Effect of oral administration of electrolyte pastes on rehydration of horses

The effects of feeding sodium chloride pellets on the gastric mucosa, acid-base, and mineral status in exercising horses

BACKGROUND

Electrolyte supplementation may be a risk factor for gastric mucosal lesions, but relevant evidence is limited in horses.

HYPOTHESIS

Investigate the effects of PO sodium chloride (NaCl) supplementation on the gastric mucosa of exercising horses. We hypothesized that NaCl supplementation would neither cause nor exacerbate existing gastric mucosal damage.

ANIMALS

Fifteen 3-year-old healthy Warmblood stallions from a stud farm.

METHODS

Placebo-controlled study with a crossover design. Horses were fed either a NaCl pellet at a dosage adequate to replace the electrolyte losses in 10 L sweat or a placebo for 19 days with a washout period of 14 days between treatments. The gastric mucosa was evaluated by gastroscopy before and after treatment. Blood samples were collected for evaluation of acid-base status, packed cell volume (PCV), and total protein, creatinine and blood urea nitrogen concentrations. Urine was collected, and urine specific gravity, electrolyte, creatinine, and urea concentrations were measured.

RESULTS

The initial prevalence of gastric mucosal lesions was 85%. Sodium chloride pellets did not adversely affect the gastric mucosa and treatment did not significantly alter the hematologic and serum biochemical variables. Urine creatinine concentrations significantly decreased and urinary sodium concentrations significantly increased after supplementation with NaCl pellets. Water intake did not significantly differ between treatments.

CONCLUSIONS AND CLINICAL IMPORTANCE

Daily NaCl pellet supplementation is a palatable and safe way to replace electrolyte losses from sweating in exercising horses and has no negative effects on the gastric mucosa.

The Effect of Water Flavor on Voluntary Water Intake in Hospitalized Horses

Hospitalized horses are at risk for colic due to several factors, all of which may reduce voluntary water intake (VWI) further contributing to the development of colic during hospitalization. Our objectives were to determine if using flavored water (sweet feed, peppermint, or apple-flavored electrolyte) increases VWI of hospitalized horses and to determine if horses consumed more flavored water versus plain water. We hypothesized that (1) in hospitalized horses the availability of flavored water results in more VWI than the availability of unflavored water and that (2) average intake of flavored water is larger for flavored versus unflavored within the experimental (flavored) group. Four groups of hospitalized horses (n = 10/group) were recruited. All horses were provided two buckets of water. Control horses were provided two buckets of plain water. The other three groups were provided one bucket of plain water and one bucket of flavored water (sweet feed, peppermint, or a commercial apple-flavored electrolyte). The total and the flavor-specific water consumed was recorded during a 72-hour period. There was weak evidence to suggest that the use of flavored water increases median total water intake of hospitalized horses by a factor of 1.76 [95% CI: 0.98 to 3.11] for sweet feed (P = .05) and 1.85 [95% CI: 1.03 to 3.33] for peppermint (P = .04). The results strongly supported that horses consumed more sweet feed-flavored water (27.0 mL/kg/day [95% CI: 14.6 to 39.3] more water) compared with plain water (P = .0001).

Effects of oral electrolyte supplementation on endurance horses competing in 80 km rides

REASONS FOR PERFORMING STUDY

There is no evidence that use of oral electrolyte pastes enhances performance in competing endurance horses.

OBJECTIVE

To ascertain whether oral administration of a high dose (HD) of sodium chloride (NaCl) and potassium chloride (KCl) to endurance horses would differentially increase water intake, attenuate bodyweight (bwt) loss and improve performance when compared to a low dose (LD).

METHODS

A randomised, blinded, crossover study was conducted on 8 horses participating in two 80 km rides (same course, 28 days apart). Thirty minutes before and at 40 km of the first ride 4, horses received orally 02 g NaCl/kg bwt and 0.07 g KCl/kg bwt. The other 4 received 0.07 g NaCl/kg bwt and 0.02 g KCl/kg bwt. Horses received the alternate treatment in the second ride. Data were analysed with 2-way ANOVA for repeated measures (P<0.05).

RESULTS

Estimated water intake was significantly greater with HD both at the 40 km mark and as total water intake; however, differences in bwt loss and speed between HD and LD were not found. Treatment significantly affected serum Na+, Cl-, HCO3, pH and water intake, but not serum K+ or bwt. Serum Na+ and Cl- were significantly higher at 80 km when horses received HD, but no differences were found in early recovery. Venous HCO3- and pH were significantly lower throughout the ride and in early recovery when horses received HD.

CONCLUSIONS AND POTENTIAL RELEVANCE

Other than enhancing water intake, supplementing endurance horses with high doses of NaCI and KCl did not provide any detectable competitive advantage in 80 km rides. Further, the elevated serum electrolyte concentrations induced with HD might not be appropriate for endurance horses.

Effect of repeated oral administration of hypertonic electrolyte solution on equine gastric mucosa

REASONS FOR PERFORMING STUDY

Electrolyte supplementation is common in horses during endurance competitions, but the effect on the gastric mucosa is unknown.

HYPOTHESIS

Repeated oral administration of hypertonic electrolyte solution is associated with exacerbation of gastric ulcers in mature horses.

