Uncertainty in the “detection times” for drugs in horses

There are three major sources of uncertainty in the times for which drugs can be detected in a horse's blood or urine. First, horses are treated with drugs at one million-fold different doses, and they eliminate these doses at rates that vary about 300-fold. Second, the sensitivity of the tests that the analyst uses to detect these drugs can vary up to 100-fold or more. Third, horses treated with exactly the same doses of drugs can “spread out” or distribute the plasma levels of these drugs about50-fold in a skewed or irregular manner. In this distribution, a large proportion of horses show lowerblood levels of drugs, but a small proportion of horses show relatively much higher blood levels of drugs. Beyond this, the different pH (acidity) values of urine samples can cause urinary levels of drugs to vary by at least 200-fold. These factors cause large uncertainties concerning the blood or urinary levels of drugswhich are found even after the same doses of the same drug. These uncertainties result in considerable technical difficulties for the regulatory process of medication control.     

Medication control: The efficacy and cost of drug testing

The rate of illegal drug use in unregulated racing appears to run from 12 to 20% or more. When effective drug testing and sanctions are introduced, the rate of illegal drug use may be expected to drop to between 0.3 and 3.0 per thousand samples tested. For individual drugs, the rate of drug use will drop to zero if the sanctions against its use are sufficiently aversive. However, there appears to always be a tendency on the part of horsemen to “try the lab”, and a certain background incidence of illegal medication and its detection may be inevitable. It appears, therefore, that the positive call rates experienced in NorthAmerica are a function of both the efficacy of the testing process, and also of the severity of the penalties imposed.

The cost of this testing varies from $3/sample in Montana to $75/sample in Washington State. Based on these figures, the cost to call a “positive” varies from about $2,000 in Montana to $188,000 in Washington State. While this may appear very expensive on a per positive basis, it in fact represents medication control in a much larger range of samples that wouldcontain illegal medications in the absence of effective testing.     

Effects of the sodium‐glucose cotransporter 2 (SGLT2) inhibitor velagliflozin,a new drug with therapeutic potential to treat diabetes in cats

Sodium‐glucose cotransporter 2 (SGLT2) inhibitors are used in the treatment of human diabetics. They increase glucose excretion and correct hyperglycemia. We examined the investigational SGLT2 inhibitor velagliflozin in two groups of six neutered adult obese cats (equal gender distribution). Placebo (Pl) or drug (D; 1 mg/kg) was administered for 35 days. Routine blood examinations, fructosamine, beta‐hydroxybutyrate (BHB), nonesterified fatty acids (NEFA), glucagon, adiponectin, and leptin were measured before and after treatment, also water intake, and urinary electrolytes, glucose, and volume. Indirect calorimetry, an intravenous glucose tolerance test (IVGTT; 0.8 g/kg) and insulin tolerance test (IVITT) were conducted. All cats tolerated treatment well. Significant changes with D included a decrease in the respiratory exchange ratio, an increase in cholesterol, a small increase in albumin, and a rise in BHB and NEFA. Glucose clearance was unaltered, although less insulin was secreted during the IVGTT (p = .056) suggesting improved insulin sensitivity. IVITT was unchanged. Treatment did not affect glucagon, leptin, or adiponectin. Water intake, urine output, urinary glucose excretion, and the glucose/creatinine ratio but not urinary electrolytes were significantly higher post‐D. We conclude that velagliflozin is a promising drug, which increases urinary glucose excretion in cats and could thereby be beneficial for the treatment of hyperglycemia.     

The use of phenylbutazone in the horse

This review presents a brief historical prospective of the genesis of regulated medication in the US racing industry of which the nonsteroidal anti-inflammatory drug (NSAID) phenylbutazone (PBZ) is the focus. It presents some historical guideposts in the development of the current rules on the use of PBZ by racing jurisdictions in the US. Based on its prevalent use, PBZ remains a focus of attention. The review examines the information presented in a number of different models used to determine the effects and duration of PBZ in the horse. They include naturally occurring lameness and reversible-induced lameness models that directly examine the effects and duration of the administration of various doses of PBZ. The review also examines indirect plasma and tissue models studying the suppression of the release of arachidonic acid-derived mediators of inflammation. The majority of studies suggest an effect of PBZ at 24 h at 4.4 mg/kg. This reflects and substantiates the opinion of many clinical veterinarians, many of whom will not perform a prepurchase lameness examination unless the horse is free of NSAID. This remains the opinion of many regulatory veterinarians responsible for the prerace examination of race horses that they wish to examine a horse without the possibility of an NSAID interfering with the examination and masking possible musculoskeletal conditions. Based on scientific studies, residual effects of PBZ remain at 24 h. The impact of sustained effect on the health and welfare of the horse and its contribution to injuries during competition remains problematic.     

Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs

Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1 mg/kg and the levels of flunixin were measured in plasma for up to 96 hr and in urine for up to 120 hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1 ng/ml and the irrelevant urine concentration was determined as 30 ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72 hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control.     

Expert judgement in a risk assessment model for Salmonella spp. in pork: The performance of different weighting schemes

A structured expert judgement study was carried out in order to obtain input parameters for a quantitative microbial risk assessment (QMRA) model. This model aimed to estimate the risk of human Salmonella infections associated with the consumption of minced pork meat. Judgements of 11 experts were used to derive subjective probability density functions (PDFs) to quantify the uncertainty on the model input parameters.The performance of experts as probability assessors was measured by the experts’ ability to correctly and precisely provide estimates for a set of seed variables (=variables from the experts’ area of expertise for which the true values were known to the analyst). Subsequently different weighting schemes or “decision makers” (DMs) were applied using Cooke's classical model in order to obtain combined PDFs as a weighted linear combination of the expert's individual PDFs.The aim of this study was to compare the performance of four DMs namely the equal weight DM (each expert's opinion received equal weight), the user weight DM (weights are determined by the expert's self-perceived level of expertise) and two performance-based DMs: the global weight DM and the item weight DM. Weights in the performance-based DMs were calculated based on the expert's calibration and information performance as measured on the set of seed variables.The item weight DM obtained the highest performance with a calibration score of 0.62 and an information score of 0.52, as compared to the other DMs. The weights of the performance-based DMs outperformed those of the best expert in the panel. The correlation between the scores for self-rating of expertise and the weights based on the experts’ performance on the calibration variables was low and not significant (r = 0.37, p = 0.13).The applied classical model provided a rational basis to use the combined distributions obtained by the item weight DM as input in the QMRA model since this DM yielded generally more informative distributions for the variables of interest than those obtained by the equal weight and user weight DM. Attention should be paid to find adequate and relevant seed variables, since this is important for the validation of the results of the weighting scheme.     

Testing for drugs in horses

Drug testing today depends primarily on post-race urine testing, with blood testing and pre-race testing as adjuncts to the testing process. Drugs are extracted from urine by a process called liquid-liquid extraction, and then screened for the presence of illegal agents. Screening is generally done by Thin Layer Chromatography (TLC analysis). If a drug is detected in the screening process, its presence in the sample is confirmed by other chromatographic methods, and most especially by Gas Chromatography-mass Spectrometry (GC-MS.) The qualitative detection of drugs in forensic samples is a well worked-out art, and most drugs can be identified in blood or urine samples with a high degree of accuracy. Drugs can be quantitated in blood or urine with an accuracy of plus or minus 25% or more. Thesescientific determinations on a sample can be independently verified in referee samples, and form the scientific basis of the regulatory process of medication control.     

Pharmacodynamics of amoxicillin against Mannheimia haemolytica and Pasteurella multocida and pharmacokinetic/pharmacodynamic (PK/PD) correlation in sheep

Silicone-made tissue cages were implanted in sheep. Blood serum (SBS) and tissue cage fluid (TCF) samples were collected after amoxicillin intravenous and intramuscular administrations, at the dose of 15 mg/kg. Amoxicillin pharmacodynamics were studied in an artificial culture medium, SBS and TCF with use of a Mannheimia haemolytica and a Pasteurella multocida strain. A concentration-independent antimicrobial activity of amoxicillin was confirmed for levels higher than 0.79–1.75 × MIC. This result favored the use of the percentage of the 24 h dosing interval during which drug levels remain above MIC as the appropriate pharmacokinetic/pharmacodynamic index. The subsequent correlation revealed that intravenous administration could be considered effective against “deep” infections caused by bacteria with MICs < 1 μg/mL or “shallow” infections caused by bacteria with MICs < 0.1 μg/mL. Intramuscular administration could be safely considered effective against both “deep” and “shallow” infections when the MICs of the targeted pathogens are lower than 1 μg/mL.     

