All you need to know about Cushing’s disease

All you need to know about Cushing’s disease

The adrenal gland sits above both kidneys and is responsible for making many vital hormones essential for life. One of those is cortisol. Cortisol is the body’s natural version of the chemical many of us are familiar with – cortisone or steroids. 

When the adrenal glands malfunction and produce too much cortisol, known as ‘steroid excess’, a syndrome called ‘Cushing’s disease’ or ‘Cushing’s syndrome’, named after the Professor who discovered this condition in the 1920s. 

There are two primary forms of Cushing’s disease: 

  1. A cortisol-producing tumour in the adrenal gland 
  2. An over-excited pituitary gland in the brain makes too much of the hormone that instructs the adrenal glands to make cortisol.  

 There’s also an atypical form of Cushing’s disease. For succinctness, the rest of this information relates specifically to (2) above or ‘pituitary-dependant hyperadrenocorticism – P HAC for short. 

The disease can cause damage to multiple organ systems, which shows up as symptoms that you may notice as an owner – and even subtle changes that are out of the ordinary. These symptoms occur because they cause disease in the organs with which they’re associated.  

Symptoms and signs

Cushing’s causes many symptoms, but the most common symptoms of Cushing’s disease include some or all of the following, but not always: 

  • Higher than normal thirst 
  • Panting even when not hot 
  • Higher than normal appetite 
  • Skin problems 
  • Wispy ‘old man’, thinning fur 
  • Dermatitis 
  • blackheads (AKA comedones) 

 When Cushing’s disease causes the following conditions, you can also see the associated symptoms. 

cushings table 

As you can see, Cushing’s can cause diseases to multiple organ systems and specific symptoms and the opposite of certain symptoms (less appetite if Cushing’s causes pancreatitis, more appetite if there’s no pancreatitis as cortisol is an appetite stimulant). 

Cushing’s disease is not fatal itself, but the conditions it causes can shorten the lifespan and quality of life, and complications associated with untreated or undertreated Cushing’s disease are a common reason for euthanasia. 

How do you diagnose it? 

Years ago, the diagnosis was based only on the veterinarians’ suspicion – thankfully, we’re more certain these days with advanced diagnostics to confirm the suspicion. The three main ways we diagnose Cushing’s disease are: 

  1. ACTH Stimulation test – considered the gold standard. A synthetic version of the hormone released by the brain to tell the adrenal glands to pump out cortisol is given, and a blood sample in one hour is taken to measure how much cortisol is in the blood. In dogs with Cushing’s, their adrenal glands are very sensitive to this hormone, and so the glands release a much higher amount of cortisol than would be expected with an average dog.   

ACTH Stim test

 Figure 1: Example of Dr Sam’s dog’s ACTH stimulation test result 

2. Low Dose Dexamethasone Suppression Test (LDDST) 

This test is associated with more false negatives (misdiagnoses) than the above and so is only used when Cushing’s is suspected, and the ACTH stim test above is normal. Occasionally Cushing’s is a ‘two test disease’, and you need both the ACTH stimulation and the LDDST to diagnose it properly 

3. Abdominal ultrasound – this test is used often in conjunction with other tests, and it looks at how big and plump the adrenal glands are (2x big, fat adrenal glands are suspicious), and an adrenal tumour is obvious mostly. 

  abdominal ultrasound for cushings


For succinctness, this section refers to trilostane use only. While there are other drugs (Mitotane, selegiline and ketoconazole) and surgical options to remove the adrenal glands, these other treatments we consider not to current standards 

There is no prescriptive way to treat Cushing’s disease in our patients, and we use a range of factors to decide how aggressively (starting dose of trilostane) to treat this chronic disease.  

Family factors 

  • Willingness to perform regular blood tests 
  • Cost concerns 
  • Observance – can the family accurately monitor the dog’s symptoms and status, like changes in thirst and appetite. Does the dog live in one home or multiple homes.
  • Risk level – would the family be prepared to take any risks to potentially extend the life of the dog but make an Addison’s episode more likely? 

 Dog factors 

  • Frailty – the older the dog, the gentler we are with starting new medication of any kind 
  • Comorbidities – does the dog have other conditions that should be treated and investigated first, like a heart murmur 
  • Other medications – is the dog on other medications, for example, meloxicam for arthritis – if so, we take into account the interaction of these meds with trilostane.   
  • Severity of symptoms 

While some have a conservative approach to treating Cushing’s, and opt for a very low-risk dosing protocol, if the above factors are all weighed in favour of a higher dose trilostane protocol, we have a proactive approach to treating Cushing’s.  To avoid complications, we opt for an approach that includes regular testing to ensure the dose is personalised.  

We insist that when starting trilostane, the family must be around for at least two months and have no holidays or time away planned, so we can get the dose optimised. 

Whenever a dog is diagnosed with Cushing’s disease and put on trilostane, they are given cortate– a synthetic version of the body’s cortisol, to be given in the case of the opposite disease to Cushing’s occurring – more on that later. 

Compounded vs off the shelf ‘Vetoryl’ brand 

We only compound when there is no dose of trilostane readily available. Vetoryl is a brand of trilostane, and it is available in Vetoryl 10mg, Vetoryl 30mg, Vetoryl 60mg, and Vetoryl 120mg. 

For example, if your pet needs 70mg or 90mg of trilostane, we will compound it. 

It can be made into whatever flavour your pet likes, and capsules or a liquid are available.  

Common flavours include chicken, liver, beef, fish or cheese. 

