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Topic:Pathology
Pathology in horses involves the study of diseases and abnormalities affecting equine health, encompassing a range of conditions that can impact various systems within the horse's body. This field examines the causes, mechanisms, and effects of diseases, as well as the structural and functional changes they induce in equine tissues and organs. Common pathological conditions in horses include laminitis, colic, equine infectious anemia, and respiratory disorders. Understanding these diseases involves evaluating clinical signs, diagnostic methods, and treatment options. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, pathogenesis, and clinical implications of pathological conditions in horses.
Obstruction of equine small intestine associated with focal idiopathic eosinophilic enteritis: an emerging disease? Idiopathic focal eosinophilic enteritis (IFEE) is a rare disease in the horse and few cases have been reported in the literature. The objective of this paper was to describe the clinical, surgical, histological features and post-operative progress of 12 horses with IFEE, a disease that had not been identified in the authors' hospital population prior to 2000. Diagnosis of IFEE was made at laparotomy and confirmed by histological examination of resected abnormal small intestine. In all 12 horses colic was associated with jejunal obstruction involving visibly striking and palpably thickened sero...
Haycocknema-like nematodes in muscle fibres of a horse. A 14-year-old horse (imported to Switzerland from Ireland 8 years earlier) showed signs of chewing muscle atrophy. A severe chronic myositis, caused by numerous immature and mature female nematodes, was diagnosed in muscle samples obtained by biopsy and subsequently at necropsy. Most of the nematodes had invaded muscle fibres of the masseter, root of the tongue and anterior breast, only a few were found in the intermuscular interstitium. Isolated nematodes and parasite sections were clearly different from muscle larvae of Trichinella spp. but showed morphological similarities to Haycocknema pe...
Degenerative suspensory ligament desmitis as a systemic disorder characterized by proteoglycan accumulation. Degenerative suspensory ligament desmitis (DSLD) is a debilitating disorder thought to be limited to suspensory ligaments of Peruvian Pasos, Peruvian Paso crosses, Arabians, American Saddlebreds, American Quarter Horses, Thoroughbreds, and some European breeds. It frequently leads to persistent, incurable lameness and need to euthanize affected horses. The pathogenesis remains unclear, though the disease appears to run in families. Treatment and prevention are empirical and supportive, and not effective in halting the progression of the disease. Presently, the presumptive diagnosis of DSLD is ...
Comparison of four staining methods for detection of mast cells in equine bronchoalveolar lavage fluid. Mast cells normally are present in equine bronchoalveolar lavage fluid (BALF), but usually represent <2% of all cells in healthy horses. An increased percentage of mast cells has been associated with airway hyperactivity and inflammatory airway diseases, but marked differences are reported between studies in normal and diseased horses. Because an abnormal mast cell count may be of clinical relevance, we compared the ability of a fast Romanowsky method to stain mast cell granules with that of 3 metachromatic stains: automated Romanowsky, May-Grünwald Giemsa, and toluidine blue stains. The B...
Severe pulmonary disease due to multisystemic eosinophilic epitheliotropic disease in a horse. Multisystemic eosinophilic epitheliotropic disease was diagnosed histologically in a 17-year-old Quarter Horse intact mare that was presented with a chronic history of respiratory distress. At necropsy, the lungs were poorly collapsed and the pulmonary parenchyma contained innumerable, discrete, spherical nodules in a miliary pattern. A few similar nodules were scattered in the liver and the renal lymph nodes. Histologically, these nodules consisted of fibrosing eosinophilic granulomas. Based on histologic findings and the absence of an etiologic agent, a diagnosis of multisystemic eosinophili...
Lymphoscintigraphy of draught horses with chronic progressive lymphoedema. Early diagnosis of chronic progressive lymphoedema (CPL) may result in more effective interventions and provide a basis for further investigation of whether early diagnosis could be used as a means of eliminating potential genetic influences by cessation of breeding from affected individuals. Objective: Lymphoscintigraphy may be useful in draught horses to differentiate early lesions of CPL from other conditions in the pastern region. Methods: Forelimbs of 2 normal and 5 CPL-affected draught horses were evaluated with lymphoscintigraphy. Results: Lymphoscintigraphy showed clearly the presence ...
