Why I
Joined GGCP

The Graduate Group in Comparative Pathology (GGCP) is one of multiple graduate groups on the UC Davis campus offering a graduate education in the biological sciences. Why did I apply for this graduate program? In conversations with graduate students who had received the same training as myself (veterinary degree in the U.S. or abroad and internship and residency in one of the veterinary specialties) and others with very different backgrounds, I learned about the wide variety of faculty members in this graduate group, many of them researchers in veterinary or human medicine, and the friendly and collaborative atmosphere among faculty, staff, and students. During a first meeting with graduate group advisor Dr. Joe Zinkl and his assistant, Darlene Flemming, I was impressed with the structured and efficient approach to the wealth of potential classes for graduate education, an approach that was supportive, personal, and formed by many years of experience in graduate education. I was offered valuable advice, not only regarding classes that can be tailored to the specific interests and research needs of each student but also regarding funding applications and choosing my future major professor. I felt a genuine interest in graduate student progress and success.

During my residency in Small Animal Internal Medicine at the UC Davis Veterinary Medical Teaching Hospital, I was fortunate to work with Dr. Richard Nelson and Dr. Edward Feldman, both highly respected veterinary endocrinologists, who sparked my interest in this field. I decided to pursue further research in endocrinology and was fortunate again to find a major professor who is a specialist in steroidogenesis research and a member of the GGCP—Dr. Alan Conley.

After enrolling in the GGCP PhD program, I met many domestic and international GGCP students with very diverse backgrounds and research interests. The term "comparative pathology" does not simply imply a focus on the pathology of various species (in classes or research) but reflects the diversity of cutting-edge research performed within this group. Through this diversity, GGCP provides a wealth of collaborative opportunities with researchers on the UC Davis campus and beyond.

Naturally occurring hyperadrenocorticism in dogs is characterized by excessive production and secretion of steroid hormones from the adrenal glands, either secondary to increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland or by autonomously functioning adrenocortical tumors. Diagnosis of this debilitating disease is based on typical clinical signs (increased urine volumes, increased drinking and appetite, abdominal distension, muscle weakness) and clinicopathologic abnormalities, abdominal ultrasound, and function tests of the pituitary-adrenal axis demonstrating abnormally high levels of cortisol in the circulation. Treatment options include medical adrenolytic treatment, enzyme blockers affecting steroidogenesis, and surgical removal of an adrenal gland tumor or irradiation of a pituitary tumor. The disease is well documented in the veterinary literature.

More recently, cases of "atypical hyperadrenocorticism" have been reported. Clinical signs are similar, but results of conventional endocrine function tests focusing on cortisol measurements are within reference ranges. Recognition of these cases has increased markedly over the last few years. Steroid precursor hormones like 17-hydroxyprogesterone are increased in the face of normal cortisol concentrations. Increased concentrations of other hormones in the steroid synthesis pathways (progesterone, dehydroepiandrosterone sulfate, androstenedione, testosterone, and estradiol) also are detected in dogs with Cushing's syndrome due to adrenocortical carcinomas. Abnormally high serum steroid precursor hormones may be associated with clinical signs of hyperadrenocorticism. Aberrations in steroid biosynthesis associated with these tumors are suspected, but the exact cause is unknown. Under the guidance of my major professor, Dr. Alan Conley, and co-investigators Dr. Richard Nelson and Dr. Edward Feldman, I am investigating aberrations in adrenal steroidogenesis in dogs with naturally occurring hyperadrenocorticism to contribute to our understanding of canine steroidogenesis.

Figure 1. Ultrasound image of a normal canine adrenal gland (markers indicate measurement of adrenal gland width).


Figure 2. Adrenal gland tumor surgically removed from a seven-year-old dog with hyperadrenocorticism.