Hematology in horses involves the study of blood, its components, and related disorders in equine species. This field encompasses the analysis of red blood cells, white blood cells, platelets, hemoglobin, and hematocrit levels to assess the health status of horses. Hematological parameters are used to evaluate various physiological and pathological conditions, including anemia, infections, and immune-mediated diseases. Techniques such as complete blood counts (CBC) and blood smear evaluations are commonly employed to gather insights into the equine circulatory system. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and clinical implications of hematological assessments in equine medicine.
Weiser MG.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...
Russell KE, Perkins PC, Grindem CB, Walker KM, Sellon DC.To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry. Methods: 16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, EIAV-positive horses and ponies; and 2 thrombocytopenic, EIAV-negative horses. Methods: Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample ...
White SD, Maxwell LK, Szabo NJ, Hawkins JL, Kollias-Baker C.To determine pharmacokinetics of azathioprine (AZA) and clinical, hematologic, and serologic effects of i.v. and oral administration of AZA in horses. Methods: 6 horses. Methods: In study phase 1, a single dose of AZA was administered i.v. (1.5 mg/kg) or orally (3.0 mg/kg) to 6 horses, with at least 1 week between treatments. Blood samples were collected for AZA and 6-mercaptopurine (6-MP) analysis 1 hour before and at predetermined time points up to 4 hours after AZA administration. In study phase 2, AZA was administered orally (3 mg/kg) every 24 hours for 30 days and then every 48 hours for ...
Weiss DJ, Evanson OA, McClenahan D, Fagliari J, Walcheck B.To determine whether platelets become activated and form platelet-platelet or platelet-neutrophil aggregates, or both, when subjected to shear. Methods: Blood obtained from 3 Thoroughbreds. Methods: Blood, with PCV adjusted to 32 (low hematocrit) or 60 (high hematocrit)%, was subjected to shear rates of 11.25, 22.5, 45, 90, 225, and 750/s for 3 minutes by use of a cone-plate viscometer. Flow cytometric techniques were used to identify activated platelets, platelet-platelet aggregates, and platelet-neutrophil aggregates. Results: Shear resulted in decreased platelet count, increased mean platel...
Sneddon JC, Van der Walt J, Mitchell G.1. The resistance of sub-tropical horses, and desert-dwelling horses to 72 hr dehydration/24 hr rehydration was investigated via changes in red cell parameters and plasma protein concentration. 2. Red cell count, haemoglobin and haematocrit increased up to 48 hr dehydration. Between 48 and 72 hr dehydration these parameters decreased, implying a fluid shift onto the intravascular space from the interstitium/hindgut. Most parameters had regained baseline values by 24 hr rehydration. 3. Mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration and total plasma protein were not...
Hopfer SM, Van Kruiningen HJ, Daniels WH.Twelve horses were divided into three groups and given various doses of a mixed species strongyle inoculum, representing light, moderate, and heavy infections. Three weeks after the larval inoculations, three animals from each group were given larvicidal doses of thiabendazole (TBZ) (440 mg kg-1 on two consecutive days); one animal from each group served as a non-medicated control. Treatment was repeated three weeks later. One treated animal from each group was designated for long-term study; others were necropsied to study adult and larval parasite loads. Six of the twelve animals with strong...
Rose RJ, Ilkiw JE, Hodgson D.Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid-ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnorma...
Hayes AM, Kastl B, Perry E, Moore AR, Springer NL.Myeloma-related disorders, including multiple myeloma, extramedullary plasmacytoma, and solid osseous plasmacytoma, are rare in horses. Clinical complaints for myeloma-related disorders are nonspecific, and when present, M-protein location is more variable on protein electrophoresis in horses relative to dogs and cats. Here, we describe a case of a 15-year-old Thoroughbred mare who presented with recurrent blepharitis. Marked hyperglobulinemia was an incidental finding on routine hematologic and biochemical testing. Bone marrow aspiration consisted of >30% plasma cells, and serum protein el...
