BACKGROUND:Desoxycorticosterone pivalate (DOCP) is commonly used to treat mineralocorticoid deficiency in dogs with hypoadrenocorticism (HA). HYPOTHESIS/OBJECTIVE:To determine the pharmacokinetics and pharmacodynamics of DOCP. ANIMALS:Twenty-one dogs with newly diagnosed HA. METHODS:Prospective clinical trial. Dogs were randomly assigned to treatment with an SC injection of either 1.1 mg/kg (low-dose) or 2.2 mg/kg (label-dose) DOCP. Blood samples were collected at set time points for measurement of serum drug concentrations, serum electrolyte concentrations, and plasma renin activities (PRAs). A one-compartment model was used to determine pharmacokinetics variables. Pharmacodynamics variables including duration of DOCP action and duration of overtreatment were estimated from serum electrolyte concentrations and PRA. Pharmacokinetics and pharmacodynamics variables were compared between low-dose and label-dose groups. RESULTS:Maximum drug concentrations and overall drug exposures were higher in label-dose dogs (1.22 ± 0.46 ng/mL and 32.1 ± 12.3 day × ng/mL) than in low-dose dogs (0.69 ± 0.32 ng/mL and 19.6 ± 5.3 day × ng/mL; P = .008 for both comparisons). However, duration of DOCP action as determined by PRA in label-dose (55 ± 16 days) and low-dose (45 ± 12 days) dogs was not different (P = .2). Serum electrolyte concentrations overestimated the duration of action in the combined group by a mean of 10 days when compared with PRA (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE:Pharmacokinetics and pharmacodynamics data suggest that low-dose DOCP administered every 5-7 weeks is a reasonable treatment strategy for most dogs with HA. Prolonging dosing intervals > 7-8 weeks based solely on electrolyte concentrations should be avoided.

Acetylpromazine, 1-{10-[3-(dimethylamino)propyl]-10H-phenothiazin-2-yl}ethenone, C19H22N2OS, 326.46 g·mol-1 is a phenothiazine derivative at one time used in human medicine as an antipsychotic medication but now predominantly used in veterinary medicine as a sedative/tranquilizer and referred to as acepromazine. In performance horses its use is regulated by using a 10 ng/mL threshold for the major urinary metabolite 2-(1-hydroxyethyl) promazine-sulfoxide (HEPS) in equine urine. To enable accurate quantitation of HEPS in equine urine we have synthesized and purified hydroxyethylpromazine sulfoxide-d4 (HEPS-d4) to be used as a stable isotopically labeled internal standard. Although labeled HEPS is commercially available (CAS 1346605-30-8), to the best of our knowledge there is no published synthetic procedure in the scientific literature. Here we demonstrate a viable synthetic procedure consisting of four major steps: (i) freebasing the Acepromazine maleate salt, (ii) H-D exchange of Acepromazine at room temperature, (iii) reduction of the ketone with NaBD4, and (iv) oxidation of the thioether via hydrogen peroxide and acetic acid. This deuterated internal standard will allow for precise LC/MS quantitation of HEPS at regulatory threshold concentrations, enabling accurate detection and quantitation of picogram/mL concentrations in equine urine samples, thereby supporting regulatory compliance for equine medication control programs.

OBJECTIVE:To describe the clinical utility and toxin removal kinetics of a commercially available medium cut-off (MCO) haemodialyser as emergent treatment of severe metaldehyde intoxication in three dogs. SERIES SUMMARY:Three dogs presented to the emergency department with severe acute neurological signs, including seizures and incoercible tremors following metaldehyde ingestion. Medical therapy, including gastric decontamination and intravenous lipid emulsion, was unsuccessful in improving the neurological condition in all three dogs. Haemodialysis (HD) with an MCO dialyser was performed as emergency treatment to control the clinical signs of intoxication. Resolution of neurological signs was achieved in all dogs within a 4-h HD session without adverse effects. Metaldehyde concentration was measured serially during each treatment. Drug extraction rate, clearance and mass elimination by the MCO dialyser were calculated. The dialytic clearance was 12.5 times higher than the measured intrinsic clearance. UNIQUE INFORMATION PROVIDED:This case series describes the clinical efficacy of an MCO dialyser in the treatment of severe metaldehyde intoxication in dogs and provides unique insights on the metaldehyde clearance kinetics through an MCO dialyser.

