Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

NEPHRITIS AND NEPHROSIS
Nephritis and nephrosis are diseases of the kidneys that produce scarring and
kidney failure. The diagnosis of nephritis or nephrosis is established by kidney
biopsy.
Nephritis is an inflammatory process associated with certain infectious diseases,
including canine hepatitis, canine ehrlichiosis, Lyme disease, Rocky
Mountain spotted fever, and others. Dogs with systemic lupus erythematosus
and chronic pancreatitis can develop nephritis. A familial predisposition for a
condition called glomerulonephritis occurs in Doberman Pinschers, Samoyeds,
and Bull Terriers. In Bull Terriers this is an autosomal dominant problem.
Nephrosis is the result of degenerative changes caused by toxins and
poisons that target the kidneys or by ischemia (inadequate blood flow to the
kidneys). The most important nephrotoxins are aspirin, ibuprofen, and butazolidin.
Certain antibiotics are nephrotoxic, particularly when given for prolonged
periods or in high doses. They include polymyxin B, gentamicin,
amphotericin B, and kanamycin.
The nephrotic syndrome may develop in dogs with nephritis or nephrosis.
Large amounts of protein are excreted into the urine from the damaged kidneys.
In consequence, serum protein levels are low. This results in loss of fluid
from the blood, which pools in the legs (edema), the abdominal cavity
(ascites), and the chest cavity (pleural effusion). The swollen limbs and potbellied
appearance of the nephrotic syndrome suggest right-sided congestive
heart failure, but laboratory studies will distinguish between this condition
and kidney problems.
Treatment: If caught in time, nephritis and nephrosis respond to elimination
of the predisposing cause. For treatment of the nephrotic syndrome, see
Uremia, page 424. Nephritis caused by Lyme disease is usually fatal.
UREMIA (KIDNEY FAILURE)
THE URINARY SYSTEM • 423
Kidney failure is defined as the inability of the kidneys to remove waste products
from the blood. The buildup of toxins produces the signs and symptoms of
uremic poisoning. Kidney failure can appear suddenly (acute kidney failure) or
come on gradually over months. Most cases are of the gradual onset type and
are caused by nephritis and nephrosis.
Causes of acute kidney failure include:
• Complete urinary tract obstruction caused by a stone
• Rupture of the bladder or urethra
• Shock, with inadequate blood flow to the kidneys
• Congestive heart failure with low blood pressure and reduced blood flow
to the kidneys