Balance In Horses Research Articles

Effects of total parenteral nutrition associated with glutamine, enteral fluid therapy with or without glutamine, and fluid therapy on the acid base and electrolyte balance of horses starved after exploratory laparotomy

This study aimed to evaluate the effects of the total parenteral nutrition associated with glutamine, enteral fluid therapy with or without glutamine, and fluid therapy on the acid–base and electrolyte balance of horses starved after exploratory laparotomy. Sixteen healthy male and female adult horses of mixed breed, aged between 4 and 14 years, and having a mean body weight of 248.40 ± 2.28 kg and a body score index of 3–4 (scale of 1–5) were divided into four groups with four animals per group. After an adaptation period of 30 days, they were randomly divided into four experimental groups: enteral fluid therapy, enteral fluid therapy associated with glutamine, total parenteral nutrition associated with glutamine, and parenteral fluid therapy. The experiment was further divided into two phases: Phase 1 and Phase 2. In Phase 1, an exploratory laparotomy was performed, treatments were administered to the groups and the horses received no food or water other than those given to their respective groups. In Phase 2, the animals were re-fed. Each phase had a total duration of 144 h. Venous blood samples were collected every 24 h throughout the experimental period for blood gas and electrolyte analyses. The following parameters were evaluated: pH, partial pressure of carbon dioxide, total carbon dioxide, bicarbonate, base shift, anion gap, sodium, potassium, chloride, total calcium and magnesium. Completely randomized designs with a 4 × 7 factorial scheme (groups × harvest time) in Phase 1 and a 4 × 6 factorial scheme (groups × harvest time) in Phase 2 were used with four replications. All values were considered significant when p≤0.05 (95% probability). Blood pH, bicarbonate concentration, and base shift in the PARGL group decreased, indicating metabolic acidosis. Changes in the acid–base and electrolyte balance were more intense in the PARGL group than in the other groups. These results demonstrated the need to monitor blood gas and electrolyte balance in horses with food restriction under nutritional support or prolonged fluid therapy so that such changes are promptly corrected.

Digestibility and nitrogen and water balance in horses fed rhizoma peanut hay.

Rhizoma peanut (RP, Arachis glabrata) hay has the potential to meet horses' crude protein (CP) requirements with less nitrogen excretion than other legumes. This study aimed to evaluate nutrient intake, apparent digestibility, and nitrogen balance of RP "Florigraze" hay compared with alfalfa (ALF, Medicago sativa L. "Legendary XHD") and bermudagrass (BG, Cynodon dactylon L. "Coastal") hays when fed to maintenance horses at 2% body weight/d on a dry matter (DM) basis. We hypothesized that nutrient intake would be comparable between the legume hays and lesser for BG and that RP would result in reduced nitrogen excretion compared with ALF. Six mature Quarter Horse geldings (593 ± 40 kg; mean ± SD) were randomly assigned to one of the hays in a replicated 3 × 3 Latin square with 21-d periods. A 14-d adaptation phase was followed by a 3-d total fecal and urine collection. Days 18 to 21 were used for a companion study. Intake of nutrients is reported on a DM basis. Digestible energy (DE) intakes from ALF (29.91 Mcal/d) and RP (29.37 Mcal/d) were greater (P < 0.0001) than BG (20.78 Mcal/d). CP intake was greater (P < 0.0001) for ALF (2.5 kg/d), followed by RP (1.9 kg/d) and BG (1.5 kg/d). All hays exceeded maintenance requirements for DE, CP, Ca, and P. Apparent digestibility of DM and CP was greatest (P < 0.0001) for ALF (69% and 84%), intermediate for RP (61% and 72%), and least for BG (46% and 64%). Apparent digestibility of neutral detergent fiber did not differ (P = 0.2228) among hays, while digestibility of acid detergent fiber (P = 0.0054) was least for RP but similar for ALF and BG. Water intake (kg/d) for ALF (57) was greater (P = 0.0068) than RP (45) and BG (41). Greater (P = 0.0271) water retention (kg/d) was observed for ALF (13.5), followed by RP (10.8) and BG (7.5). There was a difference in nitrogen excretion, with greatest urinary nitrogen excretion for ALF (P < 0.0001) and greatest fecal nitrogen excretion for BG (P = 0.0001). Total nitrogen excretion was greater (P < 0.0001) for ALF (278 g/d), followed by RP (211 g/d) and BG (179 g/d). Nitrogen retention was greater (P = 0.0005) for ALF when represented as g/d (ALF: 129, RP: 86, and BG: 57 g/d) but similar (P = 0.0377) to RP when presented as percent of nitrogen intake (ALF: 32%, RP: 29%, and BG: 24%). Results indicate that RP hay is a suitable legume for horses by meeting DE and CP requirements and having a significant reduction in nitrogen compared with ALF.

