Equine vitreous humor chemical concentrations: correlation with serum concentrations, and postmortem changes with time and temperature.

Samples of equine vitreous humor were analyzed for urea nitrogen, creatinine, sodium, chloride, phosphorus, calcium, potassium, and magnesium concentrations. Fresh vitreous chemical concentrations were compared to corresponding serum concentrations and expressed as a vitreous to serum ratio. The effects of postmortem time and temperature on the stability of the chemical concentrations were determined by incubation of the samples at 4 degrees C, and 20 degrees C and 37 degrees C for 6, 12, 24, or 48 h. Chemical concentrations were generally more stable at lower temperatures and shorter incubation times.     

Changes in vitreous humor associated with postmortem interval in rabbits.

Concentrations of serum and vitreous humor constituents at time of death, and concentrations of vitreous humor constituents at time of death and at 7 postmortem intervals were compared in 70 domestic, female New Zealand White rabbits (Oryctolagus cuniculus). Urea nitrogen concentration was significantly (P = 0.0094) different, but was linearly correlated in serum and vitreous humor at time of death and at the 4- and 8-hour postmortem intervals. Concentrations of gamma-glutamyltransferase were not significantly different in serum and vitreous humor at time of death, nor were concentrations significantly different in vitreous humor at time of death and at the 4-hour postmortem interval. The vitreous humor concentrations of glucose, triglycerides, sodium, potassium, cholesterol, total protein, albumin, lactate dehydrogenase, creatine kinase, aspartate transaminase, bilirubin, cortisol, and IgG were neither similar to nor predictive of serum constituents. Vitreous humor can be used as a source for estimates of serum urea nitrogen and gamma-glutamyltransferase up to 8 and 4 hours after death, respectively.     

Changes in urea nitrogen and creatinine concentrations in the vitreous humor of cattle after death

The mean urea nitrogen concentration in vitreous humor (VUN) in 97 healthy steers after death was 15.7 mg/dl. The mean serum urea nitrogen concentration in the same cattle was 20.0 mg/dl. The mean vitreous creatinine (VC) concentration was 0.7 mg/dl, and the serum creatinine value was 1.5 mg/dl. The VUN and VC were both significantly lower than serum urea nitrogen and serum creatinine, respectively, but varied in a consistent, predictable manner. In tests with 10 cows, postmortem intervals as long as 36 hours and ambient temperatures up to 30 C had no significant effects on VUN and VC. Evaluation of 8 animals with uremia confirmed that the vitreous humor is a stable fluid compartment after death, usable as an indicator of serum urea nitrogen and creatinine.     

Estimation of antemortem serum electrolytes and urea concentrations from vitreous humor collected postmortem.

Electrolyte and urea levels of vitreous humor collected from bovine eyes at various times postmortem, were compared with serum levels in the same animals. Provided the vitreous humor was filtered immediately after collection, measured levels of total calcium (Ca), potassium ions (K+), sodium ions (Na+) and urea nitrogen were very consistent. For 24 hours postmortem the concentrations of Ca, Na+ and urea nitrogen remained stable, while K+ increased to approximately 55% more than the immediate postmortem level. A small study using anesthetized dogs indicated that urea nitrogen levels of vitreous humor take several hours to equilibrate with elevated blood levels. Analysis of vitreous humor may be a useful adjunct to diagnosis in cases where antemortem clinical chemistry is absent or inadequate.     

The effect of time at which plasma separation occurs on biochemical values in small island flying foxes (Pteropus hypomelanus).

Heparinized blood samples from 15 adult small island flying foxes (Pteropus hypomelanus) were stored at 22 degrees C for 0-, 6-, and 24-hr intervals prior to centrifugation and separation of plasma from erythrocytes. Mean plasma biochemical values of 16 analytes were determined from all samples. Mean values of blood urea nitrogen, creatinine, total protein, albumin, globulin, alkaline phosphatase, alanine transaminase, aspartate transaminase, cholesterol, calcium, sodium, and bilirubin did not change significantly over 24 hr at 22 degrees C. Glucose was decreased at 6 and 24 hr. Potassium and phosphorus increased and chloride decreased, respectively, between 6 and 24 hr.     

