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Anatomical Structure🐕 Dogs🐈 Catsendocrine

Adrenal Glands

🗣️ Pronounced:uh-DREE-nul GLANDZ
In One Sentence (Plain English)

Paired, small endocrine glands located immediately in front of each kidney that produce vital stress hormones, steroid hormones, and adrenaline.

Editorial Status: Verified from peer-reviewed veterinary sources (v1.0)
Updated: 2026-01-15

💬 In Plain English

The adrenal glands are two small, bean-to-peanut-shaped endocrine glands sitting right in front of each kidney near the aorta and vena cava. Despite their tiny size (usually less than a centimeter thick in dogs), they are metabolic powerhouses essential for life. The outer shell (cortex) makes aldosterone to balance electrolytes, cortisol to control stress and metabolism, and sex hormones. The inner core (medulla) makes epinephrine (adrenaline) for the fight-or-flight response. When they make too much cortisol, Cushing’s occurs; when they fail to make hormones, Addison’s occurs.

🔬 Clinical & Technical Depth

For Vets & Technicians

Formal Clinical Definition

Bilateral retroperitoneal endocrine glands situated craniomedial to the kidneys. Histologically organized into an outer cortex (zona glomerulosa producing mineralocorticoids, zona fasciculata producing glucocorticoids, and zona reticularis producing sex steroids) and an inner medulla (chromaffin cells producing catecholamines: epinephrine and norepinephrine).

Why Veterinarians Use It

Veterinarians measure adrenal thickness and symmetry on abdominal ultrasound to evaluate hyperadrenocorticism (bilateral enlargement in pituitary Cushing’s; unilateral mass in adrenal Cushing’s) and hypoadrenocorticism (small atrophied glands in Addison’s).

Clinical Context Encountered

Investigated during workups for excessive drinking, urination, pot-bellied appearance, or electrolyte collapses.

Clinical Reference Guide (Anatomical Structure)

Anatomical Location

Retroperitoneal space, situated craniomedially to each kidney in close proximity to the abdominal aorta (left) and caudal vena cava (right).

Normal Physiological Function

Regulation of electrolyte and fluid balance (aldosterone), carbohydrate and protein metabolism and stress response (cortisol), and sympathetic fight-or-flight autonomic response (epinephrine/norepinephrine).

🐕 vs 🐈 Species Differences

In cats, the adrenal glands are smaller and more oval-shaped (~3–4 mm thickness) compared to the peanut/comma shape in dogs (~5–7.5 mm thickness).

🚨 Red Flag Warnings (When to Contact an Emergency Vet)
  • •Total bilateral destruction of the adrenal cortex eliminates aldosterone and cortisol production, precipitating a fatal hypovolemic Addisonian crisis if untreated.

❓ Questions to Ask Your Veterinarian

Take these actionable questions with you to your next clinic visit or appointment:

  • 1What were the measurements (caudal pole thickness in millimeters) of both adrenal glands on ultrasound?
  • 2Are the adrenal glands symmetrically enlarged (pointing to a pituitary-dependent trigger) or is one gland an asymmetrical tumor?
  • 3Are the adrenal glands invading any nearby blood vessels like the caudal vena cava?

Academic & Clinical References