What are the first signs of Cushing's disease in dogs?

Early signs of Cushing's disease in dogs include increased thirst and urination (polydipsia and polyuria), increased appetite, pot-bellied appearance, hair loss (especially on flanks and body), thin skin, lethargy, and panting. These symptoms often develop gradually over months.

How long do dogs live with Cushing's disease?

With proper treatment and monitoring, many dogs with Cushing's disease can live 2-4 years or longer after diagnosis. Life expectancy depends on the type of Cushing's (pituitary vs adrenal), the dog's age, overall health, and how well they respond to treatment.

What causes Cushing's disease in dogs?

Cushing's disease is caused by excessive production of cortisol. About 80-85% of cases are pituitary-dependent (caused by a tumor on the pituitary gland), while 15-20% are adrenal-dependent (caused by a tumor on the adrenal gland). Iatrogenic Cushing's can also occur from long-term steroid medication use.

What foods should dogs with Cushing's disease avoid?

Dogs with Cushing's should avoid high-fat foods (as they're prone to pancreatitis), excessive carbohydrates (due to insulin resistance risk), and high-sodium foods (due to hypertension risk). A moderate protein, low-fat diet with complex carbohydrates is generally recommended.

How is Cushing's disease diagnosed in dogs?

Diagnosis involves blood tests including ACTH stimulation test, Low-Dose Dexamethasone Suppression Test (LDDS), and urine cortisol:creatinine ratio. Additional tests like abdominal ultrasound help determine if the cause is pituitary or adrenal. No single test is 100% definitive.

Understanding Canine Cushing's disease

A comprehensive guide to canine hyperadrenocorticism - what it is, how to recognize it, and what you can do

What Is Cushing's disease?

Cushing's disease (also called Cushing's syndrome or hyperadrenocorticism) is a hormonal disorder caused by chronic excess of cortisol production. The medical name is hyperadrenocorticism: "hyper" means overactive, "adreno" refers to the adrenal glands, and "corticism" relates to the cortisol production from the adrenal cortex.

These small glands sit next to the kidneys and produce essential substances that regulate many body functions and are vital for survival. The best-known of these is cortisol. When the adrenal glands produce too little or too much of these hormones - especially cortisol - it can put a dog's life at risk.

In most cases, Cushing's disease is caused by a tumour mostly benign - either on the pituitary gland in the brain (80-85% of cases) or on one of the adrenal glands (15-20% of cases). A third form occurs from long-term steroid medication use.

In simple terms: Cushing's disease is a hormonal disorder that happens when a small tumour forms either in the brain (pituitary gland) or on one of the adrenal glands. That tumour mostly benign continuously drives excess cortisol production, even when the body already has enough. This constant hormone overload slowly wears down the body's systems, affecting the liver, kidneys, skin, muscles, immune system, and even mood or behaviour.

Source: VCA Animal Hospitals

The Four Types of Cushing's disease

Pituitary-Dependent Cushing's (PDH)80-85% of cases

•A tumour mostly benign on the pituitary gland in the brain produces excess ACTH (adrenocorticotropic hormone)
•ACTH signals both adrenal glands to continuously produce cortisol
•Requires lifelong medication management with Vetoryl (trilostane)

Adrenal-Dependent Cushing's (ADH)15-20% of cases

•A tumour on one adrenal gland produces cortisol directly
•Most commonly treated with Vetoryl (trilostane)
•Surgical removal of the affected adrenal gland is possible but carries some risks: anesthesia complications, technical difficulty due to the gland's location near major blood vessels, and post-operative complications
•Surgery is typically reserved for cases where the tumour causes severe complications or when medication is ineffective

Iatrogenic (Steroid-Induced) Cushing'sReversible

•Caused by long-term use of corticosteroid medications (such as prednisone or prednisolone) prescribed for other conditions like allergies, inflammatory bowel disease, or immune disorders
•Not caused by a tumour
•Resolves when the steroid medication is gradually withdrawn under veterinary supervision
•This is the only form of Cushing's that can be resolved rather than managed lifelong

Critical: Steroids must never be stopped abruptly – sudden withdrawal can cause life-threatening Addisonian crisis.