Persistent organic pollutants (POPs) including chlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs) are among anthropogenic toxicological stressors of endangered leatherback sea turtles (Dermochelys coriacea). We examined livers from 17 juvenile-to-adult leatherbacks stranded along the North American east coast (2005-2014). We employed GC-MS/MS combined with an existing OCP method while validating new PCB methods, one based on Aroclor 1260 as an analytical standard and another based on specific PCB congeners (#52, 101, 118, 153, 138, 187, 183, 126, 180, 170). Validation covered linearity, limits of detection/quantitation, accuracy, precision and specificity. OCPs were found on a dry weight basis as: trans-nonachlor (n = 3), trans-chlordane (n = 5), cis-chlordane (n = 9), p,p'-DDE (n = 10), aldrin (n = 6) and dieldrin (n = 7). All bore PCBs. Those with the aldrin metabolite dieldrin had dieldrin/aldrin ratios > 1.0 indicating historical exposure. The Aroclor-based PCB method reported on total PCB exposure at concentrations averaging 46 ± 28 ppb with predominance of hexa-, hepta-, and pentachlorobiphenyls, indicating possible acquisition of the PCBs in mid-oceanic latitudes. The congener-specific approach showed the greatest prevalence of PCB #153 (16 of 16 samples). Nevertheless, the total concentration results of the two PCB methods correlated with one another as shown for heptachlorobiphenyls with a correlation coefficient of 0.826 (p < 0.001). Overall, the leatherbacks showed universal exposure to PCBs, while 12 of 17 carried between one and five of the OCPs, similar to findings of other researchers.

Recent increases in cannabis use and dog ownership have elevated the risk of canine cannabis intoxication, prompting a need for efficient diagnostic tools. Enzyme immunoassays (EIAs) that employ monoclonal antibodies specific to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) are commonly employed for preliminary screening and frequently return positive results in canine urine, yet these are not corroborated by gas chromatography-mass spectrometry (GC-MS), suggesting immunoassay cross-reactivity that raises concerns about false positives. The present study incorporated confirmatory GC-MS and GC-MS/MS analyses with mass spectral deconvolution to investigate EIA-positive, GC-MS-negative samples. Two novel compounds with molecular weights of 446 and 460 were identified following trimethylsilylation in the corresponding urine samples. Structural analysis suggests these compounds may be metabolic derivatives of tetrahydrocannabivarin (THCV), a cannabinoid with growing presence in consumer products. These compounds are structurally distinct from Δ9-THC-COOH yet exhibit EIA-reactivity. Ion fragmentation patterns, derivatization behavior, and comparison to established mass spectral libraries support the possibility of 11-hydroxylated and 9-carboxylated THCV analogs. The findings point to THCV metabolism as a plausible source of EIA-cross-reactivity in canines, raising important implications for veterinary toxicology and drug screening protocols. This study contributes crucial insights into canine cannabinoid metabolism and highlights limitations of existing immunoassays when influenced by structurally similar analytes.

