Large or Food Animal and Equine Medicine Commons^™

Enhanced Bovine Colostrum Supplementation Shortens The Duration Of Respiratory Disease In Thoroughbred Yearlings, Clara K. Fenger, Thomas Tobin, Patrick J. Casey, Edward A. Roualdes, John L. Langemeier, Ruel Cowles, Deborah M. Haines

Maxwell H. Gluck Equine Research Center Faculty Publications

Bovine colostrum (BC) is used in humans as a nutritional supplement for immune support and has been shown to reduce Respiratory disease (RD). Other nutritional supplements, minerals and vitamins including mannan oligosaccharides (MOS), zinc and vitamins A, C and E have also been used for immune support. The aim of this prospective blinded randomized clinical trial was to evaluate the effects of a BC, MOS, zinc and vitamin based enhanced bovine colostrum supplement (BCS) on incidence and duration of RD occurring in yearling horses. 109 yearlings on two Thoroughbred farms in Central Kentucky were randomly assigned to treatment or placebo …

Large Deletions At The Shox Locus In The Pseudoautosomal Region Are Associated With Skeletal Atavism In Shetland Ponies, Nima Rafati, Lisa S. Andersson, Sofia Mikko, Chungang Feng, Terje Raudsepp, Jessica Pettersson, Jan Janecka, Ove Wattle, Adam Ameur, Gunilla Thyreen, John E. Eberth, John Huddleston, Maika Malig, Ernest Bailey, Evan E. Eichler, Göran Dalin, Bhanu Chowdary, Leif Andersson, Gabriella Lindgren, Carl-Johan Rubin

Maxwell H. Gluck Equine Research Center Faculty Publications

Skeletal atavism in Shetland ponies is a heritable disorder characterized by abnormal growth of the ulna and fibula that extend the carpal and tarsal joints, respectively. This causes abnormal skeletal structure and impaired movements, and affected foals are usually killed. In order to identify the causal mutation we subjected six confirmed Swedish cases and a DNA pool consisting of 21 control individuals to whole genome resequencing. We screened for polymorphisms where the cases and the control pool were fixed for opposite alleles and observed this signature for only 25 SNPs, most of which were scattered on genome assembly unassigned scaffolds. …

Effect Of Dietary Starch Source And Concentration On Equine Fecal Microbiota, Brittany E. Harlow, Laurie M. Lawrence, Susan H. Hayes, Andrea Crum, Michael D. Flythe

Animal and Food Sciences Faculty Publications

Starch from corn is less susceptible to equine small intestinal digestion than starch from oats, and starch that reaches the hindgut can be utilized by the microbiota. The objective of the current study was to examine the effects of starch source on equine fecal microbiota. Thirty horses were assigned to treatments: control (hay only), HC (high corn), HO (high oats), LC (low corn), LO (low oats), and LW (low pelleted wheat middlings). Horses received an all-forage diet (2 wk; d -14 to d -1) before the treatment diets (2 wk; d 1 to 14). Starch was introduced gradually so that …

Equine Protozoal Myeloencephalitis: An Updated Consensus Statement With A Focus On Parasite Biology, Diagnosis, Treatment, And Prevention, S. M. Reed, M. Furr, Daniel K. Howe, A. L. Johnson, R. J. Mackay, J. K. Morrow, N. Pusterla, S. Witonsky

Veterinary Science Faculty Publications

Equine protozoal myeloencephalitis (EPM) remains an important neurologic disease of horses. There are no pathognomonic clinical signs for the disease. Affected horses can have focal or multifocal central nervous system (CNS) disease. EPM can be difficult to diagnose antemortem. It is caused by either of 2 parasites, Sarcocystis neurona and Neospora hughesi, with much less known about N. hughesi. Although risk factors such as transport stress and breed and age correlations have been identified, biologic factors such as genetic predispositions of individual animals, and parasite-specific factors such as strain differences in virulence, remain largely undetermined. This consensus statement …

Differential Gene Expression In Equine Cartilaginous Tissues And Induced Chondrocytes, Emma N. Adam

Theses and Dissertations--Veterinary Science

Degenerative joint disease, or osteoarthritis, is a major cause of lameness and morbidity in horses, humans, and dogs. There are no truly satisfactory cures for this widespread problem and current treatments all have limitations or unwanted side effects.

