Dog Breeds Prone to Cushing's Disease: Age & Risk

Hyperadrenocorticism (HAC) is one of the most prevalent endocrine disorders in dogs, estimated to affect approximately 0.2% of the general canine population — roughly one to two dogs per thousand per year. But that prevalence is not evenly distributed — some dog breeds are far more prone to Cushing’s than others. Breed, age, sex, and body size all influence the likelihood of developing HAC, the form it takes (pituitary-dependent vs. adrenal-dependent), and, in the case of adrenal tumors, whether it is benign or malignant.

Understanding these patterns is clinically useful: it informs index of suspicion, shapes diagnostic reasoning, and helps owners of predisposed dogs recognise early signs before significant disease progression has occurred.

Age at Diagnosis

Canine Cushing’s disease is predominantly a disorder of middle-aged to older dogs. The median age at diagnosis across published case series is approximately 10 years, with most cases falling between 7 and 12 years. Dogs under 6 years of age are rarely diagnosed with naturally occurring HAC, and when they are, adrenal-dependent disease or an atypical presentation warrants particular scrutiny.

This age pattern reflects the biology of the disease: pituitary adenomas and adrenal tumours accumulate slowly over time, and the clinical signs of HAC — which develop insidiously — typically require months to years before they prompt veterinary investigation. By the time a diagnosis is made, the pathological process has almost always been underway for considerably longer than the owner’s history suggests.

Sex Predisposition

For pituitary-dependent hyperadrenocorticism (PDH), which accounts for 80–85% of naturally occurring HAC cases, no strong sex predisposition has been consistently established across large case series. Some studies have reported a modest overrepresentation of females; others have found no significant difference.

The picture is clearer for adrenal-dependent hyperadrenocorticism (ADH): females are overrepresented, comprising approximately 60–65% of cases in multiple published series. The basis for this sex predisposition is not fully elucidated but may relate to differences in adrenocortical tumour biology between sexes.

Body Size and the Pituitary-Adrenal Distinction

Body size has a meaningful relationship with the form of HAC a dog develops.

Small and medium breeds are significantly overrepresented in PDH. The breeds most commonly implicated in pituitary-dependent disease are compact, and the pattern holds across geographic regions and referral populations.

Large and giant breeds are more likely to develop adrenal-dependent HAC when they are affected. Critically, large breed dogs with adrenal tumours face a higher probability of malignancy: adrenocortical carcinomas account for roughly 50% of adrenal tumours overall, but this rate may be higher in larger dogs. Adrenal carcinomas carry a substantially different prognosis than adenomas, given their potential for vascular invasion, local tissue infiltration, and distant metastasis.

Breed Predisposition: Pituitary-Dependent HAC

The following breeds are consistently overrepresented in PDH case series across the veterinary literature.

Poodles (Miniature and Toy): Among the most heavily predisposed breeds, particularly miniature poodles. Some referral centre data suggest poodles may account for a disproportionate share of all PDH diagnoses. The predisposition appears breed-specific rather than reflecting size alone.

Dachshunds: Both standard and miniature Dachshunds are well-documented in PDH case series. Their compact, low-slung conformation is not relevant to the mechanism — the predisposition is genetic.

Boxers: Overrepresented in PDH, and also notable as a breed prone to pituitary macroadenomas, which carry a higher risk of neurological complications.

Boston Terriers: Consistently included in PDH breed lists across North American and European series.

Beagles: A breed with strong pituitary-adrenal research history — Beagles have been used in experimental models of HAC — and a recognised clinical predisposition to PDH.

Yorkshire Terriers: Documented predisposition, particularly in European case series.

Jack Russell Terriers and Staffordshire Bull Terriers: Reported overrepresentation in UK-based studies.

Breed Predisposition: Adrenal-Dependent HAC

ADH has a less tightly defined breed pattern than PDH, reflecting its different aetiology (primary adrenal tumour rather than pituitary pathology). However, larger breeds are represented at higher rates than in PDH:

German Shepherds, Labrador Retrievers, and other large and giant breeds appear more commonly in ADH series than one would expect from their representation in the general dog population. In these dogs, the probability of an adrenocortical carcinoma rather than an adenoma warrants early imaging and careful surgical planning.

Iatrogenic Hyperadrenocorticism: Any Breed, Any Age

A clinically important and distinct form of Cushing’s syndrome is iatrogenic hyperadrenocorticism — caused not by an internal tumour but by exogenous glucocorticoid administration. Any dog receiving prolonged or high-dose glucocorticoid therapy (oral, injectable, topical, or ophthalmic) can develop the full clinical syndrome of Cushing’s, as the administered glucocorticoids suppress the HPA axis and replicate the effects of endogenous cortisol excess.

Iatrogenic HAC is distinguished from naturally occurring disease by several features. Endogenous ACTH is suppressed (rather than elevated or autonomous), and the adrenal glands are typically small and atrophied rather than enlarged. On endocrine testing, the ACTH stimulation test characteristically shows a blunted or flat response — the adrenals, long suppressed, cannot mount a normal cortisol output.

Crucially, abrupt discontinuation of glucocorticoids in a dog with iatrogenic HAC carries the risk of an Addisonian crisis: the suppressed adrenal glands cannot produce adequate cortisol when the exogenous source is removed. Tapering protocols must be used, and veterinary supervision is essential.

The Intersection of Breed, Age, and Clinical Presentation

In practice, the combination of breed predisposition, age, and clinical signs forms the foundation of clinical suspicion before any testing begins. A 10-year-old miniature poodle presenting with PU/PD, symmetrical alopecia, pot-bellied abdomen, and markedly elevated ALP has a high pre-test probability of PDH. A 9-year-old German Shepherd with similar signs, a unilateral adrenal mass on ultrasound, and a female sex tips probability toward ADH and raises the question of malignancy.

Neither pattern is diagnostic on its own — endocrine testing is required for confirmation — but understanding the epidemiology allows clinicians and informed owners to recognise the presentation earlier, investigate sooner, and avoid the extended delays that remain common in HAC diagnosis.

In the next post, we examine what happens once HAC is confirmed: the pharmaceutical and surgical treatment options available, how they work, and what monitoring looks like during therapy.

If you’re researching natural supportive options while managing a Cushing’s diagnosis, our sponsors at lignans.com provide detailed information on SDG lignans and melatonin for dogs with hyperadrenocorticism.

The information on this site is educational and not a substitute for veterinary diagnosis or treatment. Always work with a licensed veterinarian for your dog’s care.

Which Dogs Get Cushing’s? Breed Predisposition, Age, Sex, and Risk Factors for Canine Hyperadrenocorticism