Suspected spontaneous hyperadrenocorticism in a young experimental beagle dog

Area of Science:

• Veterinary Pathology
• Endocrinology
• Toxicology

Background:

• A 6-month-old female beagle dog in a toxicity study exhibited clinical signs suggestive of hyperadrenocorticism.
• Pre-dose findings included elevated erythroid parameters, a stress leukogram, and increased plasma levels of total protein, gamma-glutamyl transferase, total cholesterol, and triglycerides.

Purpose of the Study:

• To evaluate compound toxicity and investigate the cause of spontaneous hyperadrenocorticism in a beagle dog.
• To correlate clinical, pathological, and ultrastructural findings with potential endocrine dysfunction.

Main Methods:

• Clinical examination, hematology, plasma biochemistry, necropsy, histopathology, and electron microscopy.
• Comparative analysis of clinical pathology and organ weights against reference data.
• Ultrastructural examination of adrenocortical cells and measurement of plasma cortisol and adrenocorticotropic hormone levels.

Main Results:

• Necropsy revealed increased adipose tissue, enlarged adrenal glands and liver. Histopathology showed adrenocortical hyperplasia, thymic atrophy, and hepatic glycogen accumulation.
• Electron microscopy indicated adrenocortical cell hyperfunction, characterized by altered lipid droplets, abundant smooth endoplasmic reticulum, and numerous atypical mitochondria.
• Pre-dose plasma cortisol was slightly elevated, while adrenocorticotropic hormone levels were normal, suggesting a possible primary adrenal issue.

Conclusions:

• The observed systemic changes in the beagle dog were incidental to the toxicity study and likely caused by spontaneous hyperadrenocorticism.
• Ultrastructural evidence strongly supports adrenocortical hyperfunction as the underlying pathology.
• This case highlights the importance of considering spontaneous endocrine diseases in toxicology studies.