50 Intake, digestibility, and nitrogen balance in horses fed rhizoma peanut hay

Rhizoma peanut hay has the potential to meet horses’ crude protein requirements with reduced nitrogen excretion. This study aimed to evaluate nutrient intake, apparent digestibility, and nitrogen balance of rhizoma peanut (RP, Arachis glabrata cv Florigraze) hay compared with alfalfa (ALF, Medicago sativa L. cv Legendary XHD) and bermudagrass (CB, Cynodon dactylon L. cv Coastal) hays when fed to maintenance horses at 2% BW/d on a dry-matter (DM) basis. Six mature Quarter Horse geldings (593 ± 40 kg; mean ± SD) were randomly assigned to one of the hays in a replicated 3 × 3 Latin square with 21-d periods. A 14-d adaptation phase was followed by a 3-d total fecal and urine collection. Intake of nutrients is reported on a DM basis. Both legumes (ALF = 1.99% BW and RP = 1.97% BW) provided DM intake greater ( P < 0.05) than CB (1.82% BW) but were not different from one another. Digestible energy (DE) intake of ALF (29.9 Mcal/d) and RP (29.4 Mcal/d) were greater ( P < 0.05) than CB (20.8 Mcal/d). Crude protein (CP) intake was greater ( P < 0.05) for ALF (2,542 g/d), followed by RP (1,859 g/d), and then CB (1,477 g/d). Alfalfa provided the highest ( P < 0.05) calcium to phosphorus ratio of 6.3:1, while RP provided 4.4:1, and CB provided the lowest (1.7:1). Intake of all hays exceeded maintenance DE, CP, Ca, and P requirements. Apparent DM ( P < 0.05) and CP ( P < 0.05) digestibility were greater for ALF (69%, 84%), followed by RP (61%, 72%), and lowest for CB (46%, 64%). Neutral detergent fiber apparent digestibility did not differ ( P = 0.2228) among the 3 hays, while acid detergent fiber digestibility ( P = 0.0054) was lower for RP and similar for ALF and CB. Apparent digestibility of non-structural carbohydrate ( P < 0.05) was greater for ALF, followed by RP, and lowest for CB, while starch ( P < 0.05) digestibility was similar between the legumes and lowest for CB. Water intake for ALF was greater ( P < 0.05) than RP and CB. Greater urinary excretion ( P < 0.05) was observed for alfalfa, while water excreted through feces was greater ( P < 0.05) for CB, followed by RP, and lower for ALF. Urinary nitrogen (N) excretion was greater ( P < 0.05) for ALF, followed by RP, and lower for CB whereas fecal N excretion for both RP and CB were greater ( P < 0.05) than for ALF. Total N excreted was greater ( P < 0.05) for ALF (278 g/d), followed by RP (211 g/d), and lower for CB (179 g/d). Nitrogen retention was greater ( P < 0.05) for ALF when represented as g/d, but similar to RP when presented as percent of N intake. Results indicate that rhizoma peanut hay is a suitable legume for horses by meeting DE and CP requirements with significantly less N excretion than alfalfa.

Unipodal stance influences radiographic evaluation of foot balance in horses.

Lifting the contralateral forelimb (unipodal stance) is often used as a method of restraint in horses. This experimental one group pretest, posttest study was conducted to evaluate the effects of unipodal stance on quantitative radiographic parameters in equine forefeet. Seven nonlame horses were randomly selected. Lateromedial (LM) and dorsopalmar (DP) projections were acquired for both forefeet, squarely placed on blocks, using two X-ray generators. Radiographs of each foot were acquired first in a bipodal stance, immediately followed by the same radiographic projections obtained in a unipodal stance. The following measurements were recorded for each stance: distal interphalangeal joint (DIPJ) space width on both projections; mediolateral joint balance as the difference between lateral and medial DIPJ space widths on DP projections; extensor process-to-middle phalangeal condyle distance; and deep digital flexor tendon angle on LM projections. A matched pairs design and Student's t-test with a 95% confidence level were used to test for statistical significance. Compared to a bipodal stance, lateral DIPJ space width was significantly reduced on unipodal DP views, whereas mediolateral joint imbalance and to a lesser extent medial DIPJ space width were significantly increased. On unipodal LM views, there was a significant higher degree of DIPJ flexion. These findings suggest that stance should be carefully taken into consideration when measuring radiographic parameters in equine forefeet, especially if assessing foot balance and conformation, as unipodal stance significantly affects the mediolateral balance of the DIPJ on DP radiographs and significantly alters the phalangeal axis on LM radiographs.

