Page 266 - Problem-Based Feline Medicine

258 PART 4 CAT WITH URINARY TRACT SIGNS

difficult to control, and increased aldosterone concen- one cat was reported to have an estradiol- and testos-
trations. terone-secreting tumor.
Other causes of hypertension in elderly cats including The few cats reported were middle-aged to older cats
hyperthyroidism and renal disease need to be ruled out. (aged 7–14 years).

Hyperadrenocorticism may be associated with an In humans and dogs, progesterone binds to cortisol-
adrenal mass and polyuria, polydipsia, but can be ruled binding proteins displacing cortisol and resulting in
out based on clinical signs and a low dose dexametha- increased concentrations of free cortisol. Progesterone
sone test. is also a potent insulin antagonist.
Cats with progesterone-secreting tumors have clinical
Diagnosis
signs indistinguishable from hyperadrenocorticism,
An index of suspicion is required to make a presump- including concurrent diabetes mellitus.
tive diagnosis. Systemic hypertension together with an
adrenal mass, in the absence of signs of hyperadreno-
Clinical signs
corticism or hypokalemia are suggestive of pheochro-
mocytoma. In cats with a progesterone-secreting tumor, skin and
hair coat changes are the most common signs. Thin,
The mass can be imaged with ultrasound, MRI or CT.
fragile skin that bruised easily, an unkempt greasy
Biopsy may establish a definitive diagnosis.
hair coat, non-pruritic symmetrical alopecia, and skin
A definitive diagnosis based on demonstration of infections including demodicosis were the most com-
increased plasma or 24 h urinary catecholamine excre- mon signs reported.
tion is rarely performed.
Polyuria, polydipsia is typical, and in the majority of
cats was attributable to poorly controlled diabetes
Treatment mellitus.
Clinical signs can be improved using alpha (phenoxy- Weight loss occurs as a result of poorly controlled dia-
benzamine) blockers, and if needed beta blockers (e.g. betes.
atenolol).
One cat with an estradiol- and testosterone-secreting
Long-term resolution involves surgical removal of the tumor, developed behavioral changes including
adrenal mass, but perioperative care is critical, and aggression, had vulval hyperplasia, urine with a strong
includes use of preoperative alpha blockers for 1–2 “tom-cat” smell and an unkempt hair-coat.
weeks prior to surgery. Surgery is best performed
where a specialist anesthetic service is available.
Diagnosis
Diagnosis of a progesterone-secreting tumor is
PRIMARY SEX HORMONE-SECRETING
ADRENAL TUMOR based on consistent clinical signs, an abnormal dex-
amethasone suppression test (0.1 mg/kg), i.e. basal
cortisol concentrations are low–normal, but there is
Classical signs
failure of cortisol to suppress below 41 nmol/L (1.5
● Fragile skin and poor hair coat. μg/dl) at both 4 and 8 h after IV dexamethasone,
● Polyuria and polydipsia. increased basal progesterone concentrations and evi-
● Poorly controlled diabetes mellitus. dence of an adrenal mass on ultrasound. Alternatively,
as with dogs, basal cortisol may be low-normal and
suppress normally following dexamethasone.
Pathogenesis
● Cortisol concentrations were below the reference
Rarely, adrenal tumors secrete sex hormones. The range after ACTH stimulation, but that occurs in
most common is a progesterone-secreting tumor, and 50% of cats with hyperadrenocorticism.