Feline hypoadrenocorticism: Emerging insights into clinical features, diagnosis, and treatment

Hypoadrenocorticism in cats is a rare endocrine disorder that should be considered in patients presenting with vague, intermittent, or waxing and waning clinical signs. Chronic gastrointestinal signs, poor growth, or episodes of hypovolemic shock should raise clinical suspicion. British Shorthair cats may be overrepresented among affected cats, and clinicians should be particularly alert when this breed presents with compatible signs. Definitive diagnosis requires an ACTH stimulation test, which should be performed prior to the initiation of any glucocorticoid treatment to avoid diagnostic interference. In clinically stable cats, baseline cortisol measurement may be used as an initial screening tool. However, as no feline-specific thresholds have been validated, the commonly used cut-off of >2 µg/dL (>55 nmol/L) to rule out hypoadrenocorticism should be interpreted with caution, as it may be less reliable than in dogs. Long-term management involves lifelong glucocorticoid replacement, typically using oral prednisolone. Cats generally require higher maintenance doses than dogs to maintain clinical stability. Mineralocorticoid deficiency is managed with subcutaneous administration of an extended-release desoxycorticosterone preparation (Zycortal®) given monthly at a starting dose of 2,2 mg/kg - substantially higher than canine doses. As an alternative, daily oral fludrocortisone acetate (Florinef® or Astonin®H) could be used at 0,01-0,02 mg/kg/day in selected cases. Regular monitoring of sodium and potassium levels is essential to adjust mineralocorticoid dosages and optimize treatment. Because affected cats cannot mount an adequate stress response, additional glucocorticoid supplementation («glucocorticoid boost») is required during stressful situations or concurrent illness. Owners must be educated about the signs of adrenal crisis, which can be more subtle and difficult to recognize in cats compared to dogs. Emphasis should be placed on consistent medication administration and routine veterinary monitoring to ensure long-term disease control and quality of life.