Anesthesia case of the month. Malignant hyperthermia

Retrospective analysis of hops toxicosis in dogs (2002-2014): 71 cases

OBJECTIVE

To describe a population of dogs with hops toxicosis, including clinical signs observed, treatments performed, patient outcome, and overall prognosis. Clinical findings and treatment interventions were evaluated for their potential effects on outcome. This study also aims to review hops toxicosis and treatment options.

DESIGN

Retrospective observational study.

SETTING

Poison Control Center.

ANIMALS

Seventy-one dogs presenting for hops ingestion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Records of 71 dogs with known hops ingestion from the ASPCA - Animal Poison Control Center (ASPCA-APCC) database and the Tufts University medical record system were reviewed. Fifty-nine (77%) of the dogs survived. The most common clinical signs on presentation were hyperthermia and tachycardia, with presenting temperatures and heart rates significantly higher in nonsurvivors. There was no significant difference between survivors and nonsurvivors in regard to signalment. Time to presentation was shorter in survivors (5.0 vs 5.5 h; P < 0.0001). The median amount of hops ingested was higher in nonsurvivors (2 vs 2.5 oz; P < 0.0001). Hops ingestion caused hyperthermia in 96% (68/71) of dogs. The median time to death in the nonsurvivor group was 10.7 hours (2-30 h). None of the decontamination, cooling, or treatment measures (dantrolene, cyproheptadine, sedatives) evaluated in this population were associated with improved survival. After adjusting for cooling, time to presentation, and dantrolene administration, every degree of elevation in temperature was associated with a 78% increased chance of death. All dogs that survived to discharge had complete resolution of clinical signs.

CONCLUSIONS

Hops toxicosis can result in significant hyperthermia, tachypnea, and tachycardia. Seventy-seven percent of dogs survived with intensive treatment. Continued education of the potential for hops toxicosis is advised.

Hyperkalemia during general anesthesia in two Greyhounds

CASE DESCRIPTION

A 36-kg (79-lb) castrated male Greyhound (dog 1) and a 25-kg (55 lb) spayed female Greyhound (dog 2) underwent general anesthesia for dental care with similar perianesthetic protocols on multiple occasions from 2013 to 2016. Both dogs had periodontal disease but were otherwise deemed healthy. Both dogs developed clinically relevant hyperkalemia, with signs including loss of P waves on ECG tracings, during multiple anesthetic events.

CLINICAL FINDINGS

Dog 1 developed hyperkalemia during 2 of 2 anesthetic events, with ECG changes noted during the first event. Dog 2 developed hyperkalemia during 3 of 4 anesthetic events, with ECG changes identified during the second and third events. Serum potassium concentration for both dogs was within the reference range prior to and between anesthetic events. No underlying etiopathogenesis for hyperkalemia was identified for either dog.

TREATMENT AND OUTCOME

In each hyperkalemic event, the clinician stopped the dental procedure and continued to provide supportive care and monitoring while the dog recovered from anesthesia. The ECG changes resolved, and serum potassium concentration returned to the reference range rapidly after inhalant anesthetic administration was discontinued. The dogs were discharged from the hospital without further complications.

CLINICAL RELEVANCE

Hyperkalemia in anesthetized Greyhounds resulted in serious cardiac conduction abnormalities, which could be potentially fatal if not recognized and promptly treated. Further investigation into the etiopathogenesis, prevention and treatment strategies, and genetic or familial components of this condition is indicated.

Personalized medicine: going to the dogs?

Interindividual variation in drug response occurs in canine patients just as it does in human patients. Although canine pharmacogenetics still lags behind human pharmacogenetics, significant life-saving discoveries in the field have been made over the last 20 years, but much remains to be done. This article summarizes the available published data about the presence and impact of genetic polymorphisms on canine drug transporters, drug-metabolizing enzymes, drug receptors/targets, and plasma protein binding while comparing them to their human counterparts when applicable. In addition, precision medicine in cancer treatment as an application of canine pharmacogenetics and pertinent considerations for canine pharmacogenetics testing is reviewed. The field is poised to transition from single pharmacogene-based studies, pharmacogenetics, to pharmacogenomic-based studies to enhance our understanding of interindividual variation of drug response in dogs. Advances made in the field of canine pharmacogenetics will not only improve the health and well-being of dogs and dog breeds, but may provide insight into individual drug efficacy and toxicity in human patients as well.