Metabolomic studies as a tool for determining the post-mortem interval (PMI) in stillborn calves.

BACKGROUND: Perinatal mortality may vary between herds, but the cost of deaths are always higher than value of the calf. When diagnosing the cause of a calf's death it is important to determine when it occurred, before or after calving. Metabolomics is widely used to identify many human diseases, but quite rarely applied in veterinary science. The aim of this study was to compare the metabolic profiles of calves with different times of death and those of calves born alive. Into the study, twenty one healthy controls (singleton, normal assisted calving, born alive) and 75 stillborn (SB) calves (with a gestation length of ≥260 days, SB, or dead within 6 h of birth) were enrolled. Plasma and urine from SB and control calves were investigated by proton nuclear magnetic resonance based metabolomic methods. SB calves were divided into four PMI groups. One PMI group included calves that died after calving and the other groups - three comprised in utero deaths, based on pathophysiological changes (lung inflation, autolysis in internal organs, hemoglobin imbibition in the pleura and aortic arch). Partial Least Squares - Discriminant Analysis models based on plasma metabolites were calculated, reflecting assumed data clustering. RESULTS: Twenty six metabolites in plasma and 29 in urine changed significantly with PMI according to one way analysis of variance. Half the metabolites in plasma and the majority in urine increased with PMI. Six metabolites increased simultaneously in plasma and urine: acetate, sn-glycero-3-phosphocholine (GPC), leucine, valine, creatine, and alanine. CONCLUSIONS: Post-mortem changes in calves were associated with molecular variations in blood plasma and urine, showing the greatest differences for the group in which the post-mortem pathological changes were the most advanced. The results of the study show that evaluation of calf plasma or urine may be used as a diagnostic method for the determination of the PMI. Moreover, the metabolites, which unambiguously increased or decreased, can be used as potential biomarkers of PMI.

Antibiotic Treatment Preventing Necrotising Enterocolitis Alters Urinary and Plasma Metabolomes in Preterm Pigs.

Necrotising enterocolitis (NEC) is a serious gut inflammatory condition in premature neonates, onset and development of which depend on the gut microbiome. Attenuation of the gut microbiome by antibiotics can reduce NEC incidence and severity. However, how the antibiotics-suppressed gut microbiome affects the whole-body metabolism in NEC-sensitive premature neonates is unknown. In formula-fed preterm pigs, used as a model for preterm infants, plasma and urinary metabolomes were investigated by LC-MS and 1H NMR, with and without antibiotic treatment immediately after birth. While it reduced the gut microbiome density and NEC lesions as previously reported, the antibiotic treatment employed in the current study affected the abundance of 44 metabolites in different metabolic pathways. In antibiotics-treated pigs, tryptophan metabolism favored the kynurenine pathway, relative to the serotonin pathway, as shown by specific metabolites. Metabolites associated with the gut microbiome, including 3-phenyllactic acid, 4-hydroxyphenylacetic acid, and phenylacetylglycine, all from phenylalanine, and three bile acids showed lower levels in the antibiotics-treated pigs where the gut microbiome was extensively attenuated. Findings in the current study warrant further investigation of metabolic and developmental consequences of antibiotic treatment in preterm neonates.

Early diet impacts infant rhesus gut microbiome, immunity, and metabolism.

Epidemiological research has indicated a relationship between infant formula feeding and increased risk of chronic diseases later in life including obesity, type-2 diabetes, and cardiovascular disease. The present study used an infant rhesus monkey model to compare the comprehensive metabolic implications of formula- and breast-feeding practices using NMR spectroscopy to characterize metabolite fingerprints from urine and serum, in combination with anthropometric measurements, fecal microbial profiling, and cytokine measurements. Here we show that formula-fed infants are larger than their breast-fed counterparts and have a different gut microbiome that includes higher levels of bacteria from the Ruminococcus genus and lower levels of bacteria from the Lactobacillus genus. In addition, formula-fed infants have higher serum insulin coupled with higher amino acid levels, while amino acid degradation products were higher in breast-fed infants. Increases in serum and urine galactose and urine galactitol were observed in the second month of life in formula-fed infants, along with higher levels of TNFα, IFN-γ, IL-1ß, IL-4, and other cytokines and growth factors at week 4. These results demonstrate that metabolic and gut microbiome development of formula-fed infants is different from breast-fed infants and that the choice of infant feeding may hold future health consequences.

