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.
Effects of a single dose of enrofloxacin on body temperature and tracheobronchial neutrophil count in healthy Thoroughbreds premedicated with interferon-α and undergoing long-distance transportation. To evaluate effects of a single dose of enrofloxacin (5 mg/kg, IV) on body temperature and tracheobronchial neutrophil count in healthy Thoroughbreds premedicated with interferon-α and undergoing long-distance transportation. Methods: 32 healthy Thoroughbreds. Methods: All horses received interferon-α (0.5 U/kg, sublingually, q 24 h) as an immunologic stimulant for 2 days before transportation and on the day of transportation. Horses were randomly assigned to receive enrofloxacin (5 mg/kg, IV, once; enrofloxacin group) or saline (0.9% NaCl) solution (50 mL, IV, once; control group) ≤ 1 hou...
An African horse sickness virus serotype 4 recombinant canarypox virus vaccine elicits specific cell-mediated immune responses in horses. A recombinant canarypox virus vectored vaccine co-expressing synthetic genes encoding outer capsid proteins, VP2 and VP5, of African horse sickness virus (AHSV) serotype 4 (ALVAC(®)-AHSV4) has been demonstrated to fully protect horses against homologous challenge with virulent field virus. Guthrie et al. (2009) detected weak and variable titres of neutralizing antibody (ranging from <10 to 40) 8 weeks after vaccination leading us to hypothesize that there could be a participation of cell mediated immunity (CMI) in protection against AHSV4. The present study aimed at characterizing the CMI ind...
Effects of collecting serial tracheal aspirate and bronchoalveolar lavage samples on the cytological findings of subsequent fluid samples in healthy Standardbred horses. To evaluate the effect of collecting serial tracheal aspirate (TA) and bronchoalveolar lavage (BAL) samples on the cytological findings of subsequent fluid samples obtained from horses without clinical signs of respiratory disease. Methods: Experimental. Methods: Six healthy Standardbred horses. Methods: Endoscopically-guided TA samples, and BAL samples collected using the blind field technique were obtained from the six horses on days 1, 2, 3, 4, 5, 12, and 17. On day 17, horses were sampled three times: at baseline and at 2.5 h and 4 h apart. The differential cytology of the fluid samples co...
Highly deoxynivalenol contaminated oats and immune function in horses. The aim of the present study was to investigate the impact of deoxynivalenol (DON) on cellular and humoral immune parameters in horses. A feeding trial using naturally contaminated oats with high (20.2 mg/kg) and low (0.49 mg/kg) levels of DON was conducted. Two groups of five mares were fed 2 kg oats daily with high or low DON levels for two weeks, using a crossover design with a three-week wash-out period. No adverse effects on general health were observed. Only minor diet-related changes in differential blood counts and serum biochemistry were noted. Serum haptoglobin concentration was sign...
Infected dendritic cells are sufficient to mediate the adjuvant activity generated by Venezuelan equine encephalitis virus replicon particles. Replicon particles derived from Venezuelan equine encephalitis virus (VEE) are infectious non-propagating particles which act as a safe and potent systemic, mucosal, and cellular adjuvant when delivered with antigen. VEE and VEE replicon particles (VRP) can target multiple cell types including dendritic cells (DCs). The role of these cell types in VRP adjuvant activity has not been previously evaluated, and for these studies we focused on the contribution of DCs to the response to VRP. By analysis of VRP targeting in the draining lymph node, we found that VRP induced rapid recruitment of TNF-s...
Evaluation of the veterinary application of a point-of-care device measuring white blood cell counts. A point-of-care device (POCD) for measuring total white blood cell count was evaluated for feline, canine, equine and bovine blood samples collected into EDTA. Mean biases were -9.2% (range, -12% to -6.3%) for feline samples, 20.2% (range, 15.3-25.1%) for canine samples, -7.1% (range, -8.3% to -5.9%) for equine samples, and 0.7% (range, -1.1% to 2.5%) for bovine samples. The results were influenced by the presence of nucleated red blood cells. The POCD provided precise, reliable data for feline, equine and bovine samples but the values obtained for the canine counts were overestimations.