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

Colic remains a life-threatening condition in the horse. Ischaemia and reperfusion following correction of small intestinal strangulation may produce oxidative stress. The ability to withstand oxidative stress depends on antioxidant levels and may be linked to horse survival. To measure peripheral antioxidant levels in horses undergoing exploratory laparotomy with small intestinal strangulation. Case-control study. Blood and plasma were collected from horses undergoing exploratory laparotomy for small intestinal strangulation and stored at -80°C. Controls involved non-colic horses. Total plasma glutathione was measured spectrophotometrically at 412 nm using the 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB, Ellman's reagent) reaction. Samples containing scavenger (to remove reduced glutathione, GSH) were used to measure oxidised glutathione (GSSG). Glutathione reductase (GR) activity (u/l) was measured as the rate of GSH production at 412 nm. Glutathione peroxidise (GPx) activity (u/l) was measured as the change in optical density (340 nm) following the consumption of NADPH after GSSG production. All assays were purchased from BioAssay Systems (Hayward, California). Clinical data including arterial blood gas analysis were collected on admission. Glutathione reductase activity in horses with strangulating small intestinal lesions was significantly reduced compared to control horses (12.2 ± 1.1 u/l vs. 15.9 ± 0.8 u/l, P = 0.03, n = 6) whereas GPx activity did not significantly differ between colic and control horses (155.7 ± 48.7 u/l vs. 167.3 ± 30.1 u/l, P = 0.84, n = 6). Total glutathione, reduced or oxidised glutathione did not differ significantly between control and colic horses. A positive correlation existed between GR activity and Ca(2+) (r = 0.93) and K(+) (r = 0.75) whereas a strong negative correlation was present between GR activity and HCO3 (-) (r = -0.92) and PaCO2 (r = -0.96). Reduced plasma glutathione reductase activity with small intestinal strangulation indicates oxidative stress and may be related to systemic electrolyte/bicarbonate abnormalities. Ethical animal research: Study approval No. VREC219a. Explicit owner informed consent for inclusion of animals in this study was not stated. Supported by the School of Veterinary Sciences, University of Liverpool. Competing interests: None declared.

Effect of a 12-Week Conditioning Period on Nitrogen Balance in Horses

Fourteen horses were used in two 12-week experiments. Horses were fed to meet crude protein needs for exercising horses and participated in light-to-moderate exercise. Total feces and urine output were measured in 4-day collections at the beginning and the end of each experiment. Fecal nitrogen (FN) and urine nitrogen (UN) were used to calculate nitrogen balance and digestibility. Nitrogen intake (NI) was higher in the end collection (P = .001). Fecal nitrogen expressed as a daily amount or as a percentage of NI was not different (P = .63 and .39, respectively). Nitrogen digestibility was not different (P = .39); however, the amount of nitrogen absorbed (NA) was lower in the initial collection (P = .001). Urine nitrogen was lower in the end collection when expressed as a total loss per day (P = .041), percent of NI (P = .001), or as a percent of NA (P = .001). Daily nitrogen retention (NR), NR expressed as a percentage of NI and as a percentage of NA, was higher in the end collection (P = .001). The improvement in NR in the end collection is due to the reduction in UN loss. This suggests more efficient use of dietary protein because there was no difference in FN loss; but without a significant change in body weight or body condition score, it cannot be concluded that the additional retained nitrogen was because of a need to support additional muscle mass.

