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Topic:Veterinary Medicine

Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Pharmacokinetics of tilmicosin in equine tissues and plasma.
Journal of veterinary pharmacology and therapeutics    January 8, 2008   Volume 31, Issue 1 66-70 doi: 10.1111/j.1365-2885.2007.00909.x
Clark C, Dowling PM, Ross S, Woodbury M, Boison JO.The macrolide antibiotic tilmicosin has potential for treating bacterial respiratory tract infections in horses. A pharmacokinetic study evaluated the disposition of tilmicosin in the horse after oral (4 mg/kg) or subcutaneous (s.c.) (10 mg/kg) administration. Tilmicosin was not detected in equine plasma or tissues after oral administration at this dose. With s.c. injection, tilmicosin concentrations reached a maximum concentration of approximately 200 ng/mL in the plasma of the horses. Tilmicosin concentrations in plasma persisted with a mean residence time (MRT) of 19 h. Maximum tissue resid...
A nodular granulomatous posthitis caused by Halicephalobus sp. in a horse.
Veterinary dermatology    January 8, 2008   Volume 19, Issue 1 44-48 doi: 10.1111/j.1365-3164.2007.00643.x
Muller S, Grzybowski M, Sager H, Bornand V, Brehm W.This report describes a case of nodular posthitis caused by Halicephalobus gingivalis in a 24-year-old warmblood horse. Macroscopic examination revealed a multinodular, partially ulcerated mass on the external lamina of the prepuce. Nematode migration from unfixed biopsy material in phosphate-buffered saline revealed adult nematodes with the typical morphological features of H. gingivalis: distinctive rhabditiform oesophagus with corpus, isthmus and bulb and the dorsoflexed ovary. The main histopathological features consisted of submucosal confluent granulomatous foci containing cross- and tan...
Pharmacokinetics of tramadol in horses after intravenous, intramuscular and oral administration.
Journal of veterinary pharmacology and therapeutics    January 8, 2008   Volume 31, Issue 1 60-65 doi: 10.1111/j.1365-2885.2007.00929.x
Shilo Y, Britzi M, Eytan B, Lifschitz T, Soback S, Steinman A.Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat moderate to moderately severe pain in humans. The present study investigated tramadol administration in horses by intravenous, intramuscular, oral as immediate-release and oral as sustained-release dosage-form routes. Seven horses were used in a four-way crossover study design in which racemic tramadol was administered at 2 mg/kg by each route of administration. Altogether, 23 blood samples were collected between 0 and 2880 min. The concentration of tramadol and its M1 metabolite were ...
Actinomyces species as a cause of abscesses in nine horses.
The Veterinary record    January 8, 2008   Volume 162, Issue 1 18-20 doi: 10.1136/vr.162.1.18
Fielding CL, Magdesian KG, Morgan RA, Ruby RE, Sprayberry KA.The characteristics, history, clinical signs, treatment and outcome of nine horses with abscesses caused by Actinomyces species were reviewed. dna sequencing was used to determine the species of one of the isolates. The horses were one to 11 years of age, and the abscesses were most commonly located in the submandibular and retropharyngeal regions. The bacterium was usually cultured as the sole isolate and the horses were most often affected in the autumn. Most of the abscesses were treated with antimicrobials and drainage, but some of them recurred. The horses with submandibular abscesses had...
A comparison of coprological, serological and molecular methods for the diagnosis of horse infection with Anoplocephala perfoliata (Cestoda, Cyclophyllidea).
Veterinary parasitology    January 8, 2008   Volume 152, Issue 3-4 271-277 doi: 10.1016/j.vetpar.2007.12.032
Traversa D, Fichi G, Campigli M, Rondolotti A, Iorio R, Proudman CJ, Pellegrini D, Perrucci S.Anoplocephala perfoliata (Cestoda, Cyclophyllidea), the commonest intestinal tapeworm of horses, can cause colic, intussusceptions, ileal impactions and intestinal perforations. Common diagnostic techniques for A. perfoliata infection, i.e. coprology and serology, show inherent limitations in terms of sensitivity and specificity and new approaches are thus required. Hence, the present study compared the reliability of coprological, serological (i.e. ELISA) and molecular (i.e. nested PCR) methods in detecting A. perfoliata infection in naturally infected horses and in horses treated with a comb...
