EDEMA is visible in this dog's face. Would the edema be confined to the subcutaneous tissues of the head of an animal with the Nephrotic Syndrome?
The edema is generalized as seen in this visual. Can you think of a pathogenesis for the edema and the SYNDROME?
There are four components of the nephrotic syndrome - PROTEINURIA, HYPOPROTEINEMIA, EDEMA and HYPERCHOLESTEROLEMIA.
Note that a common cause for these signs is increased permeability of the glomerulus. Damage to the glomerulus would result in increased permeability, allowing protein to escape from the blood into the glomerular filtrate. This would result in hypoproteinemia with subsequent edema formation due to decreased oncotic pressure. Hypercholesterolemia is thought to result from altered metabolism that occurs following the protein loss.
There is a life threatening risk for animals with nephrotic syndrome. Do you know the risk?
Because the animal is dehydrated AND hypoproteinemic, the addition of vascular fluids will further dilute the plasma proteins. Thus edema would become more severe due to the decreased plasma oncotic pressure. Pulmonary edema is a serious and often fatal consequence. Uremic animals (especially proteinuric and uremic animals, those with glomerular disease) are at risk for another fatal outcome. Do you remember this one?
There are proteins which inhibit coagulation (i.e. Anti-thrombin III) that are lost in the urine of proteinuric animals. Since they are depleted, inhibition of coagulation is decreased, and thrombosis may result.
Can you think of some types of glomerular lesions (or diseases) that would result in the NEPHROTIC SYNDROME?
Any alteration in the glomerular capillary wall may result in altered glomerular ultrafiltration. Renal glomerular amyloidosis is one example of glomerular disease that can result in the nephrotic syndrome. The amyloid deposits would alter glomerular ultrafiltration and result in increased loss of protein (proteinuria).