Furosemide Administration Affects Mineral Excretion in Exercised Thoroughbreds

IntroductionFurosemide is widely administered to Thoroughbred and Standardbred racehorses to reduce the incidence and severity of EIPH. The magnitude and duration of mineral loss following furosemide administration has not previously been measured in horses.MethodsSix fit Thoroughbreds (age 6.8 ± 1.2 y; bwt 585 ± 19 kg) were used in a 3 x 3 Latin square design trial to measure the effect of furosemide on urinary and fecal mineral excretion for 24 h before (−24 h) and 24 h, 48 h and 72 h after a standardized exercise test (SET) on an inclined (3o) high speed treadmill. The treatment groups consisted of an untreated control (C) and two groups (F and FE) which received furosemide (0.5 mg/kg, IV) 4 h before the SET. C and F were fed 60 g/d NaCl and (FE) was fed 200 g/d of an electrolyte mix (14 g K, 37.7 g Na and 43.3 g Cl) for 21 days before the SET. Following the SET the FE group was supplemented with an additional 10 g/d Ca and 10 g/d Mg.ResultsUrinary Ca, P, Na and Cl excretion increased 24 h post treatment in the F and FE groups (P&lt;0.05). 72 h Ca and Cl balance was decreased in F (P&lt;0.05) and 72 h Mg and Cl balance was decreased in FE (P&lt;0.05). The digestibility of P and Mg was decreased in FE (P&lt;0.05) and Na digestibility was increased in F and FE (P&lt;0.05).ConclusionsA single dose of furosemide negatively affected calcium balance in horses for 72 h post administration. Further research is needed to assess the effect of chronic furosemide use in racehorses on mineral balance and soundness.Ethical Animal ResearchStudy approved by the Kentucky Equine Research Institutional Animal Care and Use Committee. Sources of funding: Kentucky Equine Research. Competing interests: none.

Acid‐Base Imbalances in Endurance Racing Using Traditional and Quantitative Approaches

IntroductionAcid‐base disturbances are frequently assessed using traditional variables PCO2, pH, and bicarbonate. This study aimed to compare the changes in acid‐base balance in horses performing a CEI endurance race (160 km) using traditional and quantitative methodologies.MethodsBlood samples were drawn before racing, at the vet‐gate (66 km), immediately after racing, and 2 and 15 h after racing from 18 participating horses. The mean velocity of the horses was 17 km/h. PCO2 and pH were measured (I‐Stat). Strong ion difference (SID), anion gap (AG), strong ion gap (SIG) and total volatile buffers (Atot) were calculated using formulas from the literature. Data for finishers (F) and non‐finishers (N) was compared with an unpaired test. Data collected for finishers at all time‐points was compared by repeated ANOVA followed by Tukey's test.ResultsPCO2 was lower in group N at the 66 km time‐point. In group F, AG had a bimodal behaviour, declining immediately after exercise and then increasing at 2 and 15 hours. There was a slight increase in pH post‐exercise. After 2 hours, Atot increased while PCO2 decreased. Compared to SIG immediately after racing, SIG at 2 and 15 hours after racing was decreased. Traditional methodology suggested mild respiratory and metabolic alkalosis, possibly due to hyperventilation of the finishers. Quantitative methodology suggested metabolic acidosis reflected by decreasing SID trend and a significant increase of Atot.ConclusionsAcid‐base imbalances are present in endurance racing horses and differences were found between the traditional and quantitative methods of assessment.Ethical Animal ResearchAll procedures were approved by the institutional animal care and use committee of the university (CEUA, Process: 007347/13). Explicit owner informed consent for participation in this study is not stated. Sources of funding: FAPESP ‐ Fundação de Amparo à Pesquisa do Estado de São Paulo (Process 2013/00449‐8). Competing interests: none.

The effect of dietary carbohydrate composition on apparent total tract digestibility, feed mean retention time, nitrogen and water balance in horses

A total of four diets with different carbohydrate composition were investigated in a 4×4 Latin square design experiment with four Norwegian Coldblooded trotter horses. The objective of the present study was to increase the fermentable fibre content and reduce the starch intake of the total ration obtained by partly substituting mature hay and barley with sugar beet pulp (SBP), a soluble fibre source. The diets investigated were hay only (HAY), hay (85% of dry matter intake (DMI)) and molassed SBP (15% of DMI) (SBP), hay (68% of DMI) and barley (32% of DMI) (BAR), and hay (68% of DMI), barley (26% of DMI) and SBP (6% of DMI) (BAR+SBP). The feeding level was 18.5, 17.3, 15.7 and 15.7 g DM/kg BW per day for the HAY, SBP, BAR and BAR+SBP diets, respectively. Each diet was fed for 18 days followed by 10 days of data collection, where apparent total tract digestibility (ATTD), total mean retention time (TMRT) of ytterbium-labelled hay, water balance, digestible energy (DE) intake and nitrogen balance were measured. An enzymatic chemical dietary fibre (DF) method was used to get detailed information on the composition and ATTD of the fibre fraction. Inclusion of SBP in the diet increased the ATTD of the constituent sugars galactose and arabinose (P<0.01). Feeding the HAY and SBP diets resulted in a lower TMRT owing to a higher DF intake than the BAR and BAR+SBP diets (P<0.01). There was no difference in water intake between HAY and SBP, but faecal dry matter was lower for HAY than the other diets (P=0.017), indicating that water was more tightly bound to fibre in the HAY diet. The diets were iso-energetic and provided enough DE and protein for light to moderate exercise for a 550 kg horse. In conclusion, this study showed that the DF intake had a larger effect on TMRT than partly substituting hay or barley with SBP, and that highly fermentable pectin-rich soluble DF from SBP maintains high nutrient utilization in horses.

