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Topic:White Blood Cells
White blood cells (WBCs) are integral components of the equine immune system, responsible for protecting horses against infections and foreign invaders. These cells circulate in the bloodstream and are produced in the bone marrow. The primary types of white blood cells in horses include neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with distinct functions in immune defense. Neutrophils are involved in the immediate response to infections, while lymphocytes play a role in adaptive immunity. Monocytes are involved in phagocytosis and the regulation of immune responses. Eosinophils and basophils are associated with allergic reactions and parasitic infections. Variations in white blood cell counts can indicate health conditions, making them valuable in veterinary diagnostics. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and clinical relevance of white blood cells in equine health.
Aerosolized Micropolyspora faeni antigen as a cause of pulmonary dysfunction in ponies with recurrent airway obstruction (heaves). Ponies with recurrent airway obstruction (principal ponies) and their controls were given aerosolized Micropolyspora faeni antigen via endotracheal tube during a period when the principal ponies were in disease remission. In both groups of ponies, we performed bronchoalveolar lavage (BAL) and measured pulmonary function at base line, and 5 hours after aerosol administration of 30 ml of 0.9% NaCl solution or 30 ml of 1% w/v particulate M faeni antigen in 0.9% NaCl solution. In both groups of ponies, aerosolized M faeni antigen increased WBC count, neutrophil numbers, and albumin concentration i...
Hematologic and blood chemical characteristics of feral horses from three management areas. Blood was collected from 486 feral horses of mixed sex and age classes captured from three wild horse management areas in Nevada and Oregon from December 1985 to February 1986. Males were significantly outnumbered by females in the Flanigan area, but both sexes were represented in approximately equal numbers in the Wassuk and Beaty's Butte areas. Hematology and chemistry values averaged 16.4 +/- 0.11, 46.3 +/- 0.28, 9.9 +/- 0.07, 6.9 +/- 0.10, 47.1 +/- 0.24, 16.6 +/- 0.09, 35.2 +/- 0.09, 10.4 +/- 0.14 and 23.4 +/- 0.25 for hemoglobin (HGB), hematocrit (HCT), red blood cells (RBC), white blood ...
Quantitative buffy coat analysis for hematologic measurements of canine, feline, and equine blood samples and for detection of microfilaremia in dogs. A quantitative buffy coat (QBC) analysis was evaluated for 175 canine, 125 feline, and 125 equine blood samples. The method used centrifuged whole blood and yielded rapid results expressed as respective band lengths for RBC, granulocytes, nongranulocytes, and platelets. Simple regression analysis of band lengths and reference laboratory methods yielded correlation coefficients (r) ranging from 0.72 to 0.99. The PCV, granulocyte count, and total WBC count, as determined by the 2 methods, correlated well (r greater than or equal to 0.93 in all cases). Platelet and nongranulocyte counts were less...
A monoclonal antibody identifying a T-cell marker in the horse. A cell surface molecule of equine T lymphocytes was identified and characterized using a mouse monoclonal antibody, HT23A. The molecule was detected on all T cells but not on other cells in peripheral blood, with the possible exception of a small subpopulation (about 5%) of B cells, as assessed by indirect immunofluorescence and flow cytometry. HT23A labelled T cell areas of horse lymph nodes and spleen when used in an indirect immunoperoxidase assay on frozen sections. Macrophages and neutrophils were not labelled by the antibody nor were frozen sections of horse liver, kidney, or brain. HT23...
Assessment of neutrophil migration, phagocytosis and bactericidal capacity in neonatal foals. Comparison of neutrophil function was made between 8 clinically normal pony foals (3 to 7 days of age), and their dams. Random migration, stimulated migration to zymosan-activated serum, bacterial phagocytosis and bactericidal capacity of neutrophils were determined in vitro. Random migration was greater (P less than 0.01) and stimulated migration was less (P less than 0.01) in foals than in their dams. Bacterial phagocytosis and bactericidal capacity of neutrophils were not different (P greater than 0.05) between foals and mares. Results of this study suggested that neonatal foals have altere...
Size referenced electronic leukocyte counting threshold and lysed leukocyte size distribution of common domestic animal species. Using a single channel electronic cell counter and attached particle size analyzer, leukocyte size distribution histograms were determined on canine, feline, bovine, and equine blood diluted with chloride-based diluent and treated with a conventional stromatolysin. Histograms were usually unimodal, but a few were bimodal. Mean values for mean lysed leukocyte particle volume were 49.2, 51.1, 55.4, and 65.0 fl for canine, feline, equine, and bovine blood, respectively. From inspection of histograms, a lower threshold of 30 fl referenced to latex spheres was interpreted to be appropriate for coun...