Sperm morphology and chromatin integrity in Swedish warmblood stallions and their relationship to pregnancy rates.
Acta veterinaria Scandinavica    January 7, 2008   Volume 50, Issue 1 2 doi: 10.1186/1751-0147-50-2
Morrell JM, Johannisson A, Dalin AM, Hammar L, Sandebert T, Rodriguez-Martinez H.Artificial insemination is not as widely used in horses as in other domestic species, such as dairy cattle and pigs, partly because of the wide variation in sperm quality between stallion ejaculates and partly due to decreased fertility following the use of cooled transported spermatozoa. Furthermore, predictive tests for sperm fertilising ability are lacking. The objective of the present study was to assess sperm morphology and chromatin integrity in ejaculates obtained from 11 warmblood breeding stallions in Sweden, and to evaluate the relationship of these parameters to pregnancy rates to i...
Cystic echinococcosis in equids in Italy.
Parasitology research    January 6, 2008   Volume 102, Issue 4 815-818 doi: 10.1007/s00436-007-0862-7
Varcasia A, Garippa G, Pipia AP, Scala A, Brianti E, Giannetto S, Battelli G, Poglayen G, Micagni G.Between March 2003 and February 2007, the livers and the lungs of 2,231 horses from various Italian regions were examined for cystic echinococcosis presence at the time of slaughter. Hydatid cysts were found in six horses, namely four from Sardinia, one from Sicily, and one from Tuscany. The location, number, morphology, and fertility of the cysts found were determined. DNA was extracted from the germinal layers and protoscoleces of the fertile cysts and polymerase chain reactions (PCR) were performed in order to strain type DNA isolates for reduced nicotinamide adenine dinucleotide dehydrogen...
Retrospective study of palmar/plantar annular ligament injury in 71 horses: 2001-2006.
Equine veterinary journal    January 4, 2008   Volume 40, Issue 3 237-244 doi: 10.2746/042516408X271217
Owen KR, Dyson SJ, Parkin TD, Singer ER, Kristoffersen M, Mair TS.Constriction of the digital flexor tendon sheath (DFTS) and its contents by the palmar/plantar annular ligament (PAL) is well recognised. However, primary injury of the PAL has not been well documented. Objective: To describe the clinical features of PAL injury, determine its prevalence with or without subcutaneous fibrosis and/or concurrent injury within the DFTS, and assess response to treatment. Methods: Horses were selected for inclusion based upon clinical features consistent with PAL injury and the presence of a thickened PAL (> or =2 mm) verified ultrasonographically. A retrospective...
Effects of dexamethasone administration on insulin resistance and components of insulin signaling and glucose metabolism in equine skeletal muscle.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 51-58 doi: 10.2460/ajvr.69.1.51
Tiley HA, Geor RJ, McCutcheon LJ.To determine the effects of dexamethasone treatment on selected components of insulin signaling and glucose metabolism in skeletal muscle obtained from horses before and after administration of a euglycemic-hyperinsulinemic clamp (EHC). Methods: 6 adult Standardbreds. Methods: In a balanced crossover study, horses received either dexamethasone (0.08 mg/kg, IV, q 48 h) or an equivalent volume of saline (0.9% NaCl) solution, IV, for 21 days. A 2-hour EHC was administered for measurement of insulin sensitivity 1 day after treatment. Muscle biopsy specimens obtained before and after the EHC were a...
In vitro cell compatibility and antibacterial activity of microencapsulated doxycycline designed for improved localized therapy of septic arthritis.