Atypical Cushing's (Non-Cortisol Secreting)Debated Diagnosis

While typical Cushing's involves an overproduction of cortisol, "Atypical" cases involve the overproduction of adrenal sex hormone precursors (such as progesterone or androstenedione).

The Scientific Reality

•Diagnosis: Standard tests (LDDS/ACTH) often return "normal" results because they only measure cortisol. Diagnosis requires an Extended Adrenal Hormone Panel (the University of Tennessee protocol) to identify which specific steroid pathways are overactive.
•Treatment: This platform focuses exclusively on documented, clinically trialed medical interventions. For Atypical Cushing's, mitotane (Lysodren) is the primary pharmaceutical intervention. It is used for its unique ability to cause selective necrosis of the Zona Reticularis, the layer of the adrenal gland responsible for sex hormone production.
•Evidence vs. Speculation: While various supplements are often discussed in online forums based on in vitro (test tube) studies, there are currently no large-scale, peer-reviewed clinical trials proving their efficacy in live dogs. Our platform does not track or recommend these interventions due to the lack of documented clinical evidence.

The "Atypical" Debate: A Scientific Controversy

Within the veterinary community, there is significant debate over whether "Atypical Cushing's" is a distinct clinical entity. Many leading endocrinologists believe that cases labelled as "atypical" generally fall into one of three categories:

1.Early-Stage Typical Cushing's: The disease is present, but cortisol levels haven't yet breached the threshold for standard LDDS or ACTH stimulation tests.
2.Precursor Elevation: The adrenal gland is under stress, causing a "leakage" of sex hormones (precursors) rather than a primary disease of those hormones.
3.Non-Adrenal Illness: Other systemic diseases can cause "false positive" elevations on hormone panels, leading to a misdiagnosis of Cushing's.

Our Platform's Stance: Because this diagnosis is debated and lacks standardised clinical trials in live dogs, we categorise these cases as "Suspected/Non-Cortisol Secreting Adrenal Change." We only track data from dogs that show clinical "cardinal signs" and are being managed under the strict supervision of a specialist. We do not include data based on "in vitro" theories or unsupported supplement protocols.

Treatment approaches vary and should be guided by a veterinary internal medicine specialist. We are actively collecting real-world case data to expand this section. If your dog has been diagnosed with atypical Cushing's and you're willing to share your journey, please contact us.

Why Early Detection Changes Everything

Cushing's disease often starts with subtle signs that appear well before the more recognisable symptoms such as pot belly (abdominal swelling), increased thirst and/or hunger. These early changes frequently go unnoticed, resulting in delayed diagnosis when dogs have already experienced unnecessary discomfort and pain. Early testing, even after noticing minor changes, can lead to treatment before further complications develop.

The earlier we catch it, the better we can help our dogs. Early testing, even after noticing minor changes, can lead to treatment before further complications develop.

Who Discovered It

In humans, the syndrome was first identified by neurosurgeon Dr. Harvey Cushing in 1912. The first formal description in dogs appeared in 1939 by veterinarians Verstraete & Thoonen, marking the start of canine-specific recognition.

Most (and Less) Common Signs

Adapted from Behrend, E.N., et al. (2013). Diagnosis of spontaneous canine hyperadrenocorticism: 2012 ACVIM Consensus Statement.

Classic Signs (More Obvious)

•Drinking and urinating more than usual (polyuria/polydipsia)
•Ravenous appetite (polyphagia)
•'Pot-bellied' look due to fat redistribution and muscle wasting
•Hair thinning or bald patches
•Excessive panting, low energy

Subtle, Easily Missed Signs

Often the first clues

•Incomplete seasonal shedding or coat changes
•Skin that bruises or thins easily
•Recurrent infections (skin, urinary)
•Behaviour shifts: restless pacing, confusion, clinginess
•Muscle weakness or minor tremors

When to Test: If two or more subtle signs persist - especially in middle-aged or senior dogs - it's worth testing even if nothing "classic" shows. Trust your observations: owners know their dogs best, and veterinary specialists rely on those reports to provide the right care.

