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Topic:Histopathology
Histopathology in horses involves the microscopic examination of tissue samples to study the manifestations of disease. This field provides insights into the structural and cellular changes that occur in equine tissues as a result of various pathological conditions. Common applications of histopathology in equine medicine include the diagnosis of neoplastic, inflammatory, and degenerative diseases. Techniques such as tissue staining and immunohistochemistry are employed to identify specific cellular components and pathological markers. This page aggregates peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of histopathological investigations in equine health.
Equine insect hypersensitivity: skin test and biopsy results correlated with clinical data. Forty-four seasonally pruritic horses and 21 asymptomatic horses in Florida, USA, were tested for insect, grass and mould hypersensitivity by intradermal injection of allergenic extracts. The affected horses ranged in age from 10 months to over 30 years and included a variety of breeds. Affected horses reacted to varying dilutions of extracts made from Culicoides, mosquitoes, horse flies and black flies. Reactions to Culicoides were more intense than those caused by injection of antigens from other arthropods. Mild pruritus existed from the end of February until the end of June when the condit...
Fumonisin B1 levels associated with an epizootic of equine leukoencephalomalacia. During the fall of 1989, an episode of equine leukoencephalomalacia involved 18 of 66 purebred Arabian horses at a breeding/training stable in Arizona. Of the 18 horses affected, the condition was fatal in 14. These horses, as well as 48 unaffected horses, had been fed a diet containing a substantial amount of white corn screenings. Gross pathologic findings included liquefactive necrosis in parts of the cerebral white matter and hemorrhagic foci of various sizes in the brain stem. Histopathologic findings included rarefied white matter with pyknotic nuclei and eosinophilic cytoplasm. Thin-lay...
Infarction of the pons and medulla oblongata caused by arteriolar thrombosis in a horse. Infarction of the pons and rostral medulla secondary to arteriolar thrombosis was documented histologically in a 17-year-old mixed-Arabian female horse. Clinically, the animal experienced a sudden onset of a head tilt and subsequent non-controllable seizures. There was no historical, clinical or histological evidence to suggest the presence of infection of Equine Herpesvirus-1 or the feeding of corn contaminated by Fusarium moniliforme.
Squamous cell carcinoma originating from an epithelial scar in a horse. A Quarter Horse stallion developed an abscess over the left gluteal region after an IM injection of antihistamine. The wound healed with considerable fibrous scarring and some persistent granulation tissue. The lesion was static for 2 years before the granulation tissue went through a 6-month period of progressive enlargement. At that time, histopathologic diagnosis of squamous cell carcinoma was made from excisional biopsy. Six months after diagnosis, the horse had lost body weight and the lesional diameter had further increased, so the horse was euthanatized.
Pleuroscopic diagnosis of disseminated hemangiosarcoma in a horse. A 7-year-old Thoroughbred mare was examined because of persistent bilateral epistaxis and respiratory distress. Evidence of bilateral pleural effusion was found during physical examination, and a large amount of serosanguineous fluid was drained from the right side of the thorax. Cytologic examination and bacteriologic culture of the transtracheal aspirate and pleural fluid did not yield evidence of sepsis. A coagulation profile was unremarkable. Radiographic and echographic changes were seen in the lung parenchyma. Pleuroscopy, with the horse standing, revealed numerous dark nodules on the pl...
Evaluation of a bronchoalveolar lavage technique. The bronchoalveolar lavage (BAL) technique described produced no detectable gross or histopathological lesions. Airway fluid accumulation was observed for up to 4 h post lavage. There was good qualitative correlation between BAL cytopathological and diffuse pulmonary pathological changes. The technique provided an accurate assessment of the presence and extent of exercise induced pulmonary haemorrhage.
Histopathological development of equine cutaneous papillomas. The histopathological development of equine cutaneous papillomas was studied in 78 warts naturally occurring in 50 one to 3-year-old Thoroughbred or Arab horses and in 54 warts experimentally induced in three 2-year-old Thoroughbreds. Lesions in the natural cases were categorized into three phases, growth, development and regression. Main lesions of the growing phase were marked hyperplasia of the basal cells and mild to moderate acanthosis, hyper- and parakeratosis with a few intranuclear inclusion bodies (IIB) which were positive with anti-bovine papillomavirus serum. In the developing phase...
