serum chemistry panel, and urinalysis. The finding of dilute urine,
coupled with an elevated level of
kidney toxins in the blood, indicates that kidney function is compromised. The two primary renal
toxins that we monitor are blood
urea nitrogen (often abbreviated
BUN) and creatinine. Other abnor-malities, such as elevated phosphorus, low potassium, and anemia
(decreased amount of red blood
cells) might also be detected.
Although CKD is incurable, a
variety of diet and drug interventions are now available that
might slow the progression of the
disorder, improve the cat’s quality
of life, and extend a cat’s survival
time. Cats who are suitable candidates may be eligible for a kidney
transplant. This is a major endeavor
requiring the expertise of a skilled
surgical team at a university or
referral center. The procedure, as
you might expect, is very expensive,
and post-operatively, the cat will
require long-term administration of
drugs to prevent rejection of the
Acute kidney injury
Although chronic kidney disease
is by far the most commonly
seen feline kidney disorder, other
kidney ailments are occasionally
encountered in cats.
Acute renal failure (the currently
preferred term is acute kidney injury,
abbreviated AKI) is a disorder char-
acterized by a sudden, dramatic
decrease in kidney function.
This is a serious condition that,
if not recognized and addressed
quickly, can lead to rapid decline
and possible death. Unfortunately,
the clinical signs of AKI — poor
appetite, vomiting, extreme leth-
argy, weakness, decreased urine
production — are nonspecific and
might result in delayed recognition
that the cat is ill.
The most common causes
of AKI in cats are ingestion of
ethylene glycol (antifreeze) and
ingestion of lilies. Many people
are unaware that all parts of the
lily plant — even the pollen — are
toxic to cats if ingested. Other
possible causes include unintentional administration of toxic
drugs (for example, giving ibupro-fen to a cat), and any situation
that results in decreased blood
flow to the kidneys (for example,
Bacterial infection of the kidney,
called pyelonephritis, is occasionally seen in cats. In this disorder,
one or both kidneys become
enlarged and tender, and the cat
usually develops a fever, high
white blood cell count, and poor
appetite. Elevated BUN and creatinine levels might occur if kidney function becomes impaired.
Pyelonephritis usually requires
hospitalization and treatment with
intravenous fluids and antibiotics.
Kidney stones (nephroliths) are
uncommon in cats and are usually
of minimal clinical consequence.
However, if a small stone leaves
the kidney and becomes lodged
in the ureter (the tube that connects the kidney to the bladder),
the obstruction of urine flow
causes a pressure buildup in the
kidney that can lead to functional
impairment and, if not relieved,
ultimate destruction of the kidney. Fortunately, this is an uncommon occurrence.
Feline infectious peritonitis
Feline infectious peritonitis is a
viral infection that may affect
cats of all ages, although it has a
predilection for young cats. There
are two forms of the infection:
the “wet” form, in which fluid
accumulates in the abdomen (and
sometimes the chest cavity) and
the “dry” form, in which clusters
of inflammatory cells infiltrate
various solid organs in the body.
The liver and kidney are the favorite target organs for the FIP virus.
When FIP affects the kidneys,
their function eventually becomes
impaired as the viral infection
progresses. At present, there is
no treatment for FIP, and all cats
eventually succumb to this disease. Treatment of FIP, however, is
a very active area of research, and
veterinarians are more optimistic
than ever that an effective treatment will soon be discovered.
Sadly, cancer of the kidney is a
well-documented illness in cats.
The cancer can be primary, i.e.
arising from the kidney itself. An
example would be a renal carcinoma. In primary kidney cancer,
usually only one kidney is affected.
Cancer can also spread from other
organs to the kidneys. The most
common type of cancer occurring
in feline kidneys is lymphoma, in
which both kidneys are infiltrated
with cancerous lymphocytes. Renal
carcinomas, being unilateral, may
be amenable to surgical removal.
Lymphoma of the kidneys, however,
is almost always bilateral and must
be treated with chemotherapy.
Dr. Arnold Plotnick is the found-
er of Manhattan Cat Specialists,
a feline-exclusive veterinary
practice on Manhattan’s upper
west side. He is also an author
of The Original CAT FANCY Cat Bible. Dr.
Plotnick is the former Ask the Veterinarian
columnist for CAT FANCY magazine and
is a frequent contributor to feline publica-
tions and websites, including his own blog,
Cat Man Do. He lives in New York City
with his cat, Mittens.