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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.
Microvascular circulation of the small intestine in horses. The microvascular anatomic features of the small intestine was described by correlating results of microangiography, light microscopy, gross studies, and scanning electron microscopy of vascular replicas in 14 horses. After heparinization, the horses were euthanatized, a length of jejunum was transected, and blood was flushed free of the circulation, using isotonic NaCl solution. In six horses, the circulatory system was perfused with a modified radiopaque medium and evaluated radiographically. These sections were then evaluated by standard histologic methods. Sections from 8 horses were perfu...
Cryptococcosis in seven horses. The clinical, radiographic and post-mortem findings in 6 horses with cryptococcal pneumonia and one horse with an abdominal cryptococcal granuloma are described. In pulmonary cryptococcosis, the lesions were either diffuse and multiple, with bilateral lung involvement, or localised mainly to the dorsocaudal region of one lung. The cases of diffuse multiple cryptococcosis were thought to be associated with haematogenous spread of the fungus after gastrointestinal infection and dissemination from regional lymph nodes. The localised form of the disease was thought to have been associated with inh...
Immunohistochemical observations on pneumonic lesions caused by Rhodococcus equi in foals. An immunohistochemical analysis of Rhodococcus equi-induced pneumonia in 10 foals was performed by biotin-streptavidin system. The detection of R. equi was more sensitive in immuno-stain using anti-R. equi serum than in Gram's stain. This bacteria also reacted to anti-BCG serum. Lysozyme and alpha 1-antitrypsin were detectable in macrophages. A particularly intense staining was observed in association with intracellular bacteria. Though a degree of reaction for alpha 1-antichymotrypsin was very low in comparison with lysozyme and alpha 1-antitrypsin, it was also demonstrated in macrophages ing...
[Scanning electron microscopic findings of the navicular bone and deep flexor tendon in podotrochlosis of horses]. In 25 adult horses the podotrochlea of 49 forelimbs was examined by means of light and electron microscopy in order to correlate clinical and morphological findings. According to the clinical diagnosis the animals were divided into three groups: lameness due to syndrome of podotrochlosis (group 1) or due to tendopathy (group 2) and horses without lameness (group 3). The most striking pathological findings of the navicular bone and the opposite surface of the deep flexor tendon were found in horses with podotrochlosis, consisting of loss of cartilage and tendon matrix with denudation of collage...
Bioavailability and bioequivalence of veterinary drug dosage forms, with particular reference to horses: an overview. The route of administration and formulation of the dosage form affect the bioavailability (rate and extent of absorption) of a drug and may thereby influence the intensity and duration of the pharmacological effect. Location of injection site may affect the plasma concentration profile of drugs administered as aqueous suspensions or sustained release parenteral preparations (procaine penicillin G). When absorption influences the rate of elimination ('flip-flop' phenomenon), the apparent half-life of the drug will be increased (cefazolin sodium, i.m.; meclofenamic acid, p.o.). Absorption genera...
Evaluation of sulbactam plus ampicillin for treatment of experimentally induced Klebsiella pneumoniae lung infection in foals. Efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin, was evaluated for treatment of experimentally induced pneumonia caused by beta-lactam-resistant Klebsiella pneumoniae. Infection was experimentally induced in 18 healthy weanling foals that were randomly allocated to 3 treatment groups: sulbactam plus ampicillin (S/A, 3.3 and 6.6 mg/kg of body weight, respectively), ampicillin (6.6 mg/kg), or vehicle only. Foals were treated daily for 7 days; the observer was unaware of treatment status. Compared with ampicillin and vehicle, treatment with S/A resulted in a stat...
In vitro comparison of equine granulocytes labeled with 99mTc-hexamethylpropyleneamine oxime or 111In-oxine. Isolated equine granulocytes (WBC), radiolabeled with 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) or 111In-oxine, were evaluated in vitro for their labeling characteristics, viability, and phagocytic function over a 6-hour postlabeling period. Mean +/- SD labeling efficiency for 111In-oxine-WBC was 62.2 +/- 15.3%, which was significantly (P less than 0.001) higher than that for 99mTc-HMPAO-WBC (32.0 +/- 17.0%). In vitro elution of radiolabel from cells was significantly (P less than 0.02) greater for 99mTc-HMPAO-WBC at 0.5, 2, and 4 hours, but was not significantly different from elutio...
Necropsies of eight horses infected with Strongylus equinus and Strongylus edentatus. Ponies (n = 8) approximately 18 months old, were infected with 20,000 to 30,000 infective larvae of Strongylus equinus with less than 10% contamination with Strongylus edentatus larvae and necropsied 7 months post-infection. Lesions were present in the omentum, liver, pancreas, ventral colon, caecum and occasionally in the lungs. There were numerous intraabdominal adhesions and severe multiple granulomatous omentitis. Pancreatic damage, which characterises S. equinus, was exceptionally mild and was manifested mainly by slight periductular infiltration of eosinophils. Granulomas associated with...