Contracture test and histologic and histochemical analyses of muscle biopsy specimens from horses with exertional rhabdomyolysis. Biopsy specimens of the cutaneous omobrachialis muscle were obtained from 10 horses with a problem of myositis from mild exercise. One horse had been evaluated previously and malignant hyperthermia-like contractures developed in its muscle biopsy specimen during the contracture test. In this study, the halothane-caffeine contracture test and histologic and histochemical evaluations were performed on muscle biopsy specimens. In the contracture test, no muscle biopsy specimen developed contracture in the presence of 2 or 4% halothane alone. The mean (+/- SEM) caffeine-specific concentration in t...
[Endodontics in horses. An experimental study]. A total of 44 experimental endodontic treatments were performed in incisors of eight horses of different ages. Four different endodontic pastes were used: Cloropercha, AH26 De Trey, Eugenol-Endometasone, and Universal N2. Gutta-percha points were also included in the last two treatments. Access to the pulp cavity of incisors was gained through their vestibular and occlusal faces. Holes drilled in vestibular faces were sealed with composite and those drilled in occlusal faces were sealed with Amalgama. Animals were observed during eighteen months at least after endodontics. Radiographic control...
Failure to demonstrate reperfusion injury following ischaemia of the equine large colon using dimethyl sulphoxide. A study was undertaken to evaluate the significance and mechanism of reperfusion injury in the equine large colon following 1 h of haemorrhagic strangulation obstruction (HSO) or ischaemic strangulation obstruction (ISO) and to assess the effect of treatment with dimethyl sulphoxide (DMSO). ISO or HSO were created 40 cm from the pelvic flexure and maintained for 60 mins under general anaesthesia. Normal saline or 20 per cent DMSO (1 g/kg bodyweight) was administered intravenously 10 mins prior to the end of the ischaemic period. Four groups of four horses in a 2 x 2 factorial design were used....
Concurrent cryptosporidium and coronavirus infections in an Arabian foal with combined immunodeficiency syndrome. Combined immunodeficiency syndrome is an inherited disorder of the Arabian breed of horses. Affected foals usually die of infectious disease within the first few months of life, and the respiratory tract is the commonest site of infection. This report describes the clinical and pathological features of a case which showed signs of alimentary and respiratory infections. Intestinal infection by coronavirus (not previously recorded in cases of the syndrome) and cryptosporidia was identified. Histopathological evidence also suggested the presence of an adenovirus infection.
Enteric pythiosis in a horse. Enteric pythiosis was diagnosed in a 2-year-old Quarter Horse gelding. The horse had signs of colic, which appeared to be alleviated by administration of mineral oil and analgesics, but only temporarily. Intestinal distention developed after initial examination. At surgery, a thick stenotic area was observed in the middle portion of the jejunum. The thick intestine and associated mesentery contained multiple firm nodules of gritty caseous material. Histopathologic findings included sclerosing eosinophilic granulomatous enteritis and peritonitis. Although the lesion resembled a response to migr...
Twenty cases of equine osteoarthrosis detected at autopsy. A pathological study was performed on osteoarthrosis detected at autopsy in 20 horses whose ages ranged from 21 days to 17 years old. They were asymptomatic on the joints except in 3 animals, and autopsied after death or sacrificed due to accidental fracture or other diseases. Lesions of osteoarthrosis were recognized in all horses, which tended to increase in incidence and severity according to age. Lesions were concentrated at hinged joints such as the elbow, fetlock, and hock. Synovial fossae and ulcerative lesions were observed on each opposite articular cartilage, forming the so-called mi...
Primary cholangiohepatitis in a horse. An 8-year-old mare was presented to the New York State College of Veterinary Medicine Large Animal Clinic for evaluation of anorexia, fever and icterus. The mare had a 5-day history of anorexia, depression and tongue protrusion. Diagnostic procedures included serum hepatic enzyme activities, serum bile acid concentrations, blood ammonia evaluations and hepatic ultrasound and ultrasound guided biopsy. The history, clinical pathology and histopathology in this case supported a probable diagnosis of primary septic cholangiohepatitis.
Equine myenteric ganglionitis: a case of chronic intestinal pseudo-obstruction. A 4-year-old Standardbred mare was referred to the New York State College of Veterinary Medicine for colic evaluation. Physical examination revealed a small colon impaction which initially responded to conservative medical management. Her signs soon recurred, however, and an exploratory celiotomy was recommended. At surgery the small colon impaction was confirmed. The impaction was evacuated and a surgical biopsy was submitted for histopathologic evaluation. Microscopic examination of H&E and Trichrome sections revealed a massive mononuclear cell infiltration of the myenteric plexus. In ad...
