The Influence of Training and Simulated Race on Horse Plasma Serotonin Levels

Exercise represents a physical stress that challenges homeostasis affecting central and peripheral serotoninergic systems. The influence of the exercise on circulating serotonin (5-hydroxytryptamine [5-HT]) levels depends on training state as well as the exercise protocol. The purpose of the present research was to determine changes of plasma 5-HT in sport horses in response to training (T) and simulated race (SR) and in addition to assess the possible presence of significant differences on circulating 5-HT between two different sessions of exercise. In particular, the research was carried out on 18 trained horses performing daily training and race activity. Plasma 5-HT levels were analyzed in platelet poor plasma fraction by ELISA assay at T0 (before exercise), T1 (30 minutes after exercise) and T2 (2 hours after exercise). The hypothesis was that both exercise sessions could affect plasma 5-HT levels. Results showed a significant increase of plasma 5-HT levels at T1, compared with T0, both after simulated race and training activity. These effects are probably related to an increased 5-HT release from platelets and/or an increased peripheral 5-HT synthesis induced from exercise. At T2, plasma 5-HT concentrations showed a significant decrease to physiological levels in both sessions. Moreover, plasma 5-HT levels at T1 (SR) were significantly higher than those at T1 (T). Targeting peripheral 5-HT could be useful to assess the physiological adaptability of horses to the exercise, together with other selection techniques of sport horses.     

Acupuncture Needle Stimulation on Some Physiological Parameters After Road Transport and Physical Exercise in Horse

The aim of this study was to evaluate the effect of acupuncture (AG) treatment on some hematochemical parameters in five Thoroughbred horses after road transport and exercise. Horses competed in two official races. For each race, animals were transported from their stables to the racetrack. Horses transported and competed in the first race represent the control group. Two weeks later, the same horses competed in the second race. Before road transport, they were treated with AG. From animals, blood samples were collected at rest (T_PRE), after unloaded (T_POST), 30 minutes after unloaded (T_POST30), at rest in the transit stall (R_PRE), at the end of the race (R_POST), and 30 minutes after the race (R_POST30). The effect of transport, exercise, and AG was evaluated on blood lactate, glucose, red blood cell, hemoglobin, hematocrit, mean corpuscular volume, and erythrocyte osmotic fragility (EOF) values. A significant effect of transport (P < .05) and exercise (P < .01) was found on all studied parameters in both groups. A significant effect of AG on lactate, glucose, and EOF values was found in transported (P < .001) and exercised horses (P < .05). The results found in this study showed that transport and exercise are potential stressors for the athlete horse that may affect its welfare and physical performance. The data suggest that AG stimulation promoted the increase of blood glucose values and the reduction of lactate and EOF levels suggesting its role in the improvement of the physiological adaptation to stressful stimuli and of physical performance of Thoroughbred horses.     

The Effect of Cimetidine and Aminoguanidine on Pro-inflammatory Cytokines in the Horse

In this study, six horses each had three subcutaneous tissue chambers. Each horse was pretreated with intravenous saline (control), cimetidine, or aminoguanidine with a 4-week washout period. On day 0, a carrageenan (NaCl inflamed) was instilled in 1 tissue chamber. Blood and all tissue chamber fluids were sampled on days -1 to 3 and measured for activity levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6. The T_max for all cytokines (TNF-α, IL-1, IL-6) was 0.5 and 1 day post-inflammation in tissue chamber fluid. In the tissue chamber fluid, NaCl inflamed (NaCl-I), cimetidine, and aminoguanidine groups showed significant increases in IL-1 production. In the NaCl-I and cimetidine, tissue chamber fluid IL-6 was significantly increased when compared with NaCl noninflamed (NaCl-N) for the periods of study -1 to 1, -1 to 2, and -1 to 3. The cimetidine tissue chamber fluid [TCF] appeared to have a delayed, but greater, IL-6 response than the NaCl-I treatment. Even with cimetidine and aminoguanidine pretreatment, the resulting decrease in NO production demonstrated in our previously reported results in these same animals appeared to be too late to decrease the early cytokine response. However, it may assist in preventing the subsequent NO-induced upregulation of pro-inflammatory cytokine production.     

