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.
Investigation of a progressive facial deformity and stridor in an adult horse with a bone sequestrum and subsequent sinonasal abscess. Advanced diagnostic imaging and histopathological investigation were performed in an adult horse with chronic facial swelling due to a bone sequestrum and abscessation. In contrast to other cases, there were no draining tracts, difficulty eating, weight loss, head shaking, or fistula formation between the oral cavity and the maxillary sinus. Une investigation d’imagerie diagnostique avancée et un examen histopathologique ont été réalisés chez un cheval adulte présentant de l’enflure faciale chronique attribuable à un séquestre osseux et à une abcédation. Par contraste à d’aut...
A histological study of peripheral dental caries of equine cheek teeth. Peripheral caries of equine cheek teeth is a poorly described disorder and, in particular little is known of its histopathology. Histological examinations of decalcified sections of 21 equine peripheral caries-affected cheek teeth showed two different patterns of cemental lesions; including progressive enlargement of focal, flask-like lesions leading to breakdown of the adjacent cementum, and secondly; a more generalized flaking-off of thin layers of under-run, surface cementum. A thick layer of plaque and food material usually lay on the surface of affected cementum and also within cemental d...
Use of a deslorelin implant for influencing sex hormones and male behaviour in a stallion – Case report. This case report describes the use of a subcutaneously applied 4.7-mg deslorelin acetate implant in a three-year-old Arabian crossbred stallion showing unwanted strong male behaviour. Following deslorelin acetate implantation the stallion showed a short transitional increase in male behaviour. A 'gelding-like' behaviour was noted 15 days (D15) after treatment. The horse was surgically castrated at the owners request at D52 after treatment. Serum testosterone, oestradiol-17β and oestrone sulphate values decreased after deslorelin acetate implantation, but serum LH and FSH levels remained uncha...
Seasonal differences in cytokine expression in the skin of Shetland ponies suffering from insect bite hypersensitivity. Insect bite hypersensitivity (IBH) in horses is a seasonal, IgE-mediated, pruritic skin disorder primarily caused by Culicoides spp. We hypothesize that a mixed Th2/Th1-type immune status, off season, alters into Th2-dominated immune reactivity in the skin of IBH-affected ponies in the IBH season. To study these immune response patterns Culicoides-specific IgE levels, skin histopathology and cytokine and transcription factor mRNA expression (IL4, IL10, IL13, IFNγ, FoxP3 and CD3(ζ)) in lesional and non-lesional skin of ponies affected by IBH in the IBH season were compared with those of the s...
Benign intraocular teratoid medulloepithelioma causing glaucoma in an 11-year-old Arabian mare. An 11-year-old Arabian mare was presented for investigation of a visible, pale-colored intraocular mass in the right eye. Results: An intraocular mass was detected clinically and ultrasonographically as originating from the superior temporal quadrant of the ciliary body and iris and causing secondary glaucoma. The echodense mass was occupying the majority of the vitreous chamber and extended into the anterior chamber. The left eye appeared normal. Results: Enucleation was recommended for therapeutic and diagnostic purposes. No adjuvant treatment was given. Histopathological examination demonst...
Effects of the addition of endotoxin during perfusion of isolated forelimbs of equine cadavers. To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. Methods: Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). Methods: Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of ...
Hepatoencephalopathy syndrome due to Cassia occidentalis (Leguminosae, Caesalpinioideae) seed ingestion in horses. Cassia occidentalis is a bush from the Leguminosae family, subfamily Caesalpinoideae, and is a toxic plant of veterinary interest due to the occasional contamination of animal rations. This report describes the clinical and histopathological findings of an outbreak of C. occidentalis poisoning in horses. Twenty mares were poisoned after consuming ground corn contaminated with 8% of C. occidentalis seeds. Of the 20 animals affected, 12 died: 8 mares were found dead, 2 died 6 h after the onset of clinical signs compatible with hepatic encephalopathy and the 2 other animals were subjected to euth...