Renal reabsorption of magnesium and calcium by cattle with renal tubular dysplasia

The concentrations of magnesium and calcium in the serum and urine and their rates of clearance were determined in cattle with renal tubular dysplasia, an autosomal recessive hereditary disease associated with a deletion of the paracellin-1 gene in Japanese Black cattle. There were no significant differences in the serum or urine magnesium concentrations between normal cattle and cattle which were heterozygous or homozygous for the condition. Serum calcium concentrations tended to be lower in the homozygous cattle, and the serum creatinine and urea nitrogen concentrations were significantly higher in the homozygous cattle. The ratio of magnesium:creatinine and the fractional excretion of magnesium were higher in cattle with the disease than in normal cattle. There were no significant differences in urine calcium concentration, the calcium:creatinine ratio, and fractional excretion of calcium between normal cattle and cattle which were homozygous or heterozygous for the condition. The creatinine clearance was significantly lower in the homozygous cattle than in normal cattle. The clearance, excretion rate, reabsorption rate and reabsorption rate:clearance ratio of magnesium in cattle with renal tubular dysplasia were significantly lower than in normal cattle. The clearance rate and reabsorption rate of calcium were also significantly lower in the affected cattle, but the excretion rate and reabsorption rate:clearance of calcium were not different between the normal cattle and the cattle homozygous for the condition. In cattle with the condition the rate of reabsorption of magnesium by the kidneys was low, but the rate of reabsorption of calcium was normal.     

Comparison of serum and plasma for determination of blood biochemical values in Malaysian flying foxes (Pteropus vampyrus).

The effects of the anticoagulant sodium heparin and time of centrifugation on 20 biochemical analytes in the blood of Malaysian flying foxes (Pteropus vampyrus) were evaluated. Paired plasma and serum samples were centrifuged at 1 hr and 6 hr postcollection. Heparinization and time of centrifugation did not significantly affect albumin, cholesterol, triglycerides, amylase, blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransaminase, alkaline phosphatase, calcium, sodium, and total carbon dioxide levels. Plasma was associated with higher globulin and lower potassium values. Glucose and chloride levels decreased significantly over time, whereas phosphorus levels increased. Serum creatine kinase activity at 6 hr postcollection was significantly higher than the other creatine kinase means. Sodium levels were not significantly affected by sodium heparin as used as an anticoagulant in this study.     

Serum biochemical values of rusa deer (Cervus timorensis russa) in New Caledonia

Blood samples were collected from 91 rusa deer (Cervus timorensis russa), immediately after being shot. Serum mean biochemical values from shot deer are presented for blood urea nitrogen, creatinine, creatine kinase, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, total protein, albumin, calcium, and phosphorus. Mean total protein and albumin increased with age. There was an age-associated increase of gamma globulins. Mean creatine kinase activity and creatinine, albumin and phosphorus concentrations were higher in stags than in hinds. Pregnant hinds had lower mean creatine kinase activity and phosphorus and higher mean alanine aminotransferase and total protein than non-pregnant hinds. Mean calcium concentration increased when deer were agitated before bleeding.     

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.     

Postmortem eyefluid analysis in dogs, cats and cattle as an estimate of antemortem serum chemistry profiles.

This study was carried out to determine the diagnostic usefulness of postmortem eyefluid analysis in estimating antemortem concentrations of serochemical constituents. A total of 31 cattle, 18 dogs and 22 cats were selected from routine elective euthanasia submissions to a diagnostic laboratory. For all cases, a biochemical profile, including determinations for electrolytes, glucose, urea, creatinine, enzymes, cholesterol, bilirubin, protein and osmolality was performed on antemortem serum, and postmortem aqueous and vitreous humors at 0 and 24 h incubation periods. The association between serum and postmortem eyefluid chemistry values was examined using simple linear regression. A strong correlation between serum and postmortem eyefluid urea and creatinine concentrations was demonstrated in the three species examined over a 24 h postmortem interval. We concluded that an accurate estimate of antemortem serum urea or creatinine can be made from the analysis of aqueous or vitreous fluid at necropsy. An estimation of antemortem serum electrolytes (including calcium in cattle) cannot be made with a high degree of accuracy due to the amount of variability in the relationship between serum and eyefluid electrolyte values. For large molecules such as proteins, enzymes, cholesterol and bilirubin there was very poor correlation between serum and eyefluid values.     

Hypoglycemia: a factor associated with low survival rate of neonatal piglets infected with transmissible gastroenteritis virus.

The main purpose of this work was to study changes in the balance of fluids, electrolytes and blood metabolites in neonatal piglets with severe transmissible gastroenteritis. Six two day old conventional piglets were infected with transmissible gastroenteritis virus while six others were used as normal controls. Blood samples were collected in heparin when the infected piglets were moribund. The following variables were measured: packed red cell volume, total plasma protein and bicarbonate, blood pH, blood urea nitrogen and plasma glucose, creatinine, chloride, inorganic phosphorus, sodium, potassium, magnesium and calcium. Vomiting and diarrhea appeared 12 to 24 hours postinoculation in the infected piglets and they were moribund one or two days later. Before becoming moribund, most of the piglets fell rapidly into a lethargic and comatose state. The most evident changes in their blood variables were an increase in packed cell volume, total protein, blood urea nitrogen, phosphorus and magnesium levels and a decrease in pH and bicarbonate concentration as well as a severe hypoglycemia. The results suggest that severe hypoglycemia coupled with metabolic acidosis and dehydration might be an important factor contributing to the high mortality rates caused by transmissible gastroenteritis in neonatal piglets. The hypoglycemia results from a combination of the inadequate glucose metabolism inherent to neonatal piglets and the acute maldigestion and malabsorption resulting from the diffuse and severe villous atrophy induced by the virus.     

Serum concentrations of parathyroid hormone and 25-OH vitamin D3 in cats with urethral obstruction

Objective: To measure serum parathyroid hormone (PTH) and 25‐hydroxyvitamin D₃ concentrations in cats with urethral obstruction. Design: Prospective single cohort study. Setting: University affiliated veterinary teaching hospital. Animals: Male cats with urethral obstruction. Interventions: Routine blood samples drawn from male cats with urethral obstruction. Measurements and main results: Measured variables included blood gas parameters, plasma sodium, potassium, chloride, and ionized calcium concentrations, as well as serum blood urea nitrogen, creatinine, phosphorus, PTH, and 25‐hydroxyvitamin D₃ concentrations. PTH was inversely correlated with ionized calcium and positively correlated with serum phosphorus. No discernable relationship could be found between 25‐hydroxyvitamin D₃ and any of the measured parameters. Conclusions: Lack of parathyroid response does not appear to be the underlying mechanism for ionized hypocalcemia in cats with urethral obstruction.     

Influence of dietary mineral imbalance on the incidence of urolithiasis in Egyptian calves

The influence of certain dietary elements on the urolithiasis syndrome in cattle calves was elucidated. Calcium, phosphorus, and magnesium measurements were conducted on feed rations as well as on serum and urine samples collected from affected and normal calves. Analysis of the rations given to the animals showed phosphorus at higher levels than calcium, indicating mineral imbalance. Serum and urine of urolithic calves were characterised by high phosphorus, calcium, magnesium, urea, and creatinine levels. Physical examination of urine of affected animals showed a high degree of turbidity, a large amount of calcium carbonate, and triple phosphate as well as abundant amount of pus cells and red blood cells. The characteristic clinical symptoms of urine retention were observed. Moreover, some animals were found to urinate through an opening in front of the scrotal region.     

