A 12-year-old spayed female Persian cat presents with chr...

Thank you for reaching out regarding this complex feline patient. A 12-year-old Persian with IRIS Stage 3 CKD, chronic vomiting, weight loss, and significant hypertension (systolic BP 180 mmHg) requires careful, multi-faceted management. Addressing the hypertension is critical to minimize further target organ damage, particularly to the kidneys, eyes, and brain.

Amlodipine Dosing

For feline hypertension, amlodipine besylate is the calcium channel blocker of choice due to its efficacy and safety profile.

The appropriate starting dose for cats is 0.625 mg PO once daily.

While some clinicians might consider starting even lower in a very frail patient, a systolic blood pressure of 180 mmHg in an IRIS Stage 3 CKD cat warrants a standard initial dose to achieve a therapeutic effect. Amlodipine works primarily as an arterial dilator, reducing systemic vascular resistance and thereby lowering blood pressure. It generally does not significantly impact glomerular filtration directly, and in many cases, can be renoprotective by reducing intraglomerular hypertension.

Monitoring Protocol

Close monitoring is essential after initiating amlodipine, especially given her concurrent CKD and clinical signs.

Blood Pressure Reassessment:

* Recheck systolic blood pressure in 7-10 days after starting amlodipine.
The goal is to reduce systolic blood pressure to below 160 mmHg, ideally between 120-150 mmHg. Avoid dropping the pressure too aggressively, as this could* theoretically compromise renal perfusion in some fragile CKD patients, though this is uncommon with amlodipine.
* If the blood pressure remains >160 mmHg after 7-10 days, the amlodipine dose can be increased to 1.25 mg PO once daily. Subsequent dose adjustments can be made by 0.625 mg increments as needed, up to a maximum of 2.5 mg PO once daily, with rechecks every 7-10 days after each dose change.

Renal Parameters (BUN, Creatinine, SDMA, Phosphorus):

* Recheck a full chemistry panel, including BUN, creatinine, and phosphorus, concurrently with the first blood pressure recheck (7-10 days post-initiation).
* Monitoring SDMA is also valuable as a more sensitive marker of GFR.
* While amlodipine is generally renoprotective, it's crucial to ensure that the reduction in systemic blood pressure is not causing an acute worsening of azotemia due to decreased renal perfusion. This is rare, but important to rule out in a cat with advanced CKD.
* Continue to monitor phosphorus levels closely. With a baseline of 8.0 mg/dL, managing hyperphosphatemia is a high priority in Stage 3 CKD.

Electrolytes:

* Monitor potassium, sodium, and chloride levels with the chemistry panel. While amlodipine does not directly affect electrolytes, these are important to track in any CKD patient.

Clinical Signs:

* Monitor for any signs of lethargy, weakness, anorexia, or worsening vomiting, which could indicate hypotension or an adverse reaction.
* Also, be vigilant for potential side effects such as gingival hyperplasia, which can occur with chronic amlodipine use, though it is usually mild.

Integrated Management Considerations

While the focus of your question is amlodipine, it's vital to remember the holistic picture for this cat:

* Renal Diet: Transitioning to a therapeutic renal diet is paramount for managing CKD, but careful introduction is needed given her chronic vomiting and weight loss. Palatability is key.
* Phosphate Binders: With a phosphorus of 8.0 mg/dL, a phosphate binder (e.g., aluminum hydroxide) is indicated and should be started with food immediately.
* Addressing Vomiting/Weight Loss: This will likely require further investigation beyond just managing CKD and hypertension. Differentials for chronic vomiting and weight loss in a senior cat include inflammatory bowel disease (IBD), gastrointestinal lymphoma, pancreatitis, hyperthyroidism (though less likely with CKD Stage 3, still worth screening if not already done), and other metabolic derangements. An abdominal ultrasound and baseline GI diagnostics (fPLI, cobalamin/folate) would be my next steps here.
* Fluid Status: Ensure adequate hydration. If she's persistently vomiting, subcutaneous fluids may be necessary.

High confidence in this approach for managing hypertension in this complex feline CKD patient. Remember to always integrate findings from all systems to provide comprehensive care.