Electrolyte levels in feces and urine in healthy breeding calves between the ages of 5 days to 6 months

In contrast to the situation in adult cattle there are high concentrations of sodium and low concentrations of potassium in the faeces of suckling calves. It was investigated in this study in which stage of the development of the ruminant these changes in electrolyte levels occur, and whether there are changes in electrolyte levels in urine as well. Samples of faeces and urine from healthy calves were examined fortnightly starting with the 5th day after birth. There was a distinct decrease in sodium concentration in faecal water within the first three weeks of life, i.e. without any relation to the intake of solid feed. However, the levels of sodium, potassium and chloride in urine samples and of potassium in faecal water increased with the development of rumination. The concentration of chloride in faeces was on a low level during the whole period of investigation.     

Effect of a 24-hour infusion of an isotonic electrolyte replacement fluid on the renal clearance of electrolytes in healthy neonatal foals

OBJECTIVE: To determine the effects of a 24-hour infusion of an isotonic electrolyte replacement fluid (IERF) on weight, serum and urine electrolyte concentrations, and other clinicopathologic variables in healthy neonatal foals. ANIMALS: 4 healthy 4-day-old foals. DESIGN: Prospective study. PROCEDURE: An IERF was administered to each foal at an estimated rate of 80 mL/kg/d (36.4 mL/lb/d) for 24 hours. Body weight was measured before and after the infusion period. Urine was collected via catheter during 4-hour periods; blood samples were collected at 4-hour intervals. Variables including urine production; urine and serum osmolalities; sodium, potassium, and chloride concentrations in urine and serum; urine and serum creatinine concentrations; urine osmolality-to-serum osmolality ratio (OsmR); transtubular potassium gradient (TTKG); and percentage creatinine clearance (Cr(cl)) of electrolytes were recorded at 0, 4, 8, 12, 16, 20, and 24 hours during the infusion period. Immediately after the study period, net fluid and whole-body electrolyte changes from baseline values were calculated. RESULTS: Compared with baseline values, urine and serum sodium and chloride serum concentrations, urine and serum osmolalities, OsmR, and percentage Cr(cl) of sodium and chloride were significantly increased at various time points during the infusion; urine production did not change significantly. After 24 hours, weight, TTKG, serum creatinine concentration, and whole-body potassium had significantly decreased from baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of an IERF containing a physiologic concentration of sodium may not be appropriate for use in neonatal foals that require maintenance fluid therapy.     

The effects of high intensity exercise on the plasma concentration of lactate, potassium and other electrolytes

To study the effect of short term high intensity exercise on plasma lactate, potassium, sodium and chloride concentrations, five Thoroughbred horses were galloped on a treadmill at a 5 degree incline. Following a standardised warm-up period, they were galloped at 8, 10, or 12 metres/sec for 2 mins. One horse also galloped at 14 metres/sec for 1.5 mins. Sequential arterial and/or venous blood samples were collected during exercise and recovery. At 12 metres/sec, the effect of different recovery modes, ie, standing, walking or trotting, on the electrolytes was also examined. There was a progressive rise in plasma potassium concentration during galloping, with peak values occurring at the end of the exercise bout. In some cases, values above 10 mmol/litre were recorded at the highest workloads. Plasma lactate concentrations peaked during early recovery, with values up to 32 mmol/litre. A high correlation existed between peak potassium and lactate concentrations (venous r = 0.923, and arterial r = 0.989). Following exercise there was a rapid return to baseline plasma potassium concentrations, but by 12 mins recovery there was still an elevated lactate concentration, the extent depending on the intensity of the exercise bout and the recovery mode. There was a small rise in plasma sodium but no significant change in plasma chloride concentrations during exercise. However, when adjusted for the decrease in plasma volume, as determined from total plasma protein concentration, there was a decrease in circulating amounts of both electrolytes.     

