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Topic:Clinical Pathology
Clinical pathology in horses involves the study and analysis of biological samples to diagnose and monitor diseases and health conditions. This discipline encompasses various laboratory tests and procedures that assess the physiological and biochemical status of equines. Common analyses include hematology, biochemistry, urinalysis, and cytology, each providing insights into different aspects of equine health. Hematology evaluates blood components, such as red and white blood cells and platelets, to identify conditions like anemia or infection. Biochemistry tests measure enzymes, electrolytes, and metabolites to assess organ function and metabolic status. Urinalysis examines urine samples for indicators of renal function and systemic diseases. Cytology involves the microscopic examination of cells from tissues or fluids to detect abnormalities. This page aggregates peer-reviewed research studies and scholarly articles that explore the methodologies, applications, and diagnostic value of clinical pathology in equine medicine.
Congenital fetal rhabdomyoma in a foal. An Appaloosa filly was born with a ventral midline, approximately 8 x 12 x 15 cm subcutaneous cervical mass. The nonencapsulated mass was composed of interlacing and haphazard bundles of spindle cells on moderate to abundant loose myxomatous stroma. A moderate number of cells showed cross striations with minor nuclear variation and a low mitotic rate. Immunohistochemical staining for myoglobin, desmin, actin, vimentin, and S-100 was positive and negative for glial fibrillar antigen and keratin. Rhabdomyomas are rare benign tumors of striated muscle. Rhabdomyomas described previously in the vet...
Leukoencephalitis associated with selective viral replication in the brain of a pony with experimental chronic equine infectious anemia virus infection. Neurologic disease occurs sporadically in horses infected with the equine infectious anemia virus (EIAV). This report describes a case of clinically severe neurologic disease in a pony experimentally infected with EIAV. This pony did not have fever or anemia, which are the characteristic clinical signs of disease. The histopathologic changes were characterized as lymphohistiocytic periventricular leukoencephalitis. Polymerase chain reaction and in situ hybridization data showed that the brain lesions were directly associated with viral replication and that high-level viral replication occurred...
[Primary liver disease in the horse]. The clinical signs of liver disease are highly variable and non-specific. Irrespective of the cause or the duration of liver disease, more specific clinical signs, e.g. hepatic encephalopathy, become apparent in the advanced stages of the disease. Due to the non-specific clinical signs, the possible diagnosis of liver disease is frequently not taken into consideration. However, measurement of the plasma or serum concentrations of total bile acids and gamma glutamyl transferase (gamma GT) may provide valuable diagnostic information. The specific diagnosis can be confirmed by ultrasound examinat...
[Subperitoneal cyst in a Friesian mare]. The case of a 5-year-old Friesian mare with a mass in her abdomen and a gait irregularity of the left hind limb is discussed. At rectal ultrasonogrphic examination the mass appeared to be a thin-walled, anechogenic cavity in the left abdomen. By means of laparoscopy the mass could be visualized as a smooth structure, covered by peritoneum and fat. Under laparoscopic guidance the mass was punctured and fluid was aspirated. Cytological and bacteriological findings of the fluid were indicative of a cyst. After drainage of the cyst the locomotion disorder of the left hind limb disappeared. It is c...
Effects of intravenous administration of dimethyl sulfoxide on cardiopulmonary and clinicopathologic variables in awake or halothane-anesthetized horses. To evaluate the cardiopulmonary and clinicopathologic effects of rapid IV administration of dimethyl sulfoxide (DMSO) in awake and halothane-anesthetized horses. Methods: Prospective study. Methods: 6 adult horses. Methods: Horses received IV infusion of 5 L of a balanced electrolyte solution with and without 1 g/kg (0.45 g/lb) of 10% DMSO solution when they were awake and anesthetized with halothane (4 treatments/horse). Arterial and venous blood samples were collected immediately before and at intervals during or after fluid administration and analyzed for blood gases and hematologic and ser...
Effect of omeprazole paste on intragastric pH in clinically normal neonatal foals. To evaluate the efficacy of omeprazole paste, a commonly used antiulcer drug, on intragastric pH in clinically normal neonatal foals. Methods: 6 clinically normal foals between 5 and 14 days of age. Methods: Intragastric pH was recorded in each foal by use of a disposable antimony pH electrode with internal reference. Values for intragastric pH were recorded every 4 seconds by use of an ambulatory pH monitor. There were two 24-hour recordings of intragastric pH for each foal, with 24 hours between recordings. Foals were not administered any drugs during the first recording. Foals were administ...