Evaluation of the automated hematology analyzer Sysmex XT-2000iV™ compared to the ADVIA® 2120 for its use in dogs, cats, and horses: Part I–precision, linearity, and accuracy of complete blood cell count. The automated laser-based hematology analyzer Sysmex XT-2000iV™ providing a complete blood cell count (CBC) and 5-part differential has been introduced in large veterinary laboratories. The aim of the current study was to determine precision, linearity, and accuracy of the Sysmex analyzer. Reference method for the accuracy study was the laser-based hematology analyzer ADVIA® 2120. For evaluation of accuracy, consecutive fresh blood samples from healthy and diseased cats (n = 216), dogs (n = 314), and horses (n = 174) were included. A low intra-assay coefficient of variation (CV) of approxim...
Virus-specific CD8⁺ T-cells detected in PBMC from horses vaccinated against African horse sickness virus. African horsesickness (AHS) is an infectious but noncontagious viral disease affecting all species of Equidae. The recall immune response of AHSV naïve horses immunised with an attenuated African horsesickness virus serotype 4 (AHSV4) was characterised using immune assays including ELISPOT, real-time PCR (qPCR) and flow cytometry. The recall immune response detected in PBMC isolated from three inoculated horses showed an upregulation of circulating B lymphocytes that correlated with elevated IL-4 mRNA expression indicative of humoral immunity, but reduced frequency of CD4⁺ cells. In additio...
Influence of transportation on serum concentrations of acute phase proteins in horse. The modifications of Haptoglobin (Hp), Serum Amyloid A (SAA), Fibrinogen (Fbg) and White Blood Cells (WBCs) were evaluated in 15 Saddle Italian horses. Ten horses were transported covering a distance of about 320 km within 4 h with an average speed of 80 km/h (experimental group) and five horses were not subject to transportation (control group). Blood was collected via jugular venipuncture before the transportation (T0), immediately after the transportation (T1), 12 (T12), 24 (T24) and 48 (T48)hours after the transportation in experimental group and at the same time point in control group. Fo...
Systemic inflammation and priming of peripheral blood leukocytes persist during clinical remission in horses with heaves. To compare innate immune responses of peripheral blood leukocytes from healthy and asymptomatic heaves-affected horses. Methods: Heaves-affected horses (n=5-6) and healthy controls (n=4-5) kept under low dust environments (pasture or shavings and pellets). Methods: Blood neutrophil and neutrophil-depleted cell populations were isolated using MACS system. Cells were incubated with or without bacterial products (lipopolysaccharide (LPS), 100 ng/mL and fMLP, 5 ng/mL, 5 h). Cytokine (IL-1β, IL-8, TNF, IL-4, INFγ and IL-10) and receptor (TLR4) mRNA expression was assessed by qPCR. TNF concentrati...
Synovial fluid chondroitin sulphate indicates abnormal joint metabolism in asymptomatic osteochondritic horses. Alternative methods to evaluate the joint condition in asymptomatic osteochondrosis dissecans (OCD) and other joint diseases may be useful. Objective: To investigate possible changes in synovial fluid composition that may lead to joint conditions in asymptomatic OCD, in mature horses. Methods: Animals aged >2 years, of different breeds, with OCD in the intermediate ridge of distal tibia, symptomatic or not, were studied. Synovial fluid samples (10 healthy; 11 asymptomatic OCD; 25 symptomatic OCD) were collected by arthroscopy from 29 horses. Glycosaminoglycans (GAGs) were analysed by a comb...