Aminophylline Affects Glycemia Control and Increases Anaerobic Glycolysis in Horses during Incremental Exercise

A study was conducted on the effects of acute administration of aminophylline on physiological variables in purebred Arabian horses submitted to incremental exercise test. Twelve horses were submitted to two physical tests separated by a 10-day interval in a crossover study. These horses were divided into two groups: control (C, n = 12) and aminophylline (AM, n = 12). The drug at 10 mg/kg body weight or saline was given intravenously, 30 minutes before the incremental exercise test. The treadmill exercise test consisted of an initial warmup followed by gradually increasing physical exigency. Blood samples were assayed for lactic acid, glucose, and insulin. Maximal lactic acidemia was greater (P = .0238) in the AM group. Both V₂ and V₄ (velocities at which lactate concentrations were 2 and 4 mmol/L, respectively) were reduced in the AM group by 15.85% (P = .0402) and 17.76% (P = .0109), respectively. At rest as well as at 4 minutes, insulinemia was greater in the AM group (P = .0417 and .0393). Glycemia was statistically lower in the AM group at times 8 (P = .0138) and 10 minutes (P = .0432). Use of aminophylline in horses during incremental exercise does not seem to be beneficial, because this drug has a tendency to cause hypoglycemia and to increase dependence on anaerobic glucose metabolism.     

Alopecia Universalis in a Horse

Abstract— Alopecia universalis was diagnosed in a 3-year-old brown Percheron mare. Clinical and histo-pathologic findings in this previously unreported condition in the horse are described.     

Evaluation of Serum Electrolytes and Blood Lactate Concentration During Repeated Maximal Exercise in Horse

Modifications of some serum electrolyte concentration during two international *** show jumping competition performed in two consecutive weekends were evaluated. Serum sodium (Na), chloride (Cl), magnesium (Mg), potassium (K), phosphorous (P), calcium (Ca), iron (Fe), and blood lactate on 14 well-trained Italian saddle horses were assessed. Blood samples were collected before the beginning of the competition (T0B), within 10 minutes after the end of race (R1, R2, and R3), and on the day after competition (T0R). The same procedure was followed on the second weekend (R4, R5, R6, and T1R). One-way repeated measures analysis of variance was applied on collected data, and a significant effect on sampling time (P < .05) on all parameters studied was found. These results suggest that serum electrolytes and blood lactate concentration are responsive to intense exercise and could be considered an important factor for a correct management training's planning.     

Carotenodermia in a Horse

This case report describes an 11-year-old Appaloosa gelding that was examined because of yellow–orange tinting of the skin of the muzzle, eyelids, sheath, anus, and perianal region without discoloration of the sclera or mucus membranes. The horse was reported to preferentially eat dandelions which were plentiful in the pasture. Physical examination was normal, except for the discolored skin. A serum chemistry panel was normal. Carotenodermia was suspected. Serum carotenoid concentrations were higher in the affected horse as compared with concentrations in two horses with depigmented skin of normal color that were on grass pasture in the same geographic area. The horse remained systemically healthy and the abnormal skin color had almost disappeared when he was examined 7 weeks later. Carotenodermia can occur in horses and can be differentiated from jaundice because the sclera remains unaffected. Veterinarians should be aware that the condition is benign and spontaneously resolves after stopping carotenoid intake.     

Prevalence of Brucellosis in Horse North-East of Iran

Brucella preferentially infects cattle, swine, sheep, and goats. However, some epidemiological surveys have been carried out to investigate nonruminants, such as horses. Horse brucellosis has been found in clinical cases, but there are few epidemiologic patterns. Between May 2008 and April 2009, a total of 120 horses were screened for brucella infections in Mashhad, Iran, by the rose bengal test and the tube agglutination test. Sera from three horses were found positive by rose bengal test and tube agglutination test, and therefore the prevalence rate was 2.5%. In horses, the highest individual seroprevalence was in an animal kept close under the intensive system, with other animals such as cattle, sheep, and goats. The zoonotic aspects of brucellosis from the horse must, therefore, be considered because the disease is important from a public health standpoint. The present study documents the first serological evidence of Brucella spp. infection in horses in Iran.     