Association between Key-Gaskell syndrome and infection by Clostridium botulinum type C/D. There is growing evidence that equine dysautonomia is a toxicoinfection with Clostridium botulinum type C. The possibility that feline dysautonomia has the same aetiology was investigated by attempting to detect botulinum type C neurotoxin in the food, faeces and the contents of the ileum of affected cats, and by serology. The toxin was detected directly in four of eight affected cats and after enrichment in seven of them, and in their dried food. No toxin was detected in healthy control cats or in their tinned food. Recent exposure to the organism was assessed by the detection of immunoglobul...
Hypercalcemia and high serum parathyroid hormone-related protein concentration in a horse with multiple myeloma. A 13-year-old gelding was examined because of weight loss, hyperglobulinemia, and hypercalcemia. Possible causes of hypercalcemia that were considered included renal failure, primary hyperparathyroidism, vitamin D toxicosis, and malignancy. There was no history of vitamin D ingestion, and serum creatinine and parathyroid hormone concentrations were normal, making renal failure and primary hyperparathyroidism unlikely. The hypercalcemia was suspected to be a result of malignancy, but thorough testing did not reveal any neoplastic disease. Eight months later, serum parathyroid hormone-related pr...
The diagnostic and prognostic value of alkaline phosphatase activity in serum and peritoneal fluid from horses with acute colic. Alkaline phosphatase (ALP) is an enzyme present in intestinal mucosa, bile, bone, and renal tubule cells. We sought to assess the diagnostic and prognostic relationships of total ALP (ALPt) activity and that of intestine-derived ALP (ALPi) in serum and peritoneal fluid of 126 horses with colic. ALPt and ALPi activities were measured in both serum and peritoneal fluid by using both standard and L-phenylalanine-based buffers, respectively. Neither ALPt nor ALPi activity were useful in classifying type or severity of intestinal damage. ALPt and ALPi activities in peritoneal fluid were lowest in h...
Transdermal fentanyl combined with nonsteroidal anti-inflammatory drugs for analgesia in horses. This study investigated the pharmcokinetics, efficacy, and safety of the fentanyl transdermal therapeutic system (TTS) in horses in which there was an inadequate analgesic response to nonsteroidal anti-inflammatory drugs (NSAIDs) alone. Nine horses with pain that was refractory to therapeutic doses of phenylbutazone (n = 3) or flunixin meglumine (n = 6) subsequently also received between 39 and 110 microg/kg of transdermal fentanyl. Blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 60, and 72 hours after patch application, and a radioimmunoassay was used to determine serum f...
Association of a mutation in the ryanodine receptor 1 gene with equine malignant hyperthermia. Equine malignant hyperthermia MH has been suspected but never genetically confirmed. In this study, we investigated whether mutations in a candidate gene, RyR1, were associated with MH in two clinically affected horses. RyR1 gene sequences revealed polymorphisms in exons 15, 17, and 46 in WTRyR1 and MHRyR1 horses with one derived amino acid change in MHRyR1 exon 46, R2454G. The MHRyR1 horses were genetically heterozygous for this mutation, but presented an MH phenotype with halothane challenge. Skeletal sarcoplasmic reticulum from a R2454G heterozygote collected during a fulminant MH episode s...
Equine abortion and premature birth associated with Cellulosimicrobium cellulans infection. During the 2002 and 2003 foaling seasons, Cellulosimicrobium (Cellumonas) cellulans (formerly Oerskovia xanthineolytica) was the principal microorganism isolated from fetal tissues or placentas from cases of equine abortion, premature birth, and term pregnancies. Significant pathologic findings included chronic placentitis and pyogranulomatous pneumonia. In addition, microscopic and macroscopic alterations in the allantochorion from 4 of 7 cases of placentitis were similar to those caused by Crossiella equi and other nocardioform bacteria. This report confirms a causative role of C. cellulans ...
Hereditary equine regional dermal asthenia (“hyperelastosis cutis”) in 50 horses: clinical, histological, immunohistological and ultrastructural findings. Data on fifty horses with hereditary equine regional dermal asthenia (HERDA; "hyperelastosis cutis") were collected on clinical, histopathological, ultrastructural and immunohistological findings. All horses were Quarter horses or of Quarter horse ancestry. Pedigree evaluation strongly supported an autosomal recessive mode of inheritance. The most common lesions were seromas/haematomas, open wounds, sloughing skin, and loose, easily tented skin that did not return to its initial position. Definitive diagnosis could not be made via histopathology, although the presence of tightly grouped thin a...