Determination of serum anti-Müllerian hormone concentrations for the diagnosis of granulosa-cell tumours in mares. Endocrinological assays are important for evaluation of mares with granulosa-cell tumours (GCTs), and our research in mares indicates that anti-Müllerian hormone (AMH) may be a good biomarker for this type of ovarian tumour. Objective: To evaluate the use of serum AMH concentrations for endocrine diagnosis of GCTs in mares. Methods: Archived serum samples (n = 403) previously assayed for determination of serum inhibin, testosterone and progesterone concentrations (GCT panel) were assayed for serum AMH concentrations using a heterologous enzyme-linked immunosorbent assay previously validated b...
Time-related Pathological Changes in Horses Experimentally Inoculated with Equine Influenza A Virus. To investigate the pathology of equine influenza, necropsy of 7 horses experimentally infected with equine influenza A virus (EIV) subtype H3N8 was conducted on post-infection days (PID) 2, 3, 7, and 14. Histopathologically, rhinitis or tracheitis including epithelial degeneration or necrosis with loss of ciliated epithelia and a reduction in goblet cell numbers, was observed in the respiratory tracts on PIDs 2 and 3. Epithelial hyperplasia or squamous metaplasia and suppurative bronchopneumonia with proliferation of type II pneumocytes were observed on PIDs 7 and 14. Viral antigen was detecte...
Ocular manifestations of a metastatic adenocarcinoma in a horse. A 10-year-old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an e...
Equine multiple acyl-CoA dehydrogenase deficiency (MADD) associated with seasonal pasture myopathy in the midwestern United States. Seasonal pasture myopathy (SPM) is a highly fatal form of nonexertional rhabdomyolysis that occurs in pastured horses in the United States during autumn or spring. In Europe, a similar condition, atypical myopathy (AM), is common. Recently, a defect of lipid metabolism, multiple acyl-CoA dehydrogenase deficiency (MADD), has been identified in horses with AM. Objective: To determine if SPM in the United States is caused by MADD. Methods: Six horses diagnosed with SPM based on history, clinical signs, and serum creatine kinase activity, or postmortem findings. Methods: Retrospective descriptive ...
Mycotic encephalitis, sinus osteomyelitis, and guttural pouch mycosis in a 3-year-old Arabian colt. Mycotic encephalitis caused severe ataxia and other neurologic deficits in a horse. The finding of a single, large focus of cerebral malacia, with histopathologic evidence of fungal elements, suggested infection was a result of direct transfer from the frontal sinuses, rather than hematogenous spread from the guttural pouch. Une encéphalite mycotique a causé une ataxie grave et d’autres déficits neurologiques chez un cheval. La découverte d’un grand foyer unique de malacie cérébrale avec une preuve histopathologique d’éléments fongiques a suggéré que l’infection était un tr...
Idiopathic haemarthrosis in eight horses. To review eight horses diagnosed with idiopathic haemarthrosis and to describe the intra-articular use of yttrium-90 ((90) Y) and methylprednisolone acetate (MPA) in recurrent haemarthrosis cases. Methods: Retrospective case series. Methods: The medical records, diagnostic images, histopathology and outcome of all horses diagnosed with idiopathic haemarthrosis between 1998 and 2010 were reviewed. Results: Four Thoroughbred racehorses with haemarthrosis of the antebrachiocarpal joint had severe acute lameness (median, grade 4) and marked joint effusion after high-speed exercise. Another four ho...
Episodic blindness and ataxia in a horse with cholesterinic granulomas. An 11-year-old Oldenburg mare presented following three episodes of acute, transient blindness, ataxia, and disorientation within the preceding 7 months. Clinical improvement, including return of vision, occurred within 1 week of initiating corticosteroid therapy for each of the three episodes. However, mild right-sided miosis was a consistent finding on ophthalmic examinations. Routine clinicopathologic testing revealed no significant abnormalities, and testing of cerebral spinal fluid for selected infectious diseases was unrewarding. Computed tomography of the brain demonstrated a hyperatten...
Histopathological examination of chronic laminitis in Kaimanawa feral horses of New Zealand. To investigate the prevalence, histopathological and histomorphometric presentation of chronic laminitis in a population of Kaimanawa feral horses. Methods: Following the capture and euthanasia of feral horses from the Kaimanawa Ranges of New Zealand, the left forefoot of 28 stallions and 28 mares aged between 6 and 12 years were removed and processed for histology. Sections of lamellar samples from each horse were examined using light microscopy. The presence of laminitis was assessed and the histopathological lesions were described. Horses were grouped by histological diagnosis into laminiti...