Urinary excretion of low molecular weight proteins in goats during the neonatal period.

Urinary protein excretion occurs in neonates of many animal species, as well as in human neonates. However, the incidence, dynamics, and mechanism of proteinuria have not been unambiguously explained. The aims of this study were to investigate into excretion of selected protein fractions of molecular weight less than 69 kDa (LMW), evaluation of intensity and dynamics of changes during the first month of kids' life, and an attempt to explain the causes of neonatal proteinuria. The analysis were carried out on 16 kids of White Improved goats, over the period from birth until 30 days of age, using clearance methods. Urine proteins were separated electrophoretically (SDSPAGE), and their concentration and percentage content was determined by densitometric method with the use of archiving and image analysis software. The proteins found in the urine were grouped as HMW, LMW and albumin. For six fractions of LMW proteins, excretion rates and percentage content of the urinary total LMW protein pool were calculated. It has been demonstrated that neonatal proteinuria in goat kids is associated with a high level of excretion of proteins of lower molecular weight than albumin (69 kDa). A strong dynamics of changes in excretion of particular LMW protein fractions with age was observed, which may imply not only an increased permeability of glomerular filtration barrier, especially over the first days of life, but also a selectivity of reabsorption mechanisms in the nephrons. An increased permeability of glomerular filtration barrier for proteins during the first days of life may represent the adaptive mechanism for removal of protein excess from the organism. The urinary LMW protein pool may also contain proteins resulting from the hydrolysis in the tubular cells.

CD24 is a marker of exosomes secreted into urine and amniotic fluid.

Exosomes are small membrane vesicles that are secreted from a variety of cell types into various body fluids including the blood and urine. These vesicles are thought to play a role in cell-cell interactions. CD24 is a small but extensively glycosylated protein linked to the cell surface by means of a glycosyl-phosphatidylinositol anchor. In this study we found that CD24 is present in membrane vesicles characterized as exosomes that were isolated from the urine of normal individuals. CD24 was expressed by both tubule cells and podocytes and treatment of the latter with a cholesterol-extracting agent, but not with a calcium ionophore, caused the release of CD24-containing exosomes. Using CD24 as a marker, we found exosomes in the urine of newborn infants and in the amniotic fluid of pregnant women with similar findings made in mice. Interestingly, studies with CD24 knockout mice showed that the exosomes are released from the fetus but not from the mother; however, exosome release was similar from both the knockout and the wild-type mice. This indicates that CD24 is not essential for exosome formation or release but may be a convenient exosome marker. Our studies suggest that exosomal secretion from the embryonic kidney could play a biological role at the fetal-maternal interphase.

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.

Domoic acid transfer to milk: evaluation of a potential route of neonatal exposure.

Domoic acid (DA), produced by the diatom genus Pseudo-nitzschia, is a glutamate analog and a neurotoxin in humans. During diatom blooms, DA can contaminate filter-feeding organisms, such as shellfish, and can be transferred by ingestion to higher trophic levels. Several intoxication events involving both humans and various marine mammals have been attributed to DA. Affected organisms show neurological symptoms such as seizures, ataxia, headweaving, and stereotypic scratching, as well as prolonged deficits in memory and learning. Neonatal animals have been shown to be substantially more sensitive to DA than adults. However, it has not been demonstrated whether DA can be transferred to nursing young from DA-exposed mothers. This study demonstrates transfer of DA from spiked milk (0.3 and 1.0 mg/kg) to the plasma of nursing neonatal rats and an overall longer DA retention in milk than in plasma after 8 hr in exposed dams. DA was detectable in milk up to 24 hr after exposure (1.0 mg/kg) of the mothers, although the amount of DA transferred to milk after exposure was not sufficient to cause acute symptoms in neonates.