Equine congenital papilloma: pathological findings and results of papillomavirus immunohistochemistry in five cases. Abstract Congenital cutaneous papillomas were identified in five foals. Age at diagnosis ranged from 305 days' gestation to 2 days of age. Breeds were thoroughbred (2), standard-bred (1), warmblood (1) and paint (1). Two were female, one was male and the gender of two cases was not specified. Masses were pedunculated with a roughened, wart-like (verrucous) or a smoother, cauliflower-like surface. Masses occurred as single lesions on the forelimb, lip and face, or as multiple lesions on the trunk. Histological features included relatively uniform epidermal papillary hyperplasia with variable me...
Right dorsal colitis in the horse: minireview and reports on three cases in Ireland. : Right dorsal colitis (RDC) is an ulcerative inflammatory bowel disorder of the horse that has been associated with the administration of non-steroidal anti-inflammatory drugs (NSAIDs), particularly in horses treated when dehydrated or toxaemic. The acute form of RDC may result in profuse diarrhoea, severe colic, dehydration, endotoxic shock and even death; the chronic form may be manifest by mild to moderate intermittent colic, ventral oedema and weight loss with or without diarrhoea. The most consistent laboratory findings are anaemia, hypoproteinaemia, hypoalbuminaemia and hypocalcaemia. M...
Application of the comet assay for investigation of oxidative DNA damage in equine peripheral blood mononuclear cells. Oxidative stress occurs when antioxidant defense mechanisms are overwhelmed by free radicals and may lead to DNA damage, which has been implicated in processes such as aging and diseases such as cancer. The two main techniques presently used to quantify DNA damage are measurement of 8-hydroxydeoxyguanosine and the Comet assay (also known as single-cell gel electrophoresis). The aim of this study was to apply the comet assay to equine peripheral blood mononuclear cells (PBMCs) and identify two conditions in which we hypothesized that oxidative DNA damage would be increased in PBMCs: aging and e...
Investigation of the facilitation of the nociceptive withdrawal reflex evoked by repeated transcutaneous electrical stimulations as a measure of temporal summation in conscious horses. To investigate whether facilitation of the nociceptive withdrawal reflex (NWR) can be evoked and quantified as a measure of temporal summation from the distal aspect of the left forelimb and hind limb in standing nonsedated horses via repeated stimulations of various subthreshold intensities and frequencies. Methods: 10 adult horses. Methods: Surface electromyographic activity evoked by stimulation of the digital palmar and plantar nerves was recorded from the common digital extensor and cranial tibial muscles. For each horse, the NWR threshold intensity to a single stimulus was determined for...
Comparison of hematologic values and transforming growth factor-beta and insulin-like growth factor concentrations in platelet concentrates obtained by use of buffy coat and apheresis methods from equine blood. To evaluate the buffy coat and apheresis methods for preparation of platelet concentrates from equine blood by comparing platelet and growth factor concentrations. Methods: 15 mature mixed-breed geldings. Methods: Whole blood samples were collected and processed by use of a buffy coat or apheresis method to obtain platelet poor and platelet concentrated fractions. The PCV, WBC count, and platelet count were compared among whole blood samples, platelet poor fractions, concentrates obtained by use of the apheresis method (ie, apheresis platelet concentrates), and concentrates obtained by use of ...
Compensated overexpression of procollagens alpha 1(I) and alpha 1(III) following perilla mint ketone-induced acute pulmonary damage in horses. Interstitial lung disease with chronic fibrosis is a frequent cause of reduced performance in horses. The aim of this study was to establish a model of acute alveolar damage and interstitial lung disease in horses that could be used to monitor the histopathological lesions and changes in expression levels of genes relevant to pulmonary fibrosis. Six adult horses were given a single intravenous injection (6 mg per kg body weight) of perilla mint ketone (PMK). Transthoracic lung biopsy samples (1 x 0.2 x 0.2 cm) were collected before and after (days 1, 4, 8, 11, 15, 18, 22, 25 and 29) the admini...
Non-functional C-cell adenoma in aged horses. Thyroid tumours occur in older horses, and most such tumours have been considered to be of follicular epithelial origin. However, their immunohistochemical characterization has not been investigated. The purpose of this study was to confirm a suspicion that most of these tumours are in fact parafollicular cell (C cell)-derived adenomas, and to evaluate their pathogenesis and functional state. Thyroid glands from 38 horses aged 10-29 years were evaluated, all tissue samples being examined histologically, immunohistochemically and ultrastructurally. Nodular tumour masses were found in the thyroi...