Histopathological lesions associated with equine periodontal disease. Equine periodontal disease (EPD) is a common and painful condition, the aetiology and pathology of which are poorly understood. To characterise the histopathological lesions associated with EPD, the skulls of 22 horses were assessed grossly for the presence of periodontal disease, and a standard set of interdental tissues taken from each for histopathological examination. Histological features of EPD included ulceration and neutrophilic inflammation of the gingival epithelium. Mononuclear and eosinophilic inflammation of the gingival lamina propria and submucosa was commonly present irrespecti...
Necrosis of the femoral condyles in a four-week-old foal: clinical, imaging and histopathological features. A 4-week-old Thoroughbred filly foal with a history of sepsis was evaluated for right hindlimb lameness. Bilateral femoropatellar and femorotibial joint effusions were detected. Ultrasonography and radiography of the right stifle revealed signs of joint collapse and periarticular swelling. Computed tomography revealed abnormalities in the bone density of the medial femoral condyle of the right hindlimb and lateral femoral condyle of the left hindlimb. Euthanasia was recommended based on the severity of the lesions. Gross and microscopic examinations revealed extensive separation of the articul...
Use of pelvic flexure biopsy scores to predict short-term survival after large colon volvulus. To (1) determine if histologic scores of pelvic flexure biopsies can predict short-term survival in horses with large colon volvulus (LCV) and (2) identify clinical variables predictive of short-term survival. Methods: Case series. Methods: Horses (n = 28) with LCV (≥ 360°). Methods: Medical records (January 2000-February 2008) of 28 horses were reviewed and clinical data recorded. Pelvic flexure biopsies were reviewed by 2 board-certified veterinary pathologists, unaware of clinical history and outcome, using 2 scoring systems. Exact logistic regression analysis was used to determine the r...
Clinicopathologic observations on laryngoplasty failure in a horse. To report morphologic findings associated with laryngoplasty failure in a horse. Methods: Clinical report. Methods: A 9-year-old Thoroughbred cross gelding. Methods: Necropsy and histopathology were performed on a horse that died peracutely during anesthetic recovery after correction of a right dorsal displacement of the ascending colon. Three weeks earlier the horse had left laryngoplasty and ventriculocordectomy. Results: Dissection of the larynx revealed that the laryngoplasty suture had pulled through the muscular process of the left arytenoid cartilage, which appeared grossly normal. Hist...
Poisoning by Indigofera lespedezioides in horses. Poisoning by Indigofera lespedezioides is reported in horses in the state of Roraima, northern Brazil. The main clinical signs are anorexia, sleepiness, unsteady gait, severe ataxia, weakness, stumbling, and progressive weight loss. To induce the disease experimentally, a 7-year-old horse was introduced in a small paddock invaded by the plant. The first nervous signs were observed 44 days from the start of grazing. The animal was euthanized on day 59. No significant gross lesions were observed upon necropsies of the experimental horse as well as one spontaneously affected horse. Upon histologi...
Mycobacterium DNA detection in liver and skin of a horse with generalized sarcoidosis. Sarcoidosis is a rare equine skin disease characterized primarily by an exfoliative and granulomatous dermatitis but also presenting granulomatous inflammation of multiple systems. The current report presents the clinical and histopathological findings of sarcoidosis in a 16-year-old American Quarter Horse gelding with nested polymerase chain reaction Mycobacterium spp. DNA detection within hepatic and skin samples. Mycobacterium spp. may play a role in the pathogenesis of equine sarcoidosis as has been proposed for human sarcoidosis.
[Diagnostic assessment of peritoneal fluid cytology in horses with abdominal neoplasia]. To evaluate the diagnostic value of peritoneal fluid (PF) cytology for clinical diagnosis of abdominal neoplasia in horses. Methods: Ten horses with histopathologically confirmed abdominal neoplasia, in which a PF analysis was performed, were included in this retrospective study. PF was analyzed for total protein concentration and a nucleated cell count was performed. Using cytological criteria of malignancy, the PF samples were evaluated regarding their probability of malignancy. Results: Cytologic classification of cells according to criteria of malignancy allowed a positive cytologic diagno...
