Histology in horses involves the microscopic examination of tissues to understand their structure and function. This field of study provides insights into the cellular composition and architecture of equine tissues, aiding in the diagnosis of diseases and the assessment of tissue health. Histological analysis is used to identify pathological changes, such as inflammation, neoplasia, or degenerative conditions, by examining tissue samples obtained through biopsies or necropsies. Common tissues studied in equine histology include skin, muscle, bone, and internal organs. This page compiles peer-reviewed research studies and scholarly articles that explore histological techniques, findings, and their applications in equine veterinary medicine.
GAIDAMAKA MG, VAGANOV GP, DROMASHKO AS, SHVETSKAVA BD, FYADINA DD.The research examines an incident of upper respiratory tract disease in horses, marked by severe symptoms, which followed a human influenza epidemic in Kharkov in 1957, challenging previous notions that […]
DAVIES J, DEMPSEY EW, WISLOCKI GB.A fetal horse ovary at the 6th month of gestation and a fetal ovary and testis at the 9th month have been studied histochemically with special reference to the cytoplasmic lipids of the interstitial cells. At least two lipid fractions appeared to be present, one which was soluble in acetone and was mainly responsible for the positive "plasmal" reaction, and another, insoluble in acetone, which was responsible for the sudanophilic, Ashbel-Seligman and periodic acid-Schiff positive material remaining after acetone extraction. The interstitial cell lipids in the older ovary and testis were also a...
Hurst EW.The virus of equine encephalomyelitis (eastern strain) evokes in the horse, calf, sheep and dog an unusually intense encephalomyelitis characterized by acute primary degeneration of nerve cells, the appearance in neurons of the brain stem and elsewhere of nuclear inclusions resembling those in Borna disease and poliomyelitis, polymorphonuclear infiltration in the nervous tissues with early microglial proliferation, and perivascular cuffing with mononuclears and polymorphonuclears in varying proportions. The grey matter is affected more than the white. Lesions may be less marked in the striatum...
To compare ocular structures of Quarter Horses homozygous for hereditary equine regional dermal asthenia (HERDA) with those of Quarter Horses not affected by HERDA (control horses) and to determine the frequency of new corneal ulcers for horses with and without HERDA during a 4-year period. Methods: Cohort study of ocular structures and retrospective case series of horses with and without HERDA. Methods: The cohort portion of the study involved 10 Quarter Horses with HERDA and 10 Quarter Horses without HERDA; the retrospective case series involved 28 horses with HERDA and 291 horses without HE...
Unlike in Warmblood horses, aortic rupture is quite common in Friesian horses, in which a hereditary trait is suspected. The aortic connective tissue in affected Friesians shows histological changes such as medial necrosis, elastic fibre fragmentation, mucoid material accumulation and fibrosis with aberrant collagen morphology. However, ultrastructural examination of the collagen fibres of the mid-thoracic aorta has been inconclusive in further elucidating the pathogenesis of the disease. Objective: To assess several extracellular matrix (ECM) components biochemically in order to explore a pos...
Böck MJ, Fernandez TJ, Pereira VP, da Veiga ML, de Mello Bertoncheli Dos Santos C, de Morais-Pinto L.We examined 52 horse aortas to characterize the morphological aspects of the aortic bulb wall and the ascending aorta. The morphometric data were analyzed using ImageJ®-Fiji 1.5 software. The Tunica intima was composed of endotheliocytes with scarce cytoplasm and ellipsoid nuclei, supported by a collagenous subendothelial stratum. The Tunica media was composed entirely of fascicles of vascular smooth muscle cells interspersed with bundles of collagen fibers and elastic lamellae, characterizing the aortic medial lamellar unit. The Tunica adventitia consisted of two distinct sub-layers: the ext...
Vallejo-Soto P, Dorado J, Herrera-GarcÃa R, Ãlvarez-Delgado C, Gómez-Laguna J, Santiago Ã, Manrique M, González Ariza A, León Jurado JM....Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm), the number of glands (#G), and glandu...