Non-invasive testing reveals a high prevalence of simian T-lymphotropic virus type 1 antibodies in wild adult chimpanzees of the Taï National Park, Côte d'Ivoire.

Little information is available on the prevalence of retrovirus infections in populations of non-human primates living in their natural habitats. To gain such information, methods were developed to detect antibodies to simian T-lymphotropic virus type 1 (STLV-1) in urine from wild chimpanzees. Samples from more than 74 chimpanzees living in three communities in the Taï National Park, Côte d'Ivoire, were analysed. The prevalence of STLV-1 antibodies in adults and adolescents was significantly higher (35/49, 71.4 %) than that in infant and juvenile chimpanzees (3/31, 9.7 %).

Induction of the epithelial Na+ channel via glucocorticoids in mineralocorticoid receptor knockout mice.

Epithelial Na+ channel (ENaC) activity in kidney and colon is stimulated by aldosterone acting on the mineralocorticoid receptor (MR). MR and the glucocorticoid receptor (GR) show high homology in their DNA-binding domain and have similar affinities to mineralo- and glucocorticoids. We therefore asked whether the glucocorticoid-mediated activation of ENaC is restricted to the presence of MR and used the MR knockout mouse model to address this question. Due to their MR deficiency and the consecutive reduction of ENaC activity these mice die as neonates, and even after appropriate substitution therapy adult MR knockout mice suffer from high Na+ loss and hyperkalemia. In the present study, glucocorticoid treatment restored plasma K+ and almost normalized the fractional excretions of Na+ (FENa+) and K+ (FEK+) in adult salt-substituted MR knockout mice, while the effect of amiloride on FENa+ and FEK+ was augmented in these animals. In order to estimate ENaC activity, measurements of transepithelial equivalent short-circuit current (Isc) were performed. Glucocorticoids induced an amiloride-sensitive Na+ absorption in renal cortical collecting duct and distal colon of MR-/- of about 25% and 50% of the currents observed in glucocorticoid-treated wild-type mice, respectively. In the colon glucocorticoid treatment increased the mRNA abundance of all three ENaC subunits, in the kidney only alpha-ENaC was increased. The regulation of ENaC expression was the same in both genotypes and thus irrespective of the presence of MR. These data show that MR is no prerequisite for the activation of ENaC transcription and activity, and that the respective mechanisms can be stimulated via GR.

Renal citrate metabolism and urinary citrate excretion in the infant rat.

BACKGROUND: Although hypercalciuria has the same prevalence in children as adults, children rarely develop renal stones. This may be explained by a greater urinary citrate excretion in infants compared with adults. The present study examines the renal excretion of citrate and renal cortical citrate metabolism in infant and adult rats. METHODS: Adult male and newly weaned infant rats were acclimated to metabolic cages and fed synthetic diets. Urine was collected after two days, and renal cortical citrate metabolism was assayed. RESULTS: Infant rats had a lower plasma [HCO3-] and higher plasma [K+] and had a fourfold higher urinary citrate:creatinine ratio and a twofold higher concentration of citrate in their urine compared with adult rats. This higher urinary citrate excretion was not due to a difference in renal proximal tubular Na/citrate cotransporter activity, nor renal cortical citrate synthase or ATP citrate lyase activities in infants as compared with adults. However, infant rat kidneys had significantly lower mitochondrial aconitase (m-aconitase) activity. Renal cortical citrate concentrations were comparable in infant and adult rats. Manipulation of plasma [K+] to adult levels did not affect the higher urinary citrate excretion in infant rats. CONCLUSIONS: Urinary citrate excretion in infant rats is greater than in adults but does not parallel tissue [citrate]. Thus, this higher urinary citrate is likely due to maturational differences in the proximal tubule, other than Na/citrate cotransport, that directly affect citrate transport.

Nitric oxide modulates premature renal circulation in hypoxic newborn piglets.