Comparison of the effect of polysulfated glycosaminoglycan, corticosteroids, and sodium hyaluronate in the potentiation of a subinfective dose of Staphylococcus aureus in the midcarpal joint of horses. Four groups of 8 horses each had 1 midcarpal joint injected with 33 colony-forming units (CFU) of viable Staphylococcus aureus plus: 1 ml of saline solution (group 1, control), 250 mg of polysulfated glycosaminoglycan (PSGAG, group 2), 100 mg of methylprednisolone acetate (group 3), or 20 mg of sodium hyaulronate (group 4). Horses were euthanatized, and samples were obtained on the basis of clinical signs of septic arthritis that were nonresponsive to phenylbutazone administration. One group-1 horse, all 8 group-2 horses, 3 group-3 horses, and 4 group-4 horses were culture-positive for S aureu...
Complications of a permanent transvenous pacing catheter in a horse. Gross and histopathological findings in a 9-year-old horse implanted with permanent transvenous pacing cardiac catheters, 18 and 34 months before its death, are described. Lesions consisting of extensive fibrino-haemorrhagic thrombi with large numbers of bacterial colonies were present along the electrode wires and on mural and valvular endocardial surfaces of the right heart. There was a locally extensive area of suppurative endocarditis around the attachment site of the atrial electrode, which was loosely attached by a thin band of membranous tissue to the endocardium. The ventricular electr...
Ultrastructure and lectin histochemistry of equine cutaneous histiolymphocytic lymphosarcomas. Tissues from subcutaneous lymphosarcomas and regional lymph nodes were examined by light and electron microscopy and by lectin histochemistry. Tumors were composed of two major cell types: small lymphocytes with few organelles and pleomorphic histiocytic cells with undulant surfaces, large numbers of cytoplasmic vacuoles, and many mitochondria with large crystalline inclusions. A large gram-positive coryneform bacterium was isolated from tumor nodules but was not identified morphologically in tumor tissues. Evaluation of sections of tumors with lectins as histochemical probes revealed three st...
Caecal intussusception in two ponies. One case of caecocaecal intussusception (case 1) and one case of caecocolic intussusception (case 2) in ponies are described. Case 1 showed mild abdominal discomfort for seven days followed by sudden death whereas case 2 showed continuous moderate pain for three weeks. At post mortem examination, case 1 showed intussusception of the base of the caecum into the body whereas in case 2, the entire caecum had invaginated into the right ventral colon. Histopathological examination showed that the lesions in both animals had been present for a long time.
Dimethyl sulfoxide intrauterine therapy in the mare: effects upon endometrial histological features and biopsy classification. The effects upon equine endometrial histological features produced by 10 to 30% concentrations of dimethyl sulfoxide (DMSO) in sterile saline were compared with the effects of sterile saline (0.9% NaCl) alone as an intrauterine infusion therapy in 16 barren mares. No harmful histological changes were noted (P>0.05) as a result of the therapy. Thirty percent intrauterine DMSO therapy produced a significant (P0.05); however, there was a trend toward a higher pregnancy rate following DMSO therapy. The inability to control for sire variability in the breeding trials may have contributed toward ...
Lymphoid nodules in skin biopsies from dogs, cats, and horses with nonneoplastic dermatoses. In a retrospective histopathologic study of nonneoplastic dermatoses, lymphoid nodules were found in 0.3% of 3,408 canine, 5.1% of 469 feline, and 4.5% of 325 equine skin biopsies. In all 3 species, the majority of cases wherein lymphoid nodules were found were diseases of presumed immune-mediated nature. In cats and horses, the majority of cases were also diseases characterized by tissue eosinophilia.
Morphological changes of the aorta and pulmonary artery in thoroughbred racehorses. The aorta and extrapulmonary artery were examined pathologically in 33 thoroughbred racehorses ranging in age from 1 to 5 years. Many of the great vessels of these horses exhibited degenerative or sclerotic changes in the media with neither lipidosis nor deposits of cholesterol. The severe lesions were predominantly observed at the bifurcation of the pulmonary artery. The severity of the lesions in both the aorta and pulmonary artery appeared to be associated with the racing career of the racehorse rather than with increasing age. Histopathogenetically, the medial changes in the great vessels ...