Immunological correlates of vaccination and infection for equine herpesvirus 1. Equine herpesvirus 1 (EHV-1) induces a variety of disease manifestations, including respiratory disease, abortions, and myeloencephalopathy. Several vaccines are commercially available but could not previously be distinguished by serologic testing from infection with EHV-1 (or the closely related EHV-4). Currently available vaccines are not reliably protective against the severe manifestations of the disease, including fatal myeloencephalopathy. We determined immunological parameters that can differentiate vaccinated from previously infected animals by comparing humoral and cellular EHV-1-spec...
Distal aortic aneurysm presumed to be secondary to an infected umbilical artery in a foal. A 3-month-old female Warmblood foal was presented after displaying signs of colic with pyrexia for 5 days. Results: The foal continued to show signs of colic, frequently passed urine, and was pyrexic with an elevated white blood cell count. The umbilical stalk was thickened but there was no evidence of purulent material. Exploratory laparotomy revealed an enlarged left umbilical artery remnant tightly adhered to the bladder wall. The left umbilical artery continued to an aneurysm involving the distal aorta. The foal was subject to euthanasia and post-mortem examination confirmed a spherical ao...
Neutrophil function of neonatal foals is enhanced in vitro by CpG oligodeoxynucleotide stimulation. Rhodococcus equi is an intracellular bacterium that causes pneumonia in foals and immunocompromised adult horses. Evidence exists that foals become infected with R. equi early in life, a period when innate immune responses are critically important for protection against infection. Neutrophils are innate immune cells that play a key role in defense against this bacterium. Enhancing neutrophil function during early life could thus help to protect foals against R. equi infection. The objective of our study was to determine whether in vitro incubation with the TLR9 agonist CpG 2142 would enhance d...
Oral rosmarinic acid-enhanced Mentha spicata modulates synovial fluid biomarkers of inflammation in horses challenged with intra-articular LPS. A biological extract of high-rosmarinic acid mint (HRAM) has previously demonstrated inhibitory effects on lipopolysaccharide (LPS)-induced prostaglandin E(2) (PGE(2)), nitric oxide (NO) and glycosaminoglycan (GAG) release in vitro. This study was undertaken to determine whether HRAM added to feed produces similar effects in horses challenged with intra-articular LPS. Eight horses received HRAM (0 or 28.1 ± 1.3 g/day; n = 4 per group) in their feed for 24 days in a blinded manner. On day 21, all horses received an intra-articular injection of LPS (0.3 ng) into their left or right intercarpal ...
Performance evaluation of the Sysmex pocH-100iV Diff hematology analyzer for analysis of canine, feline, equine, and bovine blood. The Sysmex pocH-100iV Diff is an impedance hematology analyzer recently introduced for point-of-care use in veterinary practices in Europe. Objective: The purpose of this study was to validate the pocH-100iV Diff for analysis of blood samples from dogs, cats, horses, and cattle. Methods: Fresh EDTA-blood samples from healthy and ill dogs (115), cats (94), horses (91), and cattle (78) were analyzed on the pocH-100iV Diff and the Cell-Dyn 3500. Results of the automated WBC differential counts were compared with the manual differential counts for 77 dogs, 65 cats, 40 horses, and 46 cattle. HCT we...
Alloimmune neonatal neutropenia and neonatal isoerythrolysis in a Thoroughbred colt. A 3-day-old Thoroughbred colt was originally presented for treatment of neonatal isoerythrolysis, which was treated with a blood transfusion. However, persistent neutropenia was observed despite the absence of detectable infection. Subsequently, a granulocyte agglutination test was performed by incubating the colt's neutrophils with the mare's serum; results were positive, leading to a clinical diagnosis of alloimmune neonatal neutropenia. The diagnosis was further supported via flow cytometric analysis. The colt was hospitalized and treated prophylactically with antimicrobials and 4 separate ...
Validation of a low-dose ACTH stimulation test in healthy adult horses. To determine the lowest ACTH dose that would induce a maximum increase in serum cortisol concentration in healthy adult horses and identify the time to peak cortisol concentration. Methods: Evaluation study. Methods: 8 healthy adult horses. Methods: Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) were administered IV (5 treatments/horse). Serum cortisol concentrations were measured before and 30, 60, 90, 120, 180, and 240 minutes after injection of cosyntropin or saline solution; CBCs were per...
