The endocrine system is a fascinating network of tissues and glands responsible for vital hormones that regulate many of the body’s functions. Cortisol is one such vital hormone. It is often referred to as the stress hormone, for good reason. However, aiding stress response is only one of the critical functions of cortisol. Within the brains of dogs and cats (and other animals including humans) is the hypothalamus. Connected to the hypothalamus is the small but mighty pituitary gland. These work together to produce, regulate, and stimulate production of hormones that serve the body, including cortisol. Cortisol is a steroid hormone (glucocorticoid) and is crucial in that it aids in many major functions throughout the bodies of animals. Its importance is such that synthetic versions of cortisol are created and used in medicine to treat several ailments.

It is widely known that cortisol helps regulate the body’s stress and perceived danger responses, but that is just one (albeit important) function. Cortisol also helps regulate immune responses, as well as metabolism, blood pressure, blood sugar levels, and inflammation. It is a powerful weapon against inflammation, suppressing individual parts that create the entire process of inflammation. The adrenal glands, located in front of the kidneys, produce most of a body’s cortisol supply. The hypothalamus and the pituitary gland can sense how much cortisol is in a body’s blood. When they determine a lack of sufficient cortisol, the pituitary gland produces adrenocorticotropic hormone (ACTH) and sends it into the bloodstream. The ACTH signals the adrenal glands to produce cortisol. The cortisol then makes its way throughout the body and carries out its essential tasks.

The amount of cortisol produced and how it performs varies from day to day and depends on the variables of given situations. A body determines how much cortisol it needs at any time and for which purpose using physical, environmental, and physiological stimuli.

Adrenal gland disorders can compromise the body’s ability to produce, sense, or use cortisol properly. When cortisol levels become irregular, it can have devastating effects on the body including causing a weakened immune system, skin problems, excessive hunger or thirst, dehydration, weak muscles, organ failure, infection and death resulting from complications of disease.

Adrenal gland disorders in dogs are not uncommon, though there have been few formal studies measuring prevalence.  A 2009 publication showed the prevalence of the most common canine adrenal gland disorder (Cushing’s disease, the overproduction of cortisol) at approximately 100,000 cases per year in the United States. A 2019 study of 21, 281 dogs from four private clinics and one university reference centre in Italy concluded an overall 2% prevalence.

While cats do have adrenal disorders, it is less common than it is in dogs.

Diagnosis of adrenal gland disorders can be challenging and are sometimes delayed given the nature of symptoms. Symptoms of disease caused by irregular cortisol production can look like many other illnesses or even just normal aging. These can include lethargy, vomiting, diarrhoea, appetite changes, and weight loss or gain. Regular wellness exams and taking note of any changes in pets’ behaviours are imperative.

Cortisol is so much more than a stress aid. It is one of the many amazing hormones the body uses to function properly. It amplifies the body’s ability to fight off stress, infection, inflammation, and other bad actors that can lead to disease.