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An Urban Experience
reports of response. Studies in dogs have shown that in most cases of proteinuria, glucocorticoid administration is not beneficial and is often associated with a worsening of the proteinuria. Glucocorticoids appear
to promote glomerulosclerosis and intraglomerular hypertension. Therefore, glucocorticoids are not recommended unless the proteinuria is secondary to glucocorticoid-responsive systemic disease. Often glucocorticoids are given with severe glomerular proteinuria in order to achieve quicker control while other imunsuppressive drugs are initiated. Cyclosporine was not found to be effective in dogs with idiopathic GN in
a controlled, blinded study. Other immunosuppressive drugs that may show benefit, but that have not been evaluated in placebo-controlled, blinded studies are azathioprine (2 mg/kg PO q24h x 2 weeks, then 1 mg/ kg PO q24h, then 1 mg/kg PO q48h), cyclophosphamide (50 mg/m2 PO q48h), and chlorambucil (2-6 mg/m2 PO q24-48h). The most promising is mycophenolate (20 mg/ kg PO q12h for 3-4 weeks, then 10 mg/kg PO q12h).(6) The decision to use immunosuppressive therapy should be based on the likelihood of an immune-mediated cause of proteinuria, the patient’s overall condition, and the ability to monitor the patient. Consider diuretics
to decrease sodium retention and edema/ascites. In human beings with nephrotic syndrome, diuretics are often used to decrease ascites/edema. Commonly a combination of a loop diuretic (such as furosemide)
and a thiazide diuretic (such as hydrochlorothiazide) are used. Furosemide is often used in veterinary medicine
to decrease fluid retention and should be considered in dogs or cats that have nephrotic syndrome. Combination diuretic therapy may be considered in animals that are refractory to single agent therapy.
Management of patients with CKD1 without proteinuria
is less clear. A decrease in renal function without
a progressive underlying disease may not warrant intervention. At present there is no means of predicting progression of CKD1 disease other than monitoring trends and/or identifying and treating the underlying cause if possible. Dogs and cats with congenital renal disease may or may not have progressive disease. For example, dogs with unilateral renal agenesis may not experience progressive CKD if the solitary kidney is otherwise structurally and functionally normal. On the other hand, patients with unilateral renal lymphoma
often develop it in both kidneys and so CKD is progressive. Dogs and cats with Fanconi syndrome
are often diagnosed as CKD1; however, this is usually progressive disease. The question is in patients without identifiable specific diseases does a diagnosis of CKD1 warrant intervention? There are 3 studies in dogs(7-9) and 2 studies in cats(10, 11) that have been published. In a study of 210 client-owned dogs with normal creatinine concentrations, 18 dogs had an increased SDMA at
baseline or during a 6 month crossover dietary study. (10) Feeding a heat processed dry food containing fruits and vegetables, egg protein, wet chicken meat, lipoic acid, α-tocopherol, vitamin C, carnitine, and omega-3 fatty acids compared with a control was associated
with a decrease in SDMA in 8 of 9 dogs compared with 4 of 9 dogs when consuming the control diet. A study
of 81 geriatric research dogs were compared with 30 mature adult research dogs consuming a control diet and 2 foods that were similar to the aforementioned diet; however, one of the test diets contained additional fruits and vegetables and egg protein and did not contain corn gluten meal.(9) The geriatric dogs had lower GFR than the mature dogs. GFR increased and SDMA decreased in geriatric dogs when fed the test foods; however, the effect was greater in the geriatric dogs eating the second test diet. None of the dogs had GFR or SDMA values outside of the normal range, however. A longitudinal study of 36 client-owned dogs with CKD1 diagnosed
by having abnormal kidneys, dilute urine of renal origin, proteinuria of renal origin, or combinations evaluated
the influence of consuming a therapeutic renal diet
over a 3 to 12 month period.(7) Of the 36 dogs, 20 had dilute urine, 6 had persistent proteinuria, and 10 had both; 50% had an elevated SDMA at baseline. Serum creatinine, BUN, and SDMA decreased from baseline to 3 months and remained decreased from baseline in the 20 dogs that completed the 12 month study. Proteinuria was reduced in 12 of 16 dogs with proteinuria. Thirty- two geriatric research cats were fed two diets containing low phosphorous and protein with added omega-3 fatty acids, and L-carnitine; the second test diet contained median chain triglycerides.(12) Over a 6 month feeding period, SDMA decreased slightly, but not significantly and GFR increased in cats fed the second test diet but decreased in the cats fed the first test diet; however, results were not significantly different from baseline. A study of client-owned cats has also been published.
(10) Cats consuming owner’s choice foods showed significant increase in SDMA at 3 and 6 nonths whereas in cats consuming a test diet (described above), SDMA did not change. During the study 23 cats had an increased SDMA including 17 cats in the owner’s choice food group and 6 in the test diet group. In the 6 cats fed the test food, SDMA decreased or remained stable in 4 cats, and increased in 2 cats, whereas in the 17 cats in the owner’s choice food group, SDMA increased in 13 cats and decreased or remained stable in 4 cats. Results of these studies suggest that nutritional intervention may be beneficial in some older dogs and cats with CKD1 and that SDMA is a useful biomarker; however, there is variability in SDMA and trends in changes in SDMA may be more important in managing patients with CKD.

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