The Journal of antimicrobial chemotherapy    January 3, 2008   Volume 61, Issue 2 332-340 doi: 10.1093/jac/dkm491
Haerdi-Landerer MC, Suter MM, Steiner A, Wittenbrink MM, Pickl A, Gander BA.For the treatment of septic arthritis in large animals, the local application of antibiotics as a slow release system may be an appropriate means to reach high local bioactivity and low systemic side effects and drug residues. In this study, doxycycline microspheres were developed and tested in vitro for their drug-release properties, suitability for intra-articular application and antimicrobial activity. Methods: The development of a slow release system was achieved by microencapsulation of the drug into poly(lactide-co-glycolide) microspheres by a novel ultrasonic atomization method. Drug el...
Hypertension and insulin resistance in a mixed-breed population of ponies predisposed to laminitis.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 122-129 doi: 10.2460/ajvr.69.1.122
Bailey SR, Habershon-Butcher JL, Ransom KJ, Elliott J, Menzies-Gow NJ.To determine the metabolic phenotype of a group of laminitis-prone ponies when at pasture in summer, compared with when at pasture in winter. Methods: 40 ponies of various breeds predisposed to recurrent pasture-associated laminitis and 40 unaffected control ponies. Methods: Body condition score and size of the crest of the neck were assessed, blood samples obtained, and blood pressure measured by use of an indirect oscillometric technique, while ponies were kept on winter pasture (last week of November or beginning of December) and again on summer pasture (June). Serum insulin concentration a...
Effects of long-term oral administration of levothyroxine sodium on glucose dynamics in healthy adult horses.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 76-81 doi: 10.2460/ajvr.69.1.76
Frank N, Elliott SB, Boston RC.To determine the effects of long-term oral administration of levothyroxine sodium (L-T(4)) on glucose dynamics in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Frequently sampled IV glucose tolerance test procedures were performed on 3 occasions (24-hour intervals) before and at 16, 32, and 48 weeks during the treatment period. Data were assessed via minimal model analysis. The repeatability of measurements was evaluated. Results: During treatment, body weight decreased significantly from the pretreatment value; mean +/- ...
Lameness, athletic performance, and financial returns in yearling Thoroughbreds bought for the purpose of resale for profit.
Journal of the American Veterinary Medical Association    January 3, 2008   Volume 232, Issue 1 85-90 doi: 10.2460/javma.232.1.85
Preston SA, Trumble TN, Zimmel DN, Chmielewski TL, Brown MP, Hernandez JA.To characterize lameness during training and compare exercise variables and financial returns among yearling Thoroughbreds that were bought for the purpose of resale for profit. Methods: 40 yearling Thoroughbreds. Methods: Prospective study. Methods: Horses purchased at yearling sales (summer 2004) were trained prior to resale at 2-year-olds in training sales (spring 2005). Horses were monitored daily for diagnosis and treatment of lameness during training. Selected variables, including sex, age, purchase price, lameness, distance (No. of furlongs) galloped during training, and financial retur...
Follicle and systemic hormone interrelationships during spontaneous and ablation-induced ovulatory waves in mares.
Animal reproduction science    January 3, 2008   Volume 106, Issue 1-2 181-187 doi: 10.1016/j.anireprosci.2007.12.018
Ginther OJ, Jacob JC, Gastal MO, Gastal EL, Beg MA.The characteristics of ovulatory follicular waves were studied for spontaneous waves and waves induced during the next estrous cycle by ovarian follicle ablations and administration of PGF2alpha 10 days after ovulation in 21 mares. In the induced group, both the days of the FSH surge and day of deviation were more synchronized, LH concentrations were greater before and after deviation, estradiol concentrations were greater after deviation, and the ovulatory follicle grew at a faster rate (3.4+/-0.2 compared with 2.7+/-0.1 mm/day). The frequency of two dominant follicles/wave was not different ...
