Amino acid profiles and serum albumin and serum total protein concentrations were evaluated in dogs with renal disease. Nine dogs ranging in age from 1 to 15 years were identified as having mild to moderate chronic renal failure (CRF; exogenous creatinine clearance, 0.5 to 2.13 ml/kg of body weight/min). These dogs and a group of 10 clinically normal control dogs were fed a diet containing 31% protein for 8 weeks, at which time serum and urine amino acid assays and clearance studies were performed. All dogs then were fed a diet containing 16% protein for 8 weeks and then reevaluated. Chronic renal failure was associated with mild abnormalities in serum concentrations of amino acids. When fed the higher protein diet, dogs with CRF had lower serum concentrations of glutamine, leucine, proline, and serine and higher serum concentrations of cystathionine and 3-methylhistidine than clinically normal control dogs. When fed the low protein diet, dogs with CRF had lower serum serine concentrations and higher serum concentrations of cystathionine, phenylalanine, and 3-methylhistidine. Urine excretion of amino acids in all dogs on both diets was low, and dogs with CRF had lower renal clearances of 3-methylhistidine than control dogs. There were no significant differences in concentrations of serum albumin and total solids between either group, regardless of diet. We concluded that dogs with mild to moderately severe CRF have mild abnormalities of serum free amino acid concentrations, but renal conservation of essential amino acids is not impaired.

Urinary protein-to-creatinine ratios and serum albumin concentrations were measured in 8 adult male dogs experimentally inoculated with Ehrlichia canis. Urinary protein concentration increased significantly, but transiently, during the acute phase of infection. Urinary protein-to-creatinine ratios were highest (mean, 8.6) during the third and fourth weeks after infection, and decreased to < 0.5 by 6 weeks after infection. Correspondingly, albumin concentration decreased significantly during the acute phase. Serum albumin concentrations were lowest (mean, 2.1 g/dl) the fourth week after infection and increased to > 3.0 g/dl by 11 weeks after infection. There was an inverse linear correlation between urinary protein-to-creatinine ratio and serum albumin concentration. The magnitude of proteinuria and its inverse relationship with serum albumin concentration suggested that hypoalbuminemia associated with acute E canis infection may be attributable primarily to increased renal loss of protein, rather than decreased hepatic synthesis as previously suggested. Another dog was subsequently inoculated with E canis from 1 of the experimentally infected dogs and a renal biopsy was performed during peak proteinuria (urinary protein-to-creatinine ratio = 22 and serum albumin = 1.1 g/dl). Immunofluorescent staining revealed mild to moderate deposits of anti-canine IgM, and to a lesser extent, anti-canine IgG and complement factor C3 in the glomerular tufts and mesangium. Ultrastructural evaluation revealed distortion and fusion of podocyte foot processes and increased microvilli on podocytes. These morphologic changes were consistent with transient glomerular leakage of protein of a magnitude that would significantly contribute to hypoalbuminemia during acute E canis infection. An underlying immunologic mechanism was suggested by positive glomerular immunofluorescence and previously described histologic findings.

The relation of the glycated serum protein, fructosamine, to serum protein, albumin, and glucose concentrations was examined in healthy dogs, dogs with hypo- or hyperproteinemia, and diabetic dogs. Fructosamine was determined by use of an adaptation of an automated kit method. The reference range for fructosamine in a composite group of control dogs was found to be 1.7 to 3.38 mmol/L (mean +/- SD, 2.54 +/- 0.42 mmol/L). Fructosamine was not correlated to serum total protein, but was highly correlated to albumin in dogs with hypoalbuminemia. To normalize the data with respect to albumin, it is suggested that the lower limit of the reference range for albumin concentration (2.5 g/dl) be used for adjustment of fructosamine concentration and only in hypoalbuminemic dogs. In 6 hyperglycemic diabetic dogs, fructosamine concentration was well above the reference range. It is concluded that although fructosamine may be a potentially useful guide to assess the average blood glucose concentration over the preceding few days in dogs, further study is required to establish its value as a guide to glucose control in diabetic dogs.