Glomerulonephritis
History. A client presents his 3-year-old, spayed female springer spaniel. He reports that the dog has not been eating well for several days and seems to tire easily.
Clinical Examination.
The dog seems bright and alert and is in good flesh. The only abnormality detected by physical examination is slight pitting edema in the distal extremities. The left kidney is palpable and feels smooth and of normal size. A urinalysis yields normal results except for 3+ protein (normal, negative to trace amounts) and the presence of a few red blood cell casts. A complete blood cell count is normal, and the only abnormality on a serum chemistry profile is a serum albumin level of 1.5 g/dL (normal, 2.3-4.3 g/dL).Comment. This dog has acute glomerulonephritis. Proteinuria is indicative of glomerular disease because normally the filtration barrier established by the glomerular capillary wall prevents the passage of proteins into the tubular fluid. When the glomerulus is damaged, it becomes leaky, and protein appears in the urine. The loss of albumin in this case appears to be marked because the serum albumin level has dropped below normal levels. The peripheral edema is probably caused by the hypoalbuminemia, and thus the lowered intracapillary oncotic pressure and leakage of fluid into the extravascular space.
In this case, acute glomerulonephritis is suspected because of the recent onset of clinical signs, the absence of renal failure, and the presence of red blood cell casts in the urine. Additional tests that are helpful in assessing the patient and guiding therapy include a 24-hour urine collection to measure the severity of the protein loss and an endogenous creatinine clearance test done at the same time to determine whether the GFR has been altered. A renal biopsy is necessary to verify the type and severity of glomerular injury. Potential causes of acute glomerulonephritis, such as recent or concurrent bacterial or viral infections or autoimmune diseases, should be explored. Renal ultrasound may provide additional information on the condition of the kidneys.
Treatment. The treatment of glomerulonephritis varies. Occasionally, the initiating cause can be determined and removed. Some cases resolve spontaneously; at other times, various combinations of immunosuppressive and antiinflammatory agents are used to combat ongoing damage from immune complex deposition and glomerular inflammation. If either renal Iailure or pulmonary edema secondary to hypoalbuminemia is present, the hypoalbuminemia must be treated with plasma or other colloids to sustain the animal until the glomerular lesion is resolved or controlled. Frequent assessment of urine protein/creatinine ratios as well as serum creatinine is warranted to monitor disease progression.