Effects of an intravenous endotoxin challenge on glucose and insulin dynamics in horses.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 82-88 doi: 10.2460/ajvr.69.1.82
Tóth F, Frank N, Elliott SB, Geor RJ, Boston RC.To evaluate the effects of endotoxin administered IV on glucose and insulin dynamics in horses. Methods: 16 healthy adult mares. Methods: Each week of a 2-week randomized crossover study, each horse received an IV injection (duration, 30 minutes) of Escherichia coli O55:B5 lipopolysaccharide (LPS) in 60 mL of sterile saline (0.9% NaCl) solution (20 ng/kg) or sterile saline solution alone (control treatment). Frequently sampled IV glucose tolerance test procedures were performed at 24 hours before (baseline) and 24 and 48 hours after injection; glucose and insulin dynamics were assessed via min...
Isolation of a gammaherpesvirus similar to asinine herpesvirus-2 (AHV-2) from a mule and a survey of mules and donkeys for AHV-2 infection by real-time PCR.
Veterinary microbiology    January 3, 2008   Volume 130, Issue 1-2 176-183 doi: 10.1016/j.vetmic.2007.12.013
Bell SA, Pusterla N, Balasuriya UB, Mapes SM, Nyberg NL, MacLachlan NJ.Equids are commonly infected by herpesviruses, but isolation of herpesviruses from mules has apparently not been previously reported. Furthermore, the genomic relationships among the various equid herpesviruses are poorly characterized. We describe the isolation and preliminary characterization of a mule gammaherpesvirus tentatively identified as asinine herpesvirus-2 (AHV-2; also designated equid herpesvirus-7 (EHV-7)) from the nasal secretions (NS) of a healthy mule in northern California. The virus was initially identified by transmission electron microscopic examination of lysates of cell ...
Molecular cloning and characterization of the alphaX subunit from CD11c/CD18 horse integrin.
Veterinary immunology and immunopathology    January 3, 2008   Volume 122, Issue 3-4 326-334 doi: 10.1016/j.vetimm.2007.12.004
Espino-Solis GP, Osuna-Quintero J, Possani LD.This work reports the cloning and sequence determination of the horse alpha subunit of the integrin CD11c/CD18, a marker of dendritic cells. A cDNA clone of 4582 base pairs was obtained. It encodes a protein segment of 1086 amino acid residues of the extracellular domain with 10 potential sites of glycosylation, a transmembrane domain of 32 residues and a C-terminal cytoplasmic tail of 24 residues. A phylogenetic analysis of this integrin shows close similarity (83%) with that of Canis familiaris.
Effects of hyperbaric oxygen on full-thickness meshed sheet skin grafts applied to fresh and granulating wounds in horses.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 144-147 doi: 10.2460/ajvr.69.1.144
Holder TE, Schumacher J, Donnell RL, Rohrbach BW, Adair HS.To determine the effects of hyperbaric oxygen therapy (HBOT) on full-thickness skin grafts applied to fresh and granulating wounds of horses. Methods: 6 horses. Methods: On day 0, two 4-cm-diameter circular sections of full-thickness skin were removed from each of 2 randomly selected limbs of each horse, and two 4-cm-diameter circular skin grafts were harvested from the pectoral region. A skin graft was applied to 1 randomly selected wound on each limb, leaving the 2 nongrafted wounds to heal by second intention. On day 7, 2 grafts were harvested from the pectoral region and applied to the gra...
Effects of systemic inflammation on insulin sensitivity in horses and inflammatory cytokine expression in adipose tissue.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 130-139 doi: 10.2460/ajvr.69.1.130
Vick MM, Murphy BA, Sessions DR, Reedy SE, Kennedy EL, Horohov DW, Cook RF, Fitzgerald BP.To determine whether an inflammatory challenge induces insulin resistance in horses and examine possible contributions of adipose tissue to inflammatory cytokine production. Methods: 15 adult mares. Methods: Lipopolysaccharide (0.045 mug/kg, IV) or saline solution was administered, and insulin sensitivity was determined by means of the hyperinsulinemic, euglycemic clamp procedure or an adipose tissue biopsy was performed. Adipose tissue samples were collected, and mature adipocytes were obtained. Mature adipocytes were stimulated with lipopolysaccharide or dedifferentiated into preadipocytes a...