An T, Dugarjaviin M.(1) Background: The dun coat color, a wild-type phenotype in horses characterized by pigment dilution and primitive markings, is regulated by . This study explored the expression and localization of in the Bider marking (a primitive mark unique to the shoulder of horses); (2) Methods: We compared skin tissues from Bider-marked and non-Bider dun Mongolian horses. Samples were collected from the Bider area (dark-colored/light-colored shoulder), dorsal midline, and croup. Histological staining, qRT-PCR, and Western blotting were used to analyze pigment distribution and expression at mRNA and pr...
Rissi DR, Mendes RE.Squamous cell carcinoma (SCC) is the most common ocular and periocular neoplasm of horses, typically arising from the limbus, third eyelid mucosa or mucocutaneous junctions of the upper and lower eyelids. Tumours are locally invasive, prone to recurrence and may rarely metastasize. Histological evaluation is required for definitive diagnosis and atypical SCC subtypes may be diagnostically challenging. Here we describe a clear cell SCC in the third eyelid of a 16-year-old female Quarter Horse. The red and invasive mass was surgically excised for histological evaluation. The lesion consisted of ...
Keller LE, Kelly TN, Chevalier JM, Jung HJ, Pearson GB, Begum L, Beane OS, Bhumiratana S, Fortier LA.Fresh osteochondral allograft (OCA) transplantation effectively repairs cartilage and subchondral bone; however, the persisting shortage of available donor OCAs and their short shelf-life make scheduling surgeries and meeting patient demand challenging. Attempts have been made to develop tissue-engineered solutions to address the limitations of OCA; nonetheless, these have failed to progress beyond the preclinical stage. Objective: To assess the safety and efficacy of a tissue-engineered osteochondral allograft (TE-OCA) as compared with equine OCA in an equine osteochondral defect model. Metho...
Campos Schweitzer A, Mespoulhes-Rivière C, Perkins JD, Ducharme NG, Piercy RJ, Lynch N, Rossignol F.To evaluate functional and histopathologic outcomes of standing selective laryngeal reinnervation using the spinal accessory nerve (SAN) in horses with experimentally induced recurrent laryngeal neuropathy (RLN). Methods: Five Thoroughbred mares. Methods: Prospective cohort study. Methods: The horses underwent left recurrent laryngeal neurectomy followed 8 weeks later by selective laryngeal reinnervation using the SAN. Follow-up evaluations at 4.5, 6, 8, and 12 months included treadmill exercising endoscopy, ultrasonography of intrinsic laryngeal muscles, and percutaneous electrical stimul...
Hmb O, L W, M V, Jm W, Ct F.A systematic study of regional skin thickness in different types of horses has not yet been described. Knowledge about regional skin thickness has long been used in human medicine to optimise wound care and skin grafting outcomes and similar knowledge could prove useful in equine wound management. The objective of the current study was to report the topographical variation in skin thickness of Warmblood (WB) and Coldblood (CB) type horses and to compare different methods for measuring skin thickness. Horses free of skin conditions and euthanised for reasons unrelated to this study were include...
Rosa MCB, Campos MEST, Albuquerque AS, Braz MS, Mapele RO, de Oliveira MCG, Toma HS, Ferraz PFP, Pereira RN, Raymundo DL.Skin wounds in horses, particularly in the distal extremities, often heal slowly due to mechanical stress, compromised perfusion, and excessive fibroplasia. This study evaluated the effects of topical Croton lechleri (CL) cream, alone or in combination with nitroglycerin, on the healing of skin wounds in the metatarsal region of horses. Six mares received six standardized wounds in each region and were treated with: saline solution, nitroglycerin (0.1 or 1 mg/mL), CL (1 or 10 µg/mL), or CL + nitroglycerin (10 µg/mL + 1 mg/mL). Wound contraction, histology, and bacterial culture were evaluate...
González N, Varela A, de Blas N, Gil L.At present, oviductal pathologies and their influence on mare fertility have not been clearly determined. Checking changes throughout the year in the oviductal structure may be relevant to understand the influence on the appearance of problems in oviductal functionality and, thus, the impact on fertility, which is the objective of this work. The oviducts of 56 mares were examined. Their anatomy, permeability, oviductal cellularity and the presence of pathologies were assessed to establish the correlations between the time of the year and each of these parameters. We cannot conclude whether the...