New cell-based strategies to repair joint surface lesions have generated a high level of interest, but have yet to achieve the full restoration of articular cartilage structure and function. Currently used therapy cells include autologous chondrocytes and adult mesenchymal cells such as bone marrow derived cells and adipose derived cells. Unfortunately, the resultant repair tissue is biomechanically inferior fibrocartilage. A critical gap …

In Vivo-Expressed Proteins Of Virulent Leptospira Interrogans Serovar Autumnalis N2 Elicit Strong Igm Responses Of Value In Conclusive Diagnosis, Veerapandian Raja, Santhanam Shanmughapriya, Murugesan Kanagavel, Sergey Artiushin, Sridhar Velineni, John F. Timoney, Kalimuthusamy Natarajaseenivasan

Maxwell H. Gluck Equine Research Center Faculty Publications

Leptospirosis is a serious zoonosis that is underdiagnosed because of limited access to laboratory facilities in Southeast Asia, Central and South America, and Oceania. Timely diagnosis of locally distributed serovars of high virulence is crucial for successful care and outbreak management. Using pooled patient sera, an expression gene library of a virulent Leptospira interrogans serovar Autumnalis strain N2 isolated in South India was screened. The identified genes were characterized, and the purified recombinant proteins were used as antigens in IgM enzyme-linked immunosorbent assay (ELISA) either singly or in combination. Sera (n = 118) from cases of acute leptospirosis along …

Tissue Restricted Splice Junctions Originate Not Only From Tissue-Specific Gene Loci, But Gene Loci With A Broad Pattern Of Expression, Matthew S. Hestand, Zheng Zeng, Stephen J. Coleman, Jinze Liu, James N. Macleod

Maxwell H. Gluck Equine Research Center Faculty Publications

Cellular mechanisms that achieve protein diversity in eukaryotes are multifaceted, including transcriptional components such as RNA splicing. Through alternative splicing, a single protein-coding gene can generate multiple mRNA transcripts and protein isoforms, some of which are tissue-specific. We have conducted qualitative and quantitative analyses of the Bodymap 2.0 messenger RNA-sequencing data from 16 human tissue samples and identified 209,363 splice junctions. Of these, 22,231 (10.6%) were not previously annotated and 21,650 (10.3%) were expressed in a tissue-restricted pattern. Tissue-restricted alternative splicing was found to be widespread, with approximately 65% of expressed multi-exon genes containing at least one tissue-specific splice junction. …

Complete Genome Sequence Of Noncytopathic Bovine Viral Diarrhea Virus 1 Contaminating A High-Passage Rk-13 Cell Line, Bora Nam, Ganwu Li, Ying Zheng, Jianqiang Zhang, Kathleen M. Shuck, Peter J. Timoney, Udeni B. R. Balasuriya

Maxwell H. Gluck Equine Research Center Faculty Publications

A high-passage rabbit kidney RK-13 cell line (HP-RK-13[KY], originally derived from the ATCC CCL-37 cell line) used in certain laboratories worldwide is contaminated with noncytopathic bovine viral diarrhea virus (ncpBVDV). On complete genome sequence analysis, the virus strain was found to belong to BVDV group 1b.

Recurrent Streptococcus Equi Subsp. Zooepidemicus Bacteremia In An Infant, Joshua R. Watson, Amy Leber, Sridhar Velineni, John F. Timoney, Monica I. Ardura

Maxwell H. Gluck Equine Research Center Faculty Publications

We describe a case of an infant with recurrent bacteremia caused by Streptococcus equi subsp. zooepidemicus, likely transmitted from mother to infant. Our case highlights the importance of an epidemiological history and molecular diagnostics in ascertaining insights into transmission, pathogenesis, and optimal management.

