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Journal of Equine Veterinary Science xx (2014) 1–6

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Journal of Equine Veterinary Science

journal homepage: www.j -evs.com

Original Research

Enteral Fluid Therapy: Biochemical Profile of Horses Treatedwith Hypotonic Enteral Electrolyte Solutions Associatedwith Energy Sources

José D.R. Filho PhD a,*, Ana E. Pessin MS a, Kátia Atoji MS b, Maria V. Souza PhD a,Claúdio L.N. Gomes PhD c, André R. Silva PhD a

aDepartment of Veterinary Medicine, Federal University of Viçosa, Viçosa, Minas Gerais, BrazilbCoordination of Zootechnics, Federal Technological University of Paraná, Dois Vizinhos, Paraná, BrazilcDepartment of Veterinary Clinics, State University of Maranhão, São Luiz, Maranhão, Brazil

a r t i c l e i n f o

Article history:Received 18 September 2013Received in revised form 13 December 2013Accepted 6 January 2014Available online xxxx

Keywords:Hypotonic solutionElectrolyteMaltodextrinDextroseSucrose

* Corresponding author at: Dr. José D.R. Filho, PhVeterinária, Universidade Federal de Viçosa, Viçosa,000, Brazil.

E-mail address: jdribeirofilho@gmail.com (J.D.R.

0737-0806/$ – see front matter � 2014 Elsevier Inchttp://dx.doi.org/10.1016/j.jevs.2014.01.004

a b s t r a c t

The present study evaluated the biochemical profile of horses that received hypotonicelectrolyte solutions associated with energy sources by enteral route in continuous flowusing a small caliber tube for naso-esophageal administration. Experimental design was alatin square 3 � 3 with two replicates and three periods. The assays were carried out with“six adult females horses”, divided into three groups submitted to the following treatmentseach: electrolyte solution containing dextrose (ESDext)d“5 g sodium chloride, 0.5 g po-tassium chloride”, 1 g of calcium gluconate, 200 mg of magnesium pidolate, and 15 g ofdextrose diluted in 1,000 mL of water with measured osmolarity of 264 mOsmol/L; elec-trolyte solution containing maltodextrine (ESMalt)d5 g of sodium chloride, 0.5 g of po-tassium chloride, 1 g of calcium gluconate, 200 mg of magnesium pidolate, and 15 g ofmaltodextrin diluted in 1,000 mL of water with measured osmolarity of 203 mOsmol/L;and electrolyte solution containing sucrose (ESSucr)d“5 g sodium chloride, 0.5 g potas-sium chloride”, 1 g of calcium gluconate, 200 mg of magnesium pidolate, and 15 g of sugardiluted in 1,000 mL of water with measured osmolarity of 234 mOsmol/L. The electrolytesolutions were administered at the dosage 15 mL/kg/h during 12 hours. Hypotonic enteralelectrolyte solutions that contain maltodextrin (ESMalt) and dextrose (ESDext) wereeffective to increase glycemia in horses without causing any adverse effects, whereasESSucr presented slight effect on blood glucose, but without causing electrolyteimbalances.

� 2014 Elsevier Inc. All rights reserved.

1. Introduction

Fluid, electrolyte, and acid–base imbalances usuallyappear associated with important clinical problems inhorses, such as diarrhea, colic, and exhausting physical ex-ercise, among others. Corrections of these disorders are

D, Departamento deMinas Gerais 36570-

Filho).

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commonly performed by administration of enteral electro-lyte solutions (EES) through nasogastric route. Indeed,enteral fluid therapy with appropriate solutions is animportant therapeutic option in equinemedicine and canbeconsidered the most righteous choice because of its effec-tiveness, practical use, and especially the reduced cost [1].

