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Topic:Clinical Pathology
Clinical pathology in horses involves the study and analysis of biological samples to diagnose and monitor diseases and health conditions. This discipline encompasses various laboratory tests and procedures that assess the physiological and biochemical status of equines. Common analyses include hematology, biochemistry, urinalysis, and cytology, each providing insights into different aspects of equine health. Hematology evaluates blood components, such as red and white blood cells and platelets, to identify conditions like anemia or infection. Biochemistry tests measure enzymes, electrolytes, and metabolites to assess organ function and metabolic status. Urinalysis examines urine samples for indicators of renal function and systemic diseases. Cytology involves the microscopic examination of cells from tissues or fluids to detect abnormalities. This page aggregates peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and diagnostic value of clinical pathology in equine medicine.
Sepsis-From human organ failure to laminar failure. The horse with gram negative sepsis is known to be at particular risk of succumbing to laminitis. This review summarizes recent evidence indicating that similar pathologic events relating to inflammatory injury occur in laminar failure in laminitis as occur in organ injury/failure in human sepsis. The discussion also points out some important differences between the laminae and target organs in human sepsis that impact the clinical nature of the disease.
Extracellular matrix, leukocyte migration and laminitis. The structure and dynamic nature of extracellular matrix is discussed in the context of healthy and diseased tissues particularly the equine digital laminae.
Equid herpesvirus 2-associated oral and esophageal ulceration in a foal. A case of a 1-month-old Thoroughbred foal with dysphagia, salivation, pyrexia, oral mucosal pustules, and esophageal ulceration is reported. Swabs from the ulcerated lesions yielded Equid herpesvirus 2 (EHV-2) in virus isolation assays, and histopathology of a biopsy from the esophageal lesion identified nuclear inclusions suggestive of herpesviruses. Immunohistochemical staining with antibodies specific for EHV-2 was positive for epithelial cells in the vicinity of the ulcer but not in more distant mucosa. Electron microscopic evaluation of the biopsy showed herpesviral particles in epithelia...
Leukocyte-derived and endogenous matrix metalloproteinases in the lamellae of horses with naturally acquired and experimentally induced laminitis. Inflammation and dysregulation of endogenous matrix metalloproteinase (MMP) production are implicated in the development of equine laminitis. In this study, we examine quantitative relationships among levels of leukocyte-derived proMMP-9 and MMP-9, lamellar proMMP-2 and MMP-2, and expression of proMMP-2 processing enzymes, MT1-MMP/PACE4, as steps towards determining whether inflammation and dysregulation of endogenous MMP production are independent or co-dependent processes. Methods: Archived samples of lamellae from horses with naturally acquired laminitis (n = 12), and from horses administer...
Pathophysiologic effects of phenylbutazone on the right dorsal colon in horses. To determine pathophysiologic effects of phenylbutazone on the equine right dorsal colon (RDC). Methods: 12 healthy adult horses. Methods: A controlled crossover observational study was conducted. Clinical and serum variables, colonic inflammation (histologic grading), and measurement of myeloperoxidase (MPO) activity, malondialdehyde (MDA) and prostaglandin E(2) (PGE(2)) concentrations, ingesta volatile fatty acid (VFA) content, and arterial blood flow in the RDC were evaluated for a 21-day period in horses administered phenylbutazone (8.8 mg/kg, PO, q 24 h) or a control substance. Results: D...
Pharmacokinetics of firocoxib after administration of multiple consecutive daily doses to horses. To determine pharmacokinetic parameters and variables, firocoxib concentrations in urine and plasma, urine-to-plasma ratios, and the urine depletion profile of firocoxib and to evaluate whether the pharmacokinetic behavior of firocoxib was governed by linear processes after multiple doses of firocoxib were administered IV and orally. Methods: 6 healthy female horses (5 Paint horses and 1 Quarter Horse) in experiment 1 and 12 healthy male and female horses in experiment 2. Methods: In experiment 1, 6 horses were orally administered firocoxib paste once daily for 12 consecutive days, and plasma ...
Structural characterization of subchondral bone in the distal aspect of third metacarpal bones from Thoroughbred racehorses via micro–computed tomography. To characterize the microstructure of subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the condyles of third metacarpal bones (MC3s) from Thoroughbred racehorses at 2 different stages of SCB disease via micro-computed tomography (CT). Methods: 12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons. Methods: MC3s were collected from horses with mild (n = 6) or severe (6) SCB disease, as determined via micro-CT. Cubic (6 x 6 x 6-cm) specimens of SCB plate and TBB were cut from the palmar aspect of condyles and sagittal ridges and examined ...
Factors associated with survival of neonatal foals with bacteremia and racing performance of surviving Thoroughbreds: 423 cases (1982-2007). To identify factors associated with short-term survival in bacteremic neonatal foals, evaluate the racing performance of Thoroughbred survivors, and evaluate changes in causative organisms and their antimicrobial susceptibility. Methods: Retrospective case series. Methods: 423 bacteremic foals. Methods: Medical records of foals that were hospitalized in 1982 through 2007 were reviewed, and those with bacteremia were included in the study. Data retrieved included signalment, physical examination and clinicopathologic findings at admission, localized infections, concurrent illnesses, duration of...
