Effects of haloperidol and cocaine pretreatments on brain distribution and kinetics of [11C]methamphetamine in methamphetamine sensitized dog: application of PET to drug pharmacokinetic study

Methamphetamine intoxication in a dog: case report

BACKGROUND

Methamphetamine abuse has undergone a dramatic worldwide increase, and represents a significant and global issue for public health. Incidents of methamphetamine intoxication and death in humans are relatively commonplace. Because of its increasing illicit availability, together with legitimate use in human medicine, accidental or intentional exposure to methamphetamine in dogs is becoming a more likely scenario.

CASE PRESENTATION

A 3-year-old, 3.7 kg intact female Miniature Poodle who had been intentionally fed an unknown amount of a crystalline-like substance developed extreme agitation, seizures, tachycardia, hyperthermia, hypertension, disseminated intravascular coagulation (DIC), bloody diarrhea, and dilated pupils. Blood work revealed leukocytosis, erythropenia, lymphocytosis, thrombocytopenia, coagulation abnormalities, but all to a mild extent, together with mild elevation in both alanine aminotranferease (ALT) and alkaline phosphatase (ALKP), and a mild decreased in glucose. Radiologic diagnosis revealed generalized, severe distension of the stomach and small intestinal tract with air. Immunochromatographic screening tests and gas chromatography mass spectrometry analysis confirmed methamphetamine intoxication and revealed concentrations of methamphetamine in blood and urine of 0.32 μg/mL and 2.35 μg/mL respectively. The dog demonstrated progressive improvement after supportive care, with the high fever resolved over the initial 24 hours of hospitalization, and agitation was successfully controlled beyond 48 hours after initial hospitalization. Hemostatic abnormalities were progressive improved after heparin therapy and supportive care. By the sixth day of hospitalization the dog was clinically well, and all laboratory data had returned to normal with the exception of a mild elevateion of ALKP.

CONCLUSION

To the authors' knowledge, this is the second case report of methamphetamine intoxication in dogs presented in veterinary practice in open literature so far. Although rare, methamphetamine intoxication should be considered as a differential diagnosis in dogs with a toxic substance ingestion history and with typical nervous and cardiovascular system symptoms. In such cases rapid diagnosis and aggressive intervention is important for prognosis. Blood methamphetamine concentration may be a helpful value for assessment of the severity of intoxication and prediction of clinical outcomes.

Applications of positron emission tomography in animal models of neurological and neuropsychiatric disorders

Positron emission tomography (PET) provides dynamic images of the biodistribution of radioactive tracers in the brain. Through application of the principles of compartmental analysis, tracer uptake can be quantified in terms of specific physiological processes such as cerebral blood flow, cerebral metabolic rate, and the availability of receptors in brain. Whereas early PET studies in animal models of brain diseases were hampered by the limited spatial resolution of PET instruments, dedicated small-animal instruments now provide molecular images of rodent brain with resolution approaching 1mm, the theoretic limit of the method. Major applications of PET for brain research have consisted of studies of animal models of neurological disorders, notably Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington's disease (HD), stroke, epilepsy and traumatic brain injury; these studies have particularly benefited from selective neurochemical lesion models (PD), and also transgenic rodent models (AD, HD). Due to their complex and uncertain pathophysiologies, corresponding models of neuropsychiatric disorders have proven more difficult to establish. Historically, there has been an emphasis on PET studies of dopamine transmission, as assessed with a range of tracers targeting dopamine synthesis, plasma membrane transporters, and receptor binding sites. However, notable recent breakthroughs in molecular imaging include the development of greatly improved tracers for subtypes of serotonin, cannabinoid, and metabotropic glutamate receptors, as well as noradrenaline transporters, amyloid-β and neuroinflammatory changes. This article reviews the considerable recent progress in preclinical PET and discusses applications relevant to a number of neurological and neuropsychiatric disorders in humans.

Imaging addiction with PET: is insight in sight?

Neurochemical imaging studies can identify molecular targets of abused drugs and link them to the underlying pathology associated with behaviors such as drug dependence, addiction and withdrawal. positron emission tomography (PET) is opening new avenues for the investigation of the neurochemical disturbances underlying drug abuse and addiction and the in vivo mechanisms by which medications might ameliorate these conditions. PET can identify vulnerable human populations, treatment strategies and monitor treatment efficacy. Thus, with this tool and the knowledge it provides, the potential for developing novel drugs and treatment strategies for drug addiction is now close at hand.