Enteral electrolyte solutions for horses are usuallycomposed by elements that assist in fast and effectiverestoration of homeostasis, such as sodium, chloride, po-tassium, calcium, magnesium, and an additional source ofenergy. Some energy sources such as glucose, dextrose, or

Table 1Distribution of animals in treatments

Cycles Animals Treatments

1� 1, 2, 3 ESMalt, ESDext, ESSucr1� 4, 5, 6 ESMalt, ESDext, ESSucrSeven days apart2� 1, 2, 3 ESDext, ESSucr, ESMalt2� 4, 5, 6 ESDext, ESSucr, ESMalt

Seven days apart3� 1, 2, 3 ESSucr, ESMalt, ESDext3� 4, 5, 6 ESSucr, ESMalt, ESDext

ESDext, electrolyte solution containing dextrose; ESMalt, electrolyte so-lution containing maltodextrine; ESSucr, electrolyte solution containingsucrose.

J.D.R. Filho et al. / Journal of Equine Veterinary Science xx (2014) 1–62

maltodextrin in association with isotonic and hypotonicenteral electrolyte solutions (HypoEES) have already beentested in horses [2–5].

The osmolarity of electrolyte solutions influences theeffectiveness of intestinal absorption of water and elec-trolytes. Historically, it was presumed that solutions withan osmolarity similar to plasma would improve intestinalabsorption; however, recent studies demonstrate thatmodifications in tonicity of enteral rehydration solutionsresult in different effects on water and electrolyte absorp-tion. Clinical trials in children with diarrhea [6,7] and lab-oratory animals [8] confirmed that hypotonic are moreeffective than isotonic enteral electrolyte solutions fortreatment of hypoglycemia, hydroelectrolyte and acid–baseimbalances, reducing the diarrhea and the internmentlength of patients.

Reduction in sodium from 90 mmol/L to 75 mmol/L andglucose from 111mmol/L to 75mmol/L resulted in decreaseof osmolarity from 311 mOsm/L to 245 mOsm/L that wasable to reduce by 33%, the need for intravenous therapy forrehydration without any risk of hyponatremia, demon-strating a significant reduction of diarrhea and fecal losswhen compared with conventional isotonic solution [9].

The composition of EES is a controversial matter, despiteseveral experimental studies, especially regarding electro-lyte concentration, energy source, and osmolarity. Severalstudies in horses evaluated isotonic enteral electrolyte so-lutions [2,4,5,10], but only Farias et al [3] tested a hypotonicsolution associated to an energy source, registering in-crease in the concentration of plasma glucose and higherexpansion of plasma volume in animals treated with hy-potonic enteral solutions, when compared with thosetreated with isotonic enteral solution. Therefore, little isknown about the effects of HypoEES with added energysources on biochemical profile in horses.

In fact, studies on this subject still are scarce in equinespecies, especially regarding the beneficial and adverseeffects of the HypoEES associated to energy sources. It ispresumed that the use of HypoEES containing dextrose,maltodextrin, and sucrose affects positively blood glucosewithout causing electrolyte imbalances. The purpose of thepresent study was to evaluate the effects of hypotonicelectrolyte solutions associated with sucrose, dextrose, ormaltodextrin administered in continuous flow during 12hours by enteral route through a naso-esophageal tube ofsmall caliber on biochemical profile of horses.

2. Materials and Methods

This work was approved by the Ethics Committee of theVeterinary Department of the Universidade Federal deViçosa (Process no. 198/2011) in accordance with the Vet-erinary Professional Ethics Code, the Ethical Principles forAnimal Research established by the Brazilian College forAnimal Experimentation and current Brazilian legislation.

The assays were carried out with six healthy femalehorses, aged 3-year-old and averaging 300 kg in weight,with good body condition score. Animals were housed inindividual pens provided with wood shavings bed. Waterand Tifton 85 (Cynodon sp) was supplied ad libitum, and theanimals also received commercial concentrate (Equisul 15;

Total Alimentos, Três Corações, Brazil) at 1% of body weighttwice a day and mineral salt (Hiposal 80%) 50 g once a day.