Families and vets both play vital roles. The changes noticed at home are often the earliest clues of Cushing's, and sharing them clearly with your veterinary team can lead to earlier testing and treatment - and less suffering for your dog.

How It's Tested

The College of Veterinary Medicine identifies these as the main preferred screening options:

Low-Dose Dexamethasone Suppression Test (LDDST)

Also called the 8-hour test, this is considered the test of choice for diagnosing hyperadrenocorticism in dogs. Your dog has blood taken three times at 4-hour intervals (for example: 8 am → 12 pm → 4 pm). A small dose of dexamethasone (a steroid) is given after the first draw (baseline), and the later blood samples show how your dog's body reacts. Abnormal cortisol patterns are highly suggestive of Cushing's and, when interpreted alongside clinical signs, can support a diagnosis.

Please see the High-Dose Dexamethasone Suppression Protocol for a step-by-step guide.

ACTH Stimulation Test

Also called the short stimulation test, when available, this is primarily used for monitoring the response to trilostane or mitotane treatment. Your dog's blood is taken before and after being given an injection of synthetic ACTH (a hormone that normally tells the adrenal glands to produce cortisol). An exaggerated cortisol response may be seen in dogs with Cushing's, but this test is less sensitive for diagnosis and is primarily used for treatment monitoring. This test is quicker than the LDDST but may miss some mild cases.

MSD Veterinary Manual - Pituitary-dependent Hyperadrenocorticism: Diagnosis

Urine Cortisol: Creatinine Ratio (UCCR)

This is a simple, non-invasive screening test. You collect your dog's first morning urine sample at home, and a lab measures cortisol levels against creatinine.

If the result is normal, Cushing's is very unlikely.
If the result is high, it doesn't confirm Cushing's - but it means further testing (like the LDDST) is needed.

Because stress can raise cortisol, owners are usually advised to keep their dog calm before collection. This test is often used as an early screen, especially when subtle signs appear.

Adapted from Gribbles Veterinary Pathology .

Further tests: Imaging such as abdominal ultrasound, CT or MRI may be used to look directly at the adrenal glands or pituitary gland. This helps vets determine whether the disease is pituitary-dependent or caused by an adrenal tumour, which is important for planning treatment.

Understanding What You're Treating

Cushing's disease is caused by a tumour in most cases, which is typically benign. In pituitary-dependent Cushing's (80-85% of cases), the tumour on the pituitary gland produces excess ACTH, which continuously signals the adrenal glands to produce cortisol. In adrenal-dependent Cushing's (15-20% of cases), the tumour on the adrenal gland produces cortisol directly. In both types, cortisol levels remain chronically elevated.

Chronic excess cortisol progressively damages the liver, kidneys, muscles, skin, and immune system. Without treatment, this damage accumulates and worsens over time.

Evidence-Based Treatment

Currently, there are no published clinical trials or peer-reviewed studies demonstrating that dietary supplements, herbs, or alternative remedies can control tumour-driven cortisol production. Trilostane (Vetoryl) and mitotane (Lysodren) are the only FDA-approved medications proven in clinical trials to reduce cortisol production in dogs with Cushing's disease.

While good nutrition and supportive care benefit your dog's overall health, treating a hormone-producing tumour requires medication with demonstrated efficacy in controlled scientific studies.

Treating Cushing's disease

The primary goal of treating Cushing's disease (Hyperadrenocorticism) is to reduce the excessive production of cortisol to a safe, physiological level, which in turn alleviates clinical signs and prevents irreversible organ damage.

Medical Management

There are two main medications used for medical management:

1. Trilostane (Vetoryl®)2025 Gold Standard

Trilostane is the current first-line "Gold Standard" treatment for canine Cushing's disease per 2025 veterinary guidelines. It is preferred for its high tolerability, superior long-term survival rates, and its manageable safety profile.