Udder edema: biochemical studies in Holstein cattle

Udder edema was studied in 9 affected and 3 control Holstein cows ranging in age from 2.5 to 8 years. A complete physical examination was done in conjunction with serum analysis for total protein, albumin, globulin, sodium, potassium, chloride, calcium, and inorganic phosphorus 2 weeks before parturition, at parturition and 2 weeks following parturition. Mammary interstitial fluid samples also were obtained from cows with udder edema and analyzed for total protein, albumin, globulin, sodium, potassium, chloride, calcium, and inorganic phosphorus. Clinical signs of udder edema appeared as early as 7 days prepartum and persisted for as long as 9 days postpartum. There were no significant differences in serum constituents between affected and control cows at the same stage of pregnancy or lactation. There was a significant difference (P less than or equal to 0.05) between serum and mammary interstitial fluid in the total protein, albumin, globulin and calcium concentrations.     

The effect of delays in feeding colostrum and the relationship between immunoglobulin concentration in the serum of neonatal calves and their rates of growth

SUMMARY Eighty-five unsuckled newborn calves, were fed 1.5 L of colostrum of known IgG concentration at either 2, 4, 6 or 8 hours after birth with no additional colostrum feeding. Another group of 11 calves were left with their dam for 16 hours after birth, before separation. Blood samples were taken from all calves 24 hours after colostrum feeding or separation from the dam and serum Ig concentrations were measured by electrophoresis. There were no significant differences in mean serum Ig concentrations between calves fed at the different times after birth. Three of the 11 calves left to suckle were hypogamma-globulinaemic. Other calves in this group had higher serum Ig concentrations than the means of all other groups. All groups had mean serum Ig concentrations higher than the suggested minimum concentration required for adequate calf health. There were a number of calves that did not reach the suggested minimum serum concentration after feeding, but calf mortality was low and all calves were healthy apart from a slight scour for a few weeks after birth. There was no significant relationship between serum Ig concentration 24 to 48 hours after birth and either calf mortality or average growth rate over an 8- to 10-month period.     

Intermittent bolus injection versus continuous infusion of furosemide in normal adult greyhound dogs

Several studies in human subjects have demonstrated greater diuresis with constant rate infusion (CRI) furosemide than intermittent bolus (IB) furosemide. This study was conducted to compare the diuretic efficacy of the same total dose of IB furosemide and CRI furosemide in 6 healthy, adult Greyhound dogs in a randomized crossover design with a 2-week washout period between treatments. For IB administration, dogs received 3 mg/kg at 0 and 4 hours. For CRI administration, dogs received a 0.66 mg/kg loading dose followed by 0.66 mg/kg/h over 8 hours. The same volume of fluid was administered for both methods. Urine output was quantified hourly. Urine electrolyte concentrations, urine specific gravity (USG), packed cell volume (PCV), total protein (TP), serum electrolyte concentrations, total carbon dioxide (TCO2), serum creatinine (sCr), and blood urea nitrogen (BUN) were determined every 2 hours. Urine production and water intake were greater (P < or = 0.05) for CRI than IB. Urine sodium and calcium losses were greater (P < 0.05) and urine potassium loss was less (P = 0.03) for CRI than IB, but there was no evidence of a difference between methods for urine magnesium and chloride losses. Serum chloride concentration was less (P < 0.001), sCr concentration greater (P = 0.04). TP greater (P = 0.01), and PCV greater (P = 0.003) for CRI than IB. No differences in USG, TCO2, BUN, or serum potassium, sodium, and magnesium concentrations were detected between methods. The same total dose of CRI furosemide resulted in more diuresis, natriuresis, and calciuresis and less kaliuresis than IB furosemide in these normal Greyhound dogs over 8 hours, suggesting that furosemide is a more effective diuretic when administered by CRI than by IB.     

Furosemide-induced electrolyte depletion associated with echinocytosis in horses.