Mediastinal lymphoma with complete atrioventricular block in a horse. A 15-year-old, neutered-male pony presented with a history of weight loss during 4 months. Clinical evaluation revealed severe bradycardia and complete atrioventricular block. At necropsy, a lobulated mass in the anterior mediastinum and moderate enlargement of the superficial cervical lymph nodes were observed. The vagus nerve and the brachiocephalic trunk were embedded in this anterior mediastinal tumor. Histologically, the mass was composed of sheets of neoplastic lymphoid cells expressing CD3, with a low mitotic rate. To the best of our knowledge, this is the first reported case of mediast...
Primary unilateral fibroleiomyoma of the ovary in a pregnant mare: a case report. Fibroleiomyomas of the ovary are rare. This smooth muscle tumour may develop and increase in size during pregnancy. Diagnosis is based on histological and immunohistochemical analyses. Histologically, the ovarian fibroleiomyoma consists of non-invasive bundles of smooth muscle cells that synthesize collagen-like extracellular matrix. This case report describes an ovarian fibroleiomyoma in a pregnant multiparous broodmare with a history of intermittent signs of colic.
Probable reason why small strongyle EPG counts are returning “early” after ivermectin treatment of horses on a farm in Central Kentucky. Critical tests were carried out in 2008 in four yearling horses (H-2, H-4, H-10, and H-11) born and raised together on a farm (MC) in Central Kentucky. These horses were treated intraorally with ivermectin paste at the dose rate of 200 microg/kg. The main interest was to try and determine more precisely, from posttreatment (PT) worm count data, the current activity of ivermectin against small strongyles in a horse herd. These horses had been treated repeatedly with this compound and counts of small strongyle eggs per gram of feces (EPGs) of these parasites have been returning sooner than previ...
Viruses as co-factors for the initiation or exacerbation of lung fibrosis. Idiopathic pulmonary fibrosis (IPF) remains exactly that. The disease originates from an unknown cause, and little is known about the mechanisms of pathogenesis. While the disease is likely multi-factorial, evidence is accumulating to implicate viruses as co-factors (either as initiating or exacerbating agents) of fibrotic lung disease. This review summarizes the available clinical and experimental observations that form the basis for the hypothesis that viral infections may augment fibrotic responses. We review the data suggesting a link between hepatitis C virus, adenovirus, human cytomegalo...
Case of bilateral seminoma in a trotter stallion. This report describes a bilateral seminoma in a stallion. After slaughter, histological examination revealed that the tumour consisted predominantly of polyhedral tumour cells with large nuclei, obvious nucleoli and a small border of cytoplasm. The mitotic index was low and Ki67 staining revealed 4% nuclear staining. To our knowledge, this paper is the first using Ki67 staining as a method to evaluate the mitotic rate in a testicular seminoma in the stallion.
Histological and immunohistochemical characterization of equine anovulatory haemorrhagic follicles (AHFs). Anovulatory haemorrhagic follicles (AHFs) are often the reason for ovulation failure in the mare. As the underlying factors that lead to AHF development are not well understood, it was of interest to investigate the vascularization of AHFs compared with normal follicles and corpora lutea (controls). In the present study, the ovarian cell populations investigated immunohistochemically included granulosa and luteal cells as well as various vascular structures. None of these cell types showed differences in the expression of vascular endothelial growth factor A (VEGF-A) between control ovaries co...
Immunohistochemical characterization and quantitative analysis of neurons in the myenteric plexus of the equine intestine. The present study was performed on whole-mount preparations to investigate the chemical neuroanatomy of the equine myenteric plexus throughout its distribution in the intestinal wall. The objective was to quantify neurons of the myenteric plexus, especially the predominant cholinergic and nitrergic subpopulations. Furthermore, we investigated the distribution of vasoactive intestinal polypeptide and the calcium-binding protein calretinin. Samples from different defined areas of the small intestine and the flexura pelvina were taken from 15 adult horses. After fixation and preparation of the ti...
A survey of equine abortion and perinatal foal losses in Hungary during a three-year period (1998-2000). Cases of equine abortion and perinatal foal losses were investigated in Hungary during a three-year period (1998-2000). Samples from aborted equine fetuses and newborn foals (total n = 96) were examined using bacteriological, virological, pathological, immunohistochemical (IHC), molecular biological and serological methods. The cause of abortion and perinatal foal loss was identified in 67/96 cases (70%); viral infection was found in 22 (23%), viral and bacterial coinfection in 1 (1%), bacterial infection in 23 (24%), protozoan infection in 1 (1%) and fungal infection in 2 cases (2%). Morpholo...