How It Works: Reversible Enzyme Inhibition

Technically, Trilostane is a competitive inhibitor of the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD).

•The Science: It temporarily blocks the synthesis of cortisol (and other steroids) in the adrenal cortex.
•The "Dimmer Switch" Analogy: For dog families, it's helpful to think of it as a dimmer switch. It doesn't permanently "turn off" the adrenal glands; it simply lowers the intensity of cortisol production to a safe, physiological level.
•Safety Profile: Because the effects wear off within hours, the risk of permanent adrenal damage is lower than with destructive therapies (like mitotane). If cortisol drops too low, the "switch" can be adjusted back up by modifying the dose.

Real-World Management: The "Sara Journey" Call-out

Cushing's management is a dynamic process. Sara's own journey serves as a vital case study: she was stable on 20mg BID for months until her monitoring showed a significant drop in cortisol, requiring a reduction to 13mg BID.

The Lesson: This highlights that a dose reduction isn't a failure-it is precision medicine. Proper monitoring prevents the "overshoot" that leads to crisis.

Important Safety Information & Handling

Monitoring for Over-Suppression: Vets and owners must collaborate to watch for signs of Iatrogenic Addison's (adrenal insufficiency - vomiting). If these occur, stop the medication immediately. A "rescue dose" of prednisolone/prednisone may be prescribed.
Adrenal Necrosis (Rare Case): In rare cases, particularly in dogs with adrenal tumours, trilostane has been associated with adrenal necrosis. While rare, this underscores why tracking patterns-not just one-off tests-is essential.
Administration: Must be given with food to ensure consistent intestinal absorption and maximum efficacy.
Handling: Generally safe to handle. Unlike mitotane, special gloves are typically not required, though hand washing after administration is recommended.

The Bottom Line: Modern low-dose, twice-daily (BID) trilostane protocols aim to reduce risk while maximising quality of life. Treatment is not one-size-fits-all, and careful, individualised dose adjustment is essential for safe long-term management.

2. Mitotane (Lysodren)

How It Works

Mitotane works very differently from trilostane-it causes permanent, selective destruction of the cortisol-producing layers of the adrenal cortex. This makes it highly effective but requires more intensive management.

Use Today

While trilostane has become the preferred first-line treatment based on the most recent 2025 evidence showing superior long-term outcomes, mitotane remains an effective option. In dogs with adrenal tumours, survival times with mitotane were similar to trilostane (median 14.0 months).

Treatment Phases

Mitotane therapy involves two phases: an induction phase to bring cortisol levels down rapidly, followed by a lifelong maintenance phase using weekly doses.

Important Safety Information: Mitotane requires very careful monitoring. Pet owners must watch closely for side effects including loss of appetite, vomiting, diarrhoea, or lethargy. If any of these occur, stop the medication immediately, give the "rescue" prednisone your vet prescribed, and contact your vet right away.

Safety Note: Mitotane tablets are hazardous to handle-always wear gloves when administering the pill and when cleaning up pet waste.

The Bottom Line

Because mitotane "destroys" rather than "inhibits" the adrenal tissue, the risk of permanent Iatrogenic Addison's disease is higher than with trilostane.

The modern low-dose, twice-daily trilostane protocol is now considered the gold standard for the vast majority of dogs. However, your veterinarian will recommend the best option based on your dog's specific type of Cushing's, age, and your ability to manage the protocol.

Important Note on Glucocorticoid Use

Dogs with Cushing's disease (hyperadrenocorticism) already have excessive levels of cortisol in their bodies. For this reason, long-term treatment with glucocorticoids (such as prednisone, prednisolone, or dexamethasone), commonly prescribed for conditions like allergies, asthma, chronic skin disease, or inflammation, can worsen clinical signs.

Glucocorticoids should never be started, stopped, or continued long-term in dogs with suspected or diagnosed Cushing's disease without close veterinary supervision, and alternative therapies should be discussed whenever possible.

