You may have heard the term Cushing’s disease in dogs but aren’t quite sure what it means. In this article we’re going to be looking at what it is, the signs to look out for, how it’s diagnosed and how to help your dog if he does get this diagnosis.
UPDATED October 16, 2018
What is Cushing’s disease in dogs?
The pituitary gland (at the base of the brain) produces a hormone called ACTH
ACTH stimulates the adrenal gland (on top of kidneys) to produce glucocorticoid hormones/corticosteroids (Cortisol)
Something goes wrong in the pituitary or adrenal glands
Too much cortisol is produced by the adrenals
Cushing’s disease develops
There are two types of Cushing’s
This means the pituitary gland (pea sized gland at the base of the brain) is overproducing cortisol due to a tumour or enlargement of the gland. It is the most common form, affecting around 80%-85% of dogs.
A tumour in one or both of the adrenal glands (that sit on top of the kidneys) is responsible for about 15%-20% of cases. About half of these will metastasize (spread).
A third type…
I did say there were two types, but “iatrogenic” Cushing’s disease occurs as a result of high doses of steroids over a long period of time. Once the steroids are discontinued, symptoms should go away. Anyone taking steroids must be gradually weaned off them over the course of several weeks, because it is too dangerous to stop them abruptly.
What role does cortisol play
- Helps your dog cope with physical and emotional stress
- Suppresses inflammation
- Helps with wound healing
- Supports muscle and ligament health
- Controls weight
- Necessary for proper brain function
- Maintains bone health
- Fights infection
- Maintains normal blood sugar (glucose) levels
Signs and Symptoms
Cushing’s comes on very slowly and the first signs you tend to see are your dog having to drink and pee more frequently.
I cannot stress enough the importance of making an appointment with your vet when you notice any changes whether physical or behavioural. Unfortunately they are usually just attributed to the natural aging process, but in most cases they signal a problem.
Other symptoms to watch out for include
- Increased hunger
- Weight gain
- Hair loss
- Pot belly/abdominal swelling
- Thinning skin
- Tired and inactive
- Skin infections
- Muscle loss
- Fat accumulation on the neck and shoulders
- Housebroken dogs may start to have accidents
- May bruise easily
- Bladder or kidney infections
- Susceptible to blood clots
- Lack of energy
How is Cushing’s diagnosed?
It can be difficult to diagnose because in many cases the symptoms are quite mild, and especially in the case of senior dogs tend to be attributed to natural aging. In addition, many of the signs are similar to other conditions and there is no ONE definitive test for Cushing’s.
During your appointment your vet will want to hear your concerns, and what new behaviours you’ve noticed. If you’re going to a new vet he will need a detailed medical history, so you may want to have your dog’s notes emailed over ahead of your appointment.
Once you’ve had a chat your vet will exam your dog then take blood and urine for testing. Think about bringing a urine sample with you to make things easier. Urine should be collected less than 2 hours before your appointment and use a clean container.
If your vet suspects Cushing’s is a possibility based on the above, there are further tests he can run for confirmation.
Urine cortisol : creatinine ratio
This test measures the cortisol:creatinine ratio in your dog’s urine. If it is high further testing will be needed, because there are other explanations for this result not just Cushing’s.
Low dose Dexamethasone suppression test (LDDST)
The next test would be the low dose suppression test and is the most common. It involves taking a blood sample to measure a dog’s baseline cortisol level. A man made version of cortisol called Dexamethasone is injected into your dog, than blood cortisol levels are measured after 4 hours and 8 hours.
The pituitary gland should mistake it for cortisol and let the adrenal gland know to stop producing it. In a “healthy” dog there would be a significant decrease in blood cortisol levels, but if the levels are high it could mean a pituitary tumour that continues to produce ACTH, or an adrenal tumour that continues to produce cortisol.
Just a reminder of what ACTH is – Adrenocorticotropic hormone produced in the pituitary gland in the brain that regulates cortisol levels.
High Dose Dexamethasone Suppression Test
Same as the low dose test except more Dexamethasone is given.
ACTH stimulation test
Blood is drawn before and after a shot of ACTH to see how the hormone affects your dog.