Equine recurrent uveitis: new methods of management. Equine recurrent uveitis (ERU) is one of the most common causes of blindness in horses. Until recently, treatment of this condition consisted only of symptomatic therapy, typically with steroidal and nonsteroidal medications. A better understanding of the disease process(es) has permitted new medical and surgical therapies that have recently been described. This article highlights clinical features of ERU, the causes of ERU, and new management and treatment options for horses with ERU.
The precorneal tear film in horses: its importance and disorders. The precorneal tear film (PTF) is of critical importance in the physiologic and pathologic findings of the cornea. Clinicians should recall that quantitative and qualitative disorders of the PTF can be a cause of corneal diseases as well as a clinical sign of ocular surface diseases. It is also important to consider that some systemic and topical treatments may affect the PTF volume and composition. Not all interactions are known at this time. There is a continued need for basic research into PTF components in healthy and diseased equine eyes, because much remains unknown. Until additional bas...
Equine corneal surgery and transplantation. Corneal disease is common in equine ophthalmology and requires vigilant monitoring and appropriate therapy to optimize the outcome. Many equine corneal diseases, particularly those that progress rapidly, may benefit from surgical intervention. These include descemetoceles, deep corneal lacerations and ulcers, corneal perforation/iris prolapse, ulcerative keratitis, corneal stromal abscesses, and corneoscleral neoplasia. Indications for corneal transplantation include optical, tectonic, therapeutic, and cosmetic purposes. Corneal transplantation is most often implemented in equine patients for ...
Inflammatory stromal keratopathies: medical management of stromal keratomalacia, stromal abscesses, eosinophilic keratitis, and band keratopathy in the horse. This article discusses the diagnosis and medical treatment of stromal keratomalacia or "melting ulcers," stromal abscesses, eosinophilic keratitis (EK), and calcific band keratopathy. These are common and important inflammatory keratopathies of the equine corneal stroma. Keratomalacia and stromal abscesses are associated with infection, leukocytic invasion of the stroma, and loss of tissue and tear film proteinase homeostasis. Eosinophils infiltrate the stroma in response to unknown stimuli in EK. Calcium is deposited in the stroma and epithelium secondary to chronic equine recurrent uveitis i...
Nutritional and clinicopathological effects of post operative parenteral nutrition following small intestinal resection and anastomosis in the mature horse. There is an absence of data describing the nutritional requirements and nutritional status of horses following surgery for colic; furthermore, the potential effect of parenteral nutrition (PN) on improving nutritional status in such cases is unknown. Objective: Post operative colic cases suffer from a potentially detrimental negative energy balance and the PN formulation developed in this study would lead to clinicopathologically detectable improvements in the subjects' nutritional status. Methods: Several clinicopathological variables, some known to be associated with nutritional status, were...
Prevention of ischaemia-induced small intestinal adhesions in foals. Treatments addressing variously theorised pathophysiological mechanisms of small intestinal adhesions have been reported. This study applied those classes of treatments to the most clinically relevant aetiology of post operative adhesions. Objective: Treatments addressing the pathophysiology of ischaemia-reperfusion induced adhesions would accordingly reduce the incidence of adhesions from this model. Methods: Four classes of treatments were administered for 72 h to 16 foals subjected to complete ischaemia followed by reperfusion to create peritoneal adhesions. These groups were: 1) FPG group-...
Polymyxin B protects horses against induced endotoxaemia in vivo. A safe, affordable and effective treatment for endotoxaemia in horses is needed in order to reduce the incidence of this potentially fatal condition. Objective: To evaluate the effect of polymyxin B (PMB) on signs of experimentally-induced endotoxaemia. Objective: PMB ameliorates the adverse effects of endotoxaemia without causing nephrotoxicity. Methods: Four groups of 6 healthy mature horses each received 20 ng endotoxin/kg bwt i.v. over 30 mins. Additionally, each group received one of the following i.v.; 5000 u PMB/kg bwt 30 mins before endotoxin infusion; 5000 u PMB/kg bwt 30 mins after e...
Radiographic evaluation of sclerosis of the third carpal bone associated with exercise and the development of lameness in Standardbred racehorses. Sclerosis of the third carpal bone is a common radiographic finding in both lame and sound racehorses, but there are no guidelines correlating degree of sclerosis and incidence of lameness. Objective: To develop a protocol for describing subchondral bone sclerosis in C3 on dorsoproximal-dorsodistal oblique (DPr-DDiO) radiographs of the carpus and to correlate these changes with exercise history and carpal lameness. Methods: One hundred and six Standardbreds entering their first year of training (exercise group) and 7 age-matched Standardbreds at pasture (controls) were examined at approximatel...