Echinocytes have been incriminated in the pathogenesis of exertional diseases in horses. To evaluate the hypothesis that echinocytes are dehydrated erythrocytes, we decreased blood sodium and potassium concentrations in 4 horses by administering furosemide (1.0 mg/kg of body weight, q 12 h) for 2 days and we monitored CBC, serum and erythrocyte sodium and potassium concentrations, and echinocyte numbers. Serum sodium concentration decreased progressively over the 48 hours of furosemide administration, then returned to near baseline concentration at 168 hours. A statistically significant decrease (P < 0.05) in serum potassium concentration was observed at 24, 48, and 72 hours after initial furosemide administration, and remained less than the baseline value at the end of the study. Mean erythrocyte potassium concentration decreased rapidly and remained low at the end of the study. Minimal changes were observed in erythrocyte sodium concentration during the first 72 hours after furosemide administration, but the value was significantly (P < 0.05) increased at 168 hours. Type-I and type-II echinocyte numbers increased by 4 hours after furosemide administration and persisted throughout the study. Type-III echinocytes were not seen in baseline samples, but numbers increased only modestly after furosemide administration. Administration of epinephrine to well-hydrated horses increased echinocyte numbers only minimally, indicating that splenic contraction was not the likely cause for the furosemide-associated increase. To determine whether the decrease in erythrocyte potassium concentration and increase in sodium concentration was caused by furosemide acting directly on the erythrocyte membrane, we quantified erythrocyte potassium and sodium concentrations before and after incubation with furosemide in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

Udder edema in cattle: effects of diuretics (furosemide, hydrochlorothiazide, acetazolamide, and 50% dextrose) on serum and urine electrolytes

Blood and urine chemical values at parturition in clinically normal Holstein cows (n = 12) were compared with the same values in Holstein cows developing udder edema (n = 12). There was no statistically significant mean difference between the 2 groups for the serum and urine chemical data. Furosemide (500 mg) given IV caused a significant increase in serum calcium and sodium, urine chloride, potassium, and sodium, and fractional excretional ratio of chloride, potassium, and sodium. There was a significant mean decrease in the serum potassium, urine creatinine, osmolality, pH, and specific gravity. Hydrochlorothiazide (250 mg) given IV caused a significant mean increase in serum chloride, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride, potassium, and sodium. There was a significant mean decrease in serum potassium and sodium, urine osmolality, pH, and specific gravity. Acetazolamide (500 mg) given IV caused a significant mean increase in blood urea nitrogen, serum chloride and glucose, urine sodium, and fractional excretion ratio of sodium, while causing a significant mean decrease in serum potassium, sodium, and phosphorus, and urine creatinine. Dextrose (500 g) given IV as a 50% solution caused a statistical mean increase in serum glucose, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride and potassium. A statistical mean decrease occurred in the packed cell volume, blood urea nitrogen, serum calcium, potassium, sodium, and phosphorus, urine creatinine, osmolality, and pH.     

Exercise Induced Alterations in the Serum Muscle Enzymes, Erythrocyte Potassium and Plasma Constituents Following Feed Withdrawal or Furosemide and Sodium Bicarbonate Administration in the Horse

Six thoroughbreds were used in each of three trials to examine the effect of potassium depletion on exercise-associated muscle damage. Horses were exercised after a control period (Treatment 1), a 72-hour fast (Treatment 2), and furosemide and sodium bicarbonate (Treatment 3). During the preexercise period, feed withdrawal for 72 hours caused decreases in body weight, plasma sodium, chloride, and serum calcium. There were no changes in plasma potassium, erythrocyte potassium, or serum creatine phosphokinase (CK) activity. Furosemide and sodium bicarbonate administration resulted in a decrease in plasma potassium, chloride, serum calcium, and magnesium in the pre-exercise period. Erythrocyte potassium and serum CK activity were unchanged. Body weight initially decreased following furosemide and sodium bicarbonate and then increased upon access to water. In all three treatment groups plasma sodium, potassium, L-lactate, serum calcium, and magnesium were increased immediately following exercise. There was a significant increase (P less than 0.05) in serum CK activity in the furosemide and sodium bicarbonate-treated horses compared to control and withholding feed treatment groups by 30 minutes following exercise. Erythrocyte potassium was decreased immediately following exercise in the furosemide and sodium bicarbonate group but not in the other treatment groups. Potassium depletion may play a role in exercise-induced muscle damage but could not be implicated as the sole cause of the serum CK activity increase in this study.     