Blood and urinary variables in horses supplemented with electrolytes

This study was designed to evaluate changes on variables in blood, urine and water balance in horses in response to a single dose of electrolyte supplementation. The essay was conducted on a randomised 3×3 Latin Square design repeated over time, with three animals and three treatments: Treatment 1: control group (without supplementation); Treatment 2: supplementation with a medium dose of electrolytes composed of: 0.25 g of NaCl + 0.125 g of KCl + 0.05 g of CaCl + 0.025 g of MgCl per kg of BW; Treatment 3: supplementation with a high dose of electrolytes composed of: 0.625 g of NaCl + 0.3125 g of KCl + 0.125 g of CaCl + 0.0625 g of MgCl per kg of BW, equivalent to 2.5 times the medium dose of supplementation. The electrolytes were supplied through a nasogastric tube 4 h after the morning meal. The diet provided had a forage:concentrate ratio of 70:30, composed of coastcross hay and commercial concentrate, with an estimated consumption of 2% of body weigth (BW). Horses received 116 mg/kg of BW of commercial mineral salt mixed in the concentrate. Samples of blood, urine and digesta were collected over a 12 h period after supplementation for analysis of sodium, potassium, chloride, calcium and magnesium concentration. Water intake and urine output were also measured. Electrolytic supplementation enhanced (P&lt;0.05) the water intake, water retention and urine output. Blood variables were not altered by electrolyte supplementation (P≯0.05). The supplementation also influenced the sodium and chloride excretion in urine (P&lt;0.05). Urine physicochemical characteristics and the concentration of electrolytes excreted with time were significantly altered as a function of the electrolytes supplementation.

Effect of blindfolding on centre of pressure variables in healthy horses during quiet standing

In a standing horse the centre of pressure (COP), measured as the resultant vertical ground reaction force (GRF) of all supporting limbs, is adjusted in response to visual, vestibular and proprioceptive information. Stabilographic analysis measures balance by tracking COP movements in the horizontal plane. Loss of visual input affects stability of balance in people and has clinical implications in that instability inherent in some neurological diseases increases with the eyes closed. The objectives of this study were to evaluate the visual contribution to postural stability in horses. The hypothesis was that the magnitude and variability of postural sway variables increases when visual input is removed. Vertical GRFs were measured using two synchronized force plates and COP movements were tracked in 20 horses as they stood without visible movements of the hooves, head or neck. Three trials of 60s duration were recorded under sighted and blindfolded conditions. Stabilographic variables (craniocaudal and mediolateral COP amplitudes, velocities and mean power frequencies and their within-trial variabilities) were calculated and compared using univariate analysis of variance.Compared with the sighted condition, blindfolding increased the magnitude and the within-trial variability of craniocaudal and mediolateral COP amplitudes and mediolateral COP velocity. The findings indicated that loss of visual input had more effect on the measured COP variables in the time domain (amplitudes, velocities) than in the frequency domain (mean power frequency). The effects of blindfolding on postural stability should be further investigated as part of a diagnostic approach to the evaluation of balance in horses with neurological impairment.

Effect of underwater treadmill exercise on postural sway in horses with experimentally induced carpal joint osteoarthritis

To evaluate the effect of underwater treadmill exercise on static postural sway in horses with experimentally induced carpal joint osteoarthritis under various stance conditions. 16 horses. On day 0, osteoarthritis was induced arthroscopically in 1 randomly selected middle carpal joint of each horse. Beginning on day 15, horses were assigned to either underwater or overground (without water) treadmill exercise at the same speed, frequency, and duration. Two serial force platforms were used to collect postural sway data from each horse on study days -7, 14, 42, and 70. Horses were made to stand stationary on the force platforms under 3 stance conditions: normal square stance, base-narrow placement of the thoracic limbs, and removal of visual cues (blindfolded) during a normal square stance. The mean of 3 consecutive, 10-second trials in each condition was calculated and used for analysis. Displacement of the center of pressure differed significantly depending on the stance condition. Among horses exercised on the underwater treadmill, postural stability in both the base-narrow and blindfolded stance conditions improved, compared with findings for horses exercised on the overground treadmill. Horses exercised on the overground treadmill were only successful at maintaining a stable center of pressure during the normal square stance position. Variations in stance position had profound effects on the mechanics of standing balance in horses with experimentally induced carpal joint osteoarthritis. Underwater treadmill exercise significantly improved the horses' postural stability, which is fundamental in providing evidence-based support for equine aquatic exercise.