Sancler-Silva YFR, Papa FO, Esteller-Vico A, Silva-Junior E, Oliveira TES, El-Sheikh Ali H, Boakari YL, Freitas MSE, Ball BA.This study evaluated the effects of oral pentoxifylline on testicular biometry, histology, and gene expression in stallions subjected to scrotal heat stress. Fourteen stallions were divided into three groups: Control (CRL, n = 4), Testicular Degeneration (DEG, n = 5), and Testicular Degeneration Treated with Pentoxifylline (DEG + PTX, n = 5). Testicular degeneration was induced by scrotal insulation, twice daily, over two consecutive days (D-1 and D0). Starting the next day (D1), oral pentoxifylline (17 mg/kg) was administered every 12 h for 30 days. Testicular biometry was measured ...
Johnson JP, Cardenas FA, Asakawa MG, Oikawa MA.Myofibroblastic fibrosarcoma (MFS) is a malignant soft tissue tumour that is rare in domestic animals. Here we report a case of congenital MFS in an Arabian foal at birth. A large solitary subcutaneous mass arising in the left temporal region was found in the foal. On cut section, an unencapsulated hemispheric, white-yellowish, elastic fibrous mass was attached to the temporal bone. Histologically, the mass was composed of a neoplastic proliferation of spindle-shaped fibroblasts arranged in fasciculate or interwoven streams and bundles, with low nuclear atypia and mitotic rate, local invasion ...
Fischetti L, Perina F, Sarli G, Ellero N, Freccero F, Castagnetti C, Mariella J.A 286-day pregnant mare was referred for signs of impending abortion. The ultrasonographic evaluation revealed a high normal combined thickness of the utero-placental unit (CTUP), oligohydroallantois and a living fetus. No vulvar discharge was observed, and the cervical swab culture was negative. After a choke, the mare received NSAIDs and antibiotics and then developed systemic inflammatory response syndrome (SIRS) and aborted. The amniotic portion of the umbilical cord was excessively long and twisted and the chorionic side of the placenta showed a brown discoloration and rough surface area....
Jones CJP, Wilsher S, Aplin JD.We report a lectin histochemical study of oviductal ampulla and isthmus of thirteen mares euthanised at anestrus (1), estrus (5), 1-day post-ovulation (5) or diestrus (2). Staining with a panel of 5 lectins recognizing N-Acetylgalactosamine (GalNAc) residues revealed mosaicism in glycan expression in some specimens of ampulla and isthmus, peaking at estrus and 1-day post-ovulation (ov+1). In the ampulla, this presented as positively stained areas of both ciliated and non-ciliated cells in otherwise negatively-stained ampullae, ranging from small foci (diestrus) to areas up to 200 microns in le...
Zamboulis DE, Thorpe CT.The high stresses and strains experienced by the superficial digital flexor tendon (SDFT) make it prone to age-related injury. The SDFT exhibits cellular and structural specializations, localized to the interfascicular matrix (IFM), enabling it to resist its extreme mechanical environment. With aging, these specializations are lost, impacting the ability of the tendon to withstand repeated loading. Within the IFM, there is loss of mechanical properties and organization accompanying cell senescence and a decreased resolution of inflammation. Developing therapeutics to reverse these changes may,...
Medina-BolÃvar AL, Muñoz-Duque JD, MartÃnez-Aranzales JR.Information regarding Survivin protein expression in the gastric mucosa of equids is scarce. This protein has been associated with functions related to modulating apoptosis and promoting mitosis in epithelial cells and is considered part of gastric cytoprotection mechanisms in humans and mice, maintaining mucosal integrity and regulating cellular renewal. Objective: This study aimed to determine the expression of cytoplasmic and nuclear Survivin in gastric mucosae of equids (horses, donkeys, and mules). Methods: A total of 30 healthy stomachs, 10 from each species, were evaluated using histolo...
