For more than 35 years the author has treated multiple serious diseases in cats and dogs by correcting an unrecognized endocrine-immune imbalance originating with a deficiency or defect of cortisol. The cortisol abnormality creates a domino effect on feedback loops involving the hypothalamus-pituitary-adrenal axis. In this scenario, estrogen becomes elevated, thyroid hormone becomes bound, and B and T cells become deregulated. Diseases with this aberration as a primary etiological component range from allergies to severe cases of autoimmunity to cancer. The author has consistently identified excess estrogen or "estrogen dominance" as part of an endocrine-immune derangement present in many common diseases of dogs and cats. Ninety-percent of these cases involve spayed females and neutered or intact males, so the elevated estrogen cannot be attributed to ovarian activity. The author identifies the adrenal cortex as a source of the imbalance, which produces a variety of vital hormones. The author has developed an endocrine-immune blood test that measures cortisol, total estrogen, T3 and T4, and IgA, IgG, and IgM antibody levels. The protocol for corrective therapy involves the use of various cortisone medications, either standard pharmaceutical compounds or a natural bio-identical preparation made from an ultra extract of soy. The author's clinical success and the growing clinical applications of low-dosage cortisone therapy for humans strongly argue for sustained research into the nature, magnitude, and impact of cortisol defects, including an associated estrogen-immune problem, in the etiology of disease.