AbstractBackgroundIt is unknown if glucocorticoid malabsorption contributes to the approximate 50% treatment failure rate in dogs with protein‐losing enteropathy (PLE).ObjectiveTo compare pharmacokinetics (PK) of orally administered prednisolone in dogs with PLE vs healthy controls.AnimalsFourteen dogs with well‐characterized PLE and 7 control dogs.MethodsProspective case‐controlled study. Dogs were treated with 1 mg/kg prednisolone PO once daily for approximately 3 weeks. Venous blood samples were collected at set timepoints before and after prednisolone administration on the first (T1) and final (T2) study days. Total and non‐protein bound serum prednisolone concentrations were determined using liquid chromatography tandem‐mass spectrometry, and pharmacokinetics variables were derived from the drug concentration data. Pharmacokinetics variables were compared between PLE and control dogs and between PLE short‐term responders and non‐responders.ResultsThe PLE dogs had a shorter half‐life of the terminal slope than control dogs (harmonic mean of 1.3 vs 1.8 hours; P = .05) whereas the percentage of serum prednisolone that was non‐protein bound was higher in PLE dogs than in control dogs (median of 15.7% vs 6.7%; P = .02) at T1. Total prednisolone drug exposures and maximum total serum drug concentrations did not differ between PLE and control dogs at T1 or T2, nor did they differ between short‐term responders and non‐responders within the PLE population (P > .05 for all comparisons).Conclusions and Clinical ImportanceOverall drug exposures are similar between PLE dogs and healthy controls. Glucocorticoid malabsorption is unlikely to be a common cause of treatment failure in dogs with PLE.

Imidacloprid (IMI) is widely used in poultry houses in the United States to control darkling beetles. However, there is limited knowledge regarding the persistence and distribution of IMI and its metabolites in poultry products following acute exposure to subclinical concentrations. In this study, mature hens received a dose of imidacloprid (placebo, 1 mg/kg, or 10 mg/kg), and liquid chromatography tandem mass spectrometry was used to quantify IMI and its metabolites in tissues. IMI was below the limit of quantitation in plasma within 24 (1 mg/kg) and 48 h (10 mg/kg). At 10 mg/kg, IMI equivalents (sum of IMI and its metabolites) exceeded the regulatory threshold as established by the United States Code of Federal Regulations for pectoral and thigh muscle, brain, liver, spleen, kidney, fat, and eggs after 24 h. At 1 mg/kg, IMI equivalents surpassed the threshold for liver, spleen, and eggs after 24 h. These results suggest that low dose exposure to IMI may cause poultry products destined for human consumption to violate federal regulations.

Nine wild American white ibis (Eudocimus albus) were found deceased or were moribund and subsequently euthanized within 24 hours after exposure to theatrical fog containing propylene glycol and triethylene glycol at a Halloween event at a zoological institution. Gross examinations revealed that all birds had congestion, edema, and hemorrhage throughout the lungs. Histologically, all birds had pathologic changes within the trachea and lungs indicative of acute respiratory insult. Microscopic changes in the trachea included segmental to diffuse epithelial attenuation with loss of cilia, alternating with regions of goblet cells filled with abundant mucus. In the lungs, all birds had perivascular edema and degenerative changes to the epithelium lining primary and secondary bronchi including hypereosinophilia and apical cytoplasmic blebbing of bronchial epithelial cells. In addition, in the lungs of 4 birds with longer intervals between exposure and death, there was granulomatous pneumonia, heterophilic perivascular cuffing, and multifocal bronchial epithelial necrosis. Propylene glycol and triethylene glycol were detected in lung and kidney tissues by gas chromatography-tandem mass spectrometry (GC-MS/MS). Traces of oxalic acid were found, along with presence of glycolic acid. While exposure to aerosolized glycols has been shown to cause irritation and minor degenerative changes to the respiratory epithelium in laboratory animals and humans, this study represents a unique investigation into the first reported incidence of acute inhalation toxicity and death following exposure to aerosolized glycol-containing theatrical fog in birds.