Determination of reference intervals for plasma biochemical values in clinically normal adult domestic shorthair cats by use of a dry-slide biochemical analyzer

OBJECTIVE: To establish reference intervals of plasma biochemical values in healthy adult domestic shorthair (DSH) cats by use of controlled conditions. ANIMALS: 95 healthy client-owned cats. PROCEDURES: Food was withheld from the cats overnight. All blood samples were obtained on the same day, at the same location, and by the same investigator. Blood samples were collected from a cephalic vein into lithium heparin tubes. After centrifugation of blood samples, plasma supernatants were harvested and stored at -20 degrees C until assayed for total proteins, albumin, creatinine, urea, glucose, calcium, phosphates, sodium, chloride, potassium, and CO2 concentrations and alkaline phosphatase and alanine aminotransferase activities. RESULTS: Reference intervals in healthy adult DSH cats were 65 to 85 g/L for total proteins, 27 to 39 g/L for albumin, 89 to 207 micromol/L for creatinine, 6.6 to 11.3 mmol/L for urea, 4.1 to 8.2 mmol/L for glucose, 2.4 to 2.9 mmol/L for calcium, 1.1 to 2.1 mmol/L for phosphates, 153 to 161 mmol/L for sodium, 120 to 127 mmol/L for chloride, 3.3 to 4.2 mmol/L for potassium, 15 to 21 mmol/L for CO2, 32 to 147 U/L for alkaline phosphatase, and 34 to 123 U/L for alanine aminotransferase. CONCLUSIONS AND CLINICAL RELEVANCE: This study provided reference intervals for plasma analytes in adult DSH cats. The influence of potential confounding factors was minimized through use of controlled preanalytic and analytic conditions. However, these results cannot be extrapolated to other feline breeds or used to interpret results from other biochemical analyzers.     

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.     

Pre-renal azotaemia in a pony with an oesophageal obstruction.

A case of pre-renal azotaemia is described in a 12 year old pony resulting from oesophageal obstruction of 8 days duration. Blood urea nitrogen, creatinine, calcium, inorganic phosphate, sodium, potassium, chloride and bicarbonate concentrations were monitored throughout the recovery period. After relief of the obstruction normal blood concentrations were quickly restored.     

Effect of age on reference intervals of serum biochemical values in kittens

OBJECTIVE: To determine the effect of age on reference intervals of serum biochemical values in kittens. DESIGN: Prospective clinical trial. ANIMALS: 55 kittens from 12 specific-pathogen-free queens. PROCEDURE: Kittens were allocated at birth into colostrum-fed (n = 27) and colostrum-deprived (28) groups. Blood was collected at birth and on days 1, 2, 4, 7, 14, 28, and 56. Serum samples were analyzed for activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, gamma-glutamyltransferase, amylase, and lipase and for concentrations of albumin, total protein, bilirubin, urea nitrogen, creatinine, cholesterol, glucose, calcium, phosphorus, and triglycerides by use of an automated analyzer. Total serum solids concentrations were determined by use of refractometry. Serum IgG concentrations were quantified by use of radial immunodiffusion. RESULTS: For several analytes, reference intervals changed rapidly, most notably during the first few days of life. Reference intervals for alkaline phosphatase, creatine kinase, lactate dehydrogenase, and triglycerides were higher from birth to 8 weeks than adult reference intervals. Aspartate aminotransferase, bilirubin, urea nitrogen, and creatinine were higher than in adults at birth but were similar to or lower than adult reference intervals by 8 weeks. Compared with adult reference intervals, reference intervals for calcium and phosphorus concentrations were higher and for albumin and total protein concentrations were lower throughout the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Important differences exist between reference intervals for serum biochemical values of neonatal and adult cats. Age-appropriate reference intervals should be used for accurate assessment of serum biochemical test results in cats.     

