Investigating the signs of Cushing’s syndrome

Nobody wants their four-legged friend to be a Cushing’s suspect. If your dog shows similar symptoms to our prime suspects, then you must investigate the matter further.

Rehabilitation through treatment

Irrespective of the cause of Cushing's, the result is always the same - more cortisol is produced than is actually needed by the body. This results in the slow development of a combination of clinical signs that are associated with the condition.

You might have noticed a difference in your dog’s appearance or behaviour recently. The happy, healthy animal you once knew seems to be slowing down. You might think it’s just old age, but it could be Cushing’s.

This section describes the most common clinical signs associated with Cushing’s and explains why they occur.

Eight arresting signs​

Are you finding that your dog needs letting out into the garden more frequently? Are you filling up the water bowl multiple times per day? Is your dog waking you through the night to urinate, or having accidents indoors when they are normally well house trained?

If yes, then you are not alone. Most owners of dogs with Cushing’s report these findings. In fact, the most common clinical signs seen with Cushing’s are that dogs start to drink a lot more and require more frequent visits outside to urinate.

The exact mechanism behind this is not fully understood, however it is thought that the increase in cortisol interferes with water absorption in the kidney. This means more urine is produced and subsequently your dog needs to urinate more frequently.

As your dog is urinating more, they are losing water. This is replaced by an increase in drinking and water should not be withheld from your dog.

If you are finding that your once picky dog is now eating all their food and more, or is showing a change in behaviour to become more aggressive and protective around food, then you should discuss this with your vet.

Cortisol has a direct impact on the metabolism and therefore hunger of your dog. When cortisol increases, so too does appetite, and this can lead to the changes described above.

There are three reasons why a dog with Cushing’s may be more prone to a urinary tract infection: 

  1.  Excessive amounts of cortisol in the blood lower your dog’s immune system, leaving them susceptible to infection
  2. The urine produced by a dog with Cushing’s is often very dilute and therefore less toxic to bacteria. They are able to reproduce more easily – leading to infection
  3.  As most dogs are house trained, they avoid urinating indoors where possible, and this can lead to them holding large volumes of urine in their bladders. This can also lead to weakness in the bladder muscle and leave your pet prone to infection.

A one-off infection in a young dog is unlikely to be as a result of Cushing’s, however if you are visiting your vet frequently with these signs, you should definitely suspect Cushing’s.

An increase in appetite can cause your dog to gain weight, but your pet may physically look as though they have gained more weight than the scales show. This is due to a rounded appearance of their waist – otherwise known as a pot belly. 

A pot belly is seen in dogs with Cushing’s due to a combination of factors:

  1. Muscle weakness means that the abdominal muscles stretch under the weight of your dog’s internal organs
  2. Of their organs, the liver becomes enlarged and heavier – increasing the size of the belly 
  3. Fat is moved into the belly – increasing the weight being held by the abdominal muscles
  4. As mentioned under urinary tract infections, dogs with Cushing’s often hold a large volume of urine in their bladders, again adding to the weight of the abdomen and increasing the potbellied appearance

Cortisol is catabolic hormone which breaks down muscles. An increase in cortisol can therefore lead to an increase in muscle breakdown.

This may mean it is more difficult for your dog to stand up, jump on the sofa, or climb up and down the stairs.

Muscle weakness affects the entire body, including the muscles for breathing. Weakness in these muscles can lead to an increase in panting. It is also thought that cortisol may have a direct impact on the part of the brain which controls breathing.

Where Cushing’s is caused by a pituitary tumour, it is thought that lethargy may be due to increases in the hormone, ACTH. Cortisol may also impact on signaling within the brain, leading to your dog sleeping more and being less willing to exercise.

Hair loss can be common in dogs with Cushing’s and you may find that your dog is losing their fur along both sides of their body, over their belly and/or along their tail.

For some dogs this hair loss can be extreme, leaving them only with fur over their head and feet. Yet for other dogs it may more subtle – with signs such as having a dull coat, hair not growing back after being clipped or blackhead formation in the armpits or groin.

In healthy dogs, the hair is grown and shed in a constant cycle. In dogs with Cushing’s this cycle slows down, or stops completely, meaning hair that falls out fails to regrow.

Skin can also become thinner as a result of excessive cortisol and when this is combined with a reduction in the function of the immune system (as mentioned in the section on urinary tract infection) then recurrent skin infections can also become a problem.

Suspect Cushing’s? Investigate further.

Not all dogs will react to Cushing’s in the same way, and your dog may not necessarily display all of these signs. Whenever you suspect Cushing’s, it is always a good idea to keep a note of the changes you see in your dog’s habits and behaviour, so that you can investigate potential issues with your vet. 

Investigate further

It is difficult to say what impact Cushing’s could have on each individual dog’s behaviour. Certainly, behaviour in relation to eating and drinking may change, including increased food aggression; or showing appeasing behaviour after soiling in the house. Equally, lethargy and lack of exercise tolerance are known clinical signs of Cushing’s.

Behavioural/mental changes such as mood swings and depression are known clinical signs of Cushing’s in human patients. It is equally recognised that when humans are given synthetic corticosteroids (which act in the same way as cortisol), there may be behavioural side effects as a result. Those reported include mild effects such as restlessness, irritability and insomnia, depression and more severe psychiatric disturbances including psychosis and hallucinations. Effects in humans appear to be dose-dependent and generally resolve once the medicine is stopped. 

Yes, there are many other diseases which can produce signs such as drinking more and lethargy. However as your dog displays more clinical signs, the greater chance there is that Cushing’s is present.

Examples of other conditions which may present in a similar way to Cushing’s include hormonal diseases such as an underactive thyroid or diabetes, infections such as a pyometra, and organ malfunction such as kidney or liver disease.

Your vet will perform investigations to discover what is causing the unique set of signs your dog is displaying, and given some of the conditions listed above can be life-threatening, we always recommend that you visit your vet if you are concerned about your pet.



Find evidence of Cushing’s

When your veterinary surgeon suspects Cushing’s syndrome, they will perform blood and urine tests to confirm the diagnosis. Discover the tests your vet will do when searching for Cushing’s evidence.

Diagnose Cushing’s