Persson SG, Ullberg LE.The rate of disappearance of Evans blue dye from the blood after an intravenous injection was studied in young foals, between 4 and 105 days of age. This was found to be age dependant, especially during the first month, the initial dye disappearance being much faster than in the adult horse. This would mean an overestimation of plasma volume, using the single sampling technique, of about 5% during the first day of life, i.e. negligible from a practical point of view considering the standard error of estimation. The effect of exercise on the venous haematocrit was studied, too, in foals less th...
Brown SA, Barsanti JA.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...
Bodurov N, Filipov Zh.Comparative clinical and experimental investigations were carried out on 18 clinically normal horses. It was found that the single transfusion of in vitro UV-treated autogenous blood, following a previously described method, was tolerated well by horses and did not lead to any deviations from the normal indices. Under the effect of the treated blood there was an increase in the hemoglobin content, rise in the erythrocyte and leukocyte count with slightly expressed hyperleukocytosis and weak neutrophilia (simple regeneration of the blood). The sedimentation of erythrocytes also showed higher ra...
Bracher V, Steiger R, Huser S.In the present study the breath hydrogen (H2) excretion test was combined with the xylose absorption test in 4 normal horses and 9 clinical patients with chronic diarrhea (n = 3) or chronic weight loss without diarrhea (n = 6). All horses underwent a thorough clinical examination. Laboratory evaluations consisted of haematology and serum biochemistry as well as bacteriological and parasitological examination of feces. In addition, serum electrophoresis and abdominocentesis was performed in all the clinical patients. Gastroscopy was carried out in 6 patients and rectal biopsies were obtained fr...
Allen BV.Results of blood counts have been analysed in three-year-old racehorses in training comprising 77 colt stayers, 27 colt sprinters, 61 filly stayers and 35 filly sprinters. The distributions of haemoglobin, erythrocyte count and haematocrit were significantly higher in colt stayers compared to the other three groups. In fillies these values were also significantly higher in stayers compared to sprinters. The erythrocyte count was significantly higher in filly stayers compared to colt sprinters but there were no significant differences between haemoglobin or haematocrit values in these groups. N...
Mercier P, Alves-Branco F, Sapper Mde F, White CR.To evaluate the safety of an orally administered ivermectin and praziquantel paste with regard to variables associated with clinical findings, parturition, lactation, maternal care, and neonate viability in pregnant mares. Methods: 40 pregnant mares. Methods: Mares were randomly allocated into treatment (n = 20) and control (20) groups and administered a placebo or 3 times the therapeutic dosage of ivermectin (0.6 mg/kg) and praziquantel (4.5 mg/kg) at 14-day intervals until parturition. Physical examinations were performed on mares and their foals after parturition (on postpartum days 30, 60,...
Seibert BP, Newcomb KM, Michael BF.Critical tests were done on 24 naturally parasitized horses to compare the antiparasitic activity of an oral paste preparation of mebendazole and trichlorfon with that of the marketed powder formulation. Each formulation was administered at the recommended dosages of 8.8 mg of mebendazole and 40 mg of trichlorfon/kg of body weight. Efficacy of the paste formulation ranged from 97.7% to 100% against 2nd- and 3rd-stage Gasterophilus spp, adult Strongylus vulgaris, S edentatus, Parascaris equorum, small strongyles; and larval and adult forms of Oxyuris equi. Adverse effects were generally limited...
Rubio MD, Muñoz A, Santisteban R, Tovar P, Castejón FM.Exercise-induced hematological alterations were studied in 20 four-year old foals, 11 Andalusian and 9 Arabian. They were subjected to a test exercise program consisting of 4 levels of gradually increasing intensity (15, 20, 25 and 30 km/hr) with a duration of 5 min each. Blood samples were taken during resting, after each exercise level and at 10 and 30 min of recovery from exercise. The following hematic parameters were analyzed: red blood count, hematocrit value, hemoglobin, volumetric indexes (MCV, MCH and MHCH) and total plasma proteins. The alterations as a result of the physical effort ...
Casella S, Piccione D, Ielati S, Bocchino EG, Piccione G.The aim of this study was to assess the anion transport in equine erythrocytes through the measurement of the sulfate uptake operating from band 3 using different experimental temperatures and buffer solutions. Blood samples of six clinically healthy horses were collected via jugular vein puncture, and an emochrome-citometric examination was performed. The blood was divided into four aliquots and by centrifugation and aspiration the plasma and buffy coat were carefully discarded. The red blood cells were washed with an isosmotic medium and centrifuged. The obtained cell suspensions were incuba...