Changes In Serum Strongylus Vulgaris-Specific Antibody Concentrations In Response To Anthelmintic Treatment Of Experimentally Infected Foals, Martin Krarup Nielsen, Jessica Scare, Holli Sullivan Gravatte, Jennifer Lynn Bellaw, Julio C. Prado, Craig Robert Reinemeyer

Maxwell H. Gluck Equine Research Center Faculty Publications

Strongylus vulgaris is the most pathogenic nematode parasite of horses. Its extensive migration in the mesenteric blood vessels can lead to life-threatening intestinal infarctions. Recent work has shown that this parasite is still identified among managed horse populations. A serum enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of migrating larvae of S. vulgaris. Previous work has documented an increase in ELISA values following larvicidal treatment with ivermectin and suggested that the target parasite antigen is primarily produced by the later larval stages. The aim of this study was to experimentally inoculate cohorts of foals with S. …

Comparison Of The Equine Reference Sequence With Its Sanger Source Data And New Illumina Reads, Jovan Rebolledo-Mendez, Matthew S. Hestand, Stephen J. Coleman, Zheng Zeng, Ludovic Orlando, James N. Macleod, Ted Kalbfleisch

Maxwell H. Gluck Equine Research Center Faculty Publications

The reference assembly for the domestic horse, EquCab2, published in 2009, was built using approximately 30 million Sanger reads from a Thoroughbred mare named Twilight. Contiguity in the assembly was facilitated using nearly 315 thousand BAC end sequences from Twilight's half brother Bravo. Since then, it has served as the foundation for many genome-wide analyses that include not only the modern horse, but ancient horses and other equid species as well. As data mapped to this reference has accumulated, consistent variation between mapped datasets and the reference, in terms of regions with no read coverage, single nucleotide variants, and small …

Protective Efficacy Of Centralized And Polyvalent Envelope Immunogens In An Attenuated Equine Lentivirus Vaccine, Jodi K. Craigo, Corin Ezzelarab, Sheila J. Cook, Chong Liu, David Horohov, Charles J. Issel, Ronald C. Montelaro

Maxwell H. Gluck Equine Research Center Faculty Publications

Lentiviral Envelope (Env) antigenic variation and related immune evasion present major hurdles to effective vaccine development. Centralized Env immunogens that minimize the genetic distance between vaccine proteins and circulating viral isolates are an area of increasing study in HIV vaccinology. To date, the efficacy of centralized immunogens has not been evaluated in the context of an animal model that could provide both immunogenicity and protective efficacy data. We previously reported on a live-attenuated (attenuated) equine infectious anemia (EIAV) virus vaccine, which provides 100% protection from disease after virulent, homologous, virus challenge. Further, protective efficacy demonstrated a significant, inverse, linear relationship …

Sudden Death, Aortic Rupture In Horses, Literature Review, Case Studies Reported And Risk Factors, Abelardo Morales Briceño, Aniceto Mendez, Kimberly Brewer, Charlie Hughes, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

Sudden deaths of horses in multiple equestrian disciplines have been attributed to acute and chronic respiratory and cardiovascular diseases. The aim of this study was to perform a review of aortic rupture in horses analyzing, case studies and assessing risk factors. The literature has reported a total of 137 cases of aortic rupture in horses for 28 years (1986-2014), with approximately five horses dying of aortic rupture per year. Histopathologically, there are observed discrete macroscopic degenerative changes in the intima layer only in the aorta. The histological evaluation in the beginning portion of the aorta of the heart evidenced degenerative …

Reversible Downregulation Of Hypothalamic-Pituitary-Gonadal Axis In The Stallion With A Third-Generation Gnrh Antagonist, Gabriel Monteiro Davolli