Eosinophilic gastroenteritis with encapsulated nematodes in a horse. A 3-year-old Quarter Horse gelding admitted for evaluation of weight loss, signs of depression, and dermatitis of the coronary bands was found to have eosinophilic gastroenteritis. Intralesional nematodes identified as Strongylus edentatus were seen in multiple microscopic sections of the small colon, suggesting a parasitic cause of the disease.
Metastatic granulosa cell tumor in a mare. A 5-year-old Quarter Horse mare was referred for evaluation of an acute non-weightbearing lameness of the left hind limb in which musculoskeletal abnormalities had not been detected. After admission, the mare had signs of colic. Exploratory laparotomy revealed the left ovary to be large, masses in the left sublumbar space, and diffuse infiltration of the mesentery, omentum, liver, and spleen with variably-sized masses. The mare was euthanatized, and granulosa cell tumor was identified on histologic examination of the left ovary, left sublumbar and cranial thoracic lymph nodes, omentum, mesente...
Diagnosis of ruptured urinary bladder in a foal by the identification of calcium carbonate crystals in the peritoneal fluid. A 3-day-old Quarter Horse colt was examined because of signs of severe depression, discomfort, and abdominal straining. The foal seemed disoriented, and the abdomen was tense and distended ventrally. The differential diagnoses included ruptured urinary bladder, retained meconium, septicemia/bacteremia, and neonatal maladjustment syndrome. Serum biochemical analysis revealed marked hyponatremia, hypochloremia, and moderate hyperkalemia, as well as mildly high urea, creatinine, and phosphorus concentrations. The primary differential diagnosis at this time was ruptured urinary bladder. Abdominoce...
Chlamydia psittaci infection in horses: results of a prevalence survey and experimental challenge. Nasal and conjunctival swabs were obtained from 300 horses and Chlamydia psittaci was isolated from 15 of them (5 per cent). Eleven nasal swabs and six conjunctival swabs were positive on culture, but there was no association between the isolation of the organism and the presence of clinical ocular or respiratory disease. Six ponies were challenged with an equine isolate of C psittaci into the eye, nasal cavity or bronchial tree. The organism could be isolated from nasal and conjunctival swabs taken from the ponies for up to 17 days after challenge, but there was no clinical evidence of diseas...
Pulsed spectral Doppler evaluation of a peripheral arteriovenous fistula in a horse. Pulsed spectral Doppler ultrasonography was used to characterize the vascular involvement and anatomic boundaries of a peripheral arteriovenous fistula on the hemithorax of a horse. This information facilitated surgical removal of the fistula. Pulsed spectral Doppler evaluation of suspected peripheral vascular anomalies should be considered for the diagnosis of similar lesions, in which contrast angiography is not possible.
Standardised imaging technique for guided M-mode and Doppler echocardiography in the horse. Eighteen echocardiographic images useful for diagnostic imaging, M-mode echocardiography, and Doppler echocardiography of the equine heart were standardised by relating the position of the axial beam to various intracardiac landmarks. The transducer orientation required for each image was recorded in 14 adult horses by describing the degree of sector rotation and the orientation of the axial beam relative to the thorax. Repeatable images could be obtained within narrow limits of angulation and rotation for 14 of the 18 standardised images evaluated. Twenty-seven National Hunt horses were subse...
Arrhythmias in newborn thoroughbred foals. Foetal electrocardiograms (ECG) were obtained from 39 of 50 Thoroughbred foaling mares close to delivery. The 50 newborn foals were studied electrocardiographically during their adaptive period, immediately after birth. In 48 foals there were paroxysmal arrhythmias or mixed arrhythmias. The most common arrhythmias were sinus arrhythmias including wandering pacemaker (32/50) and atrial premature contraction (30/50). The others observed were atrial fibrillation (15/50), ventricular premature contraction (10/50), partial atrioventricular block (7/50), ventricular tachycardia (4/50), atrial tachyc...
Effect of experimentally induced endotoxemia on serum interleukin-6 activity in horses. A study was conducted to determine whether serum interleukin-6 (IL-6) activity increased in horses during experimentally induced endotoxemia and whether serum IL-6 activity correlated to changes in clinical or laboratory data. Six clinically normal horses were given endotoxin IV (30 ng/kg of body weight) in 0.9% NaCl solution over 1 hour. Five of these and 1 additional horse served as controls and were given only 0.9% NaCl solution. Venous blood, for determination of serum IL-6 activity and WBC count, was collected before and at various times through 8 hours after the start of endotoxin or NaC...