Paradis MR, Breeze RG, Laegreid WW, Bayly WM, Counts DF.Eight ponies were allotted to 2 groups of 4. Group-1 ponies (1-4) were given 0.2 g of indole/kg of body weight orally and group-2 ponies (5 to 8) were given 0.1 g of indole/kg. Various physical, hematologic, and physiologic measurements were obtained after administration of indole. Intravascular hemolysis and hemoglobinuria were detected in both groups within 24 hours of dosing. Hemolysis was reflected by decreases in PCV, hemoglobin concentration, and RBC count, and an increase in indirect bilirubin. Erythrocyte fragility appeared to increase in both groups at 8 hours after dosing and peaked ...
Delgado MA, Monreal L, Armengou L, Segura D, Ríos J.Peritoneal D-Dimer concentration can be determined to assess peritoneal fibrinolysis activity in horses with gastrointestinal disorders. However, blood contamination of peritoneal fluid may occur during collection and could alter peritoneal D-Dimer concentration. Objective: Blood contamination in peritoneal fluid does not affect interpretation of peritoneal D-Dimer concentration in horses with colic. Methods: Thirty-four horses with colic and 4 healthy horses. Methods: Peritoneal fluid and blood samples were simultaneously collected upon admission. Then, peritoneal fluid was serially contamina...
Frape DL.The majority of recent experiments in equine nutrition relates to the metabolism of protein, non-protein nitrogen, carbohydrate, calcium and phosphorus. An understanding of the significance of the nitrogen cycle is emerging in which there is a two-way movement of compounds across the wall of the G.I. tract. Some quantitative estimates of the role of microflora in this process have been made for comparison with similar processes in ruminants. However, the pathway by which the microflora contributes to the nitrogen economy and the extent to which this occurs is not established in the horse. It i...
Shideler RK, Voss JL, Aufderheide WM, Hessemann CP, Squires EL.Twenty mares were assigned to 1 of 4 groups: no altrenogest; altrenogest at 0.044 mg/kg BW; altrenogest at 0.132 mg/kg BW; or altrenogest at 0.220 mg/kg BW. Treatment was administered daily for 86 days. No signs of illness attributable to feeding altrenogest were observed during the trial. Treatment had no effect (P greater than .05) on the following parameters: WBC, differential WBC, platelet number, creatinine, LDH, CPK, total bilirubin, cholesterol, globulin, BSP, and erythrocyte sedimentation rate. When comparing values over time with pretreatment means or among treatment groups, there wer...
El-Sherif MA, Nabil G, Ibrahim R, Mohamed N, Mohamed M, Jaheen AH.Based on the growing attention to the Arabian horses with a lack of records regarding their normal physiological parameters, which are critically vital for disease diagnosis &convenient drug administration, we give great attention to their thyroid gland normalcy. The thyroid gland is one of the key players in regulating many physiological processes. Therefore, we tackled thyroid biology & morphology in 14 Arabian stallions & 18 Arabian mares from the beginning of March to the middle of April on animals from 4 to 19 years old. First, the blood samples taken from their jugular vein ...
Gu XL, Dai FY, Xiao X, Li GZ, Zhang LM, Qu WJ.The effect of Ageratina adenophora on pathological characteristics of the liver and lungs as well as serum biochemical parameters in horses were investigated. Ten horses without ingestion history of Ageratina adenophora were classified into the control group, and 10 poisoned but survived horses with 3 months ingestion history were set as the case group. Results showed that serum AST, ALT, ALP, magnesium and phosphorus were elevated significantly, while creatinine was decreased remarkably. Hematoxylin and eosin staining of liver tissues showed diffuse swelling or destruction of hepatocytes, nar...
Goldztein S, Carreras Vescio LA, Salamone HJ, Calahonra R, Kohan AI, Sánchez Avalos JC.A 24-year-old male patient with a severe aplastic anemia (SAA) was treated with equine-antilymphocyte globulin (ALG). As complication of this treatment he developed a severe heteroimmune hemolytic anemia mediated by anti-species pan-agglutinin antibodies present in ALG. In spite of the fact that ALG is absorbed with red-cell stroma and platelets to remove anti-erythrocyte and anti-platelet contaminating antibodies, often only partial absorption is achieved, and the remaining antibodies are passively acquired by the recipient. Neutropenia and especially thrombocytopenia are usual complications ...