We studied the role of nitric oxide (NO) on the regulation of blood flow in the immature kidney during hypoxia, resuscitation and the recovery period using the NO inhibitor N(omega)-nitro-L-arginine (L-NNA) in a newborn piglet model, and the possibility of urinary cGMP as an index of renal function. After administration of L-NNA, the blood flow in both the cortex and medulla significantly decreased, indicating that NO is constantly released to maintain renal circulation. During hypoxia, the renal blood flow fell remarkably, and there were no differences between the control and L-NNA groups. During the post-resuscitation period, the recovery of renal blood flow was significantly suppressed in L-NNA administration, and it was speculated that NO might be an important factor for recovery of circulation from vasoconstriction due to hypoxemia. Urinary cGMP/cr was significantly increased on recovery from hypoxemia and was suppressed by L-NNA administration. This result suggested that the change in cGMP/cr represents renal blood flow change. We conclude that NO may play an important role in maintaining basal hemodynamics, and may also be a crucial factor for recovery from post-hypoxic vasoconstriction in premature kidneys. Urinary cGMP/cr might serve as one of the indices for assessment of premature renal circulation.

Urinary diagnostic indices in calves.

OBJECTIVE: To establish reference values for urinary diagnostic indices in healthy calves from birth to 90 days of age. DESIGN: Prospective field trial. ANIMALS: 12 Holstein heifer calves. PROCEDURE: Urine and serum samples were collected daily for the first 5 days after birth, then weekly until calves were 90 days old. Urine:serum creatinine ratio, urine:serum urea nitrogen ratio, urine:serum osmolality ratio, fractional clearances of sodium and inorganic phosphate, and urine gamma-glutamyltransferase activity were measured. Data were grouped by age of calves at the time of sample collection: 1 to 5 days old (neonatal period), 7 to 27 days old (suckling period), and 28 to 90 days old (weanling period). RESULTS: Mean urine:serum creatinine, urea nitrogen, and osmolality ratios were significantly higher during the weanling period than during the other 2 periods. There were no significant differences in mean fractional clearances of sodium among age periods. CLINICAL IMPLICATIONS: Urinary diagnostic indices calculated for these healthy calves may be used as reference values for early recognition of renal damage or renal failure.

Endogenous angiotensin II inhibits natriuresis after acute volume expansion in the neonatal rat.

Compared with the adult, the neonatal renal natriuretic response to acute volume expansion (VE) is attenuated. To test the hypothesis that antinatriuresis is mediated by endogenous angiotensin I (ANG II), Sprague-Dawley rats were given losartan, an ANG II type 1 (AT1)-receptor inhibitor (40 mg.kg-1.day-1) from birth to 14-17 days. Control littermates received saline vehicle. Anesthetized rats underwent acute saline VE for measurement of mean arterial blood pressure (MAP), plasma aldosterone concentration (Paldo), plasma atrial natriuretic peptide (PANP), glomerular filtration rate (GFR), sodium excretion (UNaV), potassium excretion (UKV), and urine guanosine 3',5'-cyclic monophosphate excretion (UcGMPV). Losartan increased basal urine flow fivefold, UNaV 10-fold, and UKV twofold. Acute VE induced marked diuresis, natriuresis, and kaliuresis in the losartan but not in the saline group. This occurred without change in Paldo and PANP and despite lower MAP, GFR, and UcGMPV. In addition, losartan did not affect release of cGMP from isolated glomeruli stimulated by ANP or sodium nitroprusside. We conclude that the limited renal response to acute VE in the neonate results from stimulation of tubular Na reabsorption by ANG II acting on the AT1 receptor.

The effect of diabetes mellitus on urinary calcium excretion in pregnant rats and their offspring.