The interaction of Rhodococcus equi and foal neutrophils in vitro. Polymorphonuclear neutrophil leukocytes (PMNL) from 8 healthy foals (2-14 weeks of age) and 2 foals with bacterial pneumonia were separated from whole blood using a 2 step Percoll gradient. Purified PMNL were tested for bactericidal function against Rhodococcus equi and Staphylococcus aureus in the presence of normal horse serum. The percentage uptake after a 15-min pre-incubation of PMNL and bacteria was also calculated. Ultrastructural examination of the interaction of R. equi and normal foal PMNL was performed after 15 min incubation. Results indicated that foal PMNL effectively phagocytose...
Rhodococcus equi pneumonia in 48 foals: response to antimicrobial therapy. Case records of 48 foals with pneumonia due to Rhodococcus equi were reviewed. Twenty of the 48 foals survived and 28 died or were euthanized. There was no significant difference between the survivors and non-survivors in the age of onset of illness, duration of illness prior to admission, the mean white blood cell (WBC) count, or the mean plasma fibrinogen content. All foals had R. equi isolated from a tracheobronchial aspirate or lung specimens obtained at necropsy. All organisms were susceptible in vitro (Kirby-Bauer) to erythromycin and gentamicin. Susceptibilities to other drugs were: tri...
Influence of chemotactic agents on the locomotion of equine polymorphonuclear and mononuclear leucocytes. Subpopulations of equine leucocytes, polymorphonuclear and mononuclear cells, were separated from whole blood on a discontinuous Percoll gradient and used in studies of chemokinesis and chemotaxis. Polymorphonuclear cells responded to the chemo-attractant properties of zymosan-activated plasma in Boyden chamber and agarose microdroplet assays but they responded only slightly (Boyden chamber) or not at all (agarose microdroplet) to the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). Equine mononuclear cell movement was increased by FMLP in both assay systems and these cells also respond...
Pulmonary aspergillosis in a horse with myelomonocytic leukemia. Acute myelomonocytic leukemia was diagnosed in a 2-year-old Standardbred mare that had hind limb edema and fever unresponsive to antibiotics. The mare had anemia, thrombocytopenia, and leukocytosis, with circulating myeloblasts and monocytoid cells. A bone marrow specimen was hypercellular, with myeloblasts and monocytoid cells. Peroxidase, chloroacetate esterase, and alpha naphthyl acetate esterase activities were detected in many bone marrow cells. Interstitial pulmonary densities were seen radiographically. The mare was euthanatized and necropsied. Infiltrates of leukemic cells were found m...
Cellular aspects of inflammation. The Ciba-Geigy Prize for Research in Animal Health. The migration of leucocytes to sites of acute and chronic inflammation is an event of central importance to the maintenance of inflammatory processes; extravascular leucocytes are responsible for generating chemical mediators of inflammation and the phagocytosis of particulate matter. They may also be involved in the conversion of acute to chronic inflammatory lesions. Leucocytes are attracted to sites of tissue injury by a range of chemoattractants. This paper describes the development of a method for separating on Percoll gradients purified populations of equine polymorphonuclear and mononuc...
Effect of povidone-iodine on in vitro locomotion of equine neutrophils. Incubation of equine neutrophils with povidone-iodine solutions of greater than or equal to 0.2 per cent resulted in total inhibition of migration under agarose. This was caused by the cytotoxic effects of the solutions as shown by pyknosis and cell lysis. Lower concentrations of povidone-iodine, however, did not adversely affect neutrophil viability or locomotion.
Bactericidal activity of peripheral blood neutrophils during the oestrous cycle and early pregnancy in the mare. The oestrous cycles of 20 mixed-breed mares were synchronized with daily injections of 10 mg oestradiol-17 beta and 150 mg progesterone given i.m. for 10 days. On the 10th day, 10-15 mg prostaglandin F-2 alpha was administered i.m. to induce oestrus. Neutrophils were isolated from jugular blood on the 2nd or 3rd day of oestrus, Days 5 and 7 after ovulation or during early pregnancy (Days 18-34 of pregnancy). Neutrophils were challenged with Staphylococcus aureus and their bactericidal activity examined after 30 and 120 min of incubation for a reduction of colony forming units. Bactericidal act...
Micropolyspora faeni causes airway inflammation but not hyperresponsiveness in sensitized ponies. We assessed the effect of aerosol Micropolyspora faeni challenge in two groups of ponies by measuring lung function, airway reactivity to aerosol histamine, and bronchoalveolar lavage fluid cytology. One group of ponies was sensitized by subcutaneous injection of M. faeni in complete Freund's adjuvant, and the other group served as control. In both groups of ponies, measurements were made at base line and 5 h after aerosol administration of 30 ml of saline or 30 ml of 1% wt/vol particulate M. faeni antigen in saline. Saline challenge had no effect on any of the measured variables. M. faeni cha...