Inflammatory aural polyp in a horse. An inflammatory aural polyp was identified in a 1-year-old standardbred filly, which presented with otorrhea and head rubbing. The polyp was removed by traction-avulsion, and the filly showed no subsequent signs of otorrhea. Aural polyps have not been reported in horses, but they are commonly seen in companion animals and humans. Un polype auditif inflammatoire a été identifié chez une pouliche Standardbred d’un an présentée pour otorrhée et frottage de tête. Le polype a été retiré par traction-avulsion et la pouliche n’a pas manifesté de signes subséquents d’otorrhée. Les ...
Systemic Cryptococcus albidus infection in a Doberman Pinscher. Cryptococcus albidus is a saprophytic, encapsulated yeast usually found in air, both outdoor and indoor, and sometimes on human skin. It is not usually considered to be a primary pathogen. Most cryptococcal infections of humans and animals are caused by Cryptococcus neoformans. Several cases of C. albidus infection have been reported in humans over the past 20 years. In the veterinary literature, 2 equine cases have been described: genital infection and mycotic keratitis. The present report is the first documented case of C. albidus systemic infection in a dog. Veterinarians and diagnosticians...
Echocardiographic evidence of an aortico-pulmonary septal defect in a 4-day-old thoroughbred foal. We describe the echocardiographic findings in a 4-day-old thoroughbred foal with an aortico-pulmonary septal defect. The foal had labored breathing, cyanotic mucous membranes and a continuous grade 5/6 heart murmur with point of maximal intensity over the base of the heart on the right side. Echocardiographically, there was a large communication between the aorta and the pulmonary artery just dorsal to the base of the heart. The cardiac anomaly seen during the echocardiographic exam was confirmed at necropsy where a large communication between the two great vessels was observed. These findings...
Inter- and intramolecular epitope spreading in equine recurrent uveitis. To test the hypothesis that inter- and intramolecular spreading to S-antigen (S-Ag) and interphotoreceptor retinoid binding protein (IRBP)-derived epitopes occurs in a spontaneous model of recurrent uveitis in the horse. Methods: The immune response of eight horses with equine recurrent uveitis (ERU) was compared with that of five control horses with healthy eyes. Lymphocytes derived from peripheral blood (PBLs) were tested every 8 weeks for their reactivity against S-Ag and various S-Ag and IRBP-derived peptides for 12 to 39 months (median, 22 months). During uveitic episodes, additional bloo...
Navicular disease: a review of what’s new. The 21st century has heralded a reassessment of our ideas about
navicular disease. In particular, the proposal of different
pathological entities has led to alternative treatment regimes and a
sounder basis for reaching a prognosis. Further, recently generated
data have given grounds for reconsidering both terminology and
treatment. The impact of recent information on the clinical
approach to suspected navicular disease of concepts relating to
diagnostic analgesia, the evolution of diagnostic imaging
techniques, biomarkers, biomechanics and heritability require
placing into the contex...
Histopathology in horses with chronic palmar foot pain and age-matched controls. Part 1: Navicular bone and related structures. Causes of palmar foot pain and the aetiopathogenesis of navicular disease remain poorly understood, despite the high incidence of foot-related lameness. Objective: Abnormalities of the collateral sesamoidean ligaments (CSLs), distal sesamoidean impar ligament (DSIL), deep digital flexor tendon (DDFT), navicular bone, navicular bursa, distal interphalangeal (DIP) joint or collateral ligaments (CLs) of the DIP joint may contribute to palmar foot pain. Methods: Feet were selected from horses with a history of unilateral or bilateral forelimb lameness of at least 2 months' duration that was improv...
Histopathology in horses with chronic palmar foot pain and age-matched controls. Part 2: The deep digital flexor tendon. Causes of palmar foot pain and the aetiopathogenesis of navicular disease remain poorly understood, despite the high incidence of foot-related lameness. Objective: Abnormalities of the deep digital flexor tendon (DDFT) may contribute to palmar foot pain; ageing degenerative changes may be seen in horses free from lameness; and horses with lameness are likely to have a greater severity of abnormalities than age-matched horses with no history of foot pain. Methods: Feet were selected from horses with a history of uni- or bilateral forelimb lameness of at least 2 months' duration. Histology of th...