Loyd A, Neto R, Caldwell F, Boone L, White A.This study aimed to determine the safety and macroscopic/microscopic effects of fluorescence biomodulation (FBM) on experimentally induced, full-thickness, distal limb wounds in horses.This was an experimental study ( = 6 horses). Two full-thickness wounds were created on both dorsal metacarpi of six adult horses. Each forelimb was randomly allocated to either control (no FBM) or treatment (FBM) and randomly allocated to visual or histological assessment of healing. Wounds were treated within each experimental group every 7 days for four treatments. Fluorescence biomodulation wounds were ...
du Preez S, Lynch B, Lindsay S, Simon O, Ferlini Agne G.To describe the case details of an equine corneal squamous cell carcinoma (SCC) arising from the central scar of a previous conjunctival pedicle graft. Methods: An 18-year-old Thoroughbred gelding, showing a progressive increase in diameter, depth, opacity, and pigmentation of a conjunctival pedicle graft scar of the left eye, 34 months after surgery. Methods: Complete ophthalmic examination, standard histologic and immunohistochemical evaluation of an incisional biopsy to formulate a definitive diagnosis. Carbon dioxide (CO) laser photoablation combined with topical mitomycin C treatment. R...
Partusch L, Rutland CS, Martens A, Du Cheyne C, De Spiegelaere W, Michler JK.Exuberant granulation tissue (EGT) is a second intention wound healing disorder. It commonly occurs in the distal limb of horses. EGT causes significant increase in the duration and cost of treatment, potentially leading to the decision not to pursue treatment and euthanize the patient. The underlying pathomechanisms of this fibroproliferative disorder remain unclear, particularly in terms of collagen composition and the association between myofibroblasts and blood vessels. This study investigated the collagen composition in naturally occurring EGT following trimming in 19 horses (EGT group). ...
Pekkarinen HM, Simola U, Niinistö KE, Syrjä PES.Equine inflammatory bowel disease (IBD) is challenging to diagnose and treat. Although the number of horses examined due to suspicion of IBD is increasing, the different treatments in clinical patients and their responses are not well documented. We sought to characterize the demography, signs, clinical and rectal biopsy findings, and treatment response in Finnish horses suspected to have IBD. Horses undergoing clinical examination due to suspected IBD in 2022 and with a good-quality rectal biopsy were selected for the study. General information, signs, clinical and histological findings, and ...
Ibrahim L, Cornillie P, Buschmann E, Demeyere M, van Loon G.The coronary sinus (CS) and great cardiac vein (GCV) are crucial in cardiac electrophysiology and can be arrhythmogenic in humans. In horses, CS/GCV catheterisation is increasingly performed for arrhythmia diagnosis and treatment. Improved anatomical understanding of these structures is needed to clarify relationships to surrounding structures. Methods: Postmortem examinations of 64 adult warmblood equine hearts were carried out. Middle cardiac vein and vein of Marshall ostia locations were described. Right atrial myocardial sleeve (MS) length was measured from the CS ostium. In 23 horses, CS/...
Risvanli A, Salykov R, Timurkaan N, Seker I, Ekinci E.This study was conducted to examine glandular histological changes in the uterus of Kyrgyz breed mares during the first 6 months of pregnancy. The study used 53 Kyrgyz breed mares; 43 of these were at different stages of pregnancy, while 10 were non-pregnant mares. Uterine samples obtained at the slaughterhouse were evaluated histomorphometrically; endometrial thickness, gland density, gland epithelial height and gland diameter were measured. In conclusion, it was concluded that in Kyrgyz mares, endometrial thickness, glandular epithelial height and diameter increased as pregnancy progressed...
Jones CJP, Aplin JD, Wilsher S.There is little information on non-ciliated secretory cell numbers in the equine oviduct isthmus over the course of the estrous cycle and the effect, if any, of insemination. Lectin histochemistry was used on a series of 13 oviducts taken at different stages of the estrous cycle, with and without insemination, to monitor glycosylation changes and the distribution of secretory cells characterised by a prominent cytoplasmic accumulation of glycoconjugates. There appeared to be an increase in secretory cells expressing a wide range of glycans in all specimens at estrus. One day after ovulation, o...