METHODS

The study design was a randomised, blinded, crossover trial. Fourteen horses were divided randomly into equal groups and administered either 60 ml water (placebo) or 56.7 g commercial electrolyte supplement mixed with 60 ml water by dose syringe orally once an hour for 8 h. The minimum concentration of individual constituent electrolytes/28.35 g dry commercial product used was: sodium (5528 mg); chloride (11,886 mg); potassium (3657 mg); calcium (754 mg); and magnesium (153 mg). Gastric lesions were scored prior to and after oral treatments, and analysis of variance procedures were then performed.

RESULTS

Administration of hypertonic electrolytes resulted in a significant increase in mean ulcer number (P = 0.0174) and severity (P = 0.0006) scores in the nonglandular stomach. Mean ulcer number score was 3.6 and mean ulcer severity score 2.7 after hypertonic electrolyte treatment.

CONCLUSIONS

Oral hypertonic electrolyte administration to horses in this model was associated with exacerbation of gastric ulcers.

POTENTIAL RELEVANCE

Our findings suggest that one schedule of electrolyte supplementation used commonly in endurance horses may be harmful to the gastric mucosa.

Effect of varying initial drink volume on rehydration of horses

Body mass (BM), water intake (WI), and plasma osmolality (P(osm)) and electrolyte concentrations were measured in six 2-year-old Arabian horses provided either 4 l, 8 l, or an unlimited amount of water (UW) for drinking during the initial 5 min of recovery from 45-km of treadmill exercise. After weighing, horses were placed in a stall and further WI between 20 and 60 min of recovery was measured. During exercise, horses lost 3.3+/-0.3%, 3.2+/-0.1%, and 3.3+/-0.2% (P>.05) of BM and P(osm) increased by 7.2+/-0.5, 7.9+/-0.8, and 7.7+/-0.5 mOsm/kg (P>.05) for 4 l, 8 l, and UW, respectively. WI during the first 5 min of recovery was 4.0+/-0.0, 8.0+/-0.0, and 9.0+/-1.3 l and was accompanied by 2.4+/-0.4, 5.8+/-0.9, and 6.1+/-0.7 mOsm/kg decreases (P<.05) in P(osm) for 4 l, 8 l, and UW, respectively. Between 20 and 60 min of recovery, WI was 6.2+/-1.5, 1.2+/-0.6, and 1.0+/-0.7 l (P<.05) for 4 l, 8 l, and UW, respectively. Thus, total WI was 10.2+/-1.5, 9.2+/-0.6, and 10.0+/-1.1 l (P>.05) for 4 l, 8 l, and UW, respectively. After 60 min of recovery, persisting BM loss was 1.3+/-0.5%, 1.1+/-0.2%, and 1.0+/-0.2% (P>.05) for 4 l, 8 l, and UW, respectively and P(osm) had returned to pre-exercise values for all treatments. In conclusion, limiting the volume of water initially provided to horses dehydrated by endurance exercise had no significant effect on total WI during the initial 60 min of recovery; however, persisting BM loss was observed with all treatments. Further, following exercise-induced dehydration, the primary stimulus of thirst was an increase in plasma tonicity rather than hypovolemia.

Drinking salt water enhances rehydration in horses dehydrated by frusemide administration and endurance exercise

Because the primary stimulus for thirst is an increase in plasma tonicity, we hypothesised that dehydrated horses would drink a greater total volume of fluid voluntarily during the first hour of recovery when they were initially offered salt water. To test this hypothesis, bodyweight (bwt), fluid intake (FI) and [Na+] were measured in 6 Arabian horses offered 3 rehydration solutions. After dehydration was induced by frusemide administration (1 mg/kg bwt, i.v.) followed by 45 km treadmill exercise, water (W), 0.45% NaCl and 0.9% NaCl were offered, in a randomised order, during the initial 5 min after completing exercise. Horses were subsequently placed in a stall and further intake of plain water during the first hour of recovery was measured. By the end of exercise, horses lost 5.2 +/- 0.2, 5.6 +/- 0.3 and 5.7 +/- 0.2% (P>0.05) bwt and FI during the first 5 min of recovery was 10.5 +/- 0.7, 11.6 +/- 0.8 and 11.6 +/- 1.5 l (P>0.05) for W, 0.45% NaCl and 0.9% NaCl, respectively. After 20 min of recovery, [Na+] had decreased with W but remained unchanged from the end exercise values for both saline solutions. During the initial hour of recovery, further water intake was 0.9 +/- 0.4, 5.0 +/- 0.5 and 6.9 +/- 0.7 l (P<0.05) for W, 0.45% NaCl and 0.9% NaCl, respectively. Therefore, total FI was 11.4 +/- 0.5, 16.6 +/- 0.7 and 18.5 +/- 1.7 l (P<0.05) for W, 0.45% NaCl and 0.9% NaCl, respectively, and persisting bwt loss after 60 min of recovery was greater (P<0.05) for W (3.5%) than for the 2 saline solutions (24% for 0.45% NaCl and 1.9% for 0.9% NaCl). In conclusion, providing salt water as the initial rehydration fluid maintained an elevated [Na+] and resulted in greater total FI and recovery of bwt loss during the first hour of recovery, in comparison to offering only plain water.