Ectoparasites and endoparasites were controlledrespectively with deltamethrin 0.025% (Butox P; MSDSaúde Animal, São Paulo, Brazil) and ivermectin 0.12 gassociated with praziquantel 1.5 g (Padock NF gel pasta;CEVA, Paulínia, Brazil). Before the experimental period,animals were submitted to physical exam, complete bloodcells count, biochemical profile, parasitological exam, and15 days of acclimation.

Animals were randomly distributed into three groupswith two animals each in a repeatedmeasures experimentaldesign with three treatments and three periods separatedby 7 days interval (Table 1). The treatments were as follows:Hypotonic enteral electrolyte solution containing malto-dextrine (ESMalt)dsolution with 5 g of NaCl (Sulfal, BeloHorizonte, Brazil), 0.5 g of KCl (All Chemistry, São Paulo,Brazil), 1 g of calcium gluconate (All Chemistry, São Paulo,Brazil), 200 mg of Mg pidolate (Baldacci, São Paulo, Brazil),and 15 g of maltodextrine (Arve Indústria, Viçosa, Brazil)diluted in 1,000 mL of water (measured osmolarity: 203mOsm/L); Hypotonic enteral electrolyte solution containingdextrose (ESDext)dsolutionwith 5 g of NaCl, 0.5 g of KCl,1 gof calcium gluconate, 200 mg of Mg pidolate and 15 g ofdextrose (Sulfal, Belo Horizonte, Brazil) diluted in 1,000 mLof water (measured osmolarity: 264 mOsm/L); and hypo-tonic enteral electrolyte solution containing sucrose(ESSucr)dsolution with 5 g of NaCl, 0.5 g of KCl, 1 g of cal-cium gluconate, 200 mg of Mg pidolate, and 15 g of sucrose(Agrícola Pontenovense, Urucânia, Brazil) diluted in 1,000mL of water (measured osmolarity: 234 mOsm/L). All elec-trolyte solutions were administered at a dose of 15 mL/kg/hin continuous flow by a small caliber naso-esophageal tube(Provar, São Paulo, Brazil) during 12 hours.

Blood samples (10 mL) were collected by jugular veni-puncture and stored in vials with sodium fluoride andwithout anticoagulant (Vacuntainer BD, Brazil) for bio-chemical analysis. Sodium and potassium serum concentra-tions were measured using flame photometry (B462;Micronal, São Paulo, Brazil) whereas, a multi-biochemicalanalyzer (HumaStar 300; Human GmbH, Wiesbaden, Ger-many) was used to measure serum chloride, magnesium,phosphate, total protein, urea, creatinine, and also plasmalactate and glucose concentrations. Ionized calcium con-centrationwasmeasuredusinga selective ionapparatus (AVL9180; Rochedo, São Paulo, Brazil). Serum osmolarity wasmeasuredwith an osmometer (AdvancedMicro-Osmometer

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Model 3320; Advanced Instruments Inc., Norwood, MA).Analyses were performed immediately before treatment(T0h), 6 hours into treatment (T6h), at the end of treatment(T12h), and 12 hours after conclusion of treatment (T24h).

2.1. Statistical Analysis

Data were submitted to analysis of variance (ANOVA),and each treatment was evaluated during the differenttimes of observation, based on a repeated measures design.Also, the influence of time and the interaction betweentreatments and times were analyzed. When ANOVA wassignificant for one or more factors, means were comparedwith Tukey test. The statistical tests were processed bySAEG (Sistema para Análises Estatísticas) version 9.1, 2007(http://www.ufv.br/saeg), at 5% probability.

3. Results

The results for biochemical parameters, expressed asaverage � standard deviation are reported in Tables 2 and3, respectively.

