Cushing's Disease in Dogs: The Complete Owner's Guide
Cushing's disease — technically hyperadrenocorticism — occurs when the body produces chronically elevated levels of cortisol. Because cortisol affects almost every body system, the symptoms are broad, gradual, and easily attributed to normal ageing. Many dogs live with undiagnosed Cushing's for years before the pattern becomes clear enough to investigate.
Classic Signs
- Pot belly — the most visually striking sign: abdominal distension from muscle wasting and fat redistribution
- Excessive thirst and urination — often the first symptom owners notice; many dogs start having accidents indoors at night
- Symmetrical hair loss — typically starting on the flanks and trunk, sparing the head and legs initially
- Thin, fragile skin — bruises easily, wounds heal slowly
- Lethargy and exercise intolerance
- Increased appetite
- Recurrent infections — skin and urinary tract particularly
- Panting even at rest
Causes
- Pituitary-dependent (~85 %): a small tumour in the pituitary gland over-secretes ACTH, driving the adrenal glands to produce too much cortisol
- Adrenal-dependent (~15 %): a tumour on one adrenal gland produces cortisol autonomously
- Iatrogenic: long-term corticosteroid treatment — resolves on gradual withdrawal
Higher-risk breeds: Poodles, Dachshunds, Yorkshire Terriers, Boxers, Beagles — typically middle-aged to older dogs (over 6 years)
Diagnosis
The ACTH stimulation test and the low-dose dexamethasone suppression test (LDDST) are the standard screening tools. Abdominal ultrasound assesses adrenal gland size and symmetry, helping distinguish pituitary-dependent from adrenal-dependent disease. MRI may be needed to characterise a pituitary mass.
Treatment
- Pituitary-dependent: trilostane (Vetoryl) is the most common medication — blocks cortisol synthesis. Monitoring every 4–8 weeks with ACTH stim tests is mandatory.
- Adrenal tumour: surgical removal when feasible — excellent long-term outcome for benign tumours
- Iatrogenic: gradual steroid tapering under vet supervision
Track your dog's water intake, urination frequency, weight, and energy levels in Purzi. Week-on-week trends show whether treatment is working and alert you to early signs of over-suppression before the next vet visit.