Ver Goltz L, Gomes SP, Schimming BC, Abdala FCM, Miglino MA, de Castro Sasahara TH.The equine ovary exhibits unique structural and developmental features that distinguish it from those of other domestic species, including the presence of an ovulation fossa and an inversion of cortical and medullary layers. This study aimed to investigate the morphostructural development of the equine fetal ovary, with particular emphasis on the formation of the ovulation fossa. Fourteen female equine fetuses, ranging from 70 to 200 days of gestation, were collected from a commercial abattoir. Results revealed a progressive increase in ovarian volume and marked histological changes througho...
Nissen SD, Bastrup JA, Haugaard SL, Marion-Knudsen R, Schneider M, Kjeldsen ST, Carstensen H, Hopster-Iversen C, Nattel S, Jepps TA, Buhl R.Horses and humans are among the few mammals susceptible to spontaneous atrial fibrillation (AF), both suffering from high recurrence rates after treatment. Treatment resistance is often attributed to progressive atrial remodeling, but current treatment options fail to effectively address this aspect. Here, we introduce a novel horse model of spontaneous AF to investigate the biological pathway changes in early stages of the disease. Through data-independent acquisition mass spectrometry on biopsies from the right and left atrium and left ventricular chamber of horses with early-stage persisten...
Mules (Equus mulus), as sterile hybrids between mares and donkeys, present a unique uterine morphology and physiology that remains poorly characterized. This study provides the first histomorphometric evaluation and transcriptional profiling of the endometrium in adult mules. To achieve this, endometrial biopsies were analysed using quantitative stereology, histological classification (Kenney-Doig system), and qPCR of key immune-related and fibrotic genes. Histometric analyses revealed that the stratum spongiosum was the predominant component of the mule endometrium (mean volume density: 84.7â...
Lawson JM, Verheyen KL, Laroucau K, Bryan JS, Smith KC, Foote AK, de Mestre AM.Umbilical cord torsion (UCT) is the most frequent pathology of the equine umbilical cord (UC) and a prominent cause of abortion, yet objective data on its features remain limited. This study compared UCT with clinically normal pregnancies (CNP) to (i) identify gross and histological features of the UC and fetal membranes, (ii) determine whether UCT is associated with fetal growth restriction, and (iii) rule out infectious aetiologies. Gross and histological features of the UC, chorioallantois and amnion were compared between groups. Fetal weight and crown-rump length were analysed relative to ...
Sugimoto K, Nakamura J, Deng D, Hirano E.Indoxyl sulfate (IS) is a dietary metabolite of tryptophan that is produced in the liver. It is a uremic toxin that facilitates the progression of chronic kidney disease (CKD). We previously observed that equine placental extract (ePE) inhibited IS synthesis in an inhibition assay using the liver S9 fraction. Unassigned: This study was designed to investigate the effects of ePE on adenine-induced renal failure in mice at the histological and molecular levels to understand the mechanism of action of ePE. Unassigned: We assessed this effect through biochemical and histological analyses using a...
Machado M, Queiroz-Machado CRR, Queiroz F, Gardner DR, Riet-Correa F.A Mimosa pudica var. unijuga-associated toxicity affecting horses occurred in Araguari, Triângulo Mineiro, Southeast Brazil. Affected horses had gradual hair loss of the mane and tail and endocrine dermatosis after grazing for three months during the dry season on a paddock invaded by the plant. The main histological lesions include compact ortho-keratotic hyperkeratosis and numerous flame follicles. Toxicological analysis by HPLC-UV demonstrated 0.8 mg/g of mimosine in the leaves.
Ducrocq M, Kamus L, Richard H, Beauchamp G, Janvier V, Laverty S.Stifle osteoarthritis (OA) lesions are most common in the medial femorotibial (MFT) compartment. Their characterisation and mapping will inform equine veterinarians towards an accurate diagnosis of OA. Objective: Investigate and map micro-CT (μCT) changes in the hyaline articular cartilage (HAC) in the medial femoral condyle (MFC) and medial tibial plateau (MTP). Methods: Ex vivo cadaveric. Methods: Stifles (n = 7 OA and 17 control [CO]) were retrieved from a tissue bank. The MFC and MFT were imaged with μCT. Regions of interest (ROIs) were cranial (MFCcr; MTPcr) and caudal (MFCca; MTPca...