None of the three treatments altered (P > .05) theaverage serum concentration of sodium and osmolaritywhen compared between treatments or within treatmentsduring the experimental period (Tables 2 and 3). However,there was a decrease (P < .05) in concentration of potas-sium during the hydration period of animals from ESMaltand ESDext treatments (Table 2), although no differences

Table 2Means and standard deviations of sodium (mmol/L), potassium (mmol/L), chlophosphorus (mg/dL) of horses treated with ESMalt, ESDext, or ESSucr, administewith continuous flow (15 mL/kg/12 h)

Treatments Time (h)

T0h T6h

Sodium (mmol/L)ESMalt 135.66 � 1.36Aa 137.33 � 2.06A

ESDext 135.83 � 3.37Aa 136.33 � 3.66A

ESSucr 137.00 � 2.09Aa 137.66 � 1.75A

Potassium (mmol/L)ESMalt 3.93 � 0.37Aab 3.75 � 0.18A

ESDext 4.08 � 0.31Aab 3.55 � 0.30A

ESSucr 4.10 � 0.70Aa 3.90 � 0.37A

Chloride (mmol/L)ESMalt 103.50 � 1.76Aa 104.33 � 3.77B

ESDext 104.83 � 0.75Ac 109.50 � 2.66A

ESSucr 106.83 � 3.76Aa 108.66 � 3.26A

Ionized calcium (mmol/L)ESMalt 1.83 � 0.58Aa 1.98 � 0.88A

ESDext 1.82 � 0.53Aa 2.01 � 0.90A

ESSucr 1.80 � 0.49Aa 1.98 � 0.85A

Total magnesium (mg/dL)ESMalt 2.25 � 0.13Aa 2.07 � 0.31A

ESDext 1.55 � 0.18Cab 1.42 � 0.25B

ESSucr 1.97 � 0.12Ba 1.87 � 0.42A

Phosphorus (mg/dL)ESMalt 3.18 � 0.68Aa 3.38 � 0.50A

ESDext 3.85 � 0.53Aa 3.36 � 0.58A

ESSucr 4.16 � 0.92Aa 3.75 � 0.57A

ESDext, electrolyte solution containing dextrose; ESMalt, electrolyte solution contimmediately before hydration; T6h, 6 hours of hydration; T12h, at the end of hyAnalysis of variance (repeated measures).Mean values followed by different capital letters in the same column or different sTukey test.

on serum potassiumwere observed when treatments werecompared (P > .05).

During the hydration stage (T6h and T12h), the grouptreatedwith ESDext presented highermean serum chloride(P < .05) than the group that received ESMalt (Table 2).Mean values of chloride increased at T6h and T12h for theESDext group, when compared with T0h (P < .05).

Regarding ionized calcium, creatinine, and total proteinserum concentrations, no variations (P > .05) betweentreatments and during treatments over timewere observed(Tables 2 and 3).

During the experimental phase, magnesium concen-trations were different (P < .05) when treatments werecompared. The ESDext group presented lower concentra-tion of magnesiumwhen compared with the ESMalt at T6hand T12h. Throughout time, the lower concentrations ofmagnesium were detected (P < .05) in the ESDext group atT12h (Table 2).

Phosphorus concentrations were higher in the animalsfrom ESSucr group than the ones from ESMalt group atT12h (P < .05). Throughout the experimental phase, adecrease was observed at T12h in the ESMalt group whencompared with T0h (Table 2). The same could be observedin the ESDext and ESSucr during hydration (T6h and T12h)treatments.

Mean concentrations of urea did not differ (P > .05)among treatments. But in the assessment over time forESMalt and ESSucr groups, lower concentrations (P< .05) atT12h in relation to T0h were observed (Table 3). Also, a

ride (mmol/L), ionized calcium (mmol/L), total magnesium (mg/dL), andred through the enteral route by a naso-esophageal probe of small caliber

