Prophylactic use of dantrolene associated with prolonged postanesthetic recumbency in a horse

Dantrolene, a drug used in the prevention and treatment of malignant hyperthermia, was believed responsible for prolonged postanesthetic recumbency in a horse. Prophylactically, dantrolene was given orally before induction of anesthesia. Dantrolene has been recommended for use in horses at risk of developing postanesthetic myopathy. Side effects, including ataxia, may result from dantrolene administration.     

Supportive therapy in the anesthetized horse

In conclusion, vigilant supportive care is necessary to prevent morbidity and death in the anesthetized horse. Because some of the equipment and drugs are specialized and the consequences of some postanesthetic complications are severe, availability of those items must be confirmed prior to anesthesia. Proper positioning and padding will help to reduce the incidence of postanesthetic myopathy-neuropathy syndrome in these large patients. Adequate tissue perfusion is important and can be achieved by controlling anesthetic depth, increasing intravascular volume with fluid administration, and by administering sympathomimetic agents.     

Postanesthetic compartmental syndrome in a horse

After surgery, high intramuscular pressures were measured in a horse with clinical signs of postanesthetic myopathy that developed following a 2.25-hour surgical procedure. In the postoperative period, tests for muscular and neurologic integrity were made, including measurement of intracompartmental muscle pressure.     

Myonecrosis and cutaneous infarction associated with Salmonella serovar Infantum infection in a horse

A 5-year-old Quarter Horse mare was referred for evaluation of oral ulcers, limb edema, weight loss, and weakness. There was marked diffuse swelling extending from the stifle region to the tarsal region of the left hind limb, and the horse had a left hind limb lameness. Firm swellings ranging from 2 to 15 cm in diameter and consisting of nodules, plaques, and discrete masses were palpated on both sides of the neck, over the right shoulder region, over the left elbow region, and over the left caudoventral aspect of the abdomen. Laboratory abnormalities included hypoproteinemia, neutrophilia, and hyperfibrinogenemia. Results of ultrasonographic examination of the left hind limb and masses were suggestive of muscle edema, necrosis, and hemorrhage. Histologic examination of a biopsy specimen from a subcutaneous mass revealed necrotizing, suppurative myositis. The horse's condition gradually deteriorated, and the horse was euthanatized. Necropsy revealed myonecrosis, cutaneous infarcts, hepatic abscesses, and cholangitis. Salmonella serovar Infantum was cultured from liver and muscle lesions, and a diagnosis of Salmonella myonecrosis was made.     

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 complications in the horse. Evaluation of anesthesia in the last 28 years (1962-1989)]

The anesthesia routine in the horse is briefly explained. 35 postanesthetic complications resulted from the total of 4364 cases of anesthesia. They are evaluated by means of the duration of anesthesia, the time of paresis, the exemplary courses of enzymes as well as the distribution of race and sex and their ratio towards all cases of anesthesia. Finally a list of demands concerning the operative and postoperative phases is compiled to minimize postoperative myositis (PAM) and lameness (PAL).     

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.     

Clostridium perfringens type A myonecrosis in a horse in Korea

Acute hemorrhagic myonecrosis accompanied by severe inter- and intrafascicular edema and hemorrhage of the right gluteal area was diagnosed in a 13-year-old male thoroughbred horse. Once the muscular and fascicular changes were subsided, the horse then developed acute respiratory problem. Histologically, the lung had diffuse severe hemorrhage with mild neutrophilic infiltration. The cause of death was acute respiratory failure that is believed to occur secondary to toxaemic event. Alpha and beta2 toxin secreting Clostiridum perfringens type A was isolated from the muscle and lung. The diagnosis was based on the light microscopic examination, bacterial toxinotyping and toxin genotyping from the muscular and pulmonary lesion. Also, susceptibility of the isolates to antimicrobial agents was determined.     

Clostridial myonecrosis,haemolytic anaemia,hepatopathy, osteitis and transient hypertrophic cardiomyopathy after intramuscular injection in a Thoroughbred gelding

A 9‐year‐old Thoroughbred gelding was presented for swelling over the left neck and inappetence. There was recent history of intramuscular administration of flunixin meglumine into the left neck. On examination, there was evidence of focal myositis, anaemia, haemolysis and pigmenturia. Culture of aspirated fluid from the left side of the neck produced a heavy growth of a Clostridium species. Complications of infection included haemolytic anaemia, hepatopathy, osteitis and transient hypertrophic cardiomyopathy. Treatment included intravenous fluid therapy, antibiotics, anti‐inflammatory drugs, blood transfusion and surgical debridement. There was complete resolution of clinical, haematological, biochemical and echocardiographic abnormalities, and the horse returned to ridden work. This report highlights the complications that can arise from clostridial myonecrosis, including the effect on the myocardium.     

Bilateral traumatic optic nerve avulsion in a Thoroughbred gelding

This report describes an unusual case of acute blindness following traumatic head injury in a mature horse. The horse fell over backwards and subsequently presented with bilateral blindness and epistaxis. Vision did not return following medical supportive therapy and euthanasia was elected. Post mortem findings revealed a basisphenoid fracture and bilateral optic nerve avulsion rostral to the optic chiasm, an uncommon presentation of traumatic blindness not previously reported in the horse.     