Influence of administration of ovarian steroids on the function of neutrophils isolated from the blood and uterus of ovariectomized mares. The function of blood and uterine luminal neutrophils from ovariectomized mares treated with ovarian steroids was investigated 18 h after intrauterine infusion of 1 X 10(9) Streptococcus zooepidemicus. Random migration of blood neutrophils under agarose was reduced by treatment with progesterone compared with that of neutrophils from oestradiol-treated and control mares. In-vitro addition of progesterone to blood neutrophils from acyclic ponies also reduced migration. Uterine neutrophils did not migrate under agarose which was probably an effect of bacterial phagocytosis. Hormone treatment had...
Factors affecting uterine clearance of inoculated materials in mares. Twelve acyclic mares of various ages (2-29 years) and parity (maiden-multiparous) were given oestradiol-17 beta i.m. (winter 1982) or progesterone i.m. (winter 1983) to induce changes in the endometrium consistent with oestrus and dioestrus, respectively. After hormone treatment, mares were inoculated intrauterine with 50 ml saline containing 5 X 10(5) Streptococcus zooepidemicus bacteria, 51Cr-labelled 15-micron microspheres, and 500 mg charcoal (Groups E + B and P + B) or microspheres and charcoal only (Groups EC and PC). At 5 h after inoculation uteri were flushed with 50 ml saline containi...
Concentrations of uterine luminal prostaglandins in mares with acute and persistent endometritis. Intrauterine infusion of 1 per cent oyster glycogen solution was used to induce acute endometritis in four genitally normal mares. Numbers of viable neutrophils recovered in uterine washings had increased by 1 h after infusion and remained elevated for at least 72 h. There was a significant correlation between numbers of viable neutrophils and total protein concentrations and between prostaglandin (PG)F and PGE2 concentrations in washings. There was also a significant relationship between concentrations of 15-keto-13, 14-dihydro PGF2 alpha in plasma and PGF in washings. Intrauterine concentrat...
Diagnostic laparoscopy in the horse. Laparoscopy was performed in 5 clinically normal horses. Abdominal fluid protein content and WBC count increased markedly in all horses. Necropsy findings were confined to an increased amount of slightly turbid abdominal fluid. Five examples of applications of laparoscopy in horses with abdominal problems indicated that laparoscopy can be a valuable diagnostic procedure in the horse.
Adverse effects following intravenous fluid therapy in the horse using non-commercial fluids: preliminary findings. Non-commercial, endotoxin positive, intravenous fluids as well as a commercially available intravenous fluid were given to clinically normal horses. Endotoxin-positive fluids caused clinical signs attributable to endotoxaemia. Leukopenia, preceded by a fluctuating white cell count, was observed in horses showing clinical signs. The commercial intravenous fluid had no effect on the white cell count or on the clinical state. Precautions to be taken and recommendations are made with regard to the monitoring of horses in which one might be forced to use non-commercial intravenous fluids.
Evaluation of leukapheresis and thrombocytapheresis in the horse. Continuous-flow centrifugation leukapheresis techniques were used to collect 300-ml volumes of leukocyte-rich plasma from 5 nonmedicated horses and from 5 corticosteroid-stimulated horses. White blood cell counts and differential counts were performed on the horses before (base line) and up to 48 hours after leukapheresis. Systemic administration of hydrocortisone increased numbers of total WBC and neutrophils and improved harvest of these cells. Nonmedicated horses had a mean yield of 3.38 X 10(10) leukocytes in the 300-ml volume. Stimulated horses yielded a mean of 6.88 X 10(10) leukocytes. ...
Nitroblue tetrazolium reduction by neutrophils of newborn foals, adult horses, and a foal infected with Rhodococcus (Corynebacterium) equi. Equine neutrophil function was studied in 24 newborn foals, 10 adult horses, and a foal infected with R. equi by the quantitative nitroblue tetrazolium (NBT) reduction test. There was no difference between results in newborn foals and adult horses. A foal naturally infected with R. equi showed normal values of NBT reduction test at birth, and after the initial clinical signs, the spontaneous reduction of NBT by neutrophils was found to be remarkably increased until a week before death
Influence of dystocia on white blood cell and blood neutrophil counts in mares. A retrospective study was done on total white blood cell (WBC) and blood neutrophil counts of 41 mares referred to one of two veterinary hospitals for correction of dystocia. The mares were 2 to 19 years of age and included draft, light, and pony breeds. The WBC and neutrophil counts were performed at varying intervals from time of admission to 10 d after delivery of the feti. Retrospective analyses of WBC and neutrophil counts from 10 normal foaling mares from two Pennsylvania breeding farms (Thoroughbred and Trakehner) and from 14 normal foaling pony mares were done as controls. Mean WBC (10...