T12h T24h

a 136.50 � 2.42Aa 135.00 � 6.51Aaa 136.33 � 3.88Aa 138.50 � 3.01Aaa 137.66 � 1.50Aa 137.00 � 2.00Aa

b 3.70 � 0.25Ab 4.33 � 0.34Aa’b 3.75 � 0.30Ab 4.56 � 0.77Aaa 3.83 � 0.30Aa 4.45 � 0.72Aa

a 106.66 � 1.96Ba 106.00 � 1.67Aaab 112.00 � 3.89Aa 106.50 � 2.58Abcba 109.50 � 2.07ABa 107.16 � 2.56Aa

a 1.85 � 0.65Aa 2.22 � 0.80Aaa 2.02 � 1.10Aa 2.10 � 0.68Aaa 1.90 � 0.87Aa 2.16 � 0.77Aa

a 1.96 � 0.28Aa 2.27 � 0.79Aaab 1.25 � 0.23Bb 1.83 � 0.32Baba 1.70 � 0.44ABa 1.87 � 0.19Ba

ab 2.95 � 0.18Bb 3.40 � 0.44Aaba 3.06 � 0.49ABa 3.33 � 0.58Aaa 3.66 � 0.45Aa 3.46 � 0.42Aa

ainingmaltodextrine; ESSucr, electrolyte solution containing sucrose; T0h,dration; T24h, 12 hours after conclusion of hydration.

mall letters in the same row differ statistically from each other (P< .05) by

Table 3Means and standard deviations of urea (mg/dL), creatinine (mg/dL), total protein (g/dL), osmolarity (mOsm/L), glucose (mg/dL), and lactate (mg/dL) of horsestreated with ESMalt, ESDext, or ESSucr, administered through the enteral route by a naso-esophageal probe of small caliber with continuous flow (15 mL/kg/12 h)

Treatments Time (h)

T0 T6 T12 T24

Urea (mg/dL)ESMalt 32.16 � 6.64Aa 25.33 � 4.92Aab 21.16 � 3.43Ab 26.83 � 2.78Aab

ESDext 33.00 � 9.09Aa 26.16 � 5.63Aa 23.16 � 4.79Aa 28.66 � 5.08Aa

ESSucr 32.33 � 6.12Aa 24.16 � 3.37Abc 20.50 � 4.41Ac 29.16 � 3.86Aab

Creatinine (mg/dL)ESMalt 1.06 � 0.09Aa 1.01 � 0.08Aa 0.98 � 0.08Aa 1.07 � 0.13Aa

ESDext 1.00 � 0.15Aa 0.96 � 0.12Aa 1.00 � 0.09Aa 1.05 � 0.10Aa

ESSucr 1.01 � 0.09Aa 0.96 � 0.06Aa 1.00 � 0.10Aa 1.05 � 0.13Aa

Total protein (g/dL)ESMalt 7.98 � 0.84Aa 7.65 � 0.92Aa 7.37 � 0.97Aa 7.89 � 0.55Aa

ESDext 7.61 � 0.57Aa 7.58 � 0.61Aa 7.53 � 0.58Aa 8.09 � 0.58Aa

ESSucr 7.97 � 0.53Aa 7.34 � 0.74Aa 7.48 � 0.51Aa 8.19 � 0.88Aa

Osmolarity (mOsm/L)ESMalt 281.33 � 3.01Aa 283.00 � 5.32Aa 283.66 � 5.68Aa 287.66 � 14.94Aa

ESDext 277.83 � 15.85Aa 267.83 � 25.43Aa 266.83 � 29.76Aa 277.00 � 18.18Aa

ESSucr 276.50 � 15.33Aa 276.33 � 7.78Aa 279.50 � 4.59Aa 283.83 � 2.04Aa

Glucose (mg/dL)ESMalt 71.00 � 3.63Bb 101.66 � 25.82Aa 109.00 � 23.88Aa 70.50 � 5.46Bb

