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Topic:Histology
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.
Intestinal adenocarcinoma causing recurrent colic in the horse. An 8-year-old, Thoroughbred-cross mare presented with recurrent colic. Exploratory laparotomy revealed a large mass near the right dorsal colon; white, raised foci on the liver; and enlarged mesenteric lymph nodes. Cytological examination of biopsies revealed neoplastic cells. The diagnosis of adenocarcinoma was confirmed by histological examination.
Morphological study on pigmented cells in the horse testis. One of the most attractive characteristics of a horse testis is the change of the weight during development. As the testicular weight changes and the number of Leydig cells decreases, pigments appear in interstitial tissues. In the present study, the characteristics of the pigments found in the interstitial tissues were examined histochemically and ultrastructurally. Specific stainings indicated that the pigmented granules showed almost all of the histological and histochemical characteristics of ceroid or ceroid-like pigment. The cells showed positive reaction for acid phosphatase while the p...
Exercise affects the mechanical properties and histological appearance of equine articular cartilage. Dorsal carpal osteochondral injury is a major cause of reduced performance in horses undergoing high-intensity training. It was hypothesised that the mechanical behaviour and histology of cartilage are influenced by the intensity of exercise and by location within a joint. Relationships between histology and mechanical behaviour were identified in 2-year-old horses undergoing 19 weeks of high-intensity treadmill training or low-intensity exercise and then compared between groups. Dorsal and palmar test sites were identified on radial, intermediate, and third carpal articular surfaces after eut...
Cell proliferation patterns in the equine endometrium throughout the non-pregnant reproductive cycle. Immunohistochemical detection of the proliferation marker Ki-67 antigen was used to monitor mitotic activity in the endometrium of mares. The monoclonal antibody MIB1 was validated for use on equine tissues by demonstrating its reaction with activated peripheral blood lymphocytes, and endometrial biopsies were recovered from 26 non-pregnant mares at selected stages during the reproductive cycle. The proportion of positively stained nuclei was counted in five random areas on each histological section to determine the percentage and type of proliferating cells. Multiplication rates in the types ...
Lawsonia intracellularis-like organism infection in a miniature foal. A 7-month-old foal was admitted to the hospital with a history of lethargy, weight loss, mild diarrhea, and anorexia. A diagnosis of proliferative enteritis caused by Lawsonia intracellularis-like organisms was made after necropsy and histologic examination of the small intestine. Although infection with L intracellularis-like organisms is a rare cause of enteritis in foals, it should be considered in the differential diagnosis, especially if the foal was housed in the proximity of pigs or pig feces. Antemortem diagnosis remains challenging because isolation of the organism in fecal material r...
Persistent vitelline vein in a foal. A three-day-old foal died from intestinal strangulation due to a remnant of vitelline vein which extended between the umbilicus and the portal vein. The strangulating vein was identified on the basis of its morphological and histological structure. This finding, which is the first reported case of a persistent vitelline vein in a horse, is discussed in relation to the normal development and involution of the vitelline circulation.
Effects of anabolic steroid (19-nortestosterone) on the secretion of testicular hormones in the stallion. The aim of this study was to clarify the effect of anabolic steroids on the testicular endocrine function of mature stallions. Mature thoroughbred stallions were treated with 800 mg nandrolone decanoate every 3 weeks for 3 months. After the first treatment, plasma concentrations of LH, immunoreactive inhibin and testosterone decreased rapidly to the nadir. These hormones were maintained at significantly lower concentrations compared with concentrations in intact stallions. Histology of the testicular tissue indicated the arrest of advanced spermatogenesis in the seminiferous tubules and a seve...
Distribution of fast myosin heavy chain-based muscle fibres in the gluteus medius of untrained horses: mismatch between antigenic and ATPase determinants. The distribution of muscle fibres classified on the basis of their content of different myosin heavy chain (MHC) isoforms was analysed in muscle biopsies from the gluteus medius of adult untrained horses by correlating immunohistochemistry with specific anti-MHC monoclonal antibodies and standard myofibrillar ATPase (mATPase) histochemistry. Percutaneous needle biopsies were taken at 3 depths (20, 40 and 60 mm) from 4 4-y-old Andalusian stallions. The percentage of 'pure' I MHC fibres increased whereas that for pure IIX MHC fibres decreased from the most superficial to the deepest sampling sit...