The effect of maternal diabetes mellitus on renal calcium excretion in pregnant rats and their offspring has been examined in order to ascertain the role of the kidney in the disturbed calcium homeostasis of infants born to diabetic mothers. Diabetic pregnant (DP) rats exhibited severe hypercalciuria which greatly exceeded the urinary calcium losses (UCaV) in non-diabetic pregnant (CP) or non-pregnant diabetic (D) rats. Means +/- S.E.M. for UCaV at day 21 (mmol/24 h) were: DP = 1.12 +/- 0.09 (n = 7); CP = 0.06 +/- 0.01 (n = 7); D = 0.63 +/- 0.06 (n = 7) (P < 0.001 DP vs CP and DP vs D). The profile for urinary calcium excretion in the three groups was different from that of other measured ions. The degree of natriuresis, for example, was comparable in DP and D rats at all stages studied. Although magnesium output was significantly greater in DP than D rats on days 14 and 21, this appeared to result from an additive effect of the magnesiuresis seen when pregnancy and diabetes were studied separately. The marked renal calcium wasting of diabetic pregnancy will have implications for overall calcium balance in the mother. For example, an enhanced intestinal calcium absorption was seen in DP rats in the second half of gestation. Means +/- S.E.M. for day 21 (mmol/24 h) were: DP = 3.8 +/- 0.8 (n = 7); CP = 1.4 +/- 0.3 (n = 7); D = 1.6 +/- 0.3 (n = 7) (P < 0.05 DP vs CP and DP vs D).(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic oxytocin treatment during late gestation and lactation impairs development of rat offspring.

The nonapeptide oxytocin (OT) plays an important role in timing and course of parturition, and in milk ejection during lactation. Exogenously enhanced OT levels were reported to impair body development of rat offspring at birth and during postnatal stages. In the present study, this effect was further investigated by giving pregnant rats of postcoital day 17 a SC implant that delivers small amounts of OT for 2 months (approximately threefold enhancement of OT levels), and by introducing a crossfostering protocol for the offspring. A slightly reduced body weight of 5 to 7% was again observed in pups born to OT-implanted dams. When reared postnatally by OT-treated mothers, pups lost weight gain (-7 to -10%). During the weaning period, however, body size caught up with that of control animals. When nursed by an untreated mother, this recovery took place before that period. Growth of control offspring was also hampered when placed with OT-treated mothers, but these pups failed to recover from low body weights which lasted up to at least 70 days of age (-7%). Daily urine production of the pups born of and reared by the OT-treated mothers was reduced at 1 month of age, but this effect was only transient and had disappeared at 70 days of age. Notwithstanding, the recovery of body growth, brain sizes, and cerebellar DNA, i.e., cell content was reduced in the pups born and reared by OT-treated mothers, indicative of a lasting effect on brain development.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the presence of endogenous 19-nortestosterone in the cow peripartum and in the neonatal calf.

Urine samples were collected from five Brown Swiss cows during the 18 days prior to and 11 days after parturition and were analysed for 19-nortestosterone using an enzyme immunoassay. Nortestosterone concentrations ranged from 70 to 130 nmol/l in all samples taken before parturition. The levels declined within two days, and 11 days post partum no nortestosterone was detectable. In urine from newborn calves, maximal nortestosterone concentrations were determined during the first day of life (10.9-120 nmol/l), declining below 7.3 nmol/l until day 3 in most animals and remaining below the detection limit (less than 3.6 nmol/l) after day 8 in all animals. There was no obvious difference between cows carrying a male or a female calf nor between newborn male or female calves. Using the combined methods high performance liquid chromatography/enzyme immunoassay and high performance liquid chromatography/gas chromatography-mass spectrometry, the immunoreactivity in urine was identified to be 19-nortestosterone-17 alpha. Although there is unequivocal evidence for the endogenous production of nortestosterone in pregnant cows, its function for placenta physiology, pregnancy anabolism and parturition remains unclear. However, new threshold levels for residue control of nortestosterone need to be fixed in accordance with the endocrine status of the animals.

Effect of hypoxia on renal prostaglandin E2 production in human and rat neonates.