Comparison between magnetic resonance imaging and histological findings in the navicular bone of horses with foot pain. There is limited knowledge about both histological features in early navicular disease and what histological features are represented by increased signal intensity in fat-suppressed magnetic resonance (MR) images of the navicular bone. Objective: To characterise increased signal intensity in the spongiosa of the navicular bone in fat-suppressed MR images and to compare this with histopathology; and to compare objective grading of all aspects of the navicular bone on MR images with histological findings. Methods: One or both front feet of 22 horses with foot pain and a median lameness duration ...
Gluten-dependent antibodies in horses with inflammatory small bowel disease (ISBD). Equine inflammatory small bowel disease (ISBD) is an idiopathic pathologic condition seeming to increase in prevalence. Objective: To investigate the potential role of gluten in equine ISBD. Methods: Antibodies known to be important in the diagnosis of human coeliac disease (CD): IgA antibodies to human recombinant and guinea pig tissue-transglutaminase (TGA), native gliadin (AGA), deamidated-gliadin-peptides (DGPA), and primate and equine endomysium (EMA) were assessed in blood samples from three different groups of horses: ISBD affected (n = 12) on a gluten-rich diet and controls either ...
Reliability of high- and low-field magnetic resonance imaging systems for detection of cartilage and bone lesions in the equine cadaver fetlock. To determine the reliability of 2 magnetic resonance imaging (MRI) systems for detection of cartilage and bone lesions of the equine fetlock. Objective: To test the hypotheses that lesions in cartilage, subchondral and trabecular bone of the equine fetlock verified using histopathology can be detected on high- and low-field MR images with a low incidence of false positive or negative results; that low-field images are less reliable than high-field images for detection of cartilage lesions; and that combining results of interpretation from different pulse sequences increases detection of cartil...
Effect of different blood-guided conditioning programmes on skeletal muscle ultrastructure and histochemistry of sport horses. The effects of three different blood-guided conditioning programmes on ultrastructural and histochemical features of the gluteus medius muscle of 2-year-old sport horses were examined. Six non-trained Haflinger horses performed three consecutive conditioning programmes of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 1.5 (v1.5 ), 2.5 (v2.5 ) and 4 (v4 ) mm respectively] and durations (25 and 45 min). Each conditioning programme lasted 6 weeks and was followed by a 5-week resting period. Pre-, post- and deconditioning muscle biopsies were analyse...
Confirmed case of encephalitis caused by Murray Valley encephalitis virus infection in a horse. A 5-year-old Australian stock horse in Monto, Queensland, Australia, developed neurological signs and was euthanized after a 6-day course of illness. Histological examination of the brain and spinal cord revealed moderate to severe subacute, nonsuppurative encephalomyelitis. Sections of spinal cord stained positively in immunohistochemistry with a flavivirus-specific monoclonal antibody. Reverse transcription polymerase chain reaction assay targeting the envelope gene of flavivirus yielded positive results from brain, spinal cord, cerebrospinal fluid, and facial nerve. A flavivirus was isolate...
Granulosa theca cell tumour in a pregnant mare: concentrations of inhibin and testosterone in serum before and after surgery. A 14-year-old Thoroughbred mare was presented for evaluation of a rapidly enlarging ovary at 73 days gestation. The mare's owner reported behavioural changes in the mare since she returned from stud, notably aggression towards other horses. Results: Transrectal palpation and ultrasonography of the reproductive tract revealed a viable pregnancy, an enlarged, multiloculated right ovary, and a normal-sized left ovary with a corpus luteum present. Concentrations of inhibin and testosterone in serum were 13.8 ng/mL and 1,150 pg/mL, respectively, being markedly higher than reference ranges. Concentr...
Third eyelid dermoid in a horse. An 8-year-old Gypsy Vanner gelding presented to the University of Florida Ophthalmology service for the evaluation of chronic, recurrent corneal ulcers behind the third eyelid of the right eye. On ophthalmic examination, a cluster of aberrant hairs was identified growing along the margin of the third eyelid. This portion of third eyelid was surgically excised, and histopathology identified the haired tissue as a dermoid. Chronic keratitis secondary to a third eyelid dermoid was diagnosed, and excision appeared curative at 6 months post-operative follow-up.