Experimental model of hypochloremic metabolic alkalosis caused by diversion of abomasal outflow in sheep

Hypochloremic metabolic alkalosis accompanied by hypokalemia and hyponatremia was induced experimentally in 7 adult sheep by diversion (loss) of gastric contents through an Ivan and Johnston cannula placed in the cranial part of the duodenum just distal to the pylorus. Cannula placement was easily accomplished, and cannulae were tolerated well by the sheep. Volume of effluent produced during the 60- to 120-hour period of diversion ranged from 7.7 to 14.9 L and tended to be greatest during the first 24 hours. All sheep became dehydrated, with mean PCV and plasma total protein concentration increases of 94.2 and 61.7%, respectively. Plasma chloride concentration decreased in linear fashion from a prediversion mean of 113 mEq/L (range, 111 to 117 mEq/L) to an end-point mean of 54 mEq/L (range, 45 to 65 mEq/L). Plasma sodium and potassium concentrations also decreased, though potassium concentration increased terminally. There were rapid increases in arterial blood pH and bicarbonate and base excess concentrations during the first 48 hours after diversion. However, during the final stages of diversion, sheep developed superimposed metabolic acidosis with increased plasma lactate concentration and high anion gap.     

Serum Biochemical and Hematological Parameters of Captive White-tailed Fawns

Blood samples were collected, at one day of age and at weekly intervals from one through 25 weeks of age, from seven white-tailed fawns (Odocoileus virginianus) to determine the effect of age upon serum biochemical and hematological values. Serum total protein concentration increased continually during the six month period. The rate of anabolism of serum gamma-globulin exceeded the rate of catabolism at about seven weeks of age. Serum cholesterol concentration more than doubled from one day to eight weeks of age. Blood hemoglobin concentration and packed cell volume increased markedly during the first eight weeks of life, but tended to remain constant from eight to 25 weeks of age. Blood erythrocyte count increased throughout the duration of the study; however, the relative increase was greater during the first eight weeks of age than thereafter.     

Determination of synovial fluid and serum concentrations, and morphologic effects of intraarticular ceftiofur sodium in horses

OBJECTIVES: To determine the serum and synovial fluid concentrations of ceftiofur sodium after intraarticular (IA) and intravenous (IV) administration and to evaluate the morphologic changes after intraarticular ceftiofur sodium administration. STUDY DESIGN: Strip plot design for the ceftiofur sodium serum and synovial fluid concentrations and a split plot design for the cytologic and histopathologic evaluation. ANIMALS: Six healthy adult horses without lameness. METHODS: Stage 1: Ceftiofur sodium (2.2 mg/kg) was administered IV. Stage 2: 150 mg (3 mL) of ceftiofur sodium (pHavg 6.57) was administered IA into 1 antebrachiocarpal joint. The ceftiofur sodium was reconstituted with sterile sodium chloride solution (pH 6.35). The contralateral joint was injected with 3 mL of 0.9% sterile sodium chloride solution (pH 6.35). Serum and synovial fluid samples were obtained from each horse during each stage. For a given stage, each type of sample (serum or synovial fluid) was collected once before injection and 12 times after injection over a 24-hour period. All horses were killed at 24 hours, and microscopic evaluation of the cartilage and synovium was performed. Serum and synovial fluid concentrations of ceftiofur sodium were measured by using a microbiologic assay, and pharmacokinetic variables were calculated. Synovial fluid was collected from the active joints treated during stage 2 at preinjection and postinjection hours (PIH) 0 (taken immediately after injection of either the ceftiofur sodium or sodium chloride), 12, and 24, and evaluated for differential cellular counts, pH, total protein concentration, and mucin precipitate quality. RESULTS: Concentrations of ceftiofur in synovial fluid after IA administration were significantly higher (P = .0001) than synovial fluid concentrations obtained after IV administration. Mean peak synovial fluid concentrations of ceftiofur after IA and IV administration were 5825.08 microg/mL at PIH .25 and 7.31 microg/mL at PIH 4, respectively. Mean synovial fluid ceftiofur concentrations at PIH 24 after IA and IV administration were 4.94 microg/mL and .12 microg/mL, respectively. Cytologic characteristics of synovial fluid after IA administration did not differ from cytologic characteristics after IA saline solution administration. White blood cell counts after IA ceftiofur administration were < or =3,400 cells/ML. The mean synovial pH of ceftiofur treated and control joints was 7.32 (range, 7.08-7.5) and 7.37 (range, 7.31-7.42), respectively. Grossly, there were minimal changes in synovium or cartilage, and no microscopic differences were detected (P = .5147) between ceftiofur-treated joints and saline-treated joints. The synovial half-life of ceftiofur sodium after IA administration joint was 5.1 hours. CONCLUSIONS: Synovial concentrations after intraarticular administration of 150 mg of ceftiofur sodium remained elevated above minimal inhibitory concentration (MIC90) over 24 hours. After 2.2 mg/kg IV, the synovial fluid ceftiofur concentration remained above MIC no longer than 8 hours. CLINICAL RELEVANCE: Ceftiofur sodium may be an acceptable broad spectrum antimicrobial to administer IA in septic arthritic equine joints.     