Comparison of efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis.
Journal of the American Veterinary Medical Association    January 3, 2008   Volume 232, Issue 1 91-97 doi: 10.2460/javma.232.1.91
Doucet MY, Bertone AL, Hendrickson D, Hughes F, Macallister C, McClure S, Reinemeyer C, Rossier Y, Sifferman R, Vrins AA, White G, Kunkle B, Alva R....To compare efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis. Methods: Randomized controlled clinical trial. Methods: 253 client-owned horses with naturally occurring osteoarthritis. Methods: Horses were treated with firocoxib (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) or phenylbutazone (4.4 mg/kg [2 mg/lb], PO, q 24 h) for 14 days. Physical examinations and lameness evaluations were performed prior to treatment and after 7 and 14 days. Clinical improvement was defined as a reduction of at least 1 lameness grade or a combined...
In vitro efficacy of an ophthalmic drug combination against corneal pathogens of horses.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 101-107 doi: 10.2460/ajvr.69.1.101
Scotty NC, Brooks DE, Schuman Rose CD.To evaluate the in vitro efficacy of an ophthalmic drug combination against common corneal pathogens of horses. Methods: Representative isolates of 3 bacterial and 2 fungal corneal pathogens of horses. Methods: Pathogens were subjected to minimum inhibitory concentration (MIC) testing of a drug combination that consisted of equal volumes of natamycin 3.33%, tobramycin 0.3%, cefazolin 5.5%, and equine serum. Proteinase inhibitory activity of the drug combination was assessed by use of a fluorescence microplate assay with gelatin and collagen I as substrates. The MICs of the drug combination wer...
Effects of long-term oral administration of levothyroxine sodium on serum thyroid hormone concentrations, clinicopathologic variables, and echocardiographic measurements in healthy adult horses.
American journal of veterinary research    January 3, 2008   Volume 69, Issue 1 68-75 doi: 10.2460/ajvr.69.1.68
Frank N, Buchanan BR, Elliott SB.To determine the effects of long-term oral levothyroxine sodium (L-T(4)) administration on serum thyroid hormone concentrations, thyroid gland function, clinicopathologic variables, and echocardiographic examination measurements in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Every 4 weeks, physical examinations were performed; blood samples were collected for CBC, plasma biochemical analyses, and assessments of serum total triiodothyronine (tT(3)) and thyroxine (tT(4)) concentrations. Plasma creatine kinase MB activity ...
Engineering and performance standards parameters for long distance road transport in the United States: the special case of horses.
Veterinaria italiana    January 1, 2008   Volume 44, Issue 1 223-233 
Stull CL.The transportation conditions of slaughter horses for human consumption have become a public and regulatory issue in the United States in the last two decades. Federal regulations were developed partially using the results of funded research projects that examined the types of vehicles, characteristics of slaughter horse candidates, types of injuries during transport, duration of transit, stocking densities and other behavioural and physiological indices during long-distance road transport. Additionally, the physiological responses of horses travelling long distances in vans while cross-tied b...
Early migration of Sarcocystis neurona in ponies fed sporocysts.
The Journal of parasitology    January 1, 2008   Volume 93, Issue 5 1222-1225 doi: 10.1645/GE-497R.1
Elitsur E, Marsh AE, Reed SM, Dubey JP, Oglesbee MJ, Murphy JE, Saville WJ.Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days ...
Veterinary management of horse transport.
Veterinaria italiana    January 1, 2008   Volume 44, Issue 1 149-163 
Leadon D, Waran N, Herholz C, Klay M.Enormous numbers of horses are transported locally, nationally and internationally every year. National legislation and international guidelines set standards for the health and welfare of animals during transport. As a consequence, equine clinicians have major responsibilities in safeguarding the horse industry against the spread of disease and in being aware of the problems inherent in horse transport. The authors explore road, sea and air transport and their effect on horses. Various types of road transport are available and there are various sources of impact on horses. These include loadi...