基于非线性混合效应模型分析兽药药代动力学研究进展

利用数学建模分析兽药药代动力学历来已久。兽药药代动力学中应用数学建模和模拟分析可简化和加快兽药研发进程。非线性混合效应模型分析方法是兽药药代动力学建模和模拟的主要方法之一,该方法对临床合理用药、新药研发及评审更高效具有很大意义,同时阐明一些传统药动学无法回答的问题。本文综述了非线性混合效应模型在分析兽药药代动力学主要原理及应用进展,以期望非线性混合效应模型分析方法在我国新兽药研发与评审中应用提供积极有益的参考。     

A Pilot Study to Assess the Feasibility of a Submaximal Exercise Test to Measure Individual Response to Cardiac Medication in Dogs with Acquired Heart Failure

Exercise testing is not commonly used in canine medicine because of several limitations. The aim of this study was to investigate the suitability of a treadmill test to measure the exercise capacity of untrained canine cardiac patients and to measure some biological parameters that might reflect the tolerance of dogs with heart failure to submaximal exercise. The exercise capacity of seven dogs with naturally occurring heart failure was evaluated before the institution of cardiac medication and 7 days after the beginning of the study. An additional re-examination was requested after 28 days. The exercise test was performed on a motorized treadmill at three different speeds (0.5 m/s, 1.0 m/s and 1.5 m/s). The following parameters were measured at the end of each stage and after 20 min recovery: heart rate, rectal temperature, glucose, lactate, aspartate aminotransferase, creatine kinase, Pvo ₂, Pvco ₂, pH, haematocrit, bicarbonate, sodium, potassium and chloride. Serum cardiac troponin-I was also measured at the beginning of the test and at the end of the recovery period. Owners’ perception reflected the ability of their dogs to exercise on the treadmill. Lactate level increased noticeably with the intensity of the exercise test, and its variation coincided with different exercise tolerance observed by the owners. Heart rate seemed to follow a similar trend in the few dogs presented in sinus rhythm. None of the remaining parameters appeared to be sensitive indicators of activity level in the dogs used in this study. The treadmill exercise test in dogs with acquired heart failure is feasible and might provide useful information for assessing individual response to cardiac medication. Lactate and heart rate seemed to reflect individual levels of exercise tolerance, although further studies are necessary to confirm the reliability and repeatability of this test.     

Isolation of a plasmid from “canine” Staphylococcus epidermidis mediating constitutive resistance to macrolides and lincosamides

A small plasmid of 2.5 kB mediating constitutive resistance to macrolide-lincosamide-(ML)antibiotics could be detected in a “canine” Staphylococcus epidermidis-culture. This plasmid, designated as pSES 1, was identified by interspecies protoplast transformation into Staphylococcus aureus RN 4220. A detailed restriction map of pSES 1 could be constructed using the restriction endonucleases Acc I, Bcl I, Cfo I, Cla I, Hind III, Hinf I, Mbo I, Sst I and Taq I. This map allowed structural comparisons of pSES 1 with plasmids from “human” Staphylococcus- and Bacillus-species, also mediating macrolide-lincosamide resistance (ML^R). On the basis of its restriction map, pSES 1 proved to be similar to the plasmids pNE 131 from “human” S. epidermidis, pE 194 from “human” S. aureus and pIM 13 from B. subtilis.     

Emerging arthropod-borne diseases of companion animals in Europe

Vector-borne diseases are caused by parasites, bacteria or viruses transmitted by the bite of hematophagous arthropods (mainly ticks and mosquitoes). The past few years have seen the emergence of new diseases, or re-emergence of existing ones, usually with changes in their epidemiology (i.e. geographical distribution, prevalence, and pathogenicity). The frequency of some vector-borne diseases of pets is increasing in Europe, i.e. canine babesiosis, granulocytic anaplasmosis, canine monocytic ehrlichiosis, thrombocytic anaplasmosis, and leishmaniosis. Except for the last, these diseases are transmitted by ticks. Both the distribution and abundance of the three main tick species, Rhipicephalus sanguineus, Dermacentor reticulatus and Ixodes ricinus are changing. The conditions for such changes involve primarily human factors, such as travel with pets, changes in human habitats, social and leisure activities, but climate changes also have a direct impact on arthropod vectors (abundance, geographical distribution, and vectorial capacity). Besides the most known diseases, attention should be kept on tick-borne encephalitis, which seems to be increasing in western Europe, as well as flea-borne diseases like the flea-transmitted rickettsiosis. Here, after consideration of the main reasons for changes in tick vector ecology, an overview of each “emerging” vector-borne diseases of pets is presented.     

