Glomerular Disease in Cats
Glomerular disease (chronic kidney disease) is relatively uncommon in cats. It affects both purebreds and mixed-breed kitties, and can be an inherited disorder called amyloidosis in Abyssinians, Orientals and Siamese cats1.
Does glomerular disease have other names?
Veterinarians use a number of different terms interchangeably when describing “glomerular disease.” I’ll warn you, in advance, none of them are easy to pronounce:
- Protein losing nephropathy
What are glomeruli and why should you care?
To understand glomerular disease, it’s important to first understand glomeruli. Each kidney contains millions of glomeruli; these are microscopic filtration units that interface with the blood vessels that supply the kidneys. I like to think of the glomeruli as a tiny sieve or colander because the size of glomerularpores dictate which substances within the blood are allowed to enter the fluid that ultimately becomes urine. Normal glomeruli do not allow larger protein molecules, such as albumin, to pass into the urine.
Glomeruli damage causing glomerular disease
Glomeruli damage is what leads to glomerular disease. The most common means by which glomeruli are damaged include:
- Inflammation, particularly that which is immune mediated (autoimmune) in nature
- A form of scarring referred to as glomerulosclerosis
- Persistent high pressure blood flow to the kidneys (elevated blood pressure)
- A protein problem called amyloidosis.
When glomeruli are damaged, they become “leakier,” thus allowing larger protein molecules to filter into the urine. This leads to a condition called proteinuria, which means too much protein in the urine.
What problems are associated with glomerular disease?
Glomerular damage, particularly when left untreated, hastens the progression of chronic kidney disease.
Glomerular damage can arise as a primary disease process, or it can occur secondary to another, underlying disease—including:
- Feline leukemia virus
- Feline immunodeficiency virus (FIV)
- Feline infectious peritonitis (FIP)
- Cholangiohepatitis (liver inflammation)
- Infectious diseases (bacterial, fungal, tick-borne)
- Immune mediated (autoimmune) diseases
Symptoms of glomerular disease
In and of itself, protein loss in the urine does not cause any symptoms. This is why some cats with glomerular disease, particularly early on, appear completely normal. When symptoms do arise, they are usually related to one or more of the following:
- Underlying disease causing the glomerular damage (see the list above)
- Chronic kidney disease
- Complications associated with glomerular damage (high blood pressure, decreased protein in the bloodstream, blood clot formation)
Commonly observed symptoms in cats with chronic kidney disease include: