the organ baths and mechanical responses were recorded over a period of 25 min. Halothane free arteries remained quiescent and the arteries from the halothane sensitive and from the halothane resistant groups reacted similarly. All arteries in the presence of halothane responded with an initial contraction of short duration followed by a relaxation and both phenomena occurred in a concentration-dependent fashion. The iliac artery was the most sensitive to halothane and responded to 0.5% concentration while coronary and renal arteries maintained the resting tension of 4 g. These results demonstrate that vascular smooth muscle, like skeletal muscle and unlike respiratory smooth muscle, has a direct pharmacological response to halothane. These observations led to the postulate that halothane by its transient but significant vasoconstrictive action could be a contributing factor to initiate the fulminant reactions occurring in malignant hyperthermia.     

Porcine malignant hyperthermia: false negatives in the halothane test

Purebred Pietrain pigs presumed (on the basis of pedigree) to be homozygous for malignant hyperthermia (MH) susceptibility were subjected to a 3% halothane challenge test. A few (6%) pigs that should have been MH susceptible on the basis of parental genotype did not develop muscle rigidity in response to repeated halothane tests. Three of these animals were brought into the laboratory, and muscle biopsy specimens were obtained for in vitro analysis. Bundles of intact muscle cells dissected from biopsy specimens were electrically stimulated, and mechanical responses were monitored during exposure to halothane. In all instances, the muscle bundles from the halothane-negative (ie, not sensitive to halothane), but genetically susceptible, pigs gave in vitro responses that were similar of those of halothane-positive MH-susceptible pigs in that tetanic tension was depressed, tetanus relaxation was slowed, and small contractures were produced upon halothane exposure. Thus, the presence of a halothane-sensitive abnormality in the skeletal muscles, in and of itself, is not always sufficient for development of in vivo muscle rigidity during a brief halothane test. Furthermore, when the halothane testing of pigs is conducted by recommended techniques, false negatives still occur in a small percentage of the genetically MH-susceptible animals.     

Influence of Nutrition on Malignant Hyperthermia in Pigs

In 2 experiments malignant hyperthermia susceptible Danish Landrace pigs were fed, for 2 or 4 weeks, synthetic diets containing casein as protein source or no protein. Minerals and vitamins were supplied to both groups. The animals were anaesthetized weekly for a maximum of 20 min with a halothane-oxygen mixture.In the first experiment malignant hyperthermia was equally delayed in both groups. If malignant hyperthermia developed, the appearance was at the end of the anaesthetic period. In the second experiment a deeper anaesthesia was employed. Malignant hyperthermia was delayed in both groups, but most markedly in the protein-deficient animals. Malignant hyperthermia developed faster after return to the original feed.These results provide evidence for a nutritional influence on the penetrance of malignant hyperthermia susceptibility during halothane anaesthesia in pigs.     

Canine malignant hyperthermia susceptibility: erythrocytic defects--osmotic fragility, glucose-6-phosphate dehydrogenase deficiency and abnormal Ca2+ homeostasis.

Two dogs were diagnosed as malignant hyperthermia susceptible based on increased susceptibility (P less than 0.001) of biopsied muscle to caffeine-induced contracture. Erythrocytes from malignant hyperthermia and normal dogs were then examined for an antioxidant system deficiency. Values for serum muscle enzymes, reticulocytes and corpuscular hemoglobin were mildly elevated. Osmotic fragility was increased: hemolysis occurred at a NaCl concentration 10 mM higher than for normal dogs (P less than 0.001). A 35% glucose-6-phosphate dehydrogenase deficiency (P less than 0.001) with a 40% compensatory increase (P less than 0.01) in 6-phosphogluconate dehydrogenase activity was found. The membrane Ca2+-activated ATPase activity was abnormal: 100% increased with a 40% decreased Arrhenius activation energy (P less than 0.005) and increased thermostability. A 40% increased intracellular accumulation of total Ca2+ occurred in response to in vitro energy depletion in erythrocytes from one malignant hyperthermia dog (P less than 0.01). The multifactorial pattern of inheritance and the broad spectrum of malignant hyperthermia susceptibility are proposed to result from an antioxidant system deficit unmasking or aggravating an intrinsic muscle membrane anomaly. An individual from a family with a history of malignant hyperthermia or unexplained anesthetic death should be considered malignant hyperthermia susceptible if erythrocyte osmotic fragility is abnormal and there is a mild, unexplained elevation in serum creatine kinase.     