There are good and there are lousy compounding labs; we use a lab in Sydney that has been supplying us with high-quality trilostane for over ten years. We are familiar with the method they use to make it and the quality of the inactive ingredients.  

 When not to give trilostane: 

It’s crucial to stop trilostane whenever you notice your pet not being quite right 

Other things to consider before treating Cushing’s including how much does Cushing’s cost? 

Proper treatment of Cushing’s may worsen other conditions – this includes anything for which cortisone is prescribed.  

Cushing’s disease can cost multiple dollars a day (that’s thousands of dollars a year). If the family cannot afford regular testing to ensure the trilostane dose is correct, it’s safer not to treat Cushing’s disease at all.  

Addison’s disease 

The opposite, ‘steroid excess,’ is a lack of steroids; and so the opposite of Cushing’s can cause signs of ‘Addison’s disease’, which is a medical emergency to treat.  

It’s important to know that having an episode of adrenal necrosis or Addison’s does not represent treatment failure. 

Many things during the treatment of Cushing’s disease can cause this; even the ACTH in the drug administered to perform the ACTH stimulation test itself can be toxic to the adrenal glands, as can trilostane, and so even a dog maintained on the same dose of trilostane for many years can require a dose reduction either temporarily or permanently following an episode of adrenal damage.  

Dose of trilostane 

There is no standard dose of trilostane in Cushing’s disease. We have some dogs that are 10kg receiving 90mg twice daily to control their signs and others that are 40kg and receive only 30mg once daily. 

The average starting dose is around 6mg/kg/day. 

What if I don’t treat it? 

Untreated, Cushing’s disease won’t kill a family’s dog – but the complications associated with the multiple organs it attacks will eventually – whether it is acute pancreatitis, debilitating liver disease, or kidney stones. 

How often do we need to test? 

Every time a dose is changed, 7-10 days after, an ACTH stimulation test must occur to ensure the dose increase or decrease led to the expected effect. Sometimes the increase or decrease needs to be higher or higher, so another dose adjustment must happen. But remember that each time this dose is changed, a retest needs to occur. This is for your pet’s safety only. 

If everything is going well and all the symptoms of Cushing’s are being well managed, you need a repeat ACTH stimulation test at least every quarter (3 months).  

Any change to your dog’s condition or worsening of symptoms, or if lethargy or any other sign of being unwell and Addison’s is suspected, another ACTH stimulation test must occur. 

What about just monitoring the symptoms 

There is a movement by some veterinarians to rely on just the owner’s perception of how their dog’s symptoms are being controlled. We feel this is dangerous and do not believe that just monitoring the symptoms represents acceptable current standard, so serial ACTH stimulation tests are vital for us to control your dog’s Cushing’s syndrome. 

 Natural alternatives? 

There is no natural supplement or herb that controls Cushing’s disease. While there are some ‘adrenal tonics’ to help support normal adrenal function, like turmeric, ginseng and chamomile, the doses that are safe and effective in dogs are not known. So, we don’t recommend supplements for Cushing’s disease. Supplements for the conditions that Cushing’s causes – if your pet has them, is something worth considering. For example, our veterinarians often give milk thistle alongside to dogs with Cushing’s disease and liver disease or what’s called a ‘steroid hepatopathy.’  

milk thistle for cushings

Trilostane cost 

While trilostane can cost anywhere from $2 – $10 per day to give your pet, the diseases it prevents through proper control of Cushing’s disease can extend your pet’s life and have fewer costly vet visits for related conditions. 

Is there a specialist or expert in endocrinology?

There is no such thing as a specialist in Cushing’s disease. The best practitioners are those with the best internal medicine knowledge or experience treating Cushing’s disease. 

Are dogs in pain with Cushing’s disease? 

No, but the conditions associated with Cushing’s, like bladder stones, can be painful. 

Do dogs with Cushing’s disease suffer? 

Cushing’s causes diseases of multiple organs, leading to suffering. Thankfully most cases of Cushing’s are very treatable, and rapid improvements in quality of life markers are observed.  

Does Cushing’s disease cause anxiety in dogs? 

Cortisol is a stress hormone in dogs, just like people, and it is thought that by controlling excess cortisol through the correct treatment of Cushing’s disease, there could be benefits to anxiety.  

How long do dogs usually live with Cushing’s disease? 

We have some dogs with Cushing’s disease that are over 20 years old, so diligent management of Cushing’s disease can extend the healthy lifespan of dogs. 

What are the final stages of Cushing’s disease in dogs? 

The final stages of Cushing’s disease are normally associated with a complication of one of the many organ systems that Cushing’s affects. For example, end stage liver failure leading to malnutrition, or a diabetic emergency that causes septicaemia (blood poisoning). The most catastrophic end to Cushing’s disease is a stroke or heart attack as Cushing’s can cause ‘sticky’ or hypercoagulable blood that clots a lot more often. Proper treatment of Cushing’s disease can ensure that the organ systems are protected from the toxic effects of cortisol as much as possible and can delay the onset of other disease.

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

Panting when it’s not hot, high thirst, hunger, the perception by pet parents that their pet is ‘aging’ faster than expected, and skin issues are often the first signs of Cushing’s disease. 

What is the life expectancy of a dog with Cushing’s disease? 

We have some dogs with Cushing’s disease that are over 20 years old, so diligent management of Cushing’s disease can extend the healthy lifespan of dogs. 

What triggers Cushing’s disease in dogs? 

It is thought that genetics plays a big part in Cushing’s disease.