Nitric oxide synthase activity in healthy and interleukin 1beta-exposed equine synovial membrane. To quantitate nitric oxide synthase (NOS) activity in healthy and interleukin 1beta (IL-1beta)-exposed equine synovial membrane. Methods: 6 healthy horses, 2 to 8 years old. Methods: Recombinant human IL-1beta (0.35 ng/kg of body weight) was injected intra-articularly into 1 metacarpophalangeal joint of each horse. The contralateral joint served as an unexposed control. All horses were euthanatized 6 hours after injection of IL-1beta, and synovial membrane specimens were assayed for NOS activity by measuring conversion of arginine to citrulline. Severity of inflammation was semiquantitated by ...
Lectin histochemistry and identification of O-acetylated sialoderivatives in the horse sublingual gland. This study was aimed at characterizing the glycoconjugates produced by the horse sublingual gland and, in particular, at discriminating between the sialoderivatives by means of differential oxidation and saponification combined with lectin histochemistry and enzymatic degradation. The results showed a predominance of sialoglycoconjugates with beta-galactose as acceptor sugar in the salivary mucins produced by the sublingual gland. Besides being the most represented terminal residue, sialic acid was also expressed in a great variety of derivatives distinguishable on the basis of acceptor sugars...
Occlusion of the internal carotid artery by means of microcoils for preventing epistaxis caused by guttural pouch mycosis in horses. Occlusion of the internal carotid artery by insertion of intravascular platinum microcoils for guttural pouch mycosis was experimentally evaluated in 9 healthy adult Thoroughbred horses. The internal carotid artery was ligated to its origin, and an arteriotomy was made distal to the ligature, which was then occluded by insertion of the microcoil approximately 13 cm distal to its origin. Cessation of blood flow was determined visually and by angiography at the arteriotomy site. Six horses were evaluated for complication clinically and by endoscopy after surgery. One horse was necropsied after 3...
Equine nasal and paranasal sinus tumours. Part 1: review of the literature and tumour classification. The normal gross and histological anatomy of the equine nasal and paranasal sinuses are reviewed and the relationships between the local anatomy, the occurrence of different tumour types, and of tumour spread are examined. The histological classification of the more common equine sinonasal tumours and tumour-like lesions are discussed. Clinical and pathological descriptions of 50 more recently recorded such tumours are separately tabulated. The literature shows that equine sinonasal tumours, both endemic and sporadic, are relatively uncommon in horses, with non-neoplastic growths such as maxil...
[A Shetland pony with a squamous cell carcinoma of the stomach]. A 12-year-old Shetland pony was referred because of weight loss over several months and symptoms of colic. On rectal examination, enlarged mesenteric lymph nodes and an abnormal mass in the left anterior abdominal cavity were palpated. Haematological evaluation revealed leucocytosis (13 G.l-1) and an abnormal electrophoretic pattern (31.8% albumin, 18.8% alpha-globulins, 29.0% beta-globulins, 20.4% gamma-globulins). Peritoneal fluid collected by abdominal paracentesis did not contain neoplastic cells. Gastroscopy was performed and a mass, with areas of ulceration and necrosis, was visualized w...
[Development of hoof cartilage with special considerations of its ossification]. The pre- and perinatal development of the hoof cartilage is described concerning the histological structure and surrounding vessels. Beginning in the third month of fetal development, the anlage of the hoof cartilage is still present in typical shape and location. It is built out of mesenchymal connective tissue. During further fetal development, the connective tissue cells will differentiate into two cell populations, fibroblasts and chondroblasts. Vessels, traversing the hoof cartilage, are surrounded by loose connective tissue, which will partially develop fibrocartilage. At birth, hoof car...
Equine glanders in Turkey. In the course of an epidemiological study of glanders on a number of Turkish islands in the Sea of Marmara, 1128 horses were examined by using the intracutaneous mallein test. Thirty-five (3-1 per cent) developed an increase in rectal temperature and a swelling at the point of injection. Ten of these horses were killed and glanders was confirmed in five cases by the presence of lesions and by the immunohistological demonstration of the causative agent, Burkholderia mallei. Clinical and pathological findings indicated that in all cases the infection was restricted to the mucous membrane of the ...