Theses and Dissertations--Veterinary Science

The objectives of this thesis were: (1) to evaluate the downregulation of the stallion hypothalamic-pituitary-gonadal (HPG) axis by a GnRH antagonist (acyline) based upon endocrine, seminal, testicular and behavioral effects, and (2) to assess recovery after treatment. Stallions were treated for 50 days (n=4; 330µg/kg acyline q 5d) and controls (n=4) received vehicle alone. Stallions were assessed pre-treatment and for 72 days after last treatment. Treatment induced declines (p<0.05) in FSH, LH, testosterone (to castrate levels) and estrone sulfate. Gonadotropins and testosterone returned to control values within nine days and estrone sulfate by 14 days after treatment discontinuation. Acyline-treated stallions failed to respond with FSH, LH and testosterone increase after exogenous GnRH stimulation (25µg gonadorelin, IV) compared to pre-treatment and control stimulation. Total sperm numbers and motility were reduced in acyline-treated stallions, as well as total seminal plasma protein and testicular volume (p<0.05). Time to ejaculation was increased in acyline group (p<0.5). Testicular, sexual behavior and most seminal parameters regained normal levels within 72 days after treatment ceased. Sperm output of acyline-treated stallions was regained within seven months after ending treatment. Acyline reversibly suppressed the stallion HPG axis, thus has potential for treating the androgen-dependent Equine-Arteritis-Virus carrier state and as behavior modulator.

Glucocorticoid-Induced Chondrocyte Cytotoxicity At Doses Recommended For Intra-Articular Therapy In Horses, Wenying Zhu

Theses and Dissertations--Veterinary Science

Intra-articular glucocorticoid injections are commonly used to treat synovitis and osteoarthritis in horses. These agents are highly effective at relieving pain, swelling, and other symptoms of joint inflammation. The drugs also have therapeutic benefits by down regulating the expression of cytokines and protease enzymes that participate in the degradation of articular cartilage. However, detrimental effects on chondrocyte function and cell viability that is independent of osteoarthritis pathogenesis have been described and linked to glucocorticoid use. These side effects are both drug- and dose-dependent. This study tested the hypothesis that manufacture recommended dosage levels of methylprednisolone, betamethasone, and triamcinolone that are …

Bovine Colostrum Supplementation Optimises Earnings, Performance And Recovery In Racing Thoroughbreds, C. K. Fenger, Thomas Tobin, P. J. Casey, Edward A. Roualdes, J. L. Langemeier, D. M. Haines

Maxwell H. Gluck Equine Research Center Faculty Publications

Bovine colostrum (BC) is the first milk produced by cows after calving and contains numerous beneficial substances for the immunity and development of the newborn calf. Because of the growth and immune factors in BC, it has become an attractive supplement for use by athletes to support immunity and health during athletic performance. In order to evaluate the effects of oral BC supplementation on equine athletes, this study evaluated the earnings, performance, recovery and incidence of upper respiratory infections (URTI) in racing horses. The study design was a randomized cross-over racing performance study. 21 horses in race training were randomly …

Copy Number Variation In The Horse Genome, Sharmila Ghosh, Zhipeng Qu, Pranab J. Das, Erica Fang, Rytis Juras, E. Gus Cothran, Sue Mcdonell, Daniel G. Kenney, Teri L. Lear, David L. Adelson, Bhanu P. Chowdhary, Terje Raudsepp

Maxwell H. Gluck Equine Research Center Faculty Publications

We constructed a 400K WG tiling oligoarray for the horse and applied it for the discovery of copy number variations (CNVs) in 38 normal horses of 16 diverse breeds, and the Przewalski horse. Probes on the array represented 18,763 autosomal and X-linked genes, and intergenic, sub-telomeric and chrY sequences. We identified 258 CNV regions (CNVRs) across all autosomes, chrX and chrUn, but not in chrY. CNVs comprised 1.3% of the horse genome with chr12 being most enriched. American Miniature horses had the highest and American Quarter Horses the lowest number of CNVs in relation to Thoroughbred reference. The Przewalski horse …

Clones Of Streptococcus Zooepidemicus From Outbreaks Of Hemorrhagic Canine Pneumonia And Associated Immune Responses, Sridhar Velineni, John F. Timoney, Kim Russell, Heidi J. Hamlen, Patricia Pesavento, William D. Fortney, P. Cynda Crawford