Hematology and Clinical Chemistry in Amiata Donkey Foals from Birth to 2 Months of Age

The aim of the present study was to fill the void in data related to hematological and biochemical parameters of donkey foals. Whole-blood and plasma samples were obtained from 16 Amiata donkey foals at birth, at 24 and 48 hours, and at 1, 2, 3, 4, 6, and 8 weeks of age. RBC, WBC, hemoglobin concentration (Hgb), mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet count, glucose, creatinine, blood urea, triglycerides, total cholesterol, total bilirubin, aspartate aminotransferase, γ-glutamyl transferase, creatine-phosphokinase, alkaline phosphatase, total calcium, potassium, sodium, phosphorus, and albumin were measured. Similar to equine foals, values of RBC, Hgb, and Hct decreased significantly after the first 48 hours of life in Amiata donkey foals, reaching values similar to adult donkeys. No changes were found for mean corpuscular volume and mean corpuscular hemoglobin concentration during the study period. The WBC was low at birth when compared with subsequent measurements, but significantly increased in the subsequent surveys. Platelet count was lower in the first week, with a secondary peak 2 weeks later, and then a decline again up to the eighth week. In agreement with equine foals, electrolyte concentrations, triglycerides, and total cholesterol did not show significant differences. Creatinine, total bilirubin, and blood urea showed a trend similar to RBC, Hgb, and Hct. For the first time, data of hematological and biochemical parameters in Amiata donkey foals are provided.     

Blood, urine, and ruminal fluid changes associated with metabolic alkalosis induced by duodenal obstruction

Two Holstein heifers and a steer fitted with ruminal and duodenal cannulas were used to determine acid-base and electrolyte changes associated with metabolic alkalosis induced by duodenal obstruction. Obstruction was induced distally to the pylorus, but proximally to the common bile duct entrance. Ruminal fluid, blood, and urine samples were obtained before and after obstruction was induced. Duodenal obstruction resulted in increased blood pH, bicarbonate concentration, and base-excess values. Severe hypochloremia and hypokalemia were evident in 48 hours. Serum sodium concentration decreased only slightly. Packed cell volume and serum concentrations of urea nitrogen, creatinine, glucose, and inorganic phosphate increased, whereas calcium concentration showed no change. Renal chloride excretion reached near zero in 24 hours, whereas sodium and potassium excretions decreased in the steer, but were unchanged in the heifers. Urine creatinine concentration increased markedly in the heifers and steers. Acid urine was not evident up to 96 hours. Ruminal fluid pH decreased and chloride concentration increased in the steer, but remained unaffected in the heifers. Duodenal obstruction had no effect on rumen sodium, calcium, and magnesium concentrations, but the potassium concentration increased in the heifers. The degrees of alkalosis and electrolyte changes were greater in the steer than in the heifers.     