Failure of antimicrobial therapy to accelerate spontaneous healing of subclinical pulmonary abscesses on a farm with endemic infections caused by Rhodococcus equi. Mass antimicrobial treatment of foals with small ultrasonographic pulmonary lesions is common on farms with endemic disease caused by Rhodococcus equi. The objectives of this study were to compare the relative efficacy of three antimicrobial protocols for the treatment of pulmonary abscesses on a farm with endemic infections caused by R. equi and to determine the frequency of spontaneous resolution of subclinical pulmonary lesions. Foals with ultrasonographic evidence of pulmonary abscesses ≥ 1.0 cm in diameter (n=128) were randomly allocated to one of four equal treatment groups. Animals wi...
Evaluation of the Mythic 18 hematology analyzer for use with canine, feline, and equine samples. The Mythic 18 is a fully automated hematology bench-top analyzer using impedance technology for a complete blood cell count (CBC) and a 3-part white blood cell count (WBC) differential. The purpose of the current study was to evaluate the Mythic for assessment of agreement, precision, linearity, carry-over, stability, and usability under practice conditions. Ethylenediamine tetra-acetic acid-blood samples from 122 dogs, 140 cats, and 123 horses were analyzed with the Mythic and reference methods (Sysmex XT-2000iV, manual hematocrit, and microscopic WBC differentiation). Pearson's coefficient o...
Intradermal injections of equine allogeneic umbilical cord-derived mesenchymal stem cells are well tolerated and do not elicit immediate or delayed hypersensitivity reactions. BACKGROUND AIMS. The use of allogeneic mesenchymal stem cells (MSC) to treat acute equine lesions would greatly expand equine cellular therapy options; however, the safety and antigenicity of these cells have not been well-studied. We hypothesized that equine allogeneic umbilical cord tissue (UCT)-derived MSC would not elicit acute graft rejection or a delayed-type hypersensitivity response when injected intradermally. METHODS. Six Quarterhorse yearlings received 12 intradermal injections (autologous MSC, allogeneic MSC, positive control and negative control, in triplicate) followed by the sam...
Evaluation of a filter-prepared platelet concentrate for the treatment of suspensory branch injuries in horses. Platelet preparations have become a treatment for soft tissue injuries in horses. This study evaluated a novel filter-based system to concentrate platelets and assesses its value in the treatment of suspensory ligament branch desmitis. Methods: Filtered platelet concentrate was prepared from 55 ml of venous blood obtained from 21 normal horses. Platelets and white blood cells in whole blood and filtered platelet concentrate were measured, as was platelet activating factor (PAF)-induced platelet-derived growth factor-BB (PDGF-BB) release. Eleven horses with 18 focal acute suspensory ligament br...
Neutrophilic myeloperoxidase index and mean light absorbance in neonatal septic and nonseptic foals. Two neutrophilic indices reported by the ADVIA 120 Hematology Analyzer, neutrophilic myeloperoxidase index (MPXI), and mean light absorbance (neutrophil X mean [NXM]) have been proposed as indicators of systemic inflammatory disease in horses and of neutrophil activation in coronary ischemic syndromes in people. Objective: The aim of this study was to evaluate NXM and MPXI in healthy, sick nonseptic, and sick septic foals to determine whether conditions likely associated with neutrophil activation result in decreases in these variables. Methods: In this retrospective study, CBC data from 61 ne...
The evaluation of selected parameters of cellular nonspecific immunity in normal and allergic horses. The main aim of this study was to compare selected nonspecific immunity parameters in 14 allergic and 12 healthy horses. Each animal was assessed according to the following parameters: in vitro functional capacity of phagocytic cells using the nitro blue tetrazolium chloride reduction test, both spontaneous (NBT) and zymozan stimulated (NBTs), and ingestion capacity of phagocytic cells using a phagocytic index test (IF) and percentage of phagocytosing neutrophils activity (%KF). Differences were demonstrated between the group of allergic horses, especially with severe allergy symptoms, and hea...
