Friday 7:30 pm last appointment of the day:

Patient presents as having trouble holding their bladder, owner is sure their beloved pet has caught a urinary tract infection. Has noticed fluffy also getting a bit fat, probably just putting on the winter weight but the owner has acted accordingly and cut back the treats “slightly”. “Can’t believe how much they are shedding doc! he is almost naked!”.

I take a deep breath,… ok, where to start.

• Me- How long has Fluffy been having problems?
• Owner- maybe 2 months
• Me- Can you tell me a bit more about Fluffy and their daily habits?
• Owner- well he has been drinking more and more water but it has only been recent that he has had problems holding his bladder
• Me- Any vomiting or diarrhea?
• Owner- No he loves his food, maybe a bit too much,..but I really dont think I’ve fed him THAT much more than I normally have.
• Me- Has his hair looked like this before? (pointing to the half naked pot bellied “dog”)
• Owner- No that’s new,…

Pro tip: when your dog is losing fur to the point they become naked, it is not shedding.

This dog is what I would consider the text book presentation of hyperadrenocorticism or Cushing’s disease. An endocrine (hormone) disease in which endogenous hormone production has gone off the rails. It is typically caused by either dysfunction of the pituitary gland or of the adrenal gland itself. In a normal functioning system the pituitary gland (at the base of the brain) produces ACTH (adrenocortico stimulating hormone) this in turn tells the the adrenal glands (located on top of the kidneys) to pump out cortisol. As the levels of circulating cortisol increase the pituitary gland slows down/shuts off production of ACTH (negative feedback loop TA-DA!) In our dysfunctional bundles of furry joy there are two types of Cushing’s; pituitary dependent (tumors on the pituitary gland are hyper pumping ACTH) and adrenal dependent (tumors on adrenal glands pumping out cortisol independent of any signals from the brain)

The excess steroids (and this is the case of with pets on steroid medications as well) cause increased drinking and urination (which can sort of seem like your pet has a uti). High level of steroids also cause the alopecia (balding) we are seeing. Pot belly is also pretty typical. Although our above patient is looking pretty sure he wants to have Cushing’s it is important to rule out other causes that may either be masked or concurrently affecting our patient. ENTER diagnostic tools:

Blood work- lets check to see what the liver is saying, often times if we have true endogenous steroid issues we can see steroid induced hepatopathy, er angry liver due to steroids. We also look to see for any concurrent renal disease (that also causes increased drinking and urination).

Urinalysis- This ideally should be comprehensive with urine microscopy, looking for crystals and bugs, checking pH and concentration, possibly even a culture and sensitivity, ensuring there isn’t any urinary tract infection. Further I usually recommend running a cortisol and creatinine ratio on urine, this helps to quantify the amount of steroid.

Blood tests- low dose dexamethasone suppression test and high dose dexamethasone suppression test. These involve taking blood before an injection of a steroid and taking follow up samples to see if the patients own steroid production decreases. In dogs with Cushing’s the suppression does not take place.

Bonus tests- Imaging- ultrasound is a good way to assess if there are differences in sizes of the adrenal glands, this won’t tell you if they have Cushing’s but if they do, it will help differentiate between pituitary and adrenal dependent forms.

TREATMENT: for pituitary dependent forms the treatment is usually lifelong medications with regular blood tests to ensure that the medication is at a safe level and adequately controlling the Cushing’s disease. For adrenal dependent forms (approximately 10-15% of Cushing’s cases) the story is a bit more complicated. As these cases are typically dealing with a tumor of some sort there is the question of surgical removal. These procedures are difficult and some will opt for lifelong medical management instead.

Although in general Cushing’s disease isn’t one that is “cured” it is one that we can manage and help our pets live happy and comfortably.

Photo courtesy of Clinician’s Brief