Dog Cushing's Disease (Hyperadrenocorticism) Welfare

Cushing's disease is a common hormonal disorder in middle-aged to older dogs, caused by excess cortisol. Diagnosis can be challenging but treatment significantly improves quality of life.

Key Facts

Cushing's disease (hyperadrenocorticism) results from chronic excess cortisol, most commonly from a pituitary tumour (PDH, ~85% of cases) or an adrenal tumour (~15%)
It most commonly affects dogs over 6 years; predisposed breeds include Poodles, Dachshunds, Boxers, Boston Terriers, and Labrador Retrievers
Classic signs form the "PUPD + pot belly" pattern: polydipsia, polyuria, polyphagia, abdominal distension, muscle weakness, hair loss (alopecia), skin thinning, and increased susceptibility to infection
Diagnosis is complex — the LDDST (low-dose dexamethasone suppression test) is the gold-standard screening test; differentiation between PDH and adrenal tumour uses HDDST and imaging
The most common treatment is trilostane (Vetoryl), which inhibits cortisol synthesis; mitotane is an alternative with a different mechanism and narrower therapeutic window
Monitoring is essential — both under-treatment and over-treatment (causing iatrogenic Addison's disease) carry significant welfare risks
Adrenal tumours may be amenable to surgical adrenalectomy — the only potentially curative option
Untreated Cushing's leads to progressive muscle wasting, immune suppression, hypertension, thromboembolism, and in severe cases, neurological signs from a growing pituitary tumour

Welfare Considerations

Cushing's disease causes significant chronic welfare compromise through a constellation of effects: the discomfort of constant thirst and urination disrupting sleep and normal activity, the indignity of a distended abdomen from muscle weakness, skin fragility causing easy bruising and infection, and the anxiety-like state that excess cortisol produces in some animals. Many owners initially normalise these signs as ageing. Treatment with trilostane produces remarkable quality of life improvements in most dogs — restoration of normal energy, reduced drinking and urination, and gradual return of normal body condition. The welfare risk of over-treatment (adrenal crisis) requires careful monitoring; under-treatment leaves dogs in chronic discomfort from cortisol excess. With careful management, Cushing's dogs can have good quality of life for years.

What You Can Do

Be alert to the classic signs: greatly increased thirst, urination, appetite, pot-belly, and hair loss in a middle-aged or older dog
Pursue full diagnostic work-up including LDDST and imaging if Cushing's is suspected — do not treat empirically without diagnosis
Monitor trilostane treatment carefully — ACTH stimulation testing at 4 weeks post-start and after any dose change
Know the signs of over-treatment (Addisonian crisis): weakness, vomiting, collapse — this is an emergency
Consider referral to a veterinary internist for complex cases or those with large pituitary tumours showing neurological signs