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.
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.
Are you finding that your dog needs letting out into the garden much 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.
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 your dog has shown 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 many be more prone to a urinary tract 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, it may lead to an increase in suspicion of 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:
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.
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.
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, to depression and more severe psychiatric disturbances including psychosis and hallucinations. Effects in humans appear to be dose dependant and generally resolve once the medicine is stopped1
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.