Metformin is a widely prescribed oral antihyperglycemic agent and currently a first-line medication in the treatment of human type 2 diabetes, with a total of 92 million US prescriptions in 2022. The daily dose per human can be as much as 2.5 grams/day which is excreted largely unchanged into the environment. Metformin is chemically stable and a widely distributed environmental substance. Metformin therefore has the potential to be identified at trace levels in equine blood and urine samples as a result of random exposure to environmental metformin. Given these circumstances we have reviewed the scientific literature and calculated an irrelevant blood/plasma/serum concentration of metformin of 5 nanograms/ml. We now therefore propose this plasma concentration of metformin as an interim Screening Limit of Detection (SLOD) for metformin, below which concentration a blood/plasma/serum identification of metformin should not be considered appropriate for regulatory action.

Invasive fungal aspergillosis is a leading cause of morbidity and mortality in many species including avian species such as common ravens (Corvus corax). Methods were developed for mass spectral determination of voriconazole in raven plasma as a means of determining pharmacokinetics of this antifungal agent. Without further development, GC/MS/MS (gas chromatography-tandem quadrupole mass spectrometry) proved to be inferior to LC/MS/MS (liquid chromatography-tandem quadrupole mass spectrometry) for measurement of voriconazole levels in treated raven plasma owing to numerous heat-induced breakdown products despite protection of voriconazole functional groups with trimethylsilyl moieties. LC/MS/MS measurement revealed in multi-dosing experiments that the ravens were capable of rapid or ultrarapid metabolism of voriconazole. This accounted for the animals' inability to raise the drug into the therapeutic range regardless of dosing regimen unless cytochrome P450 (CYP) inhibitors were included. Strategic selection of CYP inhibitors showed that of four selected compounds including cimetidine, enrofloxacin and omeprazole, only ciprofloxacin (Cipro) was able to maintain voriconazole levels in the therapeutic range until the end of the dosing period. The optimal method of administration involved maintenance doses of voriconazole at 6 mg/kg and ciprofloxacin at 20 mg/kg. Higher doses of voriconazole such as 18 mg/kg were also tenable without apparent induction of toxicity. Although most species employ CYP2C19 to metabolize voriconazole, it was necessary to speculate that voriconazole might be subject to metabolism by CYP1A2 in the ravens to explain the utility of ciprofloxacin, a previously unknown enzymatic route. Finally, despite its widespread catalog of CYP inhibitions including CYP1A2 and CYP2C19, cimetidine may be inadequate at enhancing voriconazole levels owing to its known effects on raising gastric pH, a result that may limit voriconazole solubility.

The p-anisaldehyde reaction with yucca extract saponins has long been utilized for semi-quantitating saponins or sapogenins by reaction product UV–visible spectroscopy, likely by reaction with compound ketal functions. The methodology was easily implemented and enabled direct comparison with a new detection method generated from gas chromatography-tandem mass spectrometric (GC/MS/MS) analysis of yucca extracts prepared by a new hydrolytic method. The GC/MS/MS method was validated for properties of linearity, specificity, precision, and accuracy. The p-anisaldehyde/UV–visible approach operated well with or without hydrolysis, unlike the GC/MS/MS approach that relied on yucca extract hydrolysis. Nevertheless, the GC/MS/MS approach correlated well with the p-anisaldehyde/UV–visible method to a coefficient of determination of 0.8, despite the finding that the p-anisaldehyde/UV–visible method overestimated concentrations perhaps by as much as 1.7x. Reasons are discussed as to why this likely represents an overestimate by the p-anisaldehyde/UV–vis method. Yucca extracts predominantly contained smilagenin/sarsasapogenin epimeric pairs as well as smaller amounts of hecogenin and an epimer dubbed epi-hecogenin. Fifteen or more additional sapogenin compounds were also observed, but on average accounted for no more than 15% of the total composition of sapogenins.

