Page 1166 - Clinical Small Animal Internal Medicine

1104 Section 10 Renal and Genitourinary Disease

Because neither an ACEi nor an ARB as a single agent
Box 121.1 Management of glomerular disease in dogs
VetBooks.ir Inhibition of renin‐angiotensin‐aldosterone system provides complete blockade of the RAAS, there may be
an added benefit to combined therapy; however, this
approach should be used with caution as it has been
Angiotensin‐converting enzyme inhibitors (e.g., enal-
april, benazapril) associated with a higher risk of kidney failure and death
Angiotensin receptor blockers (e.g., telmisartan) in people. Serum aldosterone increases over time (i.e.,
Aldosterone receptor blockers (e.g., spironolactone) aldosterone escape) in people treated even with maximal
dosages of ACEi and ARB; prolonged hyperaldosteron-
Modified dietary intake ism may have adverse effects on the heart, systemic
Increased n‐3 polyunsaturated fatty acids blood vessels, and glomeruli. People with hyperaldoster-
Modified protein content onism may have a greater reduction in proteinuria when
Reduced sodium chloride an aldosterone receptor antagonist is added to their ther-
apy. Spironolactone has been used most commonly in
Antithrombotic therapy dogs; however, there are few data that support the effi-
Aspirin cacy of this drug in dogs in the management of glomeru-
Clopidogrel lar disease. Spironolactone should only be effective if
Antihypertensive therapy serum aldosterone concentrations are increased. This
Angiotensin‐converting enzyme inhibitors (e.g., enal- drug could be tried in animals that have high serum
aldosterone concentrations and persistent proteinuria in
april, benazapril) spite of treatment with an ACEi, ARB or both, with the
Angiotensin receptor blockers (e.g., telmisartan) understanding that its efficacy in reducing proteinuria
Calcium channel blocker (i.e., amlodipine)
has not been established.
Manage body fluid volume All dogs that are being treated for glomerular disease
Careful fluid therapy when fluid deficit present via RAAS inhibition should be monitored at least quar-
Diuretics for fluid excesses that are contributing to res- terly by a minimum of UPC, urinalysis, systemic arterial
piratory distress blood pressure and serum albumin, creatinine and potas-
sium concentrations. The UPC, serum creatinine, serum
Immunosuppressive therapy for immune complex‐ potassium, and blood pressure should be evaluated 1–2
mediated glomerulonephritis weeks after an ACEi or ARB has been added or altered.
The desired therapeutic effect is a reduction in proteinu-
ria without a severe worsening of renal function (i.e.,
Angiotensin‐converting enzyme inhibitors (ACEi; e.g., >30% increase in serum creatinine), a critical increase in
enalapril, benazapril), angiotensin receptor blockers (ARB; serum potassium or the unlikely development of hypoten-
e.g., telmisartan), and aldosterone receptor blockers (e.g., sion. Changes in the magnitude of urine protein are most
spironolactone) are the agents that target RAAS. accurately measured by assessing trends in the UPC over
For most dogs with glomerular‐range proteinuria, time. Day‐to‐day variations in the UPC occur in most
an ACEi is the initial agent used. Typically, an ACEi is dogs with glomerular proteinuria, with greater variation
given once daily initially, but more than half of the dogs occurring in dogs with UPC >4. Consideration should be
will eventually need twice‐daily administration and per- given to either averaging 2–3 serial UPC or measuring a
haps additional dosage escalations. Although worsening UPC in urine that has been pooled from 2–3 collections.
azotemia is a concern regarding the use of ACEi, severe The target for reduction is a UPC of <0.5 without inap-
worsening (i.e., >30% increase from baseline) due to propriate worsening of renal function; however, when
ACEi administration alone seems uncommon and dogs that is not possible, a partial response with a reduction in
that are dehydrated may be at highest risk. Less is known the UPC of 50% or more is the alternative target.
about the use of an ARB in dogs with glomerular disease Dogs with serum potassium concentrations of >6 mEq/L
although they have been extensively studied in people. should be monitored closely and therapy should be modi-
The ARB that has historically been used in dogs with glo- fied when serum potassium concentrations are >6.5 mEq/L.
merular disease is losartan, although it has not always Before modifying treatment, pseudohyperkalemia, due to
been effective. Recently, telmisartan has been shown to the high potassium content of some blood cells which may
be very effective in some dogs and may prove useful as occur in dogs with glomerular disease, should be elimi-
the initial line of therapy. Telmisartan has a more pro- nated as a cause by measuring the potassium concentra-
found effect on lowering blood pressure than ACEis and tion in lithium heparin plasma. True hyperkalemia can be
should be used carefully in dogs that have low basal blood managed by reducing the ACEi or ARB drug dosage, dis-
pressures (e.g., systolic <140 mmHg). continuing spironolactone administration, or by feeding