In vitro bactericidal efficacy of equine polymorphonuclear leukocytes against Corynebacterium equi. Polymorphonuclear leukocytes from adult horses were separated from whole blood, using a 2-step Percoll gradient, and were tested for bactericidal function against Corynebacterium equi. Staphylococcus aureus, an organism against which equine neutrophils have proved efficacy, was a positive control. The percentage of uptake after a 15-minute preincubation of the neutrophils and bacteria in the presence of normal horse serum was also calculated. The results indicated that equine neutrophils effectively phagocytosed and killed C equi and S aureus. The percentage of uptake for S aureus (95% +/- 3%)...
Diurnal changes in the hematological indices in the blood of racing Arabian horses. In 8 stallions and 6 mares of pure Arabian horses the diurnal changes in the number and certain parameters of red and white blood cells were studied. All of them showed distinct diurnal changes but they did not fulfill the conditions of circadian rhythm according to Halberg. It was found that most of peaks occurred during the dark phase of 24 hr period except the percentage of eosinophils, erythrocyte diameters and cell rate sedimentation. The majority of indices studied showed the higher mean diurnal levels in the mares than in the stallions.
Effect of intra-articular gentamicin sulfate on normal equine synovial membrane. Gentamicin sulfate (3 ml; 50 mg/ml) was administered intra-articularly into 30 normal equine radiocarpal joints after arthrocentesis. Arthrocentesis alone was performed on 10 normal radiocarpal joints. Synovial fluid evaluations and gross and microscopic examinations were performed on synovial fluid and synovial membrane of designated joints at selected daily intervals over a period of 10 days. Synovial fluid from gentamicin-injected joints had greater turbidity, higher RBC and WBC counts, and higher refractive indices than did joints not injected with gentamicin. The largest increases develop...
Bronchoalveolar lavage in ponies with recurrent airway obstruction (heaves). We performed bronchoalveolar lavage (BAL) in 2 groups of ponies. Principal ponies had a history of heaves, a disease characterized by recurrent airway obstruction and airway hyperreactivity when ponies are housed in a barn and fed hay; control ponies had no history of airway obstruction. Ponies were paired (principal and control), and BAL was performed after 2 months of being pastured when principal ponies were in clinical remission (Period A), after barn housing when principal ponies had acute airway obstruction (Period B), and after a 1- and a 2-wk recovery phase of pasture grazing (Periods ...
Effect of intrauterine infusion of Escherichia coli endotoxin in postpartum pony mares. Fifteen pony mares were assigned to 1 of 3 treatment groups after foaling: Group 1, 35 ml of sterile saline solution was infused into the uterine lumen within 24 hours after parturition (6 mares); group 2, 300 mg of Escherichia coli endotoxin was infused into the uterine lumen within 24 hours after parturition (6 mares); and group 3, 300 mg of E coli endotoxin was infused into the uterine lumen between 72 and 96 hours after parturition (3 mares). Rectal temperatures were taken at -1, -0.5, 0, 0.5, 1, 1.5, 2, 3, 4, and 5 hours after treatment. Venous blood samples were also taken at these times...
Effects of intrauterine infusion of Escherichia coli endotoxin in anestrous and steroid treated pony mares. This study was conducted to determine if Escherichia coli endotoxin was absorbed from the equine uterus and if exogenous progesterone and estrogen affected the absorption of intrauterine endotoxin. Six mature anestrous pony mares were used in three consecutive crossover experiments (Periods) with a 14 day recovery between each period. Mares were randomly assigned to one of two treatment groups (three mares per group) and received an intrauterine infusion of either saline or endotoxin. Treatment groups were reversed and readministered after 14 days completing a crossover design (Period 1). Duri...
Cardiopulmonary effects of dopamine hydrochloride in anaesthetised horses. Dopamine hydrochloride was infused intravenously into six horses anaesthetised with halothane. Three dose rates; 0.5, 2.5 and 5.0 micrograms/kg/min, were evaluated in each horse. The cardiac output was significantly increased at 15 and 30 mins following administration of dopamine at 2.5 and 5.0 micrograms/kg/min. The heart rate, facial artery pressure and pulmonary artery pressure remained unchanged. Total peripheral resistance was significantly decreased at 30 mins with 2.5 micrograms/kg/min and at 15 and 30 mins with 5.0 micrograms/kg/min. No significant change was produced in packed cell vo...
Seasonal changes in the white blood cell system, lyzozyme activity and cortisol level in Arabian brood mares and their foals. In 34 pure-breed Arabian horses divided into four groups (Gr. I, ten pregnant mares; Gr. II, seven barren mares; Gr. III, ten foals born in 1981; Gr. IV, seven foals born in 1982) seasonal changes in the white blood cell system, cortisol level and lyzozyme activity were studied. Seasonal periodicity was found in all groups for the number of lymphocytes, segmented neutrophils and eosinophils and cortisol level. Leukocyte periodicity was found in three groups, but not in the barren mares. In lyzozyme activity there was periodicity in three groups but not in the youngest foals. In the stab neutro...