Acute myeloid leukaemia (M6B: pure acute erythroid leukaemia) in a Thoroughbred foal. A 10-week-old Thoroughbred filly was referred for anaemia of 4 weeks' duration. Haematology revealed severe anaemia and panleucopenia. Cytological examination of bone marrow smears revealed a myeloid to erythroid ratio <0.02:1 (reference range 0.5-2.4:1.0) and an abundance of erythroid precursor cells. The erythroid cell population included rubriblasts, prorubricytes and rubricytes, with only scant numbers of metarubricytes present. There were numerous mitotic erythroid cells, some of which were atypical and megaloblastic. These cytomorphological changes are consistent with pure acute eryth...
Efficacy of rabbit anti-thymocyte globulin in severe aplastic anemia. A combination of horse anti-thymocyte globulin and cyclosporine produces responses in 60-70% of patients with severe aplastic anemia. We performed a phase II study of rabbit anti-thymocyte globulin and cyclosporine as first-line therapy for severe aplastic anemia. Methods: Twenty patients with severe aplastic anemia treated with rabbit anti-thymocyte globulin were compared to 67 historical control cases with matched clinical characteristics treated with horse anti-thymocyte globulin. Results: Response rates at 3, 6 and 12 months were similar for patients treated with rabbit anti-thymocyte glob...
Increased apoptosis of CD4 and CD8 T lymphocytes in the airways of horses with recurrent airway obstruction. Recurrent airway obstruction (RAO, also known as equine heaves) is an inflammatory condition similar to human asthma caused by exposure of susceptible horses to poorly ventilated stable environments. The disease is characterized by neutrophilic airway inflammation, mucus hypersecretion and reversible bronchoconstriction. This inflammatory process is mediated by several factors, including antibodies, cytokines, resident cells of the airway and inflammatory cellular components that arrive in the respiratory tract. An increasing body of evidence has lent support to the concept that a dysregulatio...
Effects of acute hyperinsulinemia on inflammatory proteins in horses. Laminitis is a painful, inflammatory disease of the equine hoof that often results in euthanasia. Elevated plasma insulin concentrations are a predictive factor for laminitis, and in previously healthy horses and ponies, laminitis was induced by infusion of insulin. Thus, we chose to determine if an infusion of insulin would increase plasma concentrations of inflammatory cytokines and cytokine mRNA abundance in subcutaneous adipose tissue, skeletal muscle, and white blood cells. Ten mature Thoroughbred mares received an insulin infusion that elevated plasma insulin concentrations for 6h or an ...
The seroprevalence of Lawsonia intracellularis in horses in The Netherlands. Equine proliferative enteropathy caused by Lawsonia intracellularis is an emerging disease of weanling foals and affects their growth and development. The prevalence of Lawsonia intracellularis in The Netherlands is not known. The aim of the study was to investigate the seroprevalence of Lawsonia intracellularis in horses in The Netherlands. Blood samples were taken from healthy foals before and after weaning and from healthy yearlings and mature horses on farms throughout The Netherlands. These samples were analysed for the presence of Lawsonia intracellularis-specific antibodies with a block...
Effect of long-term fluticasone treatment on immune function in horses with heaves. Corticosteroids currently are the most effective pharmacological treatment available to control heaves in horses. Systemically administered corticosteroids have been shown to alter immune response in horses, humans, and other species. Aerosolized administration theoretically minimizes systemic adverse effects, but the effect of inhaled corticosteroids on immune function has not been evaluated in horses. Objective: To evaluate the effects of prolonged administration of inhaled fluticasone on the immune system of heaves-affected horses. Methods: Heaves-affected horses were treated with inhaled f...