Effects of migrating Gasterophilus intestinalis larvae (Diptera: Gasterophilidae) on the mouth of the horse. Lesions were formed in the mouth of the horse by first- and second-stage Gasterophilus intestinalis larvae. The lesions resulted as larvae burrowed through the top millimeter of the tongue and then became embedded in the interdental gingiva. Appearance of the lesion was dependent on the degree of larval burrowing activity and healing that had taken place. Active tunneling production occurred at the posterior end of the lesion. Extensive change in configuration and color was apparent along the longer lesions with active larvae. Virtually all tissue in the path of the larvae was removed while fo...
Attempts to restore abduction of the paralyzed equine arytenoid cartilage. II. Nerve implantation (pilot study). The purpose of this project was to attempt restoration of abduction of a recently experimentally denervated left dorsal cricoarytenoid muscle by implanting a transected nerve-end into the paralyzed muscle. In six ponies the cut end of the second cervical nerve was implanted into a slit made in the left dorsal cricoarytenoid muscle. The nerve end was secured in place with one 5-0 polypropylene suture connecting the epineurium to the epimysium. The left recurrent laryngeal nerve was transected during this procedure. All six ponies showed signs of complete left laryngeal hemiplegia immediately af...
Distribution of histological lesions in the equine endometrium. The distribution of histopathological lesions in the equine endometrium was examined to investigate the representativeness of a single biopsy specimen in terms of the whole endometrium. Five sections from each of 110 uteri obtained from slaughtered mares were evaluated microscopically and classified according to a four-category grading system used for endometrial biopsies. Depending on the extent of agreement between the categories of the homologous sections, the uteri were considered to show either good agreement (81 uteri; 73.6 per cent), moderate agreement (26 uteri; 23.6 per cent) or poor ...
Equine herpes virus 1 (EHV-1) in liver, spleen, and lung as demonstrated by immunohistology and electron microscopy. Ten aborted foals, diagnosed as infected with Equine Herpes Virus 1 (EHV-1) on histopathological criteria, were examined for the presence of EHV-1 using immunohistology as the investigative instrument. The primary reagent was an antiserum specific for viral envelope glycoproteins. Immunohistology localised EHV-1 to areas of liver necrosis and to the cytoplasm of infected Kupffer cells and hepatocytes. Cytoplasmic immunolabelling was also prominent in reticular cells of the red pulp of the spleen and in intact and degenerated bronchiolar epithelium. Cytoplasmic immunolabelling was seen in morph...
Use of immunohistochemical methods for diagnosis of equine pythiosis. Excisional biopsy specimens were received from 8 horses with lesions suspected of being caused by Pythium sp. Pythium sp was isolated from all specimens. An indirect peroxidase technique was applied to formalin-fixed tissues from the biopsy material and there was distinct staining of hyphal cell walls in all specimens. Sections containing hyphae, other than those of Pythium sp, failed to stain. The indirect peroxidase technique could be used for confirmation of suspected cases of pythiosis.
Clinical, histopathological, and immunological responses of ponies to Ehrlichia sennetsu and subsequent Ehrlichia risticii challenge. Ehrlichia risticii has a close antigenic relationship to E. sennetsu. Sera of ponies experimentally infected with E. risticii, the etiologic agent of Potomac horse fever, consistently reacted with E. sennetsu, a human pathogen, in indirect fluorescent-antibody (IFA) testing, while human E. sennetsu convalescent serum reacted with E. risticii by IFA testing and immunoferritin labeling of cells infected in vitro. Two ponies injected intravenously with live E. sennetsu did no develop clinical illness. Subsequent injection with live E. sennetsu did not develop clinical illness. Subsequent injectio...
Diagnosis and surgical treatment of functional obstruction of the right dorsal colon in a horse. Functional obstruction of the right dorsal colon was found at surgery in a 6-year-old American Saddlebred gelding with a history of anorexia, depression, weight loss, and intermittent colic. Side-to-side anastomosis of the right dorsal colon to the small colon was done to bypass the obstruction. Histopathologic findings of the right dorsal colon and regional colonic lymph nodes were unremarkable. Surgical treatment was successful.
Gastric hyperplastic polyp in a horse. An unusually large, pedunculated (20 cm long) mass arising the gastric pylorus which produced complete obstruction of the proximal duodenum and severe gastric distension was found in a 13-year old castrated male Arabian horse. The histological diagnosis was gastric hyperplastic polyp, which has not been reported previously in the horse. The clinico-pathological findings in this horse are compared with hyperplastic (inflammatory) gastric polyps of man.