The objective of this study was to establish the pharmacokinetics of a single oral dose of trazodone in the Hispaniolan Amazon parrot (Amazona ventralis). Trazodone is a selective serotonin antagonist and reuptake inhibitor used commonly in both human and veterinary medicine as an antidepressant behavioral modification medicine. A single oral dose of compounded trazodone hydrochloride solution (20 mg/mL) at 50 mg/kg was administered to a total of 7 healthy adult Hispaniolan Amazon parrots. The 7 healthy adult parrots ranged in age from 10 to 15 years and weighed 228 to 323g. Blood was collected at baseline (2 weeks before study) and at 1, 2, 4, 6, 10, and 14 hours post-drug administration. Plasma concentrations of both trazodone and its active metabolite m-chlorophenylpiperazine (mCPP) were measured via liquid chromatography tandem mass spectrometry. Noncompartmental pharmacokinetic analysis was completed. The half-life (t(1/2)) +/- SD of trazodone for the Hispaniolan parrots was 1.89 +/- 0.49 hours, and the t(1/2) +/- SD of mCPP metabolite was 1.9 +/- 0.55 hours. Maximum serum drug concentrations, or C-max (ng/mL), were 738.3 +/- 285.3 for trazodone. Times to achieve C-max (hours) for trazadone and the mCPP metabolite were 1 hour and 2 hours postdosing, respectively. While this study did not establish the behavioral effects of trazodone, no adverse side effects were observed throughout the 48-hour period following drug administration and blood collection. Our results indicate that the oral administration of a 50-mg/kg single dose of trazodone to Hispaniolan parrots may be considered a safe dose. Plasma concentrations are comparable to previously published values in humans, dogs, horses, and pigeons (Columba livia domestica) for up to 14 hours following dosing. This study indicates that further studies are needed to establish the pharmacodynamics and the efficacy of trazodone in the medical management of behavioral problems in psittacine species.

This case report presents the first reported identifications of 20-hydroxyecdysone in post-event blood samples from an Endurance horse and a Harness horse racing in New South Wales, Australia.20-Hydroxyecdysone is a plant secondary metabolite structurally related to testosterone and used by plants to discourage insect predation.20-Hydroxyecdysone is found in many plants including spinach and is not infrequently identified at low concentrations in mammalian systems including in humans.Given its steroid-related structure, 20-hydroxyecdysone has been reported to enhance athletic performance in humans, although at this time 20-hydroxyecdysone is simply being monitored by the World Anti-Doping Agency (WADA) [31] .The Harness horse identification led the Harness Racing New South Wales (HRNSW) authorities to evaluate the home pastures of the horse in question, where they recovered at least three plants containing significant concentrations of 20-hydroxyecdysone.The HRNSW stewards were satisfied that the 20-hydroxyecdysone identification was due to "environmental contamination emanated from plants" in the trainer's establishment and did not impose a penalty on the trainer.These findings show that the pasture plant steroid 20-hydroxyecdysone is found in pasture plants from which it is bioavailable to equines and can present as low part per billion concentrations in equine blood samples, as has also been noted in humans.Based on these Australian identifications of 20-hydroxyecdysone in pasture plants and also in equine blood samples and the HRNSW decision not to penalize the trainer involved and the likelihood of no pharmacological response to pasture plant exposure to this substance we now present 2 parts per billion in equine blood/plasma as an appropriate regulatory cut-off or Screening Limit of Detection (SLOD) for 20-hydroxecdysone in equine blood/plasma.