Heart Rate,Net Cost of Transport,and Metabolic Power in Horse Subjected to Different Physical Exercises

Considering that workload can also be expressed in terms of estimated net transport cost (COT), the metabolic energy needed to transport unit mass of animal unit distance, the aim of our study was to describe the heart rate (HR), COT, and the total metabolic power requirement per kilogram (P) during different exercises (aerobic, anaerobic, and aerobic–anaerobic exercises). On the basis of their attitude, 25 horses, divided into five equal groups, traveled a distance of 6,000 m, walking at 100 m/min in a horse walker (group A); performed 20-minute treadmill walk at 130 m/min, average speed up gradient of 5% (group B); performed a 700-m-long show jumping course with 13 fences (group C); traveled a distance of 2,100 m galloping at a speed of 700 m/min (group D); and traveled a distance of 2,000 m trotting at a speed of 660 m/min (group E). On each horse, HR was continuously recorded by means of an equine HR monitor. COT was calculated with the following formula: (HR − 35) kg⁻¹ m⁻¹ 10³; P was calculated applying the formula: (HR − 35) min⁻¹ kg⁻¹. COT and P values, estimated from the mean HR, measured continuously during each experimental condition showed no linear relationship with HR and speed. The use of combined weight of horse and tack (group C and D) and horse, tack, and sulky (group E) statistically changed the results of formula application. COT and P change in different exercises and provide additional information about performance in athletic horses.     

Stress Response of Three-year-old Horse Mares to Changes in Husbandry System During Initial Equestrian Training

For initial training, horses are often transferred from group housing to individual boxes, which is a potential stressor. In this study, salivary cortisol concentrations, locomotion activity, and heart rate (HR) were analyzed and the HR variability (HRV) variables standard deviation of beat-to-beat interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated in 3-year-old mares (n = 8). Mares were transferred abruptly from a group stable with access to a paddock to individual boxes without a paddock and were studied from 4 days before to 5 days after changing the stable. Mares underwent routine equestrian training for young horses. On the days before mares were moved to individual boxes, cortisol concentrations showed a diurnal rhythm with values approximately 0.6 ng/ml in the morning and a decrease throughout the day. When horses were moved to individual boxes, cortisol concentrations increased to 1.8 ± 0.2 ng/ml within 30 minutes and did not return to baseline values within 6 hours (0.7 ± 0.1 ng/ml, P < .05 over time). On the following days, a diurnal rhythm was re-established but at a higher level than before the change of stable. Locomotion activity was higher when mares had access to a paddock than when kept in individual boxes. Heart rate increased for approximately 60 minutes when mares were separated from their group. In conclusion, separating young horses from their group and individual stabling are perceived as stressful.     

