Renal Tubular Acidosis in Cats
Renal tubular acidosis (RTA) is a rare syndrome that causes the kidney to be unable to excrete acid through the urine, leading to extreme acidity of the cat's blood. Cats with RTA will also have abnormal levels of potassium in the blood. This condition occurs as a part of the metabolic process, by which food is transformed into energy.
Although RTA is seen in both cats and dogs, it rarely occurs in cats. If you would like to learn more about how this disease affects dogs, please visit this page in the PetMD pet health library.
Symptoms and Types
Some common symptoms which may be observed include:
- Weight loss
- Muscle weakness
- Bloody urine (hematuria)
- Excessive thirst (polydipsia)
- Frequent urination (polyuria)
- Difficulty urinating (due to bladder stones)
There are two primary RTA types: type 1 RTA (or distal), involves reduced hydrogen ion secretion in the kidney, and type 2 RTA (or proximal), which is characterized by the inability to excrete acid into the urine. Abnormal metabolic processing of bicarbonates is referred to as metabolic acidosis, and is marked by abnormally high levels of acids in the blood, and abnormally low levels of acids in the urine.
Type 2 proximal RTA occurs because of reduced bicarbonate reabsorption from the kidney. This activity causes an imbalance of acids in the blood.
Some of the common underlying causes of RTA include infection of the kidney and ureter(s), and feline hepatic lipidosis, a type of liver disease. However, there are times when the RTA is idiopathic.
Your veterinarian will perform a complete physical exam on your cat, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel. Your veterinarian will use the results of the blood work to rule out or confirm an underlying systemic disease. You will need to provide a thorough history of your cat's health leading up to the onset of symptoms.
The results from a blood gases analysis, along with the results of the electrolyte panel, should indicate a normal anion gap (sum of the cations minus the anions in the plasma) with metabolic acidosis, indicating that the alkaline urine is abnormal. This is a key diagnostic feature of type 1 RTA.