A histological and immunohistochemical study of the humoral immune system of the lungs in young Thoroughbred horses. Lungs were obtained from 16 Thoroughbred horses, aged 1 day to 2 years, which had died or been humanely killed for reasons unrelated to disease of the lower respiratory tract. The lungs were then subjected to a histological and immunohistochemical examination of the humoral immune system. At birth there was no evidence of organized lymphoid tissue, and lymphocytes and plasma cells were virtually absent in all tissue compartments in the first week of life. However, by 12 weeks, foals exhibited well developed bronchus- and bronchiole-associated lymphoid tissue, but this had regressed progressive...
Evaluation of a technique to occlude the internal carotid artery of horses. To evaluate an occlusion technique for the internal carotid artery of horses using an intravascular, detachable, self-sealing, latex balloon distally and ligatures proximally. Methods: Experimental study. Methods: Six healthy adult horses. Methods: In each horse, the left internal carotid artery was occluded by placement of an intravascular, detachable, self-sealing, latex balloon distally and two ligatures proximally. Radiographs were taken on days 2, 5, 10, and 30 after surgery to evaluate balloon inflation and position. Endoscopic examination of the left guttural pouch was performed 10 days...
Amylopectinosis in fetal and neonatal Quarter Horses. Three Quarter Horses, a stillborn filly (horse No. 1), a female fetus aborted at approximately 6 months of gestation (horse No. 2), and a 1-month-old colt that had been weak at birth (horse No. 3), had myopathy characterized histologically by large spherical or ovoid inclusions in skeletal and cardiac myofibers. Smaller inclusions were also found in brain and spinal cord and in some cells of all other tissues examined. These inclusions were basophilic, red-purple after staining with periodic acid-Schiff (both before and after digestion with diastase), and moderately dark blue after staining wi...
Naturally occurring osteoarthritis in the metacarpophalangeal joints of wild horses. This study identified changes consistent with osteoarthritis; articular cartilage damage, subchondral bone sclerosis and marginal osteophytes, in the metacarpophalangeal joints of wild New Zealand horses. The articular cartilage lesions were identified by Indian ink staining techniques and histology. The lesions occurred on the proximodorsal aspect of the first phalanx (P1) and were more severe on the medial compared to the lateral eminence of the bone, and their severity increased with age. The bone mineral density of the subchondral bone underlying the cartilage lesions, assessed using conve...
Differences in second-intention wound healing between horses and ponies: histological aspects. The histological aspects of second-intention healing were studied in 5 horses and 5 ponies. Biopsies were taken weekly from standardised wounds on the metatarsus and femoral biceps muscle of one horse and one pony. Sections were stained to enable cell counting and the detection of DNA synthesis, fibrin, smooth muscle actin (SMA), collagen, and bacteria. In the ponies, the number of polymorphonuclear leucocytes (PMNs) was high during the first 3 weeks and subsequently decreased rapidly. In the horses, the initial number of PMNs was lower, but remained persistently elevated during the evaluation...
A lectin binding analysis of glycosylation patterns during development of the equine placenta. The glycosylation of the equine interhaemal barrier and areola was studied throughout the period of gestation. Placentae of 35, 37, 50, 119, 152, 200, 280 and 300 days gestation were investigated, using semithin plastic embedded sections and a panel of 15 biotinylated lectins with an avidin-peroxidase revealing system. Glycosylation of the trophoblast and maternal epithelium showed the most change during the first 50 days of gestation, being associated with the initial stages of adhesion and attachment. In the trophoblast, non-bisected tri/tetraantennary complex N-glycan was only evident after...
A permeability barrier in the dorsal wall of the equine hoof capsule. The permeability barrier in the dorsal wall of the equine hoof capsule was studied by means of horseradish peroxidase (HRP) in 0.9 N saline solution as a water soluble tracer. Section were treated with 3'3'-diaminobenzidine tetrachloride (DAB) and before dissection the quality of the horn of feet from 10 horses was assessed and given a subjective grade as either good or poor. Blocks of tissue from each horse were left in either an oven at 60 degrees C or in water for 2 weeks before treatment in HRP, sectioning and DAB solution. Regions observed were i) outer surface, ii) outermost layers of th...
Fetal development of the white line (Zona alba) of the equine hoof. The fetal development of the white line (Zona alba) in the equine hoof is described. Its specific structure of lamellar and interlamellar horn, which in turn is composed of cap and terminal horn, is formed in the second half of the hoof's fetal development. In equine fetuses with a crown-rump length of less than 550 mm, the hoof capsule lacks a 'characteristic' white line since no borders between stratum medium, stratum internum and sole horn are discernible. In the hoof of an equine fetus with a crown-rump length of 550 mm, a narrow white line has taken shape. Its shallow lamellae are arrange...
Morphology of the oocyte-follicular connection in the mare. The present study characterised the oocyte-follicular connection (i.e., oocyte fixation site) in Graafian follicles of the mare morphologically. Antral follicles were dissected in toto from ovaries obtained from oestrous, dioestrous and transitional mares after slaughter. The location of the cumulus oophorus complex in relation to the ovulation fossa, the width and density of the blood vessels surrounding the cumulus oophorus complex, the relative dimensions and histological aspects of the cumulus oophorus were investigated. For ultrastructural analysis of the junctional regions, cumulus-oocyt...
Improved hepatic and pancreatic localisation of the equine alpha-1-proteinase inhibitor family of serpins using an antigen enhancement technique and a monoclonal antibody. Equine alpha-1-proteinase inhibitor (API) consists of three, occasionally four, serum glycoproteins. This study investigated the immunohistochemical localisation of equine API in paraformaldehyde fixed, paraffin embedded equine tissue samples of liver, lung, stomach, pancreas, jejunum and colon in five horses using affinity purified sheep polyclonal and protein A purified mouse monoclonal antibodies, whose specificities were verified by Western blotting. Exposing tissue sections to boiling citrate buffer greatly enhanced antigen recovery and improved immunostaining with both antibodies, result...
Musculoskeletal system neoplasia. Tumors of the musculoskeletal system are rare in horses; however, they must be taken seriously. Diagnosis requires observation of clinical signs, radiographic findings, and histological examination. Veterinarians must realize prognosis is not favorable for most tumors; however, some of these tumors can be treated or at least ameliorated. Tumors discussed in this article include: osteoma and osteosarcoma; osteoblastoma; chondrosarcoma; fibroma and fibrosarcoma; plasma cell myeloma; synovioma; rhabdomyosarcoma and tumors metastatic to the musculoskeletal system.
Morphometric analysis of endometrial periglandular fibrosis in mares. To develop an objective, quantifiable assay for endometrial periglandular fibrosis (EPF) and correlate assay results with histologic and ultrastructural changes in equine endometrial biopsy specimens. Methods: Endometrial biopsy specimens from 70 mares from 3 to 27 years old in estrus. Methods: In a double-blinded study design, endometrial biopsy specimens were graded histologically (modified Kenney classification) for EPF and inflammation. Endometrial periglandular collagen volume fraction (%EPCVF) was determined by light microscopic image analysis of picrosirius red-stained sections. Specime...
Mechanical correlations derived from segmental histologic study of the equine superficial digital flexor tendon, from foal to adult. To assess histologic variations of the equine superficial digital flexor tendon (SDFT) according to site and to horse age and activity, and to correlate these data with reported segmental mechanical results. Methods: Superficial digital flexor tendons isolated from 42 horses 0.5 hour to 23 years old. Methods: 7 segments of each SDFT were delimited and submitted for conventional histologic examination. Each segment was examined and graded for fiber undulation, cellularity, number and size of interfascicular connective spaces (ICS), presence or absence of focal and diffuse chondroid metaplasia, ...
Functional anatomy of the cartilage of the distal phalanx and digital cushion in the equine foot and a hemodynamic flow hypothesis of energy dissipation. To examine macro- and microscopic characteristics of cartilage of the distal phalanx (ungual cartilage [UC]) and digital cushion in the equine foot and to relate them to the foot's function of energy dissipation. Methods: 85 horses and 5 foals of various breeds and ages. Methods: Feet, obtained at necropsy, were perfused with India ink (n = 30), latex (5), or polymer plastic (10). Select feet were examined histologically for tissue architecture and to identify elastic fibers. Immunochemistry to identify substance P peptides in nerves (feet from foals) and gold chloride impregnation of axons (n...
Experimental model of synovitis/capsulitis in the equine metacarpophalangeal joint. To develop and define a model of acute synovitis/capsulitis in the equine metacarpophalangeal joint (fetlock) to study clinical effects of diagnostic or therapeutic procedures. Methods: 5 adult Standardbreds. Methods: Polyvinyl alcohol foam particles were injected into the left front fetlock of horses; the right front fetlock was used as a control. Horses were examined clinically and for lameness on a regular basis. Blood samples were taken to measure routine variables. Synovial fluid samples were collected from both fetlocks, and macroscopic, microscopic, and biochemical variables were measur...