The role of councils on animal ethics in assessing acceptable welfare standards in agriculture

The way production animals are treated is a matter of public concern, and public opinion is often a driving force to introduce new animal welfare legislation. In Norway, a Council on Animal Ethics has been appointed by the authorities since 1993. The composition of the council is broad and it encounters both lay people and experts. The council is independent and advisory, only. It shall be a “guard dog” and follow the developments in animal production and other areas where man makes use of animals, and give advice to the authorities on the need for change in legislation and administrative practices. An important task for the council is also to contribute to and facilitate an informed public debate on animal welfare standards and animal ethics.     

Urinary excretion by dogs of intravenously administered simple sugars

Seven simple sugars, commonly used in intestinal function tests, were simultaneously administered intravenously to dogs and their urinary excretion was measured to assess their potential for metabolic degradation. Lactose, lactulose and 3-O-methyl-D-glucose were excreted unchanged, but small proportions of palatinose and sucrose were not, and were assumed to have been metabolised. More than half of the administered D-xylose and a quarter of L-rhamnose was not excreted and was assumed to have been metabolised. These findings may be significant for the interpretation of differential sugar absorption tests and the D-xylose tolerance test.     

Exploration of developmental approaches to companion animal antimicrobials: providing for the unmet therapeutic needs of dogs and cats

AAVPT Workshop White Paper Committee. Exploration of developmental approaches to companion animal antimicrobials: providing for the unmet therapeutic needs of dogs and cats. J. vet. Pharmacol. Therap. 33 , 196–201. The American Academy of Veterinary Pharmacology and Therapeutics (AAVPT) and the United States Pharmacopeia (USP) co‐sponsored a workshop to explore approaches for developing companion animal antimicrobials. This workshop was developed in response to the shortage of antimicrobials labeled for dogs and cats, as there is a shortage of approved antimicrobials for the range of infectious diseases commonly treated in small animal practice. The objective of the workshop was to identify alternative approaches to data development to support new indications consistent with the unmet therapeutic needs of dogs and cats. The indications for currently approved antimicrobials do not reflect the broader range of infectious diseases that are commonly diagnosed and treated by the veterinarian. Therefore, the labels for these approved antimicrobials provide limited information to the veterinarian for appropriate therapeutic decision‐making beyond the few indications listed. Industry, veterinary practice, and regulatory challenges to the development of new antimicrobial indications were discussed. The workshop resulted in short‐ and long‐term recommendations. Short‐term recommendations focus on the use of additional data considerations for product labeling. Long‐term recommendations center on legislative or regulatory legal initiatives. The workshop recommendations will need collaboration from industry, academia, and regulatory authorities and a legal shift in the drug approval and availability processes.     

Detection, quantification, and pharmacokinetics of furosemide and its effects on urinary specific gravity following IV administration to horses

Furosemide is a potent loop diuretic used for the prevention of exercise-induced pulmonary hemorrhage in horses. This drug may interfere with the detection of other substances by reducing urinary concentrations, so its use is strictly regulated. The regulation of furosemide in many racing jurisdictions is based on paired limits of urinary SG (<1.010) and serum furosemide concentrations (>100 ng/ml). To validate this regulatory mechanism, a liquid chromatography/mass spectrometry/mass spectrometry method employing a solid-phase extraction procedure and furosemide-d5 as an internal standard was developed. The method was used to determine the pharmacokinetic parameters of furosemide in equine serum samples and its effects on urinary SG after IV administration (250 mg) to 10 horses. Pharmacokinetic analysis showed that serum concentrations of furosemide were well described by a two-compartmental open model. Based on results in this study, it is very unlikely for horses to have serum furosemide concentrations greater than 100 ng/ml or urine SG less than 1.010 at 4 hours after administration (250 mg IV). However, it should be remembered that urine SG is a highly variable measurement in horses, and even without furosemide administration, some horses might naturally have urine SG values less than 1.010.     