Atypical reactions to halothane in a subgroup of homozygous malignant hyperthermia(MH)-susceptible pigs: indication of a heterogenous genetic basis for the porcine syndrome.

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle. In genetically susceptible pigs, MH can be induced by volatile, halogenated anaesthetics such as halothane. Within a series of pharmacological investigations, a fulminant MH could be induced in 59 of 66 homozygous halothane-susceptible pigs by a challenge with 3% halothane for 15 minutes. The typical MH was characterized by sudden appearance of tachycardia, muscle rigidity with typical extension of the hindlimbs, increase of body temperature, acidosis-caused by rapid increase of CO2 and lactate production-, hyperkalaemia and increased activity of creatine kinase (CK) and aspartate transaminase (AST). In seven homozygous MH-susceptible pigs, this typical MH could not be induced by halothane. These animals responded with sudden appearance of bradyarrhythmia and decrease of arterial pressure. In these MH-atypical pigs (MHA) neither the typical extension of hindlimbs nor a hyperthermia occurred. Compared to a group of 6 MH-susceptible pigs with typical reactions to halothane (MHS), the biochemical alterations were significantly retarded in MHA-pigs. These atypical reactions to halothane could be the effect of decreased cardiac output. Concerning the atypical reactions, we observed a familiar predisposition in MH-susceptible pigs. Although atypical reactions were not found in a group of homozygous halothane-nonsusceptible pigs (MHN), a possible explanation for atypical reactions could be a MH-independent halothane-susceptibility of the myocardium+ in MHA-pigs. On the other side the data may indicate that a primary defect in both the skeletal muscle and also the myocardium is involved in MH. The different reactions to halothane in MH-susceptible pigs could point to a genetic heterogeneity.     

Serum pyruvate kinase and its relation to stress susceptibility in pigs

SUMMARY: Four blood tests, complementary to the halothane test, have been screened for their capacity to discriminate between homozygous and heterozygous stress resistant and stress susceptible pigs: TBARS in plasma, lipid peroxides from erythrocytes and plasma creatine and pyruvate kinase activity. Blood samples were collected from homozygous (NN) and heterozygous (Nn) stress resistant and homozygous stress susceptible (nn) pigs, while subjected to the halothane test. Serum creatine kinase and pyruvate kinase tests were retained for a more elaborated study. Pyruvate kinase appears to be a more reliable indicator of stress susceptibility than the well-known creatine kinase. However both parameters display a considerable standard deviation. Consecutive assays show the pyruvate kinase activity to be dependent on age (weight), which accounts for part of the variation; other sources of variation are the conditions of the exeriment and the way the imposed stress is perceived by the animal. During this experiment a rapid and accurate DNA-test for HAL-genotype detection has been developed (Fujii et al. 1991; Otsu et al. 1991; Coppieters et al. 1992). In spite of this, the pyruvate kinase parameter is a much more discriminating and remarkable indicator for stress susceptibility than the, in previous years, widely used creatine kinase test. ZUSAMMENFASSUNG: Serum Pyruvat Kinase und seine Relation mit Streβanf?lligkeit bei Schweinen Vier Blutteste, komplement?r dem HAL-Test, wurden in einem Screening-Verfahren untersucht um homozygote und heterozygote stre?resistente und stre?anf?llige Schweine zu differenzieren: TBARS in Plasma, Lipid Peroxyde von Erythrocyten und Plasma Kreatine und Pyruvat Kinase Aktivit?t. W?hrend des Halothantestes wurde Blut entnommen von homozygoten (NN) und heterozygoten (Nn) stre?resistenten und homozygoten stre?anf?lligen Schweinen (nn). Mit Serum Kreatine Kinase und Pyruvat Kinase Aktivit?t Tests wurden eine umfassende überprüfung durchgeführt. Letztere zeigt sich als ein zuverl?ssiger Indikator der Stre?anf?lligkeit als die wohl bekanntere Kreatine Kinase. Mehrmalige Analysen zeigen, da? Pyruvat Kinase Aktivit?t vom Alter (Gewicht) abh?ngig ist, was teilweise die Variabilit?t verursacht; andere Quellen der Variabilit?t sind die experimentellen Umst?nde und die Weise, wie der auferlegte Stre? durch das Tier erfahren wird. W?hrend der Durchführung dieses Experimentes wurde ein schneller und akkurater DNA-Test für HAL-Genotyp Detektion entwickelt (Fujii et al. 1991; Otsu et al. 1991; Coppieters et al. 1992). Im Vergleich mit dem, in vorgehenden Jahren, h?ufig angewendeten Kreatine Kinase Test, ist der Pyruvat Kinase Parameter trotzdem ein bemerkenswerter und diskriminierender Indikator für Stre?anf?lligkeit.     