Effect of hypoxia on renal prostaglandin E2 (PGE2) production was shown in asphyxic newborn infants and experimental hypoxic rats. In asphyxic infants, at postnatal day 1, the urinary excretion of PGE2 in severe asphyxia (1.00 +/- 0.19 pg/kg/min, n = 10) was lower than that of the mild asphyxia (2.15 +/- 0.18 pg/kg/min, n = 10) or normal newborn infants (2.65 +/- 0.25 pg/kg/min, n = 8) (p less than 0.01). The urinary excretion of PGE2 was inversely correlated with the urinary N-acetyl-beta-D-glucosaminidase (r = -0.84, p less than 0.01). The urine volume in mild asphyxia (0.04 +/- 0.005 ml/kg/min) was higher in comparison to normal newborn infants (0.026 +/- 0.002 ml/kg/min) (p less than 0.01), but had no correlation with the urinary excretion of PGE2. In experimental hypoxic rats, the renal PGE2 concentration increased from 0.19 +/- 0.02 ng/mg protein to the maximum level of 0.59 +/- 0.03 ng/mg protein at 10 min of hypoxia. The renal PGE2 concentration then decreased to the minimum level (0.105 +/- 0.02 ng/mg protein) at 24 h after 20 min hypoxia. The renal ATP rapidly decreased during 20 min hypoxia, and gradually increased to 55.1 +/- 6.2 nmol/mg protein at 24 h after 20 min hypoxia, which recovered only about 60% of the control level. It seems likely that renal PGE2 does not play a major role in diuresis in mild birth asphyxia and that severe birth asphyxia suppresses the renal PGE2 production in early neonatal period.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal clearance, urinary excretion of endogenous substances, and urinary diagnostic indices in healthy neonatal foals.

Urine (U) and serum (S) were obtained every 2 hours during a 12- or 24-hour period from eight healthy 96-hour-old pony or horse foals. Dams' milk samples were obtained concurrently. Urine volume was measured during this 12- or 24-hour period. The mean amount of urine produced was 148 +/- 20 ml/kg/day. Baseline urinalyses were evaluated on all foals at two days of age, before any manipulation. Urine generally was dilute (less than 1.008) but the specific gravity was as high as 1.027 in one normal foal. Continuous (12 or 24 hour) urinary catheterization resulted in bacteriuria but not white blood cells in the urine. Prolonged catheterization did not cause foals to become febrile or exhibit clinical signs of cystitis or other illness. Urinary electrolyte excretion, urinary electrolyte clearances, and fractional electrolyte excretions (FE) were measured. When compared with normal values reported in adult horses, excretion, clearance, and FE were similar for sodium (Na) but higher for potassium (K), phosphorus (P), and calcium (Ca). There were no significant differences between data collected during different time periods, and it was concluded that the use of single sample urine/serum estimates of fractional excretion in the neonatal foal was an appropriate indicator of the renal handling of electrolytes, and when viewed in conjunction with urinalysis and other serum parameters, a valuable aid to evaluating renal function.

Simple and effective procedure for complete urine collection from infant macaques (Macaca nemestrina).

A diaper method, used in pediatric medicine, has been adapted and validated for total urine collection from infant macaques (Macaca nemestrina). The device consists of cellulose sponges and polyethylene sheets. The method proposed is non-invasive, simple, and does not significantly hinder the movement of the infant. The method should be useful when one is conducting pharmacokinetic studies in which total urine collection is required.

Indices of renal function: values in eight normal foals from birth to 56 days.

A series of blood and urine samples was collected from each of eight normal foals between birth and eight weeks. Blood chemistry relating to renal function was evaluated as well as physical and chemical characteristics of urine. During the first 4d of life it was impractical to suggest meaningful normal values due to wide variation among foals and with time. Serum urea and plasma creatinine fell markedly to levels less than those previously reported for normal adult horses, while urine, mildly hypersthenuric at birth, rapidly became hyposthenuric. There was also a marked proteinuria during the first 48h. After 4d clinicopathological values stabilised. Urea and creatinine remained at subadult levels and hyposthenuria was maintained. While there was some variation with time, generally the urinary activity of gamma-glutamyl transpeptidase (GGT) and alkaline phosphatase (AP) was greater in foals than in adults; plasma potassium, the creatinine clearance ratio of potassium (% Cr K), serum inorganic phosphate and the creatinine clearance ratio of phosphate (% Cr PO4) were greater than in adults while plasma chloride and the creatinine clearance ratio of chloride (% Cr Cl) were lower in foals than in adults. Urinary pH was acidic and epithelial cells and calcium oxalate crystals more prevalent in the urine of foals than in that of adults. The information presented here will be useful in the diagnosis and management of renal disease and azotaemia in foals.