ESDext 84.80 � 8.26Ab 123.80 � 25.01Aa 126.40 � 26.37Aa 82.40 � 7.94ABb

ESSucr 86.42 � 2.8Ab 106.52 � 14.45Aa 98.02 � 14.24Aab 83.01 � 5.80Ab

Lactate (mg/dL)ESMalt 4.65 � 1.15Aa 5.10 � 1.82Aa 4.05 � 0.79Aa 5.15 � 2.25Aa

ESDext 4.35 � 1.22Aa 4.01 � 0.78Aab 2.93 � 0.50Ab 3.01 � 0.76Aab

ESSucr 4.38 � 0.76Aa 6.01 � 1.80Aa 4.81 � 2.20Aa 3.45 � 0.71Aa

ESDext, electrolyte solution containing dextrose; ESMalt, electrolyte solution containingmaltodextrine; ESSucr, electrolyte solution containing sucrose; T0h,immediately before hydration; T6h, 6 hours of hydration; T12h, at the end of hydration; T24h, 12 hours after conclusion of hydration.Analysis of variance (repeated measures).Mean values followed by different capital letters in the same column or different small letters in the same row differ statistically from each other (P< .05) byTukey test.

J.D.R. Filho et al. / Journal of Equine Veterinary Science xx (2014) 1–64

slight decrease could be observed in the ESDext group,during the treatment period, although not significant, thelowest values also appeared at T12h, indicating a tendency.

Significant differences (P > .05) of glycemia at T6h andT12h were observed in the animals of all treatments(Table 3) and also between treatments. Mean concentra-tions of plasma lactate between treatments (P > .05) werenot significantly different, but at T12h a difference wasdetected in animals from the ESDext treatment (Table 3)and, although significant (P < .05), the concentration re-mained within the reference range ([15]).

4. Discussion

Based on concentrations of sodium and osmolarity, hy-potonic electrolyte solutions containing 5 g/L of NaCl didnot (P < .05) cause hyponatremia or decrease the values ofserum osmolarity in horses (Tables 2 and 3). This findingis important because it shows that the administration ofthis type of solution provided absorption of water andelectrolytes without causing decreases in serum sodiumand osmolarity. Although the World Health Organizationrecommends a new oral rehydration solution with lowosmolarity (245mOsm/L), which has been used and provento be safe and effective since 2005 [12], the use of HypoEESin humans is still controversial because of concerns aboutthe occurrence of hyponatremia in patients. Therefore, ac-cording to results from this study, low osmolarity of EESmaximize water absorption [11].

Although this study showed no undesirable effectson serum sodium and osmolarity of horses, as was alsoobserved by Farias et al [13], it must be emphasized thatpatients with severe hyponatremia treated with HypoEESmust have serum sodium and osmolarity monitored,because of the possibility of severe decrease, leading toadverse effects. Thus, the results of this study open newperspectives up for the use of these solutions; however, theideal adequate amount of sodium and the osmolarity of anenteral electrolyte solution for horses still need furtherstudies.

The changes observed in serum potassiumwere becauseof the composition of the electrolyte solution associatedwith hemodilution as a result from enteral fluid therapyand also potassium translocation from extracellular tointracellular fluid [14]. Despite these results (Table 2), thedecrease of serum potassium in animals from all treat-ments, as observed at T6h and T12h remained within thereference range [15]. Concentration of potassium higherthan 0.5 g/L may be more suitable [13] in cases of hypo-kalemia, commonly observed in dehydration after exerciseand diarrhea.

A slight increase in the concentration of serum chloridewas observed in animals of the three treatments in T6hand T12h (Table 2). The enteral electrolyte solution wascomposed by two sources of chloride, NaCl and KCl,consequently, the final concentration of chloride (92.2mmol/L) was higher than the sodium concentration (85.5mmol/L) resulting in higher concentration of chloride in

J.D.R. Filho et al. / Journal of Equine Veterinary Science xx (2014) 1–6 5

serum during the hydration period (T6h and T12h).Hyperchloremia in horses after administration of electro-lyte solution was also verified by Ecke et al [18]. Accordingto these authors, the higher amount of chloride than so-dium in the electrolyte solution causes hyperchloremia.

When large volumes of electrolytic solutions rich inchloride (0.9% NaCl solution) are administered, changes inacid–base balance, known as hyperchloremic metabolicacidosis, are expected [16,17]. Despite the observed in-crease of serum chloride in this study, acidosis did notoccur because it was a very slight increase, and the chlorideconcentration in the EES was 92.2 mmol/L similar to theplasma concentration of horses [15].