Monitoring Requirements

Regular blood tests are essential to determine proper dosing
Frequent vet visits in the first few months, then every few months ongoing
Dose adjustments may be needed periodically based on response

Regular monitoring blood tests such as PVC - pre pill cortisol or ACTH help ensure cortisol levels remain in the safe target range - not too high (uncontrolled Cushing's) and not too low (iatrogenic Addison's disease).

Critical Warning Signs

If your dog is being treated with Trilostane (Vetoryl) or mitotane, monitor closely for signs of over-medication, which can lead to Addisonian crisis (dangerously low cortisol):

• Lethargy or weakness
• Vomiting or diarrhoea
• Loss of appetite
• Collapse or inability to stand

If you observe any of these signs, contact your veterinarian immediately. This is a medical emergency.

IMPORTANT NOTE: Currently, there are no published clinical trials or peer-reviewed studies demonstrating that dietary supplements, herbs, or alternative remedies can control tumour-driven cortisol production. Trilostane (Vetoryl) is the only FDA-approved medication proven in clinical trials to reduce cortisol production in dogs with Cushing's disease.

Diet Considerations

While good nutrition and supportive care can benefit your dog's overall health, treating a hormone-producing tumour requires medication with demonstrated efficacy in controlled scientific studies.

However, because long-term elevated cortisol affects how the body handles fats, many dogs with Cushing's develop liver enlargement, bile sludge or gallbladder mucocele, and sometimes pancreatic inflammation. For this reason, some veterinarians recommend a controlled, low-fat diet to reduce strain on the liver, gallbladder, and pancreas, support bile flow, and help stabilise digestion.

A Suitable Diet Usually Means:

Low fat (generally under ~12% on a dry matter basis)
High-quality, digestible protein
Consistent feeding schedule (smaller, more frequent meals are generally recommended to provide consistent support for the digestive system and promote smooth bile flow, which is important for dogs prone to bile sludge or gallbladder issues)
No rich treats or table scraps

Diet does not treat Cushing's disease, but it can support organ function and may improve comfort and long-term stability, especially in dogs with gallbladder sludge or a history of pancreatitis. Reducing dietary fat can help support bile flow and reduce stress on the pancreas (WSAVA, 2021; Mansfield & Beths, JSAP, 2015).

Living with Cushing's disease: What to Expect

Pituitary-dependent and adrenal-dependent Cushing's are lifelong conditions requiring continuous medication and monitoring. There is no cure for tumour-caused Cushing's except in rare cases where surgical removal of an adrenal tumour is successful.

With Proper Treatment

•Many dogs begin to show improvement in symptoms within the first several weeks of starting trilostane/mitotane
•Dogs on properly managed medication can maintain good quality of life
•Many dogs live normal lifespans with consistent treatment and monitoring
•Progressive organ damage caused by excess cortisol is slowed or stabilised

Iatrogenic Cushing's is different: It resolves once the causative steroid medication is safely tapered and discontinued under veterinary supervision.

Without Treatment

Without treatment, Cushing's disease progressively worsens, causing:

•Irreversible organ damage (liver, kidneys, heart)
•Increased risk of blood clots and pulmonary thromboembolism
•Diabetes mellitus
•Chronic infections
•Significantly shortened lifespan
•Poor quality of life

Financial commitment: Treatment requires ongoing costs including medication (daily for life), regular blood testing (every 3-4 months once stabilised), and veterinary consultations. Planning for these expenses is important for your dog's long-term care.

Trilostane Dosage

Increasing evidence suggests that lower-dose, twice-daily trilostane protocols may offer better clinical stability and safety than higher-dose approaches. Dosage should always be individualised by the treating veterinarian.

For complete treatment information, always consult with your veterinarian and reference current veterinary literature.

Key takeaway: While Cushing's is typically lifelong, it can usually be successfully managed with proper medication and monitoring.

Ready to Learn More?

Explore Sara's personal journey with Cushing's disease, or check our comprehensive symptoms guide to help you recognize the signs.

Read Sara's Story Symptoms Guide