Hyperthermia and Delayed-Onset Myopathy after Recovery from Anesthesia in a Horse

A 13-year old Thoroughbred cross gelding (528 kg) underwent lameness investigation. Because of his temperament, general anesthesia was required to facilitate ultrasound of the left fore fetlock and intra-articular medication of three joints. Anesthesia was induced with ketamine/diazepam after acepromazine/detomidine premedication. Anesthesia was maintained for 40 minutes with a guaifenesin/detomidine/ketamine intravenous infusion. Recovery from anesthesia was initially uneventful, although of a moderate duration (70 minutes). Once standing, the horse proceeded to box walk in an agitated state and became recumbent on two occasions. The horse was manually restrained, at which time its rectal temperature was 41.8°C. Cooling measures were employed (fans, ice-water enemas, wet rugs, intravenous fluid therapy (IVFT), and topical application of surgical spirit) until rectal temperature reached 38.7°C. IVFT was continued for a further 16 hours. Four days after recovery from anesthesia, bilateral triceps, deltoideus, trapezius, and rhomboideus muscle swelling was observed. Blood creatinine kinase was elevated (24,898 IU/L). Treatment for postanesthetic myopathy was initiated (hot packing of the muscle groups, topical dimethylsulfoxide [DMSO] cream application, and oral phenylbutazone). Myoglobinuria was not observed at any time. Muscle swelling decreased over the following 3 days. The horse was discharged on day 11 and has since returned to work.     

A case of a periarticular abscess and suppurative arthritis of the atlanto-occipital joint

This Case Report describes a periarticular abscess and a suppurative arthritis of the atlanto-occipital joint in an adult horse. The horse showed a painful swelling localised on the atlanto-occipital region and ataxia in all 4 limbs. During hospitalisation, the horse developed recumbency, dysphagia, facial paralysis and seizures. Ultrasonography of the atlanto-occipital region enabled a tentative diagnosis to be made, which was later confirmed at autopsy. Culture of the abscess revealed a Staphylococcus aureus. However, the horse had a history of recurrent fever, hypertrophy and abscessation of the submandibular lymph nodes, neck pain and dyspnoea for 2 months, which was suggestive of strangles.     

Medial pterygoid myositis in a Thoroughbred gelding

This case report describes the investigation and treatment of an adult horse with purulent, malodorous exudate originating from a large intermandibular mass. Microbial culture of fluid aspirated from a draining tract yielded Peptostreptococcus and Prevotella species which are usually considered to originate from the oral cavity. Computed tomography (CT) was used to aid in the diagnosis and to allow careful presurgical planning, and the horse underwent successful debridement of the abscess cavity under general anaesthesia. Post-operatively, the horse developed trismus (reduced opening of the jaws) but repeat CT identified that the surgery site was healing appropriately. It was recommended to continue feeding the horse hay to act as physiotherapy and the masticatory action of the horse subsequently returned to normal.     

Removal of a fragmented nasogastric tube from the transverse colon of a horse undergoing exploratory celiotomy for colic

This report describes the clinical course and surgical findings of a 5-year-old Warmblood gelding referred for colic with a previous history of intermittent colic episodes, and gastric ulcers diagnosed by gastroscopy in the preceding months. The horse underwent medical treatment but remained painful and surgery was elected. The horse underwent an exploratory laparotomy during which an impaction was identified in the transverse colon that was associated with an approximately 1 metre segment of nasogastric tube. The foreign body was removed via an enterotomy in the left dorsal colon, and the horse recovered well from surgery. No complications were encountered post-operatively.     

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.     

Acquired peri-articular ganglion cyst in the lateral femorotibial joint in an 18-year-old Percheron cross mare

This report describes a case of sudden lameness in an 18-year-old Percheron cross mare after presumably being kicked by another horse, and the subsequent formation of a ganglion cyst originating from the lateral femorotibial joint. Physical examination, radiographic and ultrasonographic investigation identified a soft round 5 cm diameter mass attached to the left lateral femorotibial joint. After surgical removal, histopathological examination confirmed a ganglion cyst. The horse responded well to the surgical removal of the cyst, and 4 weeks after the surgery, the mare has returned back to her same athletic performance. According to the authors’ knowledge, this is the first reported case that describes a peri-articular ganglion cyst originating from the stifle joint.     

Right subclavian artery anomaly in an adult Friesian horse

This report describes an unusual vascular ring anomaly (VRA) that resulted in repeated oesophageal obstruction in an adult horse. Oesophagoscopy identified a luminal obstruction with secondary mucosal sloughing. Post mortem findings revealed oesophageal and tracheal stenosis secondary to an aberrant right subclavian artery. The presence of the VRA may have resulted in repeated oesophageal impactions in an adult horse and the hereditary potential for this defect should be considered.     

Traumatic neuroma of the medial palmar nerve as a possible cause of a severe gait abnormality in a Warmblood riding horse

This paper describes the history, examination and clinical findings in a riding horse with a gait abnormality. The lesion was localised to the carpal area of one of the forelimbs, but could not be properly characterised until post mortem examination, when a diagnosis of a traumatic neuroma of the medial palmar nerve could be reached. Thus, the most plausible explanation for the gait abnormality of the horse was found in the peripheral nervous system.     

Shockwave therapy for treatment of a burn injury in a horse

This article describes a horse that sustained burn injury wounds over the back extending from the withers to the tail head as a result of a fire in a trailer. The extensive nature of the burn prompted investigation into treatment options which may stimulate healing. Based on current applications in human medicine, shockwave therapy was administered. This horse recovered from a substantial burn injury. Shockwave therapy may be a viable supplemental option for treating burn injuries in the horse, with no noted adverse effects.     

Surgical resection of an osteoma of two thoracic spinous processes in a horse

This report describes the successful surgical removal of an osteoma of the thoracic dorsal spinous processes of a horse that presented with back pain. Osteomas of the spine are frequently reported in the literature in people, but have not been previously described in the horse.