Effect of Selenium and Vitamin C on Clinical Outcomes, Trace Element Status, and Antioxidant Enzyme Activity in Horses with Acute and Chronic Lower Airway Disease. A Randomized Clinical Trial

Excess production of reactive oxygen species is involved in the pathogenesis of airway disorders in horses. Trace element antioxidants have a beneficial role in oxidant/antioxidant balance. The aim of the present study was to evaluate the effect of a combination of sodium selenite and ascorbic acid on clinical outcome, antioxidant enzymes, and trace elements status in horses with lower airway disease. For this purpose, 40 draft horses with lower airway disease were randomly selected (acute, n = 20; chronic, n = 20). Both acute and chronic cases were randomly allocated into two subgroups (ten each). Groups 1 and 2 were the horses with acute disease, while groups 3 and 4 were chronically ill. For all groups, each horse was administered antibiotic, non-steroidal anti-inflammatory, and mucolytic drug. In addition, groups 2 and 4 were injected with 15mg/kg sodium selenite and 30mg/kg ascorbic acid every 24h for successive 4weeks. Venous blood samples were obtained from diseased horses on three occasions; at first examination, and at 2 and 4weeks post-treatment. Clinically, antioxidant supplementation improved the clinical signs with significant decrease (p < 0.05) of the clinical index score in both acute and chronic cases. In supplemented groups compared with non-supplemented, there was a significant increase (p < 0.05) in the levels of copper, zinc, selenium, and iron as well as in the activity of glutathione-S-transferase and catalase. Meanwhile, there was a significant decrease (p < 0.05) in the levels of manganese, malondialdehyde, hydrogen peroxide, and low-density lipoprotein and in the activity of glutathione reductase. The results of the present study indicate that administration of sodium selenite and ascorbic acid may have beneficial effect on clinical outcome and antioxidant balance in horses with acute and chronic lower airway disease.

Hemogasometria e ânion gap em equinos tratados com soluções eletrolíticas enterais contendo diferentes fontes de energia

No presente estudo, foram comparados os efeitos de soluções eletrolíticas contendo diferentes fontes de energia administradas via enteral por sonda naso-esofágica de pequeno calibre em fluxo contínuo sobre o equilíbrio ácido base em equinos. Foram utilizadas seis fêmeas adultas em dois quadrados latinos 6x3 simultâneos em modelo misto. Os animais foram distribuídos em três grupos e submetidos a cada um dos seguintes tratamentos: SEDext - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio, 1g de gluconato de cálcio e 10g de dextrose diluídos em 1.000mL de água. Osmolaridade mensurada 228mOsmol L-1; SEMalt - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio, 1g de gluconato de cálcio e 10g de maltodextrina diluídos em 1.000mL de água. Osmolaridade mensurada: 181 mOsmol L-1 e SEProp - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio e 10g de propionato de cálcio diluídos em 1.000mL de água. Osmolaridade mensurada: 282mOsm L-1. As soluções eletrolíticas foram administradas na dose de 15mL kg-1 h-1, durante 12 horas. Os tratamentos com soluções eletrolíticas enterais contendo dextrose, maltodextrina ou propionato de cálcio não alteraram os valores da hemogasometria.