Geographical clines in the size of the herb field mouse (Apodemus uralensis)

Patterns of body size variation along geographical gradients have long been searched for and generalized into eco‐geographical rules. However, no rodent species has yet been analyzed in relation to the 3 dimensions of latitude, longitude and altitude. We analyzed geographical clines and dimorphism of body and skull size in the herb field mouse (Apodemus uralensis) across the species range, based on field data and on data from the literature. Sexual dimorphism in adult A. uralensis was not expressed at a large scale, while local patterns were inconsistent. Age‐dependent size changes were most expressed in adult individuals: most characters of adults exceeded in size those of subadults, while subadult–juvenile size differences were only significant in body weight and length, zygomatic skull width, length of cranial diastema and breadth of braincase. Despite central morphological niches along the clines being separated, A. uralensis populations showed a high degree of size overlap in morphological space. We found the species to be characterized by high size variability, with the largest individuals inhabiting the eastern and southern edges of the distribution range. Tail, hind foot and ear lengths were largest in the southern part of the range, in agreement with Allen's rule. The main measurements that we analyzed, namely body mass, zygomatic skull width and condylobasal skull length, show the presence of 3 clines in the size of adult A. uralensis: (i) a decreasing south–north cline, opposing Bergmann's rule; (ii) an increasing west–east cline, in accordance with Murphy's rule; and (iii) an increasing altitudinal cline.     

Preliminary safety and biological efficacy studies of ethyl pyruvate in normal mature horses

Reasons for performing the study: Endotoxaemia causes substantial morbidity and mortality in horses with colic and sepsis. Ethyl pyruvate is a novel anti‐inflammatory medication that improved survival in preclinical models of severe sepsis endotoxaemia and intestinal ischaemia and reperfusion in rodents, swine, sheep and dogs and may be a useful medication in horses. Hypothesis: Ethyl pyruvate has no adverse effects in normal horses and is biologically active based on suppression of proinflammatory gene expression in endotoxin stimulated whole blood, in vitro. Methods: Physical and neurological examinations, behaviour scores, electrocardiograms and clinicopathological tests were performed on 5 normal healthy horses receiving 4 different doses of ethyl pyruvate. Doses included 0, 50, 100 and 150 mg/kg bwt administered in a randomised crossover design with a 2 week washout period between doses. Biological efficacy was assessed by stimulating whole blood with endotoxin from the horses that received ethyl pyruvate prior to and 1 and 6 h after drug infusion. Gene expression for TNFα, IL‐1β and IL‐6 was assessed. Results: There were no effects of drug or dose (0, 50, 100 or 150 mg/kg bwt) on any of the physical or neurological examination, behaviour factors, electrocardiogram or clinical pathological results collected from any of the horses. All parameters measured remained within the normal reference range. There was a significant reduction in TNFα, IL‐1β and IL‐6 gene expression in endotoxin stimulated whole blood from horses 6 h after receiving 150 mg/kg bwt ethyl pyruvate. There were no detectable effects on gene expression of any of the other doses of ethyl pyruvate tested. Conclusion: We were unable to detect any detrimental effects of ethyl pyruvate administration in normal horses. Ethyl pyruvate significantly decreased proinflammatory gene expression in endotoxin stimulated blood 6 h after drug administration. Clinical relevance: Ethyl pyruvate may be a safe, effective medication in endotoxaemic horses.     

New trends in regulatory rules and surveillance of antimicrobial resistance in bacteria of animal origin.

Since the introduction in the 1940s of antibiotics as drugs against bacterial infections in human and then veterinary medicine, two major events have caused a shift in the antibiotherapy era: (1) the emergence of resistant bacteria and (2) the awareness of the limits of new drug development. It rapidly became urgent to set up measures in order to evaluate the importance of resistant bacteria and their origin as well as to limit the dissemination of resistant vectors (bacteria and bacterial genes). This led to the establishment of guidelines and regulatory rules necessary for risk assessment and clearly dependent upon monitoring and research organisations. At a veterinary level, the possible dissemination of multiresistant bacteria from animals to humans, through feeding, urged various national European and international institutions to give general recommendations to monitor and contain the emergence and diffusion of resistant strains. This paper gives an overview of the evolution of regulatory rules and monitoring systems dealing with multiresistant bacteria.