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Malignant hyperthermia in a halothane-anesthetized horse.
Abstract: Malignant hyperthermia developed in a 4-year-old Thoroughbred horse following 3 hours and 15 minutes of halothane anesthesia, with supplementary succinylcholine. Clinical signs included fever, sweating, hyperventilation, tachycardia, and decreased blood pressure followed by a rapid increase in blood pressure. Biochemical aberrations included hypocalcemia, hyperkalemia, hyperphosphatemia, myoglobinuria, and high creatine phosphokinase and ornithine carbamyl transferase activities. Treatment consisted initially of surface cooling with cold water, alcohol and ice, IV administration of cooled balanced electrolyte solutions and sodium bicarbonate, and removal from the anesthetic and rebreathing circuit. Oxygen was given by endotracheal insufflation. The rectum was then packed with ice, the horse was moved to a recovery raft and pool, and his body was packed in ice. Xylazine and dantrolene were given during recovery from anesthesia. Following recovery, treatment consisted of administration of balanced electrolyte solutions, calcium borogluconate, potassium penicillin, meperidine, and additional dantrolene. Muscle biopsy demonstrated exaggerated contracture responses to halothane and caffeine, confirming a diagnosis of malignant hyperthermia. The horse was returned to training following a routine postsurgical convalescent period.
Publication Date: 1981-11-01 PubMed ID: 7341603 The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Case Reports
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The study reports a case of malignant hyperthermia observed in a 4-year-old Thoroughbred horse after being anesthetized with halothane and succinylcholine for more than 3 hours. The researchers detailed the clinical signs, biochemical deviations, treatment approaches, and recovery protocol.
Treatment Procedures and Clinical Findings
- The horse exhibited signs such as fever, sweating, heavy breathing, rapid heart rate, and a sharp decline followed by a swift increase in blood pressure, indicative of malignant hyperthermia.
- Biochemical abnormalities revealed conditions such as low calcium levels (hypocalcemia), high potassium levels (hyperkalemia), high phosphate levels (hyperphosphatemia), myoglobinuria (an abnormal concentration of myoglobin in the urine), and high creatine phosphokinase (an enzyme found mainly in heart, brain, and skeletal muscle) and ornithine carbamyl transferase activities.
Treatment Approach
- Initial treatment measures included surface cooling, intravenous (IV) administration of cooled electrolyte solutions and sodium bicarbonate, and removing the horse from the anesthetic and rebreathing circuit. Oxygen supply was maintained through endotracheal insufflation.
- Then, the horse’s rectum was iced, after which the horse was relocated to a recovery raft and pool and his body was packed in ice.
- Medications administered during recovery from anesthesia included Xylazine (a sedative and analgesic) and Dantrolene (a muscle relaxant).
Postoperative Care and Recovery
- Post-recovery care involved administering balanced electrolyte solutions, calcium borogluconate, potassium penicillin, meperidine, and additional Dantrolene. These helped to stabilize its electrolyte and mineral profile, treat any infections, provide pain relief, and further help in the relaxation of muscles.
- A muscle biopsy conducted later showed exaggerated muscle contracture in response to halothane and caffeine, confirming the diagnosis of malignant hyperthermia.
- The horse was allowed to resume training following a standard recovery period post-surgery.
Cite This Article
APA
Waldron-Mease E, Klein LV, Rosenberg H, Leitch M.
(1981).
Malignant hyperthermia in a halothane-anesthetized horse.
J Am Vet Med Assoc, 179(9), 896-898.
Publication
Researcher Affiliations
MeSH Terms
- Anesthesia, Inhalation / veterinary
- Animals
- Dantrolene / therapeutic use
- Fluid Therapy / veterinary
- Halothane / adverse effects
- Horse Diseases / chemically induced
- Horse Diseases / therapy
- Horses
- Male
- Malignant Hyperthermia / etiology
- Malignant Hyperthermia / therapy
- Malignant Hyperthermia / veterinary
- Oxygen Inhalation Therapy / veterinary
Citations
This article has been cited 6 times.- Gozalo-Marcilla M, Ringer SK. Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature. Animals (Basel) 2021 Jun 14;11(6).
- Haraschak JL, Langston VC, Wang R, Riggs C, Fellman C, Ross MK, Bulla C, Lunsford K, Mackin A, Archer T. Pharmacokinetic evaluation of oral dantrolene in the dog. J Vet Pharmacol Ther 2014 Jun;37(3):286-94.
- Cribb PH, Olfert EA, Reynolds FB. Erythrocyte osmotic fragility testing and the prediction of canine malignant hyperthermia susceptibility. Can Vet J 1986 Dec;27(12):517-22.
- O'brien PJ, Forsyth GW. Preparation of Injectable Dantrolene for Emergency Treatment of Malignant Hyperthermia-like Syndromes. Can Vet J 1983 Jun;24(6):200.
- O'brien PJ, Cribb PH, White RJ, Olfert ED, Steiss JE. Canine malignant hyperthermia: diagnosis of susceptibility in a breeding colony. Can Vet J 1983 Jun;24(6):172-7.
- Aleman M, McCue M, Bellone RR. Allele Frequencies and Genotypes for the Ryanodine Receptor 1 Variant Causing Malignant Hyperthermia and Fatal Rhabdomyolysis With Hyperthermia in Horses. J Vet Intern Med 2025 May-Jun;39(3):e70081.
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