Serum and vitreous humor antibody titers in and isolation of Leptospira interrogans from horses with recurrent uveitis

OBJECTIVE: To measure antibody titers against Leptospira interrogans in serum and vitreous humor and determine the prevalence of L interrogans in vitreous humor of horses with recurrent uveitis. DESIGN: Cross-sectional study. ANIMALS: 242 horses (270 eyes) with recurrent uveitis undergoing vitrectomy and 39 control horses (54 eyes) without any history or clinical signs of recurrent uveitis undergoing euthanasia or enucleation for unrelated reasons. PROCEDURE: Serum and vitreous humor were tested for antibodies against 13 serovars of L interrogans. Vitreous humor was submitted for leptospiral culture; isolates were typed to the serogroup level. RESULTS: Leptospira interrogans was isolated from vitreous humor from 120/229 (52%) horses (126/252 [50%] eyes) with recurrent uveitis but was not isolated from vitreous humor from 36 eyes of 21 control horses. Duration of recurrent uveitis was > or = 1 year for 45 of the 120 (38%) horses from which the organism was isolated. Geometric mean antibody titers against L interrogans in the vitreous humor and serum of horses with recurrent uveitis were 1:1,332 and 1:186, respectively. Only 91 of 120 (76%) horses from which the organism was isolated had a 4-fold or greater difference between serum and vitreous humor antibody titers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that persistent ocular infection with L interrogans is common in horses with recurrent uveitis. A 4-fold increase in vitreous humor versus serum antibody titers may not be a sensitive test for the diagnosis of L interrogans-induced recurrent uveitis. We hypothesize that the immune component of recurrent uveitis can be directly induced and maintained by persistent infection of the eye with L interrogans.     

Evaluation of biochemical analytes in vitreous humor collected after death in West Indian manatees

OBJECTIVE: To evaluate biochemical analytes in vitreous humor collected after death in West Indian manatees (Trichechus manatus latirostris). DESIGN: Prospective study. ANIMALS: 73 West Indian manatees of various ages and both sexes. PROCEDURE: The condition of manatee carcasses submitted for routine postmortem examination was categorized as fresh, moderately autolyzed, or severely autolyzed. The eyes were removed, frozen for shipping, and thawed on arrival at the laboratory. Vitreous humor was extracted, and various biochemical analytes were measured. Values for each analyte were compared with published reference ranges for corresponding biochemical analytes in serum. Values were also compared among the carcass condition groups. RESULTS: Creatinine and urea nitrogen concentrations in vitreous humor were significantly higher in severely autolyzed carcasses than in fresh carcasses. Potassium concentrations in vitreous humor were significantly higher in moderately autolyzed carcasses than in fresh carcasses but were highly variable in severely autolyzed carcasses. These data were consistent with those reported in other species. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that measurement of biochemical analytes in vitreous humor of manatees is feasible and has potential for assisting in the postmortem diagnosis of certain metabolic, renal, and nutritional diseases; determining severity of autolysis at time of necropsy; and determining the time of occurrence of human-induced trauma.     

Dietary magnesium and urolithiasis in growing calves

The effect of high levels of dietary magnesium (1.4%) alone or in combination with elevated calcium (1.8%) or phosphorus (1.6%) on growth and health of male calves was evaluated during a nine week feeding trial after weaning. Twenty calves were randomly divided into 4 feeding groups consisting of controls, high magnesium, high magnesium and calcium or high magnesium and phosphorus. Elevated dietary minerals caused decreased feed intake and growth rate. Blood urea nitrogen and serum creatinine levels were greatly elevated in calves fed high magnesium or magnesium and phosphorus and serum urea nitrogen was moderately elevated in calves fed high magnesium and calcium. These elevations suggested the occurrence of renal damage as a result of microcrystalline obstruction of renal tubules. Serum magnesium levels were three times normal in calves fed high magnesium or magnesium and phosphorus, but only twice normal in calves fed high magnesium and calcium. High dietary magnesium resulted in a significant depression in blood calcium level. This effect was somewhat overcome by additional dietary calcium Three calves fed the high magnesium diet and two calves fed the high magnesium and phosphorus diet developed urinary tract obstruction. The chemical composition of uroliths recovered from these calves was calcium apatite. Elevated dietary magnesium has been shown to be a cause of urolithiasis in growing male calves. Additional dietary calcium, but not phosphorus, appears to protect calves against urolithiasis induced by elevated dietary magnesium.