Structural and haemovascular aspects of placental growth throughout gestation in young and aged mares. This investigation was carried out to study the equine placenta from early gestation to near term, with special reference to morphological changes associated with the development of the vasculature of the fetal component of the microcotyledons. Pregnant uteri were removed post mortem from five Thoroughbred mares between 110 and 309 days of gestation, two of which were aged, multiparous animals suffering age-related degenerative changes in their endometrium (endometrosis), while the other three were young, and had primigravid normal healthy uteri. Pieces of endometrium with placenta attached we...
Agreement in histologic assessments of the pituitary pars intermedia in aged horses. To evaluate concordance among veterinary pathologists in the assessment of histologic findings in the pars intermedia of pituitary gland sections from aged horses with mild signs suggestive of pituitary pars intermedia dysfunction (PPID). Sample Population-10 pituitary glands from aged horses. Methods: 7 pathologists were provided with signalment, clinical signs, and a single H&E-stained pituitary gland section from 10 aged horses with mild signs suggestive of PPID. Pathologists described histologic findings for each section and stated whether findings were consistent with PPID. Agreement ...
Alterations of epidermal proliferation and cytokeratin expression in skin biopsies from heavy draught horses with chronic pastern dermatitis. We report the historical, clinical and histopathological characteristics of skin lesions in biopsies from 37 heavy draught horses with chronic pastern dermatitis. The skin lesions were divided into four macroscopic groups: scaling (group I, n=5), hyperkeratotic and hyperplastic plaque-like lesions (group II, n=14), nodular skin masses (group III, n=16) and verrucous skin lesions (group IV, n=2). The principal histological findings were hyperkeratosis and epidermal hyperplasia. There was a gradual increase in epidermal hyperplasia from groups I to IV, suggesting that the lesions represent diffe...
A dorsal approach for the removal of the nasal septum in the horse. To describe and evaluate a technique involving a dorsal approach for the removal of the nasal septum in adult horses. Methods: Retrospective clinical study. Methods: Four client-owned horses. Methods: Access for partial nasal septum resection was through a dorsal nasal bone flap. Septum resection was performed because of reduced airflow from septal deviation and/or thickening caused by traumatic insult or neoplasia. Preoperative clinical signs and diagnostic results were recorded. Intra- and postoperative complications were noted and follow-up information was obtained from telephone interviews...
Role of transcranial magnetic stimulation in differentiating motor nervous tract disorders from other causes of recumbency in four horses and one donkey. Transcranial magnetic stimulation and measurement of the magnetic motor-evoked potentials (MMEPs) in the thoracic and pelvic limbs of four recumbent horses and one recumbent donkey were used to assess the integrity of the descending motor pathways, in order to confirm or exclude a descending motor tract lesion as the cause of the recumbency. In two of the animals abnormal MMEPs were recorded; in one of the horses a lesion along the cervical spinal cord due to a fracture of the fifth cervical vertebra was diagnosed and confirmed by radiography and postmortem examination; in another horse, damag...
Cutaneous lymphosarcoma in a stallion. Multiple cutaneous lymphosarcomas were diagnosed in an 8-year-old Thoroughbred stallion presented for evaluation of lumps on its scrotum. Histological examination of skin biopsy samples showed a homogenous pattern of lymphoid tissue suggestive of a T-cell lymphosarcoma. Immuno-histochemical tests showed a positive reaction to Rabbit/Anti-Human T-Cell, CD3 antibodies confirming T-cell lymphosarcoma. The animal was not treated and was subsequently euthanased.
Hematuria associated with cystic hematomas in three neonatal foals. Cystic hematomas were diagnosed in 3 neonatal foals. In all 3 foals, cystic hematomas resulted from umbilical trauma or thrombocytopenia. Findings in these foals suggest that cystic hematoma should be included in the differential diagnosis of hematuria in neonatal foals. Management of cystic hematomas includes both medical and surgical options.