Incidence of osteochondrosis (dissecans) in Dutch warmblood horses presented for pre-purchase examination.
Irish veterinary journal    January 1, 2008   Volume 61, Issue 1 33-37 doi: 10.1186/2046-0481-61-1-33
Vos NJ.Data are lacking in the literature regarding the incidence of osteochondrosis (dissecans) [OC(D)] in relation to lameness evaluation in Dutch Warmblood horses. The objective of this retrospective study was to assess the incidence of radiological abnormalities consistent with osteochondrosis or osteochondrosis dissecans in 1,231 sound Dutch Warmblood (DW) horses presented for pre-purchase examination. Standardised (Dutch) pre-purchase examination protocols were evaluated. The pre-purchase examination included a clinical, lameness and radiological evaluation, performed at a private equine clinic...
Historical perspectives on long distance transport of animals.
Veterinaria italiana    January 1, 2008   Volume 44, Issue 1 19-30 
Blancou J, Parsonson I.Since Roman Antiquity, domestic and wild animals have been transported over long distances for purposes as different as improvement of livestock production, food supply, scientific interest, public entertainment, war and numerous other purposes. This long distance transportation was originally limited to the Mediterranean area but, during the Middle Ages extended to the rest of Europe. The conquest of the New World was the first major occasion to transport large numbers of horses and other livestock across the oceans. Domestic animals were necessary for the new colonies and their armies. Europ...
Joint dependent concentrations of bone alkaline phosphatase in serum and synovial fluids of horses with osteochondral injury: an analytical and clinical validation.
Osteoarthritis and cartilage    December 26, 2007   Volume 16, Issue 7 779-786 doi: 10.1016/j.joca.2007.11.008
Trumble TN, Brown MP, Merritt KA, Billinghurst RC.Validate use of a commercially available immunoassay for measurement of bone alkaline phosphatase (BAP) in equine serum and synovial fluid (SF), and investigate the effects of osteochondral (OC) injury in horses on BAP concentrations in serum and SF. Methods: SF was collected from 37 joints of 34 Thoroughbred (TB) racehorses undergoing arthroscopic surgery for the removal of OC fragments from either the carpal joints (n=18) or the metacarpo-/metatarsophalangeal (MP) joints (n=19). SF was also obtained from 52 joints of 16 normal TB horses, collected bilaterally from carpal joints of 10 horses ...
Influence of valvular insufficiency and recurrent airway obstruction on haemodynamics and therapy in warmblood horses with atrial fibrillation.
Research in veterinary science    December 26, 2007   Volume 85, Issue 2 333-339 doi: 10.1016/j.rvsc.2007.11.001
Gehlen H, Bubeck K, Rohn K, Stadler P.The aim of this study was to investigate the potential haemodynamic effects of valvular insufficiency and recurrent airway obstruction (RAO) in horses with atrial fibrillation (AF). Therefore in ten healthy horses (group 1) and 40 horses with AF a clinical examination, a lung examination, echocardiography and right heart catheterization for measurement of intracardic and pulmonary pressures were performed. According to the clinical findings the horses with AF were subdivided into 4 groups (group 2: AF; group 3: AF/valvular insufficiency; group 4: AF/RAO; group 5: AF/valvular insufficiency/RAO)...
Brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona and act as intermediate hosts.
Veterinary parasitology    December 23, 2007   Volume 153, Issue 1-2 24-43 doi: 10.1016/j.vetpar.2007.12.016
Mansfield LS, Mehler S, Nelson K, Elsheikha HM, Murphy AJ, Knust B, Tanhauser SM, Gearhart PM, Rossano MG, Bowman DD, Schott HC, Patterson JS.We tested the hypothesis that brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona, the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy sh...