An abdominal ultrasound will allow your vet to see the adrenal glands and whether or not a tumour is present.
Who is at risk of developing Cushing’s?
I had a Maltese who had Cushing’s when we adopted him, and since I was writing about this disease I was curious to learn if there were any breeds that were more susceptible to developing it than others, and at what age it typically happens.
I have read reports that say it doesn’t discriminate based on sex or breed, and others that say breeds like Beagles, Boston Terriers, Dachshunds, Yorkies, Poodles and Boxers are more prone, and females slightly more than males. I’ve also read it tends to happen around 6 years of age or 8.
Please don’t start panicking if you have one of the breeds mentioned, because it in no way means your dog will develop Cushing’s. Carry on caring for him as you do, and like I mentioned above, see your vet if you notice any changes.
If your dog has iatrogenic Cushing’s we know it is caused by steroid use, so the obvious way to reverse the condition is by stopping their use. Your vet will help you do that with a withdrawal schedule. Since there is a strong possibility the original condition that was being treated will come back, be sure to speak to your vet about alternative treatments.
If your dog has Adrenal Dependent Cushing’s the tumour could, technically, be removed by surgery. However it/they are often impossible to see, may have already spread, the operation is tricky and post op complications a big enough concern that it is not commonly done.
The following information about treatment options was taken from the FDA website.
“Vetoryl (trilostane), approved by the FDA in 2008 is the only drug approved to treat both pituitary- and adrenal-dependent Cushing’s in dogs. This prescription drug works by stopping the production of cortisol in the adrenal glands. Vetoryl should not be given to a dog that
- has kidney or liver disease
- takes certain medications used to treat heart disease
- is pregnant
The drug’s most common side effects are poor or reduced appetite, vomiting, lack of energy, diarrhea, and weakness. Occasionally, more serious side effects, including bloody diarrhea, collapse, severe sodium/potassium imbalance, and destruction of the adrenal gland may occur, and may result in death. In 2014, with input from CVM, the manufacturer updated the information about patient monitoring and side effects on the package insert. Although not proven to be caused by Vetoryl, some additional side effects reported to CVM and now included on the package insert are adrenal insufficiency, shaking, elevated liver enzymes and elevated kidney tests.
Only one other drug, Anipryl (selegiline), is FDA-approved to treat Cushing’s disease in dogs, but only to treat uncomplicated, pituitary-dependent Cushing’s.
Veterinarians have often used a human chemotherapy drug, Lysodren (mitotane), “off-label” to treat Cushing’s in dogs. Lysodren destroys the layers of the adrenal gland that produce cortisol. It requires careful monitoring and can have severe side effects.
“Off-label,” or “extra-label,” means veterinarians can legally prescribe human drugs to animals for uses not listed on the label, or for other species or at different dosage levels from those listed on the label. But because dogs may react unpredictably to human drugs, says Stohlman, it’s beneficial to have treatments available that have been studied in dogs and approved specifically for them.”
If you’re interested in alternative treatments there are options for you to explore, so I have included links to articles you may find interesting. Having said that, please do not stop the treatment your vet has recommended without first having a conversation with him or her. There may be a way to integrate the two, or if he is completely opposed find a holistic vet and make an appointment for a consultation to discuss alternatives.
This is a conversation you’re going to want to have with your vet, since the answer will depend on many factors such as –
Your dog’s overall health
The type of Cushing’s he has
His response to the treatment
Has the tumour spread and is causing other issues
Life with Cushing’s
- Follow your dog’s treatment plan to the letter
- Regular vet checks and testing
- Keep a close watch on behaviour and symptoms
- Good nutrition
- Low stress, quiet life
- Watch for any reactions to medications like lethargy, loss of appetite, vomiting, diarrhea… and call your vet immediately.
Does your dog have Cushing’s? What symptoms did you start to see that had you concerned? What tests did your vet carry out in order to arrive at this diagnosis? What treatment is your dog on and how is he doing? Sharing helps others so please leave your comments below.
**I would like to invite you to join Senior Dog Care Club, my Facebook group for senior dog parents. It is a wonderful community where you will find lots of helpful tips and advice, a place to ask questions and share experiences. I look forward to welcoming you.**