Maxwell H. Gluck Equine Research Center Faculty Publications

Acute hemorrhagic pneumonia caused by Streptococcus zooepidemicus has emerged as a major disease of shelter dogs and greyhounds. S. zooepidemicus strains differing in multilocus sequence typing (MLST), protective protein (SzP), and M-like protein (SzM) sequences were identified from 9 outbreaks in Texas, Kansas, Florida, Nevada, New Mexico, and Pennsylvania. Clonality based on 2 or more isolates was evident for 7 of these outbreaks. The Pennsylvania and Nevada outbreaks also involved cats. Goat antisera against acutely infected lung tissue as well as convalescent-phase sera reacted with a mucinase (Sz115), hyaluronidase (HylC), InlA domain-containing cell surface-anchored protein (INLA), membrane-anchored protein (MAP), SzP, …

The Roles Of Orthopaedic Pathology And Genetic Determinants In Equine Cervical Stenotic Myelopathy, Jennifer Gail Janes

Theses and Dissertations--Veterinary Science

Cervical stenotic myelopathy (CSM) is an important musculoskeletal and neurologic disease of the horse. Clinical disease occurs due to malformations of the vertebrae in the neck causing stenosis of the cervical vertebral canal and subsequent spinal cord compression. The disease is multifactorial in nature, therefore a clearer understanding of the etiology and pathogenesis of CSM will allow for improved management and therapeutic practices. This thesis examines issues of equine CSM diagnosis, skeletal tissue pathology, and inherited genetic determinants utilizing advances in biomedical imaging technologies and equine genomics. Magnetic resonance imaging (MRI) data provided a more complete assessment of the cervical …

Examination Of The Snsag Surface Antigen Gene Family In Sarcocystis Neurona, Ablesh Gautam

Theses and Dissertations--Veterinary Science

Sarcocystis neurona is a protozoan parasite that causes the serious neurologic disease equine protozoal myeloencephalitis (EPM). The life cycle of S. neurona progresses through multiple developmental stages that differ morphologically and molecularly. The S. neurona merozoite surface is covered by multiple related proteins, which are orthologous to the surface antigen (SAG) gene family of Toxoplasma gondii. The SAG surface antigens in T. gondii and another related parasite Neospora caninum are life cycle stage-specific and seem necessary for parasite transmission and persistence of infection. The present research was conducted to explore the gene family of SnSAGs in S. …

Studies On Equine Placentitis, Igor Frederico Canisso

Theses and Dissertations--Veterinary Science

Two types of placentitis were studied: ascending and nocardioform placentitis. Although the first diagnosis of nocardioform placentitis was made three decades ago, little is known about the disease, due to the lack of an experimental model. In attempt to develop a research model, Crossiela equi was inoculated through intrauterine, intravenous, intrapharyngeal, and oral routes, but none of the routes resulted in nocardioform placentitis. This may indicate that unidentified factors may play a role in disease pathogenesis and that simple presence of bacteria is not sufficient to induce nocardioform placentitis. The second and major component of this dissertation involved the identification …

Current Therapeutic Approaches To Equine Protozoal Myeloencephalitis, L. Dirikolu, Jonathan H. Foreman, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

Equine protozoal myeloencephalitis is the most important infectious neurologic disease of horses in the Western Hemisphere. Equine protozoal myeloencephalitis can interfere with a horse's ability to race, work, and perform; untreated, EPM can be lethal. Antemortem diagnosis of EPM is challenging, requiring careful evaluation of the animal's history, clinical signs, and laboratory data, with rigorous exclusion of other causes.