Farias et al [13] evaluated horses treated with EES con-taining dextrose and maltodextrin and also reported aslight increase in serum chloride. Therefore, the concen-tration of chloride in the composition of enteral electrolytesolution must be carefully observed, because the excess ofthis electrolyte may cause hyperchloremia, which dep-ending on the intensity, may turn into metabolic acidosis,as quoted by Prough and Bidani [16] and DeMorais andBiondo [17].

Administration of HypoEES in this study did not causechanges of serum ionized calcium in animals from alltreatments (P > .05) between treatments and withintreatments throughout the experimental phase (Table 2),confirming the study by Farias et al [13]. These results differfrom those obtained by Avanza et al [2] and Gomes et al [4]who found a decrease in ionic calcium (P < .05); however,the ionized calcium concentrations obtained by these au-thors remained at the baseline [15]. Also, Lopes et al [10]detected a decrease of total calcium followed by theadministration of enteral electrolyte solution, explained bythe absence of such element in the composition of the so-lution. Calcium concentrations below the reference rangeusually appears associated to important clinical problemsin horses [2,19]; thus, electrolyte solutions must containcalcium, such as those used in this study, because enteralfluid therapy is widely used in horses mainly when theseproblems occur.

A slight decrease of serum concentration of magnesiumin animals from all treatments was not expected, because0.2 g/L of Mg was added in all three electrolytic solutions.The animals in this study were healthy; thus, the decreaseobserved may be related to the hemodilution resultedfrom enteral fluid therapy as reported by Alves et al [20],Avanza et al [2], and Farias et al [13]. Therefore, the amountof magnesium in solution must be increased, especially ifthe patient presents hypomagnesemia.

Decrease in values of serum phosphorous probablyhappened because this element was not added to theelectrolyte solution composition (Table 2). Kaneko et al [15]reported that glucose induces insulin secretion and facili-tates the absorption of phosphorus and other electrolytesinto the cell; therefore, the presence of an energy source inthe electrolyte solution used in this test may have causedsuch result. Similar results to the present experimentalstudy were reported by Gomes et al [4] that evaluated anelectrolyte solution containing maltodextrin in horses.

Mean values of urea did not differ (P > .05) amongtreatment groups, but a difference was detected (P< .05) in

the assessment over time for ESMalt and ESSucr groups,with lowest values recorded at T12h when compared withT0h in both groups (Table 3). Also, a slight decrease couldbe observed in the ESDext group during the hydrationperiod reaching the lowest values also at T12h. Althoughnot significant, this slight decrease happened possiblybecause the use of electrolyte solutions increases renalperfusion, which in turn increases the excretion of urea inthe urine, decreasing its concentration in blood. Thisstatement is based on Lopes et al [21] who detected poly-uria and urine dilution in horses after the use of enteralhydration, and similar results were also obtained by Alveset al [20] and Gomes et al [4].

There was a tendency of decreased concentration ofcreatinine in ESDext and ESSucr treatments during theexperimental period at T6h and in the ESMalt treatment atT6h and T12h, and although not significant, the cause tothis decreased tendency in creatinine was the same as thedecrease of urea, described previously, confirming previousresults [4,13].

Serum proteins also tended to decrease during hydra-tion (T6h and T12h). That decrease was not significant, butthat tendency during hydration may be because of hemo-dilution as a result of enteral fluid therapy (Table 3). Theosmolarity of an electrolyte solution is a determining factorfor water absorption in the intestine; therefore, the lowosmolarity of EES used in this study contributed to thehemodilution in animals corroborating previous results[6,7,11,13].

