Dog Adrenal Hormones: What is the Difference between Adrenaline and Cortisol?

Adrenaline and cortisol are produced by your dog’s adrenal glands. Both of these hormones play a role during stress but their functions are different.

Recently I read a veterinary article about elevated liver enzymes in [senior] dogs. The author wrote it from the perspective of clinical experience. Among other things, the article explained how liver enzyme elevation can be a predictor of Cushing’s disease. And then it introduced what I thought was a typo–an explanation that Cushing’s disease is caused by over-production of adrenaline. When I asked, the veterinarian who wrote it told me that she used it on purpose–because it is a familiar word.

Dog Adrenal Hormones: What is the Difference between Adrenaline and Cortisol?

I can see that, except I can’t. I do believe in simplification–it is more important to understand concepts than terminology. But is it helpful to substitute one thing for another just because the latter is unfamiliar? I won’t be the judge of that. Instead, I will try to explain the difference in simple terms.

What is adrenaline?

Adrenaline is one of the hormones produced by adrenal glands. So far so good–everybody heard of adrenaline. And adrenal glands are the glands that make it. Btw, however fancy the term might sound, it’s nothing more than Latin for the gland’s location–near the kidneys.

So the name for the adrenal glands stems from their location. Adrenaline has its name after the glands it comes from–as far back as 1901. Except it’s not the only hormone the adrenal glands make. Bummer.

What is cortisol?

By the time cortisol was getting its name, it has been discovered that the adrenal glands are not just a one-purpose chunk of an organ. Instead, they have a distinct inner core and outer shell (cortex), each of which has a different function. So cortisol too has its name from the place of its origin–the adrenal cortex. Which works because adrenaline is actually produced in the core of the gland, not the shell.

Other than where they come from, then, the names of these two hormones tell us little about what they do.

They are related in the sense that the adrenal glands release both in response to stress.

What does adrenaline do?

Adrenaline works to provide a boost to facilitate fight or flight. That includes:

an increase in heart rate and blood pressure
expanding air passages in the lungs
maximizing glucose metabolism
and redistributing blood to the muscles

Kind of like a turbocharge boost in a race car.

What does cortisol do?

Cortisol too plays a role in stress response. It controls the processes that provide the energy needed for the above turbo boost. In other words, adrenaline facilitates the distribution and cortisol supplies the fuel. In the process, it also suspends functions that are not a priority for immediate survival–such as the immune system or tissue maintenance. Which is great when you need to run away from a predator. It is not so great when things fail to return back to normal when the danger is over.

Cushing’s disease

Adrenaline has nothing to do with Cushing’s disease–cortisol does. With Cushing’s disease, the adrenal cortex (the outer shell that produces cortisol) gets over-stimulated and produces too much. As well as too much cortisol might be introduced into the body in the form of medication.

Once in the bloodstream, the hormone doesn’t know any better–it does what is supposed to do–getting everything organized for flight or fight. Except there isn’t any. Processes that should be running get shut down, everything is focused on gathering fuel which is neither properly distributed or used.