Effects of hypercalcemia on serum concentrations of magnesium, potassium, and phosphate and urinary excretion of electrolytes in horses

OBJECTIVE: To determine effects of experimentally induced hypercalcemia on serum concentrations and urinary excretion of electrolytes, especially ionized magnesium (iMg), in healthy horses. ANIMALS: 21 clinically normal mares. PROCEDURES: Horses were assigned to 5 experimental protocols (1, hypercalcemia induced with calcium gluconate; 2, hypercalcemia induced with calcium chloride; 3, infusion with dextrose solution; 4, infusion with sodium gluconate; and 5, infusion with saline [0.9% NaCl] solution). Hypercalcemia was induced for 2 hours. Dextrose, sodium gluconate, and saline solution were infused for 2 hours. Blood samples were collected to measure serum concentrations of electrolytes, creatinine, parathyroid hormone, and insulin. Urine samples were collected to determine the fractional excretion of ionized calcium (iCa), iMg, sodium, phosphate, potassium, and chloride. RESULTS: Hypercalcemia induced by administration of calcium gluconate or calcium chloride decreased serum iMg, potassium, and parathyroid hormone concentrations; increased phosphate concentration; and had no effect on sodium, chloride, and insulin concentrations. Hypercalcemia increased urinary excretion of iCa, iMg, sodium, phosphate, potassium, and chloride; increased urine output; and decreased urine osmolality and specific gravity. Dextrose administration increased serum insulin; decreased iMg, potassium, and phosphate concentrations; and decreased urinary excretion of iMg. Sodium gluconate increased the excretion of iCa, sodium, and potassium. CONCLUSIONS AND CLINICAL RELEVANCE: Hypercalcemia resulted in hypomagnesemia, hypokalemia, and hyperphosphatemia; increased urinary excretion of calcium, magnesium, potassium, sodium, phosphate, and chloride; and induced diuresis. This study has clinical implications because hypercalcemia and excessive administration of calcium have the potential to increase urinary excretion of electrolytes, especially iMg, and induce volume depletion.     

Hematologic values in newborn beef calves.

Hematologic values were determined in 35 beef calves at birth, at 24 and 48 hours, and in 22 of these calves at 3 weeks after birth. Thirty calves did not have clinical signs of disease throughout the 3-week period. Variables that changed significantly over time in these healthy calves included hematocrit, RBC count, hemoglobin concentration, mean cell volume, mean cell hemoglobin concentration, WBC count, neutrophil-to-lymphocyte ratio, and plasma total protein and serum immunoglobulin concentrations. Of the 35 calves, 5 had clinical signs of disease at 3 weeks. Comparison of hematologic values from these calves with values for healthy calves revealed significant differences at each sample collection time, although disease was not evident at the 3 early sample times. The band neutrophil count and the neutrophil-to-lymphocyte ratio differed between the 2 groups at birth. At 24 hours, the monocyte count was higher in the 5 ill calves. At 48 hours, total leukocyte, mature neutrophil, and monocyte counts, and neutrophil-to-lymphocyte ratio also were higher in the 5 calves. At 3 weeks when clinical signs of disease were detectable in the 5 calves, the total leukocyte, band neutrophil, and mature neutrophil counts, neutrophil-to-lymphocyte ratio, and plasma total protein and fibrinogen concentrations were higher.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics of rifampin given as a single oral dose in foals

Six foals from 6 to 8 weeks of age were given a single oral dose of rifampin at a dosage of 10 mg/kg of body weight. Serum rifampin concentrations were measured serially during a 24-hour period. The mean peak serum rifampin concentration was 6.7 micrograms/ml at 4 hours after treatment. The concentration decreased slowly, and at 24 hours the mean value was 2.7 micrograms/ml. The elimination half-life was 17.5 hours, and the elimination rate constant was 0.04/hr.     

