I have been in emergency and critical care veterinary medicine for the last six years, and I have loved much of that time. I love living without a set appointment schedule, accomplishing challenging tasks, and, most importantly, saving lives. I have found that over time, you grow to love and hate certain ER-specific cases. For example, I hate lacerations. I hate feeling like I have to hurry up, get all the supplies together, and get the patient ready, but then I have to wait for an hour or more, monitoring anesthesia while the doctor stitches the wound.
On the other hand, my favorite emergency is the Addisonian crisis. Now, why in the world would I love this emergency over all the others? One simple reason: It’s fun to fix! (Fair warning, I may have a strange sense of fun). These animals often get carried in the door and have a paw or two in the grave. But, provide some fluids and a shot of steroids and they are bouncing out the door the next morning. Boom. Instant gratification!
But, why are steroids such an instant cure? Let’s take a brief tour through this interesting disease process so we can better appreciate this “miracle” cure.
The adrenal gland
Located on the cranial pole of each kidney, this little gland is in charge of many important hormones circulating around the body. The adrenal gland is separated into two parts: the cortex and the medulla. The cortex is responsible for releasing cortisol, also known as a glucocorticoid, and aldosterone, a mineralocorticoid. The medulla secretes epinephrine and norepinephrine.
Addison’s disease happens when there is a failure of the adrenal cortex. This may be a primary failure of the cortex itself, or a failure in the hormone feedback and triggering system. When circulating cortisol is low, the hypothalamus produces corticotropin-releasing hormone, which triggers the pituitary to release adrenocorticotropic hormone (ACTH), which then triggers the adrenal cortex to release cortisol. A breakdown in any part of that system causes Addison’s disease, and when circulating levels of cortisol (+/- aldosterone) drop too low, an Addisonian crisis develops.
The Addisonian crisis
Cortisol and aldosterone are essential to life and have many important functions within the body. Aldosterone (or mineralocorticoids) are responsible for:
- Increased resorption of sodium within the kidneys
- Increased resorption of free water with subsequent expansion of extracellular fluid volume (secondary to sodium resorption)
- Increased renal excretion of potassium
Cortisol receptors are found in every cell within the body, so its effect is literally body-wide. However, its main functions include:
- Gluconeogenesis, which is the production of glucose from its substrates within the liver
- Inhibition of inflammation
- Insulin counteraction
- Regulation of gastrointestinal function
- Increased production during times of stress as the “fight-or-flight” response
An animal with low cortisol levels will often have vague, non-specific signs, such as hyporexia, lethargy, GI upset, and weight loss, particularly in times of stress. An animal in an Addisonian crisis may present with the following clinical signs:
sodium and/or increased potassium levels
- Sodium-to-potassium ratio less than 28:1
- Only present with mineralocorticoid deficiency
- Azotemia with low urine-specific gravity
of stress leukogram
- Stress leukogram = neutrophilia with leukopenia
degrees of anemia
- Mild from lack of cortisol or severe from GI bleeding
- Due to lack of sodium and free water retention
- Due to hypovolemia and decreased hydrogen ion excretion
Basal cortisol plasma/serum concentration:
- A result of 1 mcg/dl or less has excellent sensitivity and good specificity for Addison’s
- A result of 2 mcg/dl or more makes it unlikely that this patient has Addison’s
ACTH stimulation test
- Cosyntropin (250 mcg/dog or 125 mcg/cat) IM or IV is given
- Serum levels of cortisol are tested at baseline, at 30 and 60 minutes in cats, and at 60 minutes in dogs
- Helps differentiate between primary and secondary Addison’s
- Must be done before administration of steroids
The good news for our patients: An Addisonian crisis and Addison’s disease can be medically managed.
- An animal in Addisonian crisis should receive fluid therapy immediately, as the lack of aldosterone will leave them hypovolemic. Although we may be tempted to give full strength saline (0.9% NaCl) for resuscitation due to the electrolyte abnormalities, it is best to give a balanced electrolyte solution with a lower sodium concentration. Even if the fluid contains small amounts of potassium, a rapid change in serum sodium may result in unwanted neurologic side effects.
- Hyperkalemia should be monitored with an electrocardiogram. Any ECG changes are considered life-threatening and should be treated promptly, although insulin therapy should be used with caution due to the potential for hypoglycemia.
- Hypoglycemia should be treated as required.
- After appropriate ACTH stimulation testing has been performed, hormonal replacement therapy should be initiated. In an acute crisis situation, Dex-SP is an appropriate treatment. For long-term management, a mineralocorticoid, such as Percorten-V, is used for animals with a reduced sodium-to-potassium ratio. For an atypical Addison’s, or one that lacks only a glucocorticoid, prednisolone therapy is adequate.
- Supportive care in the crisis situation should also be implemented. GI protectants, antibiotics, and analgesia may be warranted on a case-by-case basis. NSAIDS should be avoided.
The technician is an imperative part of diagnosing Addison’s disease. Recognizing the red flags within the history and the symptoms of this complicated disease are key to quick diagnosis and treatment. An astute technician can be the difference between life and death for patients in an Addisonian crisis. In addition, top-notch nursing care for these often-debilitated animals is important to prevent secondary infection and aspiration pneumonia. Understanding this interesting but complex disease process is necessary for the technician to provide gold-standard care, and the reward for doing so is astronomical.
Erin is an ECC specialty certified technician living in beautiful Fort Collins, Colorado. She shares her home and heart with her boyfriend, Bradford, and their chatty kitty, Kevin. While dangerously close to a workaholic, Erin and Bradford still find time to travel together. Erin also enjoys being an amateur home chef, taking photographs, and riding her horse, Katie. Professionally, Erin is passionate about the subject of technician empowerment.