Hydration and electrolyte balance in horses during an endurance season

Limited information exists about the physiological training-induced changes in electrolyte balance of horses competing in long distance endurance races. To determine the effects of endurance training and racing on hydration and electrolyte balance in horses. Blood and urine were sampled at rest in 8 endurance horses before training and after two 11 week training periods (T1 and T2). Each training was followed by a 120 km endurance ride and horses were sampled before, during and 2 h after the rides. Blood was analysed for packed cell volume (PCV), total protein (TP), urea, creatinine and electrolyte concentrations. Urine was analysed for pH, specific gravity, creatinine and electrolyte concentrations, which allowed calculation of fractional excretion of electrolytes (FE). Changes associated with training and with the rides were assessed using a Student paired t test (P ≤ 0.05). Plasma TP, urea, creatinine and sodium concentrations increased during T1 and PCV decreased significantly during T2. FE(Cl) increased during T1 then decreased. FE(K) increased significantly during both training periods. Other blood and urine parameters did not show remarkable changes with training. PCV, plasma TP, urea, creatinine and total Ca concentrations increased and plasma Na(+) and Cl(-) concentrations decreased during both rides. Urine concentrations of Na(+), K(+) and Cl(-), FE(Na) and FE(Cl) decreased during the rides while urinary creatinine increased. FE(K) increased during the first part of the rides then decreased. These data contribute to the understanding of changes associated with training and prolonged endurance exercise.

Consumo, digestibilidade aparente dos nutrientes e balanço hídrico em equinos alimentados com feno de coast-cross em diferentes formas

Este trabalho foi realizado com o objetivo de avaliar o consumo, a digestibilidade aparente dos nutrientes e o balanço hídrico em equinos consumindo feno de capim coast-cross em diferentes formas físicas. Foram utilizados quatro equinos mestiços, com idade de 30 meses e peso vivo médio de 200 kg. Os animais foram alimentados com feno de capim coast-cross em quatro formas físicas: inteiro; picado (5 cm); moído a 5 mm; ou moído a 3 mm. O delineamento experimental utilizado foi em quadrado latino 4 × 4, com 10 dias de adaptação às dietas em cada período experimental, 4 dias de coleta de fezes e 1 dia de coleta de urina.A estimativa da digestibilidade aparente dos nutrientes das dietas foi realizada pelo método de coleta total das fezes e a urina foi coletada durante 24 horas utilizando-se coletores de urina. Os coeficientes de digestibilidade aparente e o consumo de nutrientes não diferiram com o processamento do feno, no entanto, o tempo de consumo reduziu com a moagem do feno.Houve maior retenção de água, estimada pelo balanço hídrico, quando fornecido feno picado ou moído a 3 mm. O consumo e a digestão dos nutrientes não são influenciados pelo nível de moagem do feno, porém o balanço hídrico é afetado pelas formas físicas do feno. Não há relação direta entre a redução do tamanho da partícula do feno e o aumento da retenção de água.

Hemogasometria de eqüinos submetidos à obstrução experimental do duodeno, íleo e cólon maior

Visando estudar os parâmetros do equilíbrio ácido-base de eqüinos submetidos a um modelo experimental de obstrução intestinal, 24 animais foram distribuídos em quatro grupos, controle instrumentado (GI), obstrução do duodeno (GII), íleo (GIII) e cólon maior (GIV). As amostras de sangue venoso foram coletadas antes das cirurgias (T0), durante as obstruções (T30ob-T180ob) e após as desobstruções (T60des-T180des). Os eqüinos do GIV, no T30ob, e os eqüinos do GII, nos T60ob, T90ob e T120ob, apresentaram aumento do pH(v), da cHCO-3(vP) e da cBase(v) que, acrescidos do aumento da pCO2(v) e da ctCO2(v), caracterizou a alcalose metabólica com compensação respiratória. Nos T90ob e T120ob, nos animais do GII, e no T180ob, nos animais do GIII, a pO2(v) e a sO2(v) tiveram comportamento semelhante. Os valores baixos apresentados pelos animais do GII foram associados à hipercapnia ou à hipoventilação, desencadeadas para a correção da alcalose metabólica. Entretanto, a hipoxemia apresentada pelos animais do GIII foi associada à hipovolemia presente neste período. As alterações ácido-base observadas constituem-se de alterações leves e temporárias, as quais não são capazes de predizer o diagnóstico das obstruções intestinais específicas em eqüinos com cólica. Entretanto, por relacionarem-se diretamente com a precocidade do distúrbio gastrintestinal, elas auxiliam o pesquisador no prognóstico.