Influence of furosemide treatment on fluid and electrolyte balance in horses

Alterations in electrolyte and acid-base balance were studied in 6 horses for 8 hours after furosemide administration (1 mg/kg of body weight, IM), and the results were compared with those for 5 healthy untreated horses (controls) kept under identical environmental conditions. In the treated group, decreases in plasma potassium, chloride, and calcium concentrations and increases in total plasma protein content persisted for the 8-hour observation period, whereas there was no change in plasma sodium concentration, osmolality, or packed cell volume. Plasma bicarbonate concentration and PCO2 remained high throughout the study, during which time venous blood pH was modestly increased only at the 6-hour sampling time. Furosemide treatment resulted in decreases in urine pH, specific gravity, osmolality, and potassium and calcium concentrations and increases in urine volume and total urine sodium, chloride, and calcium excretion. Body weight decreased 19.2 +/- 5.2 kg (mean +/- SD) in treated horses (4 +/- 1% of body weight), compared with a weight loss of 8 +/- 2.1 kg in untreated horses (1.5 +/- 0.4% of body weight) during the 8-hour experimental period. The increased fluid losses induced by the diuretic did not cause any obvious clinical signs in the horses. Pulse pressure, skin turgor, capillary refill time, and jugular distensibility remained unchanged throughout the experimental period.     

Serum ferritin, serum iron, and erythrocyte values in foals

Twenty-one healthy Thoroughbred and Quarter Horse foals were studied from birth until 1 year of age. Foals had access to an iron-supplemented creep feed before weaning and were fed an iron-supplemented concentrate as part of their diet after weaning at 4 months of age. Initial blood samples were taken before foals were allowed to nurse. Serum iron concentration, total iron-binding capacity, and PCV decreased during the foal's first 24 hours of life. Serum iron concentration decreased rapidly from 446 +/- 16 micrograms/dl (mean +/- SE) at birth to 105 +/- 11 micrograms/dl at 3 days of age. Serum ferritin concentration increased from a mean of 85 +/- 8 ng/ml at birth to 159 +/- 11 ng/ml at 1 day of age. Thereafter, ferritin concentration decreased gradually to a minimum of 61 +/- 6 ng/ml at 3 weeks of age, and then at 6 months increased to values similar to those from reference adult horses. The ferritin concentration in colostrum at birth was 354 +/- 42 ng/ml, compared with 25 +/- 2 ng/ml in milk 1 day later. The decrease and then increase in serum ferritin concentration occurred concomitantly with opposite changes in serum total iron-binding capacity. The mean PCV decreased gradually to a minimum at 3 months of age. This decrease was associated with an increasing number of microcytes, as determined with a cell-size distribution analyzer.     

Responses of horses to a water deprivation test

An investigation was made to determine the effects of water deprivation induced dehydration on changes in urine specific gravity (Usg) and urine osmolality (Uosm) in 6 horses with normal renal function. In addition, the effects of dehydration on serum and urine urea nitrogen, creatinine and various electrolytes as well as the effects of dehydration on acid-base status were studied.Following water deprivation sufficient to produce 12–15% decrease in body weight, 95% of the normal horses should have a Usg of at least 1.042, a Uosm of 1310 mOsmg/kg and a urine osmolality/serum osmolality ratio of 4.14.After 72 hours of water deprivation, the mean weight loss was 13.5% of previous body weight. Serum and urine urea nitrogen concentrations increased by 68% and 130%, respectively, while plasma sodium and chloride concentrations increased by 10% and 14%, respectively. In contrast, urine chloride and calcium concentrations decreased by 90.8% and 52.5%, respectively. There was little change in plasma potassium, phosphorus or calcium concentrations. Urine sodium and potassium concentrations increased initially but were near normal after 72 hours of water deprivation. Azotemia developed and was considered to be of extrarenal origin on the basis of normal routine urinalysis and renal clearance ratio of sodium.