Pemphigus Foliaceus in a Horse

Abstract— A 3-year-old gelding was presented with a generalized chronic dermatitis characterized by erosions, ulcerations, crusting, scaling and widespread alopecia. The diagnosis of pemphigus foliaceus was based on history, clinical signs, histological lesions and immunohistological test results. Typical dermatohistopathological findings comprised intraepidermal acantholysis and cleft formation in both epidermis and hair follicle epithelium. Additionally, blisters and erosive lesions were found in the epithelia of various mucocutaneous junctions, the distal oesophagus and the oesophageal zone of the stomach. In formalin-fixed and paraffin-embedded tissues an immunoperoxidase technique was established to demonstrate deposits of the immunoglobulins G and M and the complement component C3 providing the opportunity to compare histological and immunohistological findings. Résumé— Un cheval hongre de 3 ans a été présenté avec une dermite chronique caractérisée par des érosions, des ulcères, des croutes, des squames et une alopécie très étendue. Le diagnostic de pemphigus foliacé reposait sur l'anamnèse, l'examen clinique et les résultats des examens histopathologiques et immunopathologiques. Les lésions histologiques typiques comprenaient des acantholyses intraépldermiques et la formation de fissures tant au niveau de lépiderme que des follicules pileux. En outre, des bulks et des érosions ont été retrouvées au niveau de différentes junctions cutanéomuqueuses et de la partie distalé de l'oesophage. Une technique d'immunopéroxydase sur tissus fixés au formol et en paraffine a été utilisée pour mettre en évidence des dépôts d'immunoglobulines G et M et de C3, permettant de comparer les observations histologiques et immunopathologiques. Zusammenfassung— Ein dreijähriger Wallach wurde mit einer generalisierten chronischen Dermatitis vorgestellt, die durch Erosionen, Ulzerationen, Krusten, Schuppen und ausgedehnte Alopezie gekennzeichnet war. Die Diagnose Pemphigus foliaceus stützte sich auf den Vorbericht, die klinischen Symptome, die histologischen Veränderungen und die Ergebnisse des immunohistologischen Tests. Die typischen histopathologischen Befunde umfaßten intraepidermale Akantholyse und Spaltbildung sowohl in der Epidermis wie im Epithel des Haarfollikels. Zusätzlich wurden Blasen und erosive Veränderungen in den Epithelien verschiedener mukokutaner übergänge, im distalen ösophagus und in der ösophagealen Zone des Magens gefunden. An formalinfixiertem und in Paraffin eingebettetem Gewebe wurde eine Immunoperoxidasetechnik durchgeführt, um die Ablagerungen von Immunglobulinen G und M und der Komplementkomponente C3 zu zeigen, wodurch die Gelegenheit bestand, histologische und immunohistologische Befunde zu vergleichen. Resumen Un caballo de tres anos fue presentado con una dermatitis crónica de tipo generalizado presentando erosiones, ulceraciones, costras y escamas epidérmicas, además de una alopecia generalizada. Una diagnosis de pémfigo foliáceo se basó en la historia y cuadro clínico, lesiones histológicas y resultados de tests inmunohistológicos. Los hallazgos dermato-histopatológicos típicos comprendieron acantolisis intraepidermica y la formación de indentaciones epidérmicas en ambos, epidermis y epitelio del folículo piloso. También se observó la presencia de vesículas y lesiones erosivas en el epitelio de las uniones mucocutaneas, asi como en áreas distales del esófago, y en zonas esofágicas del estómago. Después de la fijación en formol y sumersión en parafina de los tejidos, se utilizo la técnica de inmunoperoxidasa para la demonstratión de depósitos de inmunoglobulinas G y M, y el complemento C3, que proporcionó la oportunidad de comparar los hallazgos inmuno e histológicos.     

Effect of Physical Exercise on Thiols in the Plasma in the Athletic Horse: Connection with the Immune System

Veterinary Research Communications -     

Myofibroblastic Sarcoma in the Limb of a Horse

A case of myofibroblastic sarcoma in the left hind limb is reported in a 4-year-old male, mixed-breed horse. This report includes the clinical signs, macroscopic and microscopic lesions, and the immunohistochemical findings related to this neoplasm.     

Effect of Conditioning Horses Once,Twice, or Thrice a Week with High-Intensity Intermittent Exercise on v4

Intensive short intervals of exercise are used to condition horses for racing. In this study, the effect of exercising horses one, two, or three times a week during 6 weeks using two intervals with near-maximal speed over 100 m on v₄ (speed at which, under defined conditions, the blood lactate concentration reaches 4 mmol/L) and muscle thickness (MT) of supraspinatus and extensor carpi radialis was examined. Thoroughbreds (4-5 years of age) were exercised twice at near-maximal speed over 100 m, separated by a 10-minute period at walk, on dirt track during conditioning periods (CP) of 6-week duration. This exercise was undertaken once (six horses), twice (six horses), or thrice (five horses) a week during a CP. Before, every 2 weeks during, and 2 weeks after the CP, horses were subjected to a standardized exercise test to determine their v₄. Before and after CP, the MT of the extensor carpi radialis and the supraspinatus was examined by ultrasonography. There was no differential effect of the number of weekly exercises on v₄. Pooling the data of all horses, a decrease of v₄ was found. The decrease became evident after the sixth week of conditioning. MT did not change. The results indicate that the examined exercise protocols could negatively impact racing performance of horses.     

Bilateral Catastrophic Metacarpal Fractures in a Quarter Horse Gelding

A 5 year-old, 450 kg, American Quarter Horse gelding was presented for postmortem examination. The horse had sustained multiple fractures of the metacarpal bones of both fore limbs while being ridden at a canter. Based on the radiographic presence of parasagittal fractures in the condyles of the distal third metacarpus, we theorized that the fractures in this horse likely originated in the metacarpophalangeal joint and propagated into the diaphysis resulting in catastrophic failure. The unique finding in this case is that these injuries occurred in a horse that was not being trained for racing. Owners and trainers should be aware that horses trained for disciplines other than racing can develop condylar fractures similar to racing Thoroughbreds and Quarter Horses.