Urinary 2 Flashcards
Name two conditions that commonly cause hemoglobinuric nephrosis in dogs.
(1) IMHA (immune-mediated hemolytic anemia). (2) Leptospirosis.
In which species of domestic animal is glomerulonephritis the most common cause of renal failure?
Dogs.
Name one dog breed that has a familial/hereditary/genetic predisposition to renal amyloidosis.
Shar Pei.
You are performing a necropsy on a dog and notice that both kidneys are very darkly stained and that the renal pelvic fat is yellow. This dog has a history of passing red-brown urine. What is the most likely cause of this?
Hemoglobinuric nephrosis due to intravascular hemolysis (several causes, including IMHA in dogs, copper toxicity in sheep, leptospirosis in cattle & dogs & red maple toxicosis in horses). Myoglobinuric nephrosis is less likely because it tends not to stain fat yellow.
Explain the pathogenesis of the hypercholesterolemia that may be seen in the nephrotic syndrome.
Loss of plasma proteins into urine –> liver responds by generalized increased protein production, and cholesterol production is also upregulated.
Proteinuria, although suggestive of glomerular disease, is not exclusively caused by glomerular disease. What else can cause proteinuria?
Inflammation of the lower urinary tract.
Which type of cell in the renal corpuscle is responsible for phagocytosis of deposited immune complexes?
Mesangial cell.
How are the basement membranes of the glomerular capillary tufts different from basement membranes elsewhere in the body?
The glomerular basement membrane is thick (300-350 nm). Its negative charge and collagen network impede the passage of large protein molecules, most importantly albumin and hemoglobin.
Describe the typical gross appearance of a kidney affected by amyloidosis.
Grossly, kidneys affected by amyloid deposition are diffusely tan, waxy (firm), friable and of normal size or slightly enlarged.
What clinicopathologic finding is the hallmark of glomerular disease?
Proteinuria.
Why is it deleterious to the glomerulus having immune complexes deposited in the glomerular basement membrane? Explain the pathogenesis.
Deposition in glomeruli –> Complement fixation –> Chemotaxis of neutrophils –> Release of harmful mediators of inflammation –> Continued damage by release of inflammatory mediators from monocytes in chronic stages. All this leads to thickening of the glomerular basement membrane. Paradoxically, this thickening makes the GBM “leaky”, probably due to changes in charge and pore size.
How often is the specific cause of glomerulonephritis in domestic animals identified?
Rarely.
You are performing a necropsy on a foal and notice that both kidneys contain dozens to hundreds of randomly scattered pinpoint white foci. What is the most likely bacterial cause of this?
Actinobacillus equuli.
Name a condition that commonly causes hemoglobinuric nephrosis in horses.
Red maple toxicity.
What are the two major categories of immune complex deposition in the glomerular basement membrane and which is by far the more common in domestic animals?
(1) Deposition of circulating antibody-antigen complexes that have formed in response to a variety of chronic diseases. (2) Autoantibodies directed at the glomerular basement membrane. Cause number 1 is by far the most common in domestic animals.
Name a condition that commonly causes hemoglobinuric nephrosis in cattle.
Leptospirosis.
Which parts of the lily (leaves or flowers) are nephrotoxic to cats?
Both leaves and flowers are toxic.
How are the endothelial cells lining the glomerular capillary tufts different from endothelial cells elsewhere in the body?
Glomerular capillary endothelial cells have pores (fenestrations) in their cytoplasm that make them “leaky” (i.e., freely permeable to most blood constituents except red blood cells, white blood cells and platelets).
Give two reasons why renal tubules are preferentially damaged by circulating toxins.
[Any two] (1) The kidneys receive 25% of cardiac output, therefore a circulating toxin inevitably reaches the kidneys. (2) Substances are filtered by the glomerulus and concentrated in the renal tubules. (3) Renal tubular epithelial cells are metabolically active (especially proximal convoluted tubules) so these are damaged first.
What is the most common cause of renal failure in dogs?
Immune-mediated glomerulonephritis.