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An Urban Experience
S. Vaden1
1North Carolina State University, Department of Clinical Sciences, Raleigh, USA
Standard Therapy and Immunosuppression of Dogs with Protein Losing NEphropathy
Shelly L. Vaden
North Carolina State University CVM, Raleigh, NC
The prevalence of chronic kidney disease (CKD) in
dogs may be as high as 1.5%; glomerular disease may be the cause of renal injury in 50% or more of these dogs. Because glomerular diseases are common in
dogs and outcomes are not always favorable, there has been an enhanced effort to improve early recognition, diagnosis and treatment of all renal diseases in dogs, with particular emphasis on proteinuric renal diseases. In support of this effort, the WSAVA Renal Standardization Project developed a classification system for glomerular pathologic findings in dogs. At the same time, the International Renal Interest Society (IRIS) developed clinical guidelines for the management of dogs with glomerular disease. The latter initiative used a formal consensus method for developing several sets of recommendations, including those for standard therapy, immunosuppressive therapy when pathologic diagnosis is known and immunosuppressive therapy without a renal biopsy. The purpose of this presentation is to discuss those recommendations.
Standard Therapy
Standard therapy is the foundation of care that should given to all dogs with glomerular disease, regardless
of the inciting cause, and includes inhibition of the renin-angiotensin-aldosterone system (RAAS), and
the management of dietary intake, hypercoagulability, systemic hypertension and body fluid volume. Standard therapies be considered when the UPC is persistently >0.5.
Inhibition of RAAS. The RAAS can be therapeutically targeted to alter renal hemodynamics, leading to a reduction in proteinuria. Angiotensin-converting enzyme inhibitors (ACEi; e.g., enalapril, benazapril), angiotensin- receptor blockers (ARB; e.g., losartan, telimisartan), and aldosterone receptor blockers (e.g., spironolactone)
are the agents that target RAAS. For most dogs with glomerular proteinuria, an ACEi is the initial agent used. Typically given once daily initially, more than half of the
dogs will eventually need twice daily administration
and perhaps additional dosage escalations. Severe worsening (i.e., >30% increase from baseline) of azotemia due to ACEi administration alone seems uncommon; dehydrated dogs may be at highest risk. The ARB most commonly used in dogs with glomerular disease is telmisartan. Early results show great promise with use of this agent.
UPC, urinalysis, systemic arterial blood pressure and serum albumin, creatinine and potassium concentrations should be evaluated at least quarterly in dogs given
a RAAS inhibitor. The UPC, serum creatinine, serum potassium and blood pressure should be evaluated 1-2 weeks after an ACEi or ARB has been added or altered. The desired outcome is a reduction in proteinuria without a severe worsening of renal function (i.e., >30% increase in creatinine), a critical increase in serum potassium
or the unlikely development of hypotension (more common with telmisartan). Changes in the magnitude
of urine protein are assessed through trends in the UPC over time. Day-to-day variations in the UPC occur. To adjust for this, monitoring requires either averaging 2-3 serial UPC or measuring a UPC in urine that has been pooled from 2-3 collections. The target for reduction
is a UPC of <0.5; however, when that is not possible,
a partial response with a reduction in the UPC of 50%
or more is the alternative target. If this target is not achieved and there are no adverse effects, the dosage may be increased every 4-6 weeks. Dogs with serum potassium concentrations of >6 mEq/L should be monitored closely; therapy should be modified when serum potassium concentrations are >6.5 mEq/L. Pseudohyperkalemia should be eliminated as a cause by measuring the potassium concentration in lithium heparin plasma. True hyperkalemia can be managed by reducing the drug dosage, or by feeding diets that are reduced in potassium.
Modified dietary intake. Modification of dietary intake has a central role in the management of all dogs with kidney disease via delaying progression of kidney disease and reducing proteinuria. The consensus recommendation is that dogs with glomerular disease should be fed a modified protein diet with reduced n-6/n-3 polyunsaturated fatty acids (PUFA) ratio of approximately 5:1 (most commercially available renal diets fulfill this goal). It is unknown if there is additional benefit of supplementing n-3 PUFA beyond providing this dietary ratio. If supplementing, care should be taken to provide adequate antioxidants (e.g., vitamin E). The sodium chloride dietary intake also should be reduced. Salt restriction may enhance the beneficial effects of agents used to inhibit RAAS and reduce fluid retention.

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