Pharmacokinetics of phenobarbital in horses after single and repeated oral administration of the drug. Six healthy mature horses were orally administered a single dose of phenobarbital (26 mg/kg of body weight), then multiple doses (13 mg/kg) orally for 42 consecutive days. Seventeen venous blood samples were collected from each horse after the single dose study and again after the last dose on day 42. Plasma phenobarbital concentration was determined by use of a fluorescence assay validated for horses. Additional blood samples (n = 11) were collected on days 8 and 25 to determine peak and trough concentrations, as well as total body clearance. Phenobarbital disposition followed a one-compartme...
Determination of total protein concentration and viscosity of synovial fluid from the tibiotarsal joints of horses. Viscosity of synovial fluid (SF) from 29 clinically normal horses was determined by use of a rotational cone and plate microviscosimeter. Total protein concentration in the SF of the 29 horses, as measured with a refractometer, was less than 2.5 g/dl. When the Coomassie brilliant blue test was used to determine total protein concentration in SF for 15 horses, the mean value was 1,088 mg/dl. Viscosity values at 60, 30, 12, 6, 3, and 1.5 revolutions/min (rpm) spindle speed were 4.41 +/- 1.54 centipoise (cp), 5.29 +/- 1.94 cp, 6.76 +/- 2.76 cp, 8.52 +/- 4.27 cp. 10.41 +/- 6.30 cp, and 13.07 +/- 9...
A five year (1985-1989) retrospective study of equine neurological diseases with special reference to rabies. A retrospective study of horses necropsied between 1985 and 1989 at a diagnostic laboratory of a veterinary school in North America is documented. In this investigation over 20 per cent of the horses had clinical neurological signs. Equine protozoal myeloencephalitis (caused by Sarcocystis neurona) and cervical stenotic myelopathy (wobbler syndrome) were the most common of these disorders. The veterinary school is located in the midst of a raccoon rabies enzootic area. However, only four cases of equine rabies were diagnosed during the 5-year study. The gross microscopical and immunohistochemi...
Gastric leiomyosarcoma in a horse. Gastric leiomyosarcoma was diagnosed in a 12-year-old Thoroughbred gelding. The horse was examined because of anorexia, weight loss, and intermittent fever of 1.5 months' duration. Antemortem diagnostic testing was extensive, but a definitive diagnosis could not be reached with noninvasive methods. Exploratory celiotomy confirmed an intra-abdominal mass, and the horse was euthanatized. Necropsy revealed a firm mass associated with the distal portion of the esophagus, cranial two thirds of the stomach, and visceral surface of the liver. The histopathologic diagnosis was leiomyosarcoma.
Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses. Glomerular filtration rate (GFR) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid IV injection of 99mTc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). The first 99mTc-DTPA method used a 2-compartment model to calculate GFR blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minut...
Entomophthoromycosis due to Conidiobolus. Entomophthoromycosis due to Conidiobolus coronatus is a granulomatous infection characterized by lesions that originate in the inferior turbinate, spread through ostia and foramina to involve the facial and subcutaneous tissues and paranasal sinuses. The majority of the cases have been described from areas of tropical rainforest in West Africa, agricultural and outdoor workers (aged 20-60 years) being the ones most frequently affected. The fungus is common in soil and decaying vegetation. Infection probably occurs by implantation of the spores of the fungus in nasal mucosa. C. incongruus is a ...
Pathological aspects of Australian Stringhalt. Nine horses with clinical signs of Australian Stringhalt were killed and tissues collected for a detailed pathological study. Lesions were limited to peripheral nerves and muscles. The most severely affected nerves were the superficial and deep peroneal, distal tibial, plantar digital, volar and recurrent laryngeal nerve with changes characterised by a selective loss of large diameter myelinated fibres with various degrees of demyelination, fibrosis, Schwann cell proliferation and onion-bulb formation. A routine evaluation of the brain and spinal cord by light microscopy failed to reveal any c...
Detection of diuretics in horse urine by GC/MS. The use of diuretics in horses subject to doping control is prohibited. Thus, a sensitive screening procedure is required to identify the chemically different diuretics. We communicate here a method to detect three commonly employed acidic diuretics: bumetanide, ethacrynic acid, and furosemide. A liquid-liquid extraction on Extrelut 3 was performed at weak acidic and basic conditions using ethyl acetate as organic solvent. For analysis by GC, the diuretics were methylated on-column in the presence of MSTFA/TMAH, avoiding the commonly employed highly toxic derivatizing agent methyl iodide. For ...
Association between serum cytotoxicity and selected clinical variables in 240 horses admitted to a veterinary hospital. A total of 378 serum samples from 240 hospitalized horses and 47 sera from healthy control horses were assayed for growth effects on actinomycin D-treated L929 cells. On average, patient and control sera stimulated cell growth; however, mean percentage of the relative growth index (RGI) of sera from clinical cases was significantly (P less than 0.001) lower than that of control sera. Approximately 35% of patient sera and 6% of control sera had tumor necrosis factor-like cytotoxic activity for L929 cells (ie, RGI less than 100%). Sera from horses with either peritoneal leakage of gastrointestin...