Torsional stress in double-stranded DNA enables and regulates facets of chromosomal metabolism, replication, and transcription and requires regulatory enzymatic systems including topoisomerases and histone methyltransferases. As such, this machinery may be subject to deleterious effects from reactive mutagens, including ones from carcinogenic polycyclic aromatic hydrocarbon (PAH) adduct formation with DNA. Supercoiled plasmid DNA was investigated for its torsional responses to adducts formed in vitro from PAH benzylic carbocation reactive intermediates created spontaneously by release of leaving groups. PAH sulfate esters were found to (1) unwind DNA in a concentration dependent manner, and (2) provide maximum unwinding in a pattern consistent with known carcinogenicities of the parent PAHs, that is, 6-methylbenzo[a]pyrene > 7,12-methylbenz[a]anthracene > 3-methylcholanthrene > 9-methylanthracene > 7-methylbenz[a]anthracene > 1-methylpyrene. Supercoil unwinding was demonstrated to be dependent on the presence of sulfate or chloride leaving groups such that reactive carbocations were generated in situ by hydrolysis. In silico modeling of intercalative complex topology showed PAH benzylic carbocation reactive functional groups in alignment with target nucleophiles on guanine bases in a 5’-dCdG-3’ pocket in agreement with known formation of nucleotide adducts. Inhibitory or modulatory effects on PAH-induced supercoil unwinding were seen with ascorbic acid and an experimental antineoplastic agent Antineoplaston A10 in agreement with their known anticarcinogenic properties. In summary, the reactive PAH intermediates studied here undoubtedly participate in well-known mutational mechanisms such as frameshifts and apurinic site generation. However, they are also capable of random disruption of chromosomal supercoiling in a manner consistent with the known carcinogenicities of the parent compounds, and this mechanism may represent an additional detrimental motif worthy of further study for a more complete understanding of chemical carcinogenicity.

OBJECTIVE:To determine if a cytochrome (CYP) P450 enzyme inhibitor can maintain therapeutic plasma levels of voriconazole when administered orally.ANIMALS:11 healthy, common ravens (Corvus corax).METHODS:Birds were randomly assigned to pilot study groups to receive voriconazole orally alone or combined with a CYP inhibitor. Pilot studies with 3 CYP inhibitors launched the main study using ciprofloxacin (20 mg/kg) followed 1 hour later by voriconazole (6 mg/kg) every 12 hours for 14 days. Plasma voriconazole concentrations were measured at various time points by HPLC-MS. The study period lasted from September 2016 to December 2020.RESULTS:The birds failed to maintain therapeutic plasma levels of voriconazole during multidose administration alone or following preadministration with various CYP inhibitors. For the 14-day study period, voriconazole reached a maximum plasma concentration of 2.99 μg/mL with a time-to-peak drug concentration of 1.2 hours following preadministration of ciprofloxacin. One bird was removed from the study due to lethargy, but the other birds completed the study without incident.CLINICAL RELEVANCE:Ciprofloxacin (20 mg/kg) followed by voriconazole (6 mg/kg) maintained the concentration of voriconazole within the recommended therapeutic range of 0.5 to 5 μg/mL without toxicity. Ciprofloxacin prevented the saturable metabolism of voriconazole and maintained these levels for the study duration. This drug combination could be used in the treatment of chronic aspergillosis in the common raven.

Anabolic androgenic steroids are synthetic substances related to the male sex hormones (androgens). These agents promote the growth of skeletal muscle (anabolic effects) and the development of male sexual characteristics (androgenic effects). Anabolic steroids have been illegally used for many years as performance-enhancing drugs in human, equine, and canine sports and as growth promoters in livestock reared to provide meat for human consumption. The analytical challenge to developing effective means of control within these fields has been exacerbated by the reported endogenous nature of some of these steroids. Anabolic steroids have been employed extensively in equine practice over the past 50 years. Their usefulness is largely dependent on subjective opinions, as only minimal studies investigating pharmacodynamics have been carried out in horses. Therefore, their use will vary markedly between practitioners depending on their personal experiences and pressures by trainers to use them. They form part of rational therapy in a variety of conditions. In addition to their use for increasing muscle mass, they are used to varying extents in the raising of yearlings and in the training and racing of horses with the view of improving performance. The use of these agents is prohibited in the horseracing industry by the Association of Racing Commissioners International (ARCI), International Federation of Horseracing Authorities (IFHA), and Fédération Equestre Internationale (FEI).

