To be honest, he has become a lot like my husband.” Danny de Dachshund was 10 years old, had gained 5 kilos, lost his hair, slept all day and had to get up at night to pee. I glanced at the sleepy gentleman holding Danny in his spacious lap, and I understood.
“So he’s just an ‘old dog,’ isn’t he, Dr. Ward?”
For a moment I didn’t know whether she was talking about the husband or the sausage dog. I went with the latter.
What is Cushing’s Disease?
As we say in medicine, “Age is not a disease.” I was more concerned about a hormonal disease that is quite common in Dachshunds, Cushing’s disease.
Cushing’s disease, also known as Cushing’s syndrome or hyperadrenocorticism (HAC), is a condition that produces an excess of cortisol hormone. It is commonly diagnosed in middle-aged or older Beagles, Boston Terriers, Boxers, Dachshunds, Miniature Schnauzers, and Poodles, although any breed can develop hyperadrenocorticism.
If I suspect a dog has hyperadrenocorticism, I start with basic blood and urine tests. If the patient has elevated liver enzymes (especially very high ALP and slightly elevated ALT), high cholesterol, glucose and triglycerides, low urine specific gravity, urine glucose, proteins, or signs of infection, Cushing jumps to the top of the diagnostic list.
Danny met many of these screening criteria, which meant it was time to run confirmatory tests. Cushing’s syndrome is caused by either a benign tumor in the pituitary gland (an estimated 85% of cases), a malignant adrenal gland tumor (much rarer but more serious), or by overuse of steroids (iatrogenic HAC).
Time to test
There are several tests to choose from, each with unique advantages and disadvantages. The first is the urinary cortisol/creatinine ratio (UCCR). This test requires the dog parent to collect two first morning urine samples at home, usually two to three days after a potentially stressful event such as a vet visit, boarding or grooming. I use UCCR as a handy screening test when a patient cannot easily reach the clinic or when my suspicion of suspicion is somewhat marginal.
The UCCR is very sensitive meaning if a dog has a normal result, there’s a good chance it’s not Cushing’s. Unfortunately, the UCCR isn’t very specific, meaning a positive result may not be due to Cushing’s, requiring additional testing to confirm. Despite these limitations, a UCCR is an excellent starting point for initial testing, especially in high-risk breeds or breeds showing early or mild symptoms.
The most common, and arguably preferred, assessment for Cushing’s syndrome in dogs is the low-dose dexamethasone suppression (LDDS) test. The main drawback of this test is that it requires eight hours in the clinic and the blood samples must be carefully handled and prepared.
In the simplest terms, the patient is given a drug, dexamethasone, to suppress adrenal function, and blood cortisol levels are measured at four and eight hours. A diagnosis is made based on the level and degree of elevation. In about 70 to 80% of cases, this is the only test needed.
The ACTH response test is another classic Cushing’s test in which the hormone ACTH is administered and the resulting exaggerated cortisol stimulation is measured. This is the gold standard test for diagnosing iatrogenic Cushing’s (ie caused by giving steroids) and only requires one to two hours in the clinic. Compared to LDDS, it is less sensitive and is usually reserved for special situations or as a supplement to LDDS. Some vets prefer to start with an ACTH response test, especially in dogs that have been given certain medications, especially steroids.
Endogenous ACTH and imaging (ultrasound, MRI, CT) are also excellent choices to diagnose or verify Cushing’s in dogs, but are more complicated and often more expensive.
In Danny’s case, we took an LDDS test and he was textbook positive. As his symptoms worsened and affected his quality of life, not to mention the strain his 2am pee patrols and accidents put on his family, we opted for treatment.
I chose the newer trilostane (Vetoryl) over the classic mitotane (Lysodren) because I’ve found it causes fewer side effects and can easily be given with food once or twice a day. I instructed Danny’s owner to watch carefully for possible side effects, including vomiting, diarrhea, lethargy, and 48 hours of not eating. Those signs could indicate a side effect known as an Addisonian crisis that requires immediate medical attention.
Danny underwent follow-up ACTH response testing at 14, 30, and 90 days to enter his dosage. Within a few months, his canine mom reported a noticeable increase in energy, much less drinking and peeing, weight loss (3 pounds!) and his hair started to grow back.
He’d had very few side effects from drugs, except for some loss of appetite and a few bouts of loose stools. Overall, Danny the Dachshund was more himself and less like his dog dad. That led to an unusual question from Danny’s dog mom: “Dr. Ward, would you give my husband some of Danny’s medicine?”
Cushing’s disease, also known as Cushing’s syndrome or hyperadrenocorticism (HAC), is a condition that produces an excess of cortisol hormone.
The most common symptoms include:
- increased thirst and urination
- increased appetite and weight gain
- abdominal enlargement (pot belly)
Many dogs with Cushing’s syndrome also have:
- chronic skin infections
- poor hair growth resulting in thinning or bald areas, especially along the sides of the back and hips
- oily or greasy coats