Monreal L, Villatoro AJ, Hooghuis H, Ros I, Timoney PJ.During 1992, a widespread outbreak of Equine viral arteritis (EVA) occurred at a riding establishment near Barcelona, Spain. A total of 31 out of 186 horses on the premises displayed clinical signs, most frequently, fever, depression, mild ventral and limb oedema and a vesicular-erosive stomatitis, with hypersalivation, petechiations and small ulcerations. Affected horses developed illness of varying severity with only a few exhibiting a severe form of the disease and no mortality was recorded. Haematological and blood biochemical examination the most severely affected horses revealed a thromb...
Tennent-Brown BS, Goetz TE, Manohar M, Hassan AS, Freeman DE, Bundy JS, Evans MR.Hyperhydration, prior to prolonged moderate-intensity exercise simulating the 2nd day of a 3-day equestrian event (E3DEC), may induce arterial hypoxaemia detrimental to performance. Objective: Because moderate-intensity exercise does not induce arterial hypoxaemia in healthy horses, the effects of pre-exercise hypervolaemia on arterial oxygenation were examined during a prolonged exercise protocol. Methods: Blood-gas studies were carried out on 7 healthy, exercise-trained Thoroughbred horses in control and hyperhydration experiments. The study conformed to a randomised crossover design. The se...
Michishita M, Shibata R, Machida Y, Matsumoto M, Ochiai K, Azakami D.A 20-year-old Dutch Warmblood gelding was referred with clinical signs of anorexia, weight loss, intermittent fever, cough, subcutaneous oedema and exercise intolerance. Haematological examination revealed the presence of blast cells, decreased lymphocytes, mild thrombocytopenia and anaemia but no leucocytosis. Serum analyses detected elevated aspartate aminotransferase and gamma-glutamyl transferase activities and triglyceride concentrations. Twenty-two days after the initial visit, the horse died after showing clinical signs of decreased appetite, increased body temperature, tachypnoea and t...
Burton AG, Clark KC, Borjesson DL, Carrade DD, Burges J, Owens SD.Volume reduction and RBC depletion of equine bone marrow specimens are necessary processing steps for the immediate therapeutic use of bone marrow (BM)-derived mesenchymal stem cells (MSC), and for MSC expansion in culture. Objective: The purpose of the study was to evaluate the ability of the PrepaCyte-CB processing system to reduce volume, deplete RBC, and recover mononuclear cells (MNC) from equine BM specimens. Methods: One hundred and twenty mL of heparinized BM were obtained from each of 90 horses. A CBC was performed on the BM pre- and post-PrepaCyte-CB processing. Volume and RBC reduct...
Boyle AG, Higgins JC, Durando MM, Galuppo LD, Werner JA, Decock HE.A 22-year-old female Welsh-cross pony was evaluated because of intermittent colic, signs of depression, pyrexia, anorexia, muscle wasting with abdominal distention, and weight gain over the preceding 12 months. A large abdominal mass was detected and surgically removed; the hemodynamic alterations and complications caused by the dramatic fluid losses and shifts that can occur in association with removal of a large abdominal mass required extensive postoperative management. Monitoring of clinical and hematologic variables such as attitude, heart rate, mucous membrane color, mean arterial blood ...
Houpt KA, Perry PJ, Hintz HF, Houpt TR.Twelve ponies were fed their total daily ration either as one large meal or divided into six small meals. Pre- and post-feeding behavior was recorded six times a day. Blood samples were taken for 30 min before and two hr after the meal. Plasma protein increased from 7.0 to a peak of 7.3 g/dl with small meals and from 7.3 to 8.1 g/dl with large meals, and returned to pre-feeding levels by 90 min post-feeding. Hematocrit rose from 33.3 to 34.1% with small meals and from 33.0 to 36.0% with large meals. These rapid and short-lived increases indicate a decrease in plasma volume. Plasma osmolality r...
