Symptoms & Treatments for Feline Chronic Kidney Disease

Chronic kidney disease (CKD) in cats is not related to their age or size, and it affects a wide range of cats. It is crucial to have a clear understanding of CKD and provide appropriate care.

Cat's Kidney Structure

The primary functional unit of the kidneys is the nephron, which consists of glomeruli and tubules.

Glomeruli primarily filter water, uric acid, glucose, and small molecular proteins, but they cannot filter larger molecules like albumin and globulin.

Tubules are responsible for reabsorption, secretion, and excretion. They reabsorb almost all glucose, proteins, amino acids, and water, but creatinine is not reabsorbed.

The main functions of the kidneys include:

Maintaining acidbase balance by excreting acids and retaining bases.

Synthesizing active vitamin D, which cats convert from inactive vitamin D in their food through the liver and then the kidneys to promote calcium absorption in the intestines.

Excreting toxins, initiating the RAAS system, and maintaining normal blood pressure, renal blood flow, and glomerular filtration rate.

Secreting Erythropoietin (EPO) to promote red blood cell production in the bone marrow.

Understanding Chronic Kidney Disease

CKD is characterized by the loss of the kidneys' secretory and regulatory functions, which are difficult to recover. It primarily manifests as a reduction in nephrons, overfiltration of the glomeruli, damage to the tubules and interstitium, and an imbalance in correction, leading to impaired urine concentration, decreased urine specific gravity, decreased blood potassium, increased blood phosphorus and blood pressure, anemia, and proteinuria.

Generally, if the kidney function is reduced by 30% or more, and the disease has been present for three months or more, it can be considered CKD. However, due to the kidneys' compensatory mechanisms, even if the kidneys retain only 25% of their function, there may be no clinical symptoms.

Causes of Chronic Kidney Disease

CKD is usually caused by the accumulation of many small acute kidney injuries, especially when cats are dehydrated and given medications or anesthesia, which can cause severe kidney damage.

There are many causes of CKD, including:

Chronic interstitial nephritis and tubulointerstitial nephritis the most common cause, accounting for over 70% of cases.

Chronic glomerulonephritis accounting for over 15% of cases.

Renal lymphoma accounting for over 11% of cases.

Chronic obstruction sometimes the renal pelvis does not expand significantly, only blocking the ureter, which may require an imaging study.

Hypercalcemic nephropathy

Interstitial granuloma caused by feline infectious peritonitis

Viruses retroviruses or tuberculosis viruses

Some causes are more common in certain cat breeds, such as polycystic kidney disease in Persian, Himalayan, and Singapura cats, and amyloidosis in Abyssinian, Siamese, and Japanese Bobtail cats.

Treatment of Chronic Kidney Disease

All treatment methods for CKD must be tailored to the individual cat's condition and adjusted continuously based on monitoring and outcomes.

Generally, treatment can be divided into two categories: slowing the progression of CKD to allow the kidneys to last longer and reducing mortality and other complications through treatment.

Treatment of Proteinuria

Telmisartan can be used as the primary treatment drug (if the cat has CKD, hypertension, and proteinuria, telmisartan is the first choice). Other drugs like angiotensin II and aldosterone can cause kidney fibrosis; benazepril can lower blood pressure and reduce glomerular filtration rate, so it should be used with caution in cats with poor hydration, dehydration, or uremia.

Treatment of Hyperphosphatemia

Limiting phosphorus intake is important. The range may vary depending on the stage, with optimal levels at 3.03.5 mg/dl (11.13 mmol/L) for stage 1, 2.74.6 mg/dl (0.91.5 mmol/L) for stage 2, less than 5.0 mg/dl (