Page 243 - Problem-Based Feline Medicine

15 – THE CAT WITH POLYURIA AND POLYDIPSIA 235

Dehydration is commonly present because of inade-
DISEASES CAUSING POLYURIA AND quate water intake to balance the excessive fluid loss in
POLYDIPSIA
urine.
Ocular signs related to hypertension are common, e.g.
CHRONIC RENAL FAILURE***
scleral or conjunctival injection, hyphema or retinal
hemorrhage, retinal edema, retinal vessel tortuosity,
Classical signs
retinal detachment.
● Inappetence, anorexia, weight loss.
Terminally, seizures, stupor or coma may occur.
● Lethargy.
● Vomiting. Small and/or irregular kidneys may be palpable but
● Polyuria, polydipsia. occasionally kidneys are enlarged (associated with
● Small ± irregular kidneys, occasionally amyloid deposition, neoplasia or cystic kidneys).
enlarged kidneys.
Diagnosis
See main reference on page 333 for details (The Thin,
Inappetent Cat). Increased blood urea (BUN) and creatinine
(azotemia) concentrations together with a urine spe-
cific gravity of 1.007–1.030 (usually 1.007–1.015) is
considered presumptive evidence of renal failure.
Clinical signs
Other findings that may or may not be present are
Inappetence or anorexia is the most common sign and the following:
occurs in 80% of cats.
Hyperphosphatemia
Weight loss is frequent, together with poor body con- ● Serum phosphorus concentration increases when
dition. glomerular filtration rate (GFR) is below approxi-
mately 20% of normal, and tends to parallel BUN
Lethargy or depression are common signs.
concentration.
Polyuria and polydipsia are reported by owners in
Hypokalemia (< 3.5 mmol/l) occurs in 20% of cats.
40% of cats. Nocturia or urination in inappropriate
● Clinical signs of inappetence and generalized
places may also be observed and must be differentiated
muscle weakness (such as wobbliness, inability to
from other causes including behavioral.
jump, stiff, stilted gait and ventroflexion of the
Weakness occurs in nearly 50% of cats and is often neck) may occur when potassium < 3 mmol
associated with hypokalemia. Cats may appear reluc- (mEq)/L.
tant to jump or unsteady with jumping, and be less ● Respiratory muscle failure and death may occur at
active. < 2 mmol (mEq)/L.
Constipation is common and results from dehydration. Hyper- and hypocalcemia are infrequent abnormali-
ties, and result from derangements of calcium metabolism
Vomiting is less common, and if present, is usually
associated with renal secondary hyperparathyroidism.
intermittent and often low grade.
● Most cats have normal or low calcium; 10–20%
Diarrhea is rare, but very occasionally is hemorrhagic have mild to moderate hypercalcemia (≤ 3.1
from uremic enterocolitis. mmol/L, 12.5 mg/dl).

Halitosis, ulcers on the oral mucosa or tongue, brown- Acidosis is common (approximately 80% of cats),
ish discoloration of dorsal surface of tongue, or slough- and is evident as decreased bicarbonate and increased
ing of anterior of tongue may occur in advanced anion gap.
disease.
Normochromic, normocytic, non-regenerative ane-
Pale mucous membranes from anemia may be evident. mia is common when chronic renal failure is advanced.