Funisitis associated with leptospiral abortion in an equine placenta. Funisitis, inflammation of the umbilical cord, is well recognized in human placentas. This report describes a case of funisitis associated with leptospiral infection in the placenta of a Thoroughbred foal born prematurely. The umbilical cord had diffuse superficial yellow discoloration along its entire length. Microscopic evaluation showed an exudate of neutrophils admixed with fibrin on the surface. Warthin-Starry staining showed spirochetes in the Wharton's jelly of the umbilical cord. A locally extensive, severe placentitis not involving the star and allantoic cystic hyperplasia were the ot...
Matrix metalloproteinase 2 (MMP-2) and tissue transglutaminase (TG 2) are expressed in periglandular fibrosis in horse mares with endometrosis. Periglandular arrangement of myofibroblasts, associated with the deposition of extracellular matrix (ECM), is a cardinal feature of endometrosis in mares. We hypothesized that a disturbance in the expression of matrix degrading enzymes such as matrix metalloproteinases (MMP's) and matrix cross-linking proteins might lead to an imbalance in deposition and degradation of extracellular matrix components and thereby accentuate degeneration. Therefore, distributions of MMP-2, capable of collagen IV and laminin degradation, and tissue transglutaminase (TG2), a cross-linker of extracellular matrix pr...
Natural infection of a horse with Fascioloides magna. A 25-year-old Quarterhorse mare was euthanized for a variety of medical reasons. At necropsy, 7 liver flukes, identified as Fascioloides magna, were recovered from the liver. This is the first report of F. magna in a horse.
Unilateral basement membrane zone alteration of the regenerated laminar region in equine chronic laminitis. Between the laminar epidermis and the laminar dermis of laminar region (LR) in equine foot, it can be observed the basement membrane zone (BMZ), which is composed of a basement membrane and its accompaniments like the hemidesmosome and anchoring fibril. Alteration in the BMZ in equine laminitis is possibly related with not only development but also recovery outcome and recurrence of this disease. However, there is little known about the structure of the BMZ during the recovery phase of this disease. To assess the condition of the BMZ of LR affected by chronic laminitis, the tissue was examined...
The equine larynx. A series of landmark studies on the function of the equine larynx was conducted by a group of researchers at Massey University between 1970 and 1987. These studies commenced with investigations on the normal laryngeal anatomy and physiology (Goulden et al 1976a; Anderson et al 1980; Quinlan et al 1982), and progressed to a clinical appraisal of laryngeal hemiplegia, the most important clinical disease affecting the horse's larynx (Goulden and Anderson 198 lab, 1982). The studies concluded with a series of in-depth cytological and pathological studies of the intrinsic laryngeal muscles and nerv...
Post operative neutrophilic inflammation in equine small intestine after manipulation and ischaemia. Post operative ileus (POI) remains an important cause of post operative morbidity and mortality in the horse. However, clinical progression of naturally occurring cases of POI in both horse and man does not entirely support the 'neurogenic' hypothesis as the sole mechanism of POI; and the hypothesis that inflammation plays a major role at 12-24 h after surgery requires validation. Objective: An inflammatory infiltrate in the muscularis externa and myenteric plexus of equine jejunum is present 18 h following a period of ischaemia. Methods: Samples of normal jejunum, jejunum from the proximal re...
Isolation of equine herpesvirus-1 lacking glycoprotein C from a dead neonatal foal in Japan. We isolated a variant equine herpesvirus-1 (EHV-1), strain 5089, from the lung of a dead neonatal foal in Japan and characterized the biological nature of the virus. The virus spread in cultured cells mainly by cell-to-cell infection, unlike wild-type EHV-1, which spreads efficiently as a cell-free virus. The virus titer in cultured supernatant and the intracellular virus titer were low compared to those of wild-type EHV-1. Heparin treatment of the virus had no effect on viral infectivity in cell culture. Glycoprotein C (gC) was not detected by Western blotting and fluorescent antibody tests i...
