Page 264 - Problem-Based Feline Medicine

256 PART 4 CAT WITH URINARY TRACT SIGNS

Pituitary ablation using cryosurgery may be effective nary tract signs including dysuria, inappropriate uri-
(refer to current literature). nation, pollakiuria and stranguria (23%), and weak-
ness and/or muscle tremors (14%).
The long-acting somatostatin analog, octreotide has the
potential to lower GH concentrations, but its use has A palpable parathyroid mass is present in more than
not been reported in cats. half the cats.

Diagnosis
Prognosis
A presumptive diagnosis is based on finding hypercal-
Without specific treatment for the GH excess, the long-
cemia and demonstrating a parathyroid mass on pal-
term prognosis is poor; most eventually die with con-
pation or cervical ultrasound.
gestive heart failure, renal failure or neurologic signs
from the expanding pituitary tumor within 1–2 years. PTH concentrations are inappropriately high for the
Short-term prognosis is reasonable, provided sufficient calcium concentration, and are in the normal range or
doses of insulin are administered to control hyper- increased.
glycemia and resolve the clinical signs of diabetes
A definitive diagnosis is by surgical removal of the
mellitus.
parathyroid mass and normalization of serum calcium
concentrations. Vitamin D and calcium are usually admin-
istered following surgical removal to prevent life-threaten-
HYPERPARATHYROIDISM
ing hypocalcemia (see page 248, Hypercalcemia).
Classical signs
PRIMARY HYPERALDOSTERONISM
● Anorexia and lethargy.
● Vomiting.
Classical signs
● Weight loss.
● Dysuria, inappropriate urination, ● Weakness, cervical ventroflexion.
pollakiuria, stranguria. ● Inappetence and weight loss.
● Weakness, tremors. ● Polyuria, polydipsia.
● Palpable cervical mass. ● Blindness.

See main reference on page 245 for details of hypercal-
cemia (The Cat With Polyuria and Polydipsia). Pathogenesis

Primary hyperaldosteronism is a very rare cause of
Clinical signs polyuria and polydipsia, and results from an aldos-
terone-secreting adrenal tumor.
Primary hyperparathyroidism is an uncommon
cause of hypercalcemia, and is usually the result of an Aldosterone stimulates reabsorption of sodium in
autonomous adenoma producing excess PTH. It is usu- the distal tubule and collecting ducts. To maintain elec-
ally a solitary functional adenoma, although bilateral trical and osmotic neutrality, chloride, bicarbonate and
cystadenomas and solitary or bilateral adenocarcino- water are reabsorbed, and potassium and hydrogen ions
mas have been reported. are excreted. Hyperaldosteronism results in hypokalemia,
metabolic alkalosis, and systemic hypertension from
Affected cats are typically old (average age 13 years)
the sodium and water reabsorption.
and Siamese cats are over-represented.
Clinical signs are of hypercalcemia and include
Clinical signs
anorexia and lethargy (50% of cats), gastrointesti-
nal signs including vomiting, diarrhea or constipation Affected cats are typically old, ranging from 10–20
(27%), polyuria and/or polydipsia (24%), lower uri- years.