Increased blood glucose could be observed during thehydration therapy (T6h and T12h) in the animals thatreceived electrolyte solution containing dextrose (ESDext).These values, 123.8 and 126.4 mg/dL respectively, are abovethe reference range for the species (75–115 mg/dL). Thisresult expresses that dextrose, at a concentration of 15 g/Lof solution, may be indicated for animals with hypoglyce-mia. The ESMalt treatment (15 g/L of maltodextrin) pre-sented significant difference over time (P < .05), increasingglycemia of animals by 53.52% at the end of treatment(T12h); whereas, Farias et al [13] obtained only a 34.49%increase in glycemia when using 10 g/L of maltodextrin.This result is expressive and has important clinical signifi-cance, because the solution used in the ESMalt treatmentwas better than the others tested in this study, provingmaltodextrin to be the most suitable energy source forenteral use in horses with hypoglycemia (Table 3).

The ESDext treatment increased glycemia by 49.05% atT12h and the ESSucr in only 13.42% at T12h. This result maybe related to the molecular structure of each energy source.Maltodextrin increased glycemia by 53.52%, probablybecause this glucose polymer is easily digested, providingmore than one glucose molecule. Dextrose being a simplecarbohydrate (one molecule of glucose), is rapidly absor-bed, however, produces a smaller effect on glycemia.

Sucrose is the combination of two monosaccharides(glucose and fructose). Diets with high levels of fructosecan induce metabolic changes in lipid profile and glycemia[22]. Despite the increase of glycemia in the animals thatreceived the electrolyte solution containing sucrose(ESSucr) at T6h (23.26%) and T12h (13.42%), this increasewas lower than the observed in the ESMalt and ESDext

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treatments. The lower rise of glycemia in the ESSucr groupmay have happened because of the use of this carbohydrateby the intestinal microbiota, reducing the availability to thecell. Enteral electrolyte solutions containing energy sourcesare important to be used in clinical routine especially inanimals with dehydration and hypoglycemia.

Studies have shown that hypo-osmotic salt solutionscontaining glucose polymers promoted higher water ab-sorption in the small intestine of rats [23]. Possibly, hypo-osmotic solutions in horses could also favor higher fluidabsorption by the intestine, with positive reflect on hy-dration; therefore, further study is needed to validate this.The addition of glucose in EES, for some species, maximizesthe absorption of water by glucose-sodium combinedabsorption mechanism in the small intestine mucosa.Therefore, the treatments used in this study containingmaltodextrin, dextrose, and sucrose may have contributedto a higher water absorption by the intestine. However,in horses that received EES containing glucose, plasmavolume expansion was low when compared with ones thatreceived the EES without the addition of this substance [2].The authors reported that this probably occurred becauseof the high osmolarity of the solution (340mOsm/L), whichreduced intestinal absorption of water and resulted in a lowplasma volume expansion.

Evaluating lactate values during the hydration therapy,the ESMalt group presented a decrease of 12.9% whereasthe ESDext group presented a decrease of 32.64% at T12h.The ESSucr increased the amount of lactate in 9.81% after 6hours of hydration (T6h). Probably, the cause for this in-crease was the activity of the intestinal microbiota on su-crose triggering the production of acidic substances. Afterthe increase at T6h, there was a decrease at T12h, and thisevent was possibly triggered by compensatorymechanisms(Table 3) as quoted by DiBartola [24].

The major side effect when energy sources are used as acomponent of EES is the possibility of these substances topredispose the onset of acidosis in animals. However, theresults of this experimental study have shown thatmaltodextrin and dextrose used at 15 g/L did not cause anyside effects and, therefore, these solutions are safe forenteral hydration in dehydrated and hypoglycemic horses.

In conclusion, the results of this study indicated thatHypoEES containing maltodextrin (15 g/L) and dextrose(15 g/L) administered at a dose of 15 mL/kg/h during 12hours are the best options for treating dehydrated andhypoglycemic horses, because an effective increase ofglycemia without any adverse effects was observed. Theseare important therapeutic options for animals of thisspecies. The HypoEES containing sucrose (15 g/L) pre-sented only a slight effect on glycemia of horses and,nevertheless, can be used in dehydrated horses that arenot in severe hypoglycemia.

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