Guinea Pig Adrenal Disease: Signs, Diagnosis & Treatment
Adrenal gland disease in guinea pigs — including adrenal tumors and hyperplasia — causes hair loss, skin darkening, and hormonal imbalances that can progress to life-threatening Cushing's-like syndrome. It is underdiagnosed and most common in middle-aged to older animals. Early recognition and treatment significantly improve quality of life.
Last reviewed: June 2026
What Is Adrenal Disease in Guinea Pigs?
Guinea pigs (Cavia porcellus) develop adrenal gland disorders relatively commonly in mid-life (3–5+ years), most often adrenal cortical adenomas, carcinomas, or bilateral adrenal hyperplasia. These conditions cause excess production of cortisol, androgens, or estrogens — producing a spectrum of signs that include bilateral symmetrical hair loss, skin hyperpigmentation, and genital swelling. As described in Quesenberry & Carpenter's Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery, adrenal tumors in guinea pigs are frequently bilateral and may secrete multiple hormones, complicating both diagnosis and medical management. The AEMV Pet Care Guides, 2024 highlight adrenal gland disorders as an important differential in any middle-aged or older guinea pig presenting with flank alopecia or genital swelling.
Signs of Adrenal Disease in Guinea Pigs
- Bilateral symmetrical hair loss — typically starting at the flanks and rump; the pattern mirrors each side
- Skin hyperpigmentation — darkening of exposed skin, especially over the dorsum
- Vulvar swelling (in females) — the vulva may appear swollen or engorged; can be mistaken for ovarian cysts
- Mammary gland changes — nipple prominence or mammary swelling in females
- Pendulous abdomen — pot-bellied appearance from abdominal fat redistribution
- Polydipsia and polyuria — increased thirst and urination
- Lethargy and muscle wasting — reduced activity and hindquarter weakness
- Recurrent skin infections — immune suppression from excess cortisol
Distinguishing Adrenal Disease from Other Causes of Hair Loss
| Condition | Hair Loss Pattern | Other Signs |
|---|---|---|
| Adrenal disease | Bilateral, symmetric, flanks/rump | Skin darkening, PU/PD, vulvar swelling |
| Ovarian cysts | Flanks, often bilateral | Vulvar discharge, cystic mass palpable |
| Fungal infection (ringworm) | Patchy, irregular, crusting | Scaling, itch |
| Barbering | Patchy on subordinate animals | Other guinea pigs chewing hair |
| Sarcoptic mange | Diffuse, intense itch | Scratching, skin thickening |
Diagnosis
Diagnosis is challenging because guinea pig-specific hormonal assays are not widely standardized. Diagnostics include:
- Abdominal ultrasound — identifies adrenal gland size and architecture, and rules out ovarian cysts; $200–400
- Blood panel — evaluates liver, kidney, and blood glucose; cortisol assays may be run but reference ranges are poorly established; $100–200
- Skin scraping — rules out fungal/mite causes of hair loss; $50–100
- CT/MRI — rarely pursued but gold standard for adrenal mass characterization; $800–2,000+
Treatment
Surgical adrenalectomy is curative for unilateral tumors but carries significant anesthetic risk in guinea pigs; bilateral disease makes surgery impractical. Medical management is more commonly used:
- Trilostane — cortisol synthesis inhibitor; dosing in guinea pigs follows Carpenter's Exotic Animal Formulary guidance
- Melatonin implants — used by some exotic practitioners for androgen-secreting adrenal disease (evidence limited to ferret models)
- Mitotane — used in some cases with caution; narrow therapeutic index in small mammals
- Supportive care — high-quality diet, vitamin C supplementation, skin hygiene to reduce secondary infections
Costs: medical management medications $40–120/month; surgical adrenalectomy $800–2,500+ if elected. Follow-up bloodwork every 3–6 months.
When to See a Vet
Call your vet today if:
- Your guinea pig has symmetrical hair loss on the flanks or rump
- You notice skin darkening or pot-bellied appearance
- Your female guinea pig's vulva appears swollen or there is vulvar discharge
- Your guinea pig is drinking and urinating more than usual
Go to the ER immediately if:
- Your guinea pig is not eating, is grinding teeth, or is hunched and in apparent pain
- Vulvar swelling is extreme or discharge is purulent (possible pyometra)
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Frequently Asked Questions
Is adrenal disease in guinea pigs the same as Cushing's disease in dogs? It shares features — excess cortisol, bilateral hair loss, pot-belly — but the hormonal profiles and tumor types differ. Guinea pig adrenal disease often involves estrogen or androgen excess as well as cortisol. Management overlaps with canine Cushing's treatment but dosing and protocols are species-specific.
Can hair loss in guinea pigs be treated without a vet? Hair loss has many causes (ovarian cysts, mange mites, fungal, barbering, adrenal disease) that require different treatments. Treating without a diagnosis frequently makes things worse — mange mites, for instance, require antiparasitic drugs, and fungal requires antifungals. An exotic vet visit and skin scraping are the necessary first step.
What does guinea pig adrenal disease treatment cost? Initial exotic vet exam: $75–150. Abdominal ultrasound: $200–400. Blood panel: $100–200. Medical management medication: $40–120/month. Surgical adrenalectomy (if elected): $800–2,500+. Follow-up bloodwork: $100–200 every 3–6 months. Total first-year cost: $500–2,000+ depending on approach.
How long can a guinea pig live with adrenal disease? With medical management, many guinea pigs remain comfortable for 1–3 years after diagnosis. Benign adenomas grow slowly. Adrenal carcinomas progress more quickly. Quality of life monitoring — appetite, activity level, weight, coat condition — guides the management plan and end-of-life discussions.
Is adrenal disease in guinea pigs preventable? No known prevention exists. Genetic predisposition is suspected but not characterized. Maintaining a healthy weight and providing vitamin C-rich diet supports general immune health. Annual exotic vet exams from age 2 onward allow early detection.
Still Not Sure if Your Guinea Pig Needs a Vet?
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