The Humboldt penguin (Spheniscus humboldti) population at the Punta San Juan Marine Protected Area in Peru is considered critical to the long-term sustainability of this endangered species in Peru. Exposure of the rookery to environmental toxicants is a mounting concern because of regional growth of industries and human populations. Whole blood samples were collected from 30 free-ranging penguins in 2011 as part of a broader population health monitoring program. Dried blood spots (DBS) containing 50 mu l of blood were prepared and analyzed to assess exposure to five groups of environmental contaminants. Concentrations of elements arsenic, cadmium, iron, lead, mercury, selenium, and thallium were analyzed using inductively coupled plasma mass spectrometry. Persistent organic pollutant concentrations were measured using gas chromatography-tandem mass spectrometry to analyze organochlorine pesticides (OCP; p,p0-DDT, p,p0-DDE, b-hexachlorocyclohexane, t-nonachlor, and oxychlordane), polychlorinated biphenyls (congeners 138 and 153), and polybrominated flame retardants (polybrominated biphenyl-153 and polybrominated diphenyl ether congeners 47 and 99). Per- and polyfluoroalkyl substances, including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid were measured using liquid chromatography-tandem mass spectrometry. Results revealed low levels of exposure to these selected contaminants, at levels not considered to be of concern for wildlife health. DBS methodology was considered effective in a field-based setting for quantification of whole blood concentrations of environmental contaminants in penguins.

Background: Dried blood spot (DBS) technology is valuable in providing simple means of storing blood samples from wildlife with small blood volumes. Methods designed for heavy metal analysis on DBS become more useful if extended to elements of nutritional significance. Purpose: (1) Development of procedures for measuring Mn, Fe, Co, Cu, Zn, Se and Mo in DBS; (2) use the designed methods in health assessments of Gal ' apagos land iguanas (Conolophus species). Procedures: Elements were measured by inductively coupled plasma/mass spectrometry (ICP-MS) following acid digestion of whole blood or DBS from the same animal for direct comparison. Study animals comprised free-ranging iguanas from separate islands in the Gal ' apagos archipelago. Main Findings: DBS spikes (Mn, Fe, Co, Cu, Zn, Se and Mo) demonstrated accuracy to similar to 100 ppb; reporting limits were set there except for Fe and Zn which were set at 1000 ppb. Plasma samples - generally preferable for nutritional element diagnostics - were submitted from Galapagos land iguanas along with DBS as part of a large-scale health assessment. In plasma versus DBS concentration comparisons, Fe, Cu, Se and Mn correlated well with R<^>2 values of 0.799, 0.818, 0.896 and 0.899, respectively, and slopes ranging 0.88 - 1.3. Co and Zn showed greater scatter. Mo had insufficient points above its reporting limit and offered advantages for toxicity assessments. Bland-Altman diagrams showed flat scatter between 2x standard deviation boundaries with no undue trends except for Mn which had few points above its reporting limit. Bias, defined as the average difference [DBS - plasma] divided by the average value, was relatively low throughout, with values of - 19.3 % (Fe), - 48.7 % (Co), - 19.6 % (Cu), - 6.9 % (Zn), - 21.4 % (Se) and + 40.7 % (Mn). Normal distribution assessment of iguana Cu, Zn, Se and Fe plasma values showed unanticipated divergences between two species. Conclusions: The DBS approach for nutritional element analysis offers a suitable methodology for determining crucial elements Mn, Fe, Co, Cu, Zn, Se, and Mo in veterinary samples. Analyses of samples from Conolophus species revealed interesting divergences particularly for Cu, Zn, Se and Fe, elements generally associated with defense against oxidative stress.