Therapeutic approaches to EPM are evolving. First-generation therapeutic approaches for EPM were based on the classic anti–Toxoplasma gondii pyrimethamine–sulfonamide combinations; treatment is prolonged and can be associated with a considerable relapse rate, which may be associated with the difficulty in …

Determination Of Farm-Specific Lawsonia Intracellularis Seroprevalence In Central Kentucky Thoroughbreds And The Identification Of Factors Contributing To Equine Proliferative Enteropathy, Allen E. Page

Theses and Dissertations--Veterinary Science

Lawsonia intracellularis and the disease it causes in horses, equine proliferative enteropathy (EPE), is an emerging pathogen of increasing importance to the horse industry from both an economic and welfare standpoint. Long recognized as an economically important disease of swine, the hallmark of EPE is a protein-losing enteropathy, where affected horses suffer weight loss and some ultimately succumb to the disease despite aggressive treatment. There are currently no known EPE preventative measures and the epidemiology of the disease remains poorly defined. While EPE is a sporadic disease affecting less than 25% of exposed horses, some farms experience clinical cases year …

Chondrodysplasia-Like Dwarfism In The Miniature Horse, John E. Eberth

Theses and Dissertations--Veterinary Science

Dwarfism is considered one of the most recognized congenital defects of animals and humans and can be hereditary or sporadic in cause and expression. There are two general morphologic categories within this vastly diverse disease. These categories are disproportionate and proportionate dwarfism and within each of these there are numerous phenotypes which have been extensively described in humans, and to a lesser extent in dogs, cattle, mice, chickens, and other domestic species. Ponies and Miniature horses largely differ from full size horses only by their stature. Ponies are often defined as those whose height is not greater than 14.2 hands; …

A Toxicology And Clinical Study Of Post Race Epitaxis Associated With Exercise Induced Pulmonary Hemorrhage In Thoroughbred Race Horses At The Racecourse Rinconada, Caracas, Venezuela, Abelardo Morales Briceno, Diana Villoria Leon, Kimberly Brewer, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

The aim of this study was to describe cases of epistaxis associated with post-race Exercise Induced Pulmonary Hemorrhage (EIPH) in Thoroughbred horses at the Hippodrome "La Rinconada", Caracas, Venezuela, through a clinic pathological study. We studied a total of 29 cases of epistaxis post-race in Thoroughbred horses at the Hippodrome La Rinconada, Caracas, Venezuela, which is 2,950 meters above sea level. The study included horses between the ages of 2-5 years, 16 stallions and 13 mares, weighing between 450-510 kg. They underwent a clinical examination, although horses presenting with epistaxis were in an emergency situation. Samples of blood and urine …

Breeding Induced Endometritis In The Mare: The Local Innate Immune Response, Elizabeth Moran Woodward

Theses and Dissertations--Veterinary Science

Uterine inflammation after breeding is considered necessary for the clearance of excess semen and debris from the uterus. A subpopulation of mares fails to clear the inflammation in a timely fashion, and develops a persistent breeding induced endometritis (PBIE). Experiments were preformed to evaluate correlations of PBIE to endometrial quality and age. Mares of advanced age and poor endometrial quality had a higher incidence of PBIE. In addition, mares fluctuated in susceptibility to PBIE from one season to the next. The uterine inflammatory gene expression in susceptible and resistant mares within the first 24 hours after breeding was investigated. The …

Evaluation Of Mass Spectrometric Methods For Detection Of The Anti-Protozoal Drug Imidocarb, A. F. Lehner, J. A. Hitron, J. May, C. Hughes, R. Eisenberg, N. Schwint, D. P. Knowles, P. Timoney, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

Imidocarb [N,N'-bis[3-(4,5-dihydro-1H-imidazol-2-yl)phenyl]urea, C₁₉H₂₀N₆O₁, m.w. 348.41] is a symmetrical carbanilide derivative used to treat disease caused by protozoans of the Babesia genus. Imidocarb, however, is also considered capable of suppressing Babesia-specific immune responses, allowing Babesia-positive horses to pass a complement fixation test (CFT) without eliminating the infection. This scenario could enable Babesia-infected horses to pass CFT-based importation tests. It is imperative to unequivocally identify and quantify equine tissue residues of imidocarb by mass spectrometry to address this issue. As a pretext to development of sensitive tissue assays, we have investigated possibilities of mass …

Pyrilamine In The Horse: Detection And Pharmacokinetics Of Pyrilamine And Its Major Urinary Metabolite O-Desmethylpyrilamine, L. Dirikolu, A. F. Lehner, J Daniel Harkins, W. E. Woods, W. Karpiesiuk, R. S. Gates, M. Fisher, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

