Evaluation of the oral fludrocortisone suppression test for diagnosing primary hyperaldosteronism in cats.

BACKGROUND: Primary hyperaldosteronism (PHA) in cats is suggested by clinical signs and an elevated plasma aldosterone-to-renin ratio (ARR), but a test to confirm the diagnosis is lacking. HYPOTHESIS: Fludrocortisone does not suppress urinary aldosterone excretion in cats with PHA, but does so in cats with arterial hypertension because of other causes. ANIMALS: Nineteen client-owned cats with arterial hypertension because of PHA (n = 9) or other causes (n = 10). METHODS: Prospective clinical study. The urinary aldosterone-to-creatinine ratio (UACR) was determined in morning urine before, during, and after 4 days of oral fludrocortisone administration in a dose of 0.05 mg/kg q12h. Arterial blood pressure and plasma potassium concentration were measured before and after fludrocortisone administration. RESULTS: A basal UACR above 46.5 × 10(-9), the upper limit of the reference range, was found in 3 cats with PHA. All PHA cats had basal UACRs >7.5 × 10(-9). In all non-PHA cats with a basal UACR >7.5 × 10(-9), fludrocortisone administration induced >50% suppression. In contrast, fludrocortisone administration resulted in <50% suppression in 6 of the 9 PHA cats. Neither basal UACR, nor UACR after suppression testing, correlated with the etiology of PHA (adenoma, adenocarcinoma, or suspected bilateral hyperplasia of the zona glomerulosa). Fludrocortisone induced hypokalemia in 7 cats, but did not induce or exacerbate arterial hypertension. CONCLUSIONS AND CLINICAL IMPORTANCE: Measuring the UACR before and after 4 days of administering fludrocortisone is a practical method of confirming most cases of PHA in cats, and of substantiating the absence of PHA in cats having an ARR within the reference range.

Suprascleral removal of a foreign body from the retrobulbar muscle cone in two dogs.

The successful application of a suprascleral approach to remove a foreign body within the retrobulbar muscle cone in two dogs is described. The episcleral space was entered through a small opening in the paralimbal conjunctiva and bulbar vagina. Under ultrasound guidance, a curved haemostat with a fine tip was advanced along the scleral surface to the foreign body, which was then carefully grasped and removed using gentle traction. The conjunctival incision was left to heal secondarily. The suprascleral approach may allow the quick removal of non-cutting and non-barbed foreign bodies from the episcleral space or the retrobulbar muscle cone, without the need for extensive tissue dissection. To reduce the risk of damaging extraocular tissues, the procedure must be performed cautiously and under ultrasound guidance. The globe should be continuously observed for any movement suggesting traction or pushing forces on bulbar or adjacent anatomical structures.