Metaldehyde consumption by pets and other mammals constitute medical emergencies ideally requiring rapid poison removal. The purpose of this study was three-fold: 1) development of a sensitive method for metaldehyde quantitation in patient serum samples by gas chromatography combined with tandem quadrupole mass spectrometry (GC/MS/MS); 2) development of a sensitive method for quantitation of the volatile metaldehyde metabolite acetaldehyde by headspace analysis combined with GC/MS/MS; and 3) an initial assessment of the efficacy of combined dialysis and hemoperfusion treatments in diminishing toxin loads in canine victims of metaldehyde poisoning. Both mass spectrometric approaches relied on Multiple Reaction Monitoring (MRM) methodologies. Metaldehyde extracted via liquid-liquid partitioning from serum was detected with a limit of quantitation (LOQ) of 7.3 & PLUSMN; 1.4 ng/mL with linearity in the range 1-250 ng/mL with accuracy improved by inclusion of a deuterated metaldehyde internal standard. Acetaldehyde was determined to have an LOQ of 0.39 & mu;g/mL with linearity in the range 1-1000 & mu;g/mL. The developed methodologies were applied to canine samples taken over various time points during dialysis treatment. Two of three canine patients showed significant abatement of metaldehyde levels by over 50-fold from initial concentrations while a third was shown to be negative with no measureable metaldehyde. The toxic metabolite acetaldehyde was found in one of the metaldehyde-poisoned patients and the detected acetaldehyde was also reduced by roughly 200-fold during the course of treatment. The designed mass spectrometric techniques were thus successful in demonstrating the efficacy of the applied dialysis-hemoperfusion methods which may find wider applicability against other potentially lethal toxins in poisoned patients in future studies.

Consistent with recently increased street availability and recreational use of the potent synthetic opioid fentanyl, there has been a parallel increase in trace level plasma identifications of fentanyl in racing horses, at times in association with trace level amounts of other human recreational substances such as the synthetic cathinone eutylone, currently classified as a designer drug.Fentanyl has three basic effects in the horse, i.e., an analgesic effect, a locomotor stimulation response and a potential endurance effect.Fentanyl is considered relatively straightforward to synthesize following a four-step procedure.Eutylone is the most frequently identified cathinone-related substance identified in the US and is considered a synthetic stimulant.Eutylone is inexpensive to produce and mimics the effects of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine, commonly known as ecstasy, and is, like fentanyl, a street marketed human recreational substance.Both substances are listed in horseracing as Class 1 with Penalty Class A substances, therefore having the highest penalties for identifications in horses given their stimulant properties, according to the ARCI (Association of Racing Commissioners International).Given that racing authorities recognize the potential for substances of "human use and addiction" to inadvertently transfer to racing horses, we were asked to develop an Irrelevant Plasma Concentration (IPC) for fentanyl in horses.Additionally, the finding of a trace level of eutylone along with a trace level of fentanyl increases the likelihood that these paired trace level identifications were caused by inadvertent transfer from a human using a combination of recreational substances.With regard to fentanyl, review of the published pharmacology of fentanyl suggested that locomotor responses disappear below plasma concentrations of 5 ng/mL, with the locomotor response peaking at 50 ng/mL.Similarly, the antinociceptive effects of fentanyl require concentrations above 6.5 ng/mL.An effective plasma concentration (EPC) of 25 ng/mL was therefore decided on.Dividing this EPC by 500, the conservative Toutain & Lassourd safety factor (SF) gives a 50 pg/ml IPC for fentanyl in the horse.This value was not exceeded by any of the low fentanyl concentrations identified in 125,000 post-race samples in the 2018-2022 time range.Plasma concentrations of fentanyl in the sub-40 pg/mL range are therefore pharmacologically irrelevant with a significant likelihood of transfer from recreational users.This IPC value is consistent with a number of recent trace level plasma fentanyl identifications in equine samples and judgements in these matters by regulatory authorities that the likely source of these trace level plasma fentanyl identifications was inadvertent transfer from human recreational users to the horses in question.The first detections of fentanyl detections in racehorses occurred in the period 1978-1983 corresponding to the introduction of sensitive radioimmunoassay screening methods.This contrasts with the more recent uptick in 2018-2022, apparently due to exposure of horses to inadvertent trace level transfers from recreational users of fentanyl.Eutylone continues to be a concern, but more information on its equine pharmacokinetics is necessary before similar development of EPC and IPC can be determined.