Pyrilamine is an antihistamine used in human and veterinary medicine. As antihistamines produce central nervous system effects in horses, pyrilamine has the potential to affect the performance of racehorses. In the present study, O-desmethylpyrilamine (O-DMP) was observed to be the predominant equine urinary metabolite of pyrilamine. After intravenous (i.v.) administration of pyrilamine (300 mg/horse), serum pyrilamine concentrations declined from about 280 ng/mL at 5 min postdose to about 2.5 ng/mL at 8 h postdose. After oral administration of pyrilamine (300 mg/horse), serum concentrations peaked at about 33 ng/mL at 30 min, falling to <2 ng/mL at 8 h postdose. Pyrilamine was not detected in serum samples at 24 h postdosing by either route. After i.v. injection of pyrilamine (300 mg/horse) O-DMP was recovered at a level of about 20 ̄g/mL at 2 h postdose thereafter declining to about 2 ng/mL at 168 h postdose. After oral administration, the O-DMP recovery peaked at about 12 ̄g/mL at 8 h postdose and declined to <2 ng/mL at 168 h postdose. These results show that pyrilamine is poorly bioavailable orally (18%), and can be detected by sensitive enzyme-linked immunosorbent assay tests in urine for up to 1 week after a single administration. Care should be taken as the data suggest that the withdrawal time for pyrilamine after repeated oral administrations is likely to be at least 1 week or longer.

Detection And Confirmation Of Ractopamine And Its Metabolites In Horse Urine After Paylean® Administration, A. F. Lehner, C. G. Hughes, J Daniel Harkins, C. Nickerson, B. Mollett, L. Dirikolu, Jeffrey M Bosken, Fernanda C. Camargo, J. Boyles, A. Troppmann, W. Karpiesiuk, W. E. Woods, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

We have investigated the detection, confirmation, and metabolism of the beta-adrenergic agonist ractopamine administered as Paylean to the horse. A Testing Components Corporation enzyme-linked imunosorbent assay (ELISA) kit for ractopamine displayed linear response between 1.0 and 100 ng/ml, with an 1-50 of 10 ng/ml, and an effective screening limit of detection of 50 ng/mL. The kit was readily able to detect ractopamine equivalents in unhydrolyzed urine up to 24 h following a 300-mg oral dose. Gas chromatography-mass spectrometry (GC-MS) confirmation comprised glucuronidase treatment, solid-phase extraction, and trimethylsilyl derivatization, with selected-ion monitoring of ractopamine-tris(trimethylsilane) (TMS) m/z 267, 250, 179, and 502 …

Development Of A Method For The Detection And Confirmation Of The Alpha-2 Agonist Amitraz And Its Major Metabolite In Horse Urine, A. F. Lehner, C. G. Hughes, W. Karpiesiuk, J Daniel Harkins, L. Dirikolu, Jeffrey M Bosken, Fernanda Camargo, J. Boyles, A. Troppmann, W. E. Woods, Thomas Tobin

Maxwell H. Gluck Equine Research Center Faculty Publications

Amitraz (N′-(2,4-dimethylphenyl)-N-[[(2,4-dimethylphenyl)imino] methyl]-N-methyl-methanimidamide) is an alpha-2 adrenergic agonist used in veterinary medicine primarily as a scabicide- or acaricide-type insecticide. As an alpha-2 adrenergic agonist, it also has sedative/tranquilizing properties and is, therefore, listed as an Association of Racing Commissioners International Class 3 Foreign Substance, indicating its potential to influence the outcome of horse races. We identified the principal equine metabolite of amitraz as N-2,4-dimethylphenyl-N′-methylformamidine by electrospray ionization(+)-mass spectrometry and developed a gas chromatographic-mass spectrometric (GC-MS) method for its detection, quantitation, and confirmation in performance horse regulation. The GC-MS method involves derivatization with t-butyldimethylsilyl groups; selected ion monitoring (SIM) of m/z …