Determination of acyclovir in horse plasma and body fluids by high-performance liquid chromatography combined with fluorescence detection and heated electrospray ionization tandem mass spectrometry. Two methods are presented for the determination of 'respectively' the plasma protein unbound and total concentration of acyclovir in horse plasma and body fluids: first, a liquid-liquid extraction was performed on plasma, combined with HPLC-fluorescence detection for the total plasma concentration; second a more sensitive method using high-performance liquid chromatography combined with heated electrospray ionization tandem mass spectrometry (LC-HESI-MS/MS) was described for plasma and for body fluids analysis. To obtain the unbound concentration of acyclovir in plasma, a simple deproteinizati...
Evaluation of clinical examination for differential diagnosis of lameness by navicular apparatus or heel pain in horses. To evaluation of clinical examination for differential diagnosis of navicular region pain from other forms of palmar heel pain in the forelimb in horses the present study was undertaken. Thirty four horses with lameness referable to the palmar aspect of the hoof based on their response to the palmar digital nerves analgesia were divided into 2 groups based on their response to both distal interphalangeal joint and navicular bursa analgesia. Horses that were profoundly improved by both analgesic blocks (distal interphalangeal joint and navicular bursa) were considered to have navicular region p...
Lymphoproliferative disease with features of lymphoma in the central nervous system of a horse. Lymphoma (malignant lymphoma, lymphosarcoma) is uncommon in horses in the United Kingdom. This report describes an unusual form of lymphoproliferative disease with features of lymphoma restricted to the central nervous system (CNS) and with no evidence of a primary lesion elsewhere. Immunohistochemical examination defined an overwhelming predominance of T lymphocytes with admixed B lymphocytes and activated macrophages. This case exemplifies the challenges associated with definitive diagnosis of lymphoproliferative disease of the equine CNS.
Prevalence of ergot derivatives in natural ryegrass pastures: detection and pathogenicity in the horse. In the present study, we determined the incidence and effects of season and weather on clinical manifestations of endophyte-infected ryegrass toxicity, performed chemical detection and pharmacological bioassays on ryegrass extracts, and conducted trials on: (i) effects of domperidone or metochlopramide on ovarian inactivity induced by endophyte-infected ryegrass; (ii) efficacy of buspirone or dihydrochloro phenyl piperazine (m-CPP) for preventing suppressed milk production induced by endophyte-infected ryegrass; and (iii) efficacy of domperidone to induce ovulation during winter anestrus. Mare...
Detection of West Nile virus infection in horses, Italy, September 2008. No abstract available
The structure of the polysaccharide of the lipopolysaccharide produced by Taylorella equigenitalis type strain (ATCC 35865). Taylorella equigenitalis is a Gram-negative bacterium that causes venereally transmitted contagious equine metritis (CEM), and its identification and differentiation from other bacteria and Taylorella species is an important requirement for the control of CEM infection. Based on the results of NMR and MS analysis, the antigenic O-polysaccharide (O-PS) component of the lipopolysaccharide (LPS) produced by the type strain T. equigenitalis (ATCC 35865) was found to be a linear polymer composed of a repeating disaccharide unit, containing partially amidated 2,3-diacetamido-2,3-dideoxy-alpha-L-gulu...
Equine herpesvirus 1 entry via endocytosis is facilitated by alphaV integrins and an RSD motif in glycoprotein D. Equine herpesvirus 1 (EHV-1) is a member of the Alphaherpesvirinae, and its broad tissue tropism suggests that EHV-1 may use multiple receptors to initiate virus entry. EHV-1 entry was thought to occur exclusively through fusion at the plasma membrane, but recently entry via the endocytic/phagocytic pathway was reported for Chinese hamster ovary cells (CHO-K1 cells). Here we show that cellular integrins, and more specifically those recognizing RGD motifs such as alphaVbeta5, are important during the early steps of EHV-1 entry via endocytosis in CHO-K1 cells. Moreover, mutational analysis revea...
Correlation of quantitative computed tomographic subchondral bone density and ash density in horses. The purpose of this study was to compare subchondral bone density obtained using quantitative computed tomography with ash density values from intact equine joints, and to determine if there are measurable anatomic variations in mean subchondral bone density. Five adult equine metacarpophalangeal joints were scanned with computed tomography (CT), disarticulated, and four 1-cm(3) regions of interest (ROI) cut from the distal third metacarpal bone. Bone cubes were ashed, and percent mineralization and ash density were recorded. Three-dimensional models were created of the distal third metacarpal...
Computed tomography-guided brain biopsy for in vivo diagnosis of a cholesterinic granuloma in a horse. An 8-year-old warmblood mare was evaluated following an acute onset of neurologic abnormalities. Results: Computed tomography of the head revealed large masses in both lateral ventricles, and a presumptive diagnosis of cholesterinic granuloma was made. Results: Freehand biopsy of the intracranial masses was performed under computed tomographic guidance, and histologic examination of biopsy specimens confirmed the diagnosis. No adverse effects associated with the brain biopsy procedure were encountered. Clinical signs resolved, and long-term follow-up did not reveal any recurrence of neurologic...