Contracture test and histologic and histochemical analyses of muscle biopsy specimens from horses with exertional rhabdomyolysis

Biopsy specimens of the cutaneous omobrachialis muscle were obtained from 10 horses with a problem of myositis from mild exercise. One horse had been evaluated previously and malignant hyperthermia-like contractures developed in its muscle biopsy specimen during the contracture test. In this study, the halothane-caffeine contracture test and histologic and histochemical evaluations were performed on muscle biopsy specimens. In the contracture test, no muscle biopsy specimen developed contracture in the presence of 2 or 4% halothane alone. The mean (+/- SEM) caffeine-specific concentration in the presence of halothane was 5.23 +/- 0.5 mM for 2% halothane, and 4.46 +/- 0.6 mM for 4% halothane. The caffeine-specific concentration values were not significantly different. Contracture response for any muscle specimen did not resemble contracture associated with malignant hyperthermia. The cutaneous omobrachialis muscle was composed of type-II fibers, with type-I fibers seldom seen. For 9 of the 10 horses, overall fiber morphology was normal; 1 horse had necrotic fibers. Of the 10 muscle specimens, 9 had fibers that had positive reaction for alkaline phosphatase activity; 3 muscle specimens contained ringed myofibers. Three horses of this study were administered general anesthesia; 2 were research horses, anesthetized with halothane and succinylcholine, and 1 was a clinical case given halothane anesthesia plus a non-depolarizing muscle relaxant. One research horse developed a malignant hyperthermia-like reaction to anesthesia, with severe rhabdomyolysis evident after anesthesia, and an episode of muscle cramping in its stall 2 days after anesthesia. The other 2 horses had unremarkable postanesthetic periods.     

Exercise-induced malignant hyperthermia in an English springer spaniel

An exercise-induced malignant hyperthermia-like syndrome developed in an English Springer Spaniel. Moderate exercise resulted in pronounced hyperlactacidemia, dyspnea, and hyperthermia. Before exercise, the dog had high activities of serum muscle enzymes, mild reticulocytosis, abnormally increased erythrocyte osmotic fragility, and a positive result from the caffeine-halothane contracture test. This report supports the hypothesis of a canine stress syndrome and indicates a role for exercise/challenge tests in diagnosis of malignant hyperthermia susceptibility.     

Platelet alterations in porcine stress syndrome

Platelets in blood collected from pigs identified as normal (21) or stress susceptible (25) on the basis of their response to halothane challenge, were subjected to electron microscopic examination in order to test whether the ultrastructural features of stress susceptible pigs exhibit any deviation from those of normal. The most striking feature of the platelets from stress susceptible pigs was the extent of dilatation of the open canalicular system (OCS). The difference in platelet morphology between normal and stress susceptible pigs was consistent regardless of the anticoagulants used for blood collection indicating that the platelet alteration may be an inherent component of the porcine stress syndrome.     

Utilization of the halothane test in the detection of the malignant hypertension syndrome [MHS] in pigs]

By the halothane test we determined the development of the syndrome of malignant hyperthermia in pigs of the Belgian Landrace breed with body weight of 20 kg. We found that from 27 animals that were subjected to the test 12 positively reacted to Narcotan - Spofa anaesthesis. Pigs with the syndrome of malignant hyperthermia had considerably higher rectal temperature after anaesthesis, lower PH of venose blood, higher concentration of lactic acid and glucosis in the blood plasma. Halothane-negative animals did not produce and conspicuous changes of these indices. Most differences were statisticaly highly significant.