Mineral balance in horses fed two supplemental silicon sources

Numerous studies suggest that silicon (Si) supplementation is beneficial for mineral metabolism and bone health. Mineral balance studies have not been performed in horses to determine how these supplements affect absorption of other minerals. The purpose of these studies was to investigate the effects of two different Si supplements on mineral absorption and retention in horses. Eight geldings were randomly placed in one of two groups: control (CO) or supplemental Si, which was provided by one of two supplements. The first, sodium aluminium silicate (SA), contains a bioavailable form of Si and is high in aluminium (Al). The second supplement contains oligomeric orthosilicic acid (OSA). All horses received textured feed and ad libitum access to hay. Supplemented horses received either 200 g of SA or 28.6 ml of OSA per day. Following a 10-day adaptation period, the horses underwent a 3-day total collection. Blood samples were taken on days 0 and 13. The two balance studies were conducted 4 months apart to reduce carryover effects. Intakes of Al and Si were greater with SA supplementation (p < 0.05). Sodium aluminium silicate increased faecal and urinary Si excretion (p < 0.05). Calcium retention and apparent digestion were increased by SA (p < 0.05). It also maintained plasma Si compared with the CO which tended to have a decrease in plasma Si (p = 0.08). Supplemental OSA increased retention of Ca and B (p < 0.05) and apparent digestion of B (p < 0.01). Orthosilicic acid tended to increase Si retention (p = 0.054), apparent digestion (p < 0.065), and also increased plasma Si. Both supplements were able to alter Ca retention and B metabolism, however, only OSA was able to alter Si retention, digestibility and plasma concentration. Orthosilicic acid, an Si supplement without substantial Al, appears to be a viable option for Si supplementation as it increased Si retention and digestibility.

Effects of diet, feeding and daily variation on acid–base balance in horses

This paper reviews the acute and chronic effects of feeding, diet composition and daily variation on equine acid–base status. The dietary cation–anion difference (DCAD) has a marked effect on blood acid–base balance in both the short term and long term. In general, diets with a low DCAD generate an acute acidosis that develops into a persistent though mild systemic, strong ion acidosis with long-term feeding. In contrast, high-DCAD diets result in a mild, persistent strong ion alkalosis characterized by elevated plasma pH, [HCO3] and total CO2 (TCO2). The acute blood acid–base responses to feeding include alterations in plasma pH and plasma concentrations of HCO3, TCO2, Cl−, Na+, K+ and protein. The forage component of the diet appears to be primarily responsible for the acute responses. There is limited research examining abrupt alterations in DCAD and the influence of daily variation on equine plasma acid–base balance. It is concluded that the composition of the diet, duration of adaptation to the diet, timing of feeding and time of day need to be considered when examining acid–base balance in horses.

Relationships between exercise capacity and front hoof longitudinal balance in horses

AbstractTo the authors' knowledge, the effect of hoof balance alteration on exercise capacity or performance has not been investigated. With the aim of evaluating the relationships between longitudinal front hoof balance and exercise capacity (lactate vs. speed relationship, run time and stride characteristics), two experiments were undertaken. In the first test the horses, left unshod, performed an incremental speed test in which parameters chosen to evaluate exercise capacity were related to hoof longitudinal balance. In the second part of the study the same group of horses had the length of the toe altered (decreased and increased) with the application of shoes, while the angle of the foot and the height of the foot from the ground remained the same. The relative change in exercise capacity due to the alteration of longitudinal balance was observed. In the unshod experiment, lactate level at the speed of 10 ms-1 (5.0±2.0 mmoll-1) was significantly associated with the angles DC° (angle described by the dorsal cortex with respect to the ground; 50.0±3.2°) and PC° (angle described by the palmar cortex with respect to the ground; 29.6 ± 2.9°), while run time (14.07 ± 1.44 min) was associated with breakover indices (Breakover index1 0.33±0.03; Breakover index2 0.30 ± 0.04 – all values mean ± standard deviation (SD)) (breakover indices were created to express the distance between the point of the toe and the point of the third phalanx relative to the length of the palmar cortex or relative to the distance between the point of the third phalanx and the centre of rotation of the distal interphalangeal joint). These associations have to be judged cautiously because the influence of hoof balance on exercise capacity could be biased by other physiological factors and because hoof balance parameters themselves could reflect the conformation of other anatomical structures far from the phalanges. The selective alteration of front hoof balance in the second part of the study produced a significant difference in blood lactate level only at 6 ms-1 (mean ± SD: La6?m?s-1 0.32 ± 0.39 mmoll-1), with this benefit in terms of lactate level being associated with an increase in stride length (mean ± SD: ΔSL6ms-1 0.01 ± 0.05 m; ΔSL10ms-1 0.112 ± 0.218 m). In conclusion, while higher exercise capacity seemed to be associated with lower DC°, PC° and breakover indices, decreasing the toe length without altering the foot angle was beneficial only in terms of lactate level at the speed of 6 ms-1 for horses with DC° greater than 45°; this benefit was accompanied by a slight lengthening of the stride at both 6 and 10 ms-1.