Serum hydrocortisone (cortisol) values in normal and adrenopathic dogs as determined by radioimmunoassay

Using a specific radioimmunoassay, serum hydrocortisone values were measured in dogs. Between 9:00 AM and 10:00 AM, the base-line hydrocortisone value for 56 clinically normal dogs ranged from 6.0 to 28.5 ng/ml, with a mean value of 17.8 +/- 1.32 ng/ml (mean +/- SEM). Marked differences due to age, sex, body weight, or breed were not observed in the hydrocortisone values. In 11 dogs with definitive hyperadrenocorticism, serum hydrocortisone values were from 32 to 148 ng/ml. In 2 dogs with hyperadrenocorticism, the values were 4.5 and 3.1 ng/ml. The estimation of serum hydrocortisone values by radioimmunoassay is simple and precise, and can be utilized to aid in the diagnosis of adrenopathy in dogs.