The silent killer

A 3 year old, female spayed poodle presented to me about 2 months ago for lethargy and weakness. Her family reported that "Tia" had been having intermittent vomiting and diarrhea over about a week, but still was willing to eat.  She was lethargic today, and had been unwilling to rise for several hours.  "Tia" had been examined in the last week by her primary care veterinarian, who had dewormed her (a possible cause of v/d).  Unfortunately, she had not improved yet.

On physical exam, Tia was extremely lethargic, unwilling to lift her head, and refused to stand.  Her gums were pale pink, and her heart rate was elevated. Her pulses were not sufficient, and she was clearly experiencing shock due to dehydration.

I recommended immediate electrolytes, IV fluids, blood pressure monitoring, and full metabolic panel to be sent to the labratory.  I discussed with the clients that there were several potential causes of the chronic vomiting, however at this time, she desperately needed IV fluids and subsequent tests to determine her diganosis.   Potential causes of her illness included inflammatory bowel disease, addison's disease, ruptured foreign object resulting in severe abdominal infection, diabetic ketoacidosis, or many others.  Many of these can be determined from simple blood tests which would be performed immediately.

The clients authorized all of our attempts to stabilize their beloved Tia.

IV catheter was placed, and blood was submitted for electrolyte panels. Urine was collected and IV fluid boluses were initiated.  Her initial blood pressure was 70mmHg, below the normal minimum of 90mmHg - meaning that her vital organs (kidneys, brain, heart) were receiving inadequate oxygen.  Shock, as you have read in my blogs before, will result in death if it is left untreated.

While her first bolus was being administered, her in-hospital electrolyte panel results completed.  Significant abnormalities were present; her sodium was very low, her potassium was life-threateningly high.  Her blood pH was abnormal due to her shock state, and she was significantly dehydrated.  Her kidney values were also elevated.  The values were so abnormal that we repeated them twice be sure that they were real and not an error on the part of our machine.

The values were consistent.

Vomiting, collapse, low sodium and high potassium point to an endocrine (hormone) disorder called hypoadrenocorticism, or Addison's disease.   Addison's disease is an interesting lesson in phsyiology - and a very rewarding disease to treat.

In a nutshell, patients with Addison's disease cannot make specific hormones, (cortisol and aldosterone) that are required for vital body processes, includign sodium and water retention, potassium excretion, response to stress, maintenence of normal blood sugar, and other processes.  Lack of the mineralocorticoid hormone aldosterone (or insufficient quantities) result in loss of sodium and build up of potassium.  Loss of sodium results in severe dehydration, and buildup of potassium results in heart irregularities, and even cardiac arrest.

Tia's blood pressure improved with administration of IV fluids.  She also received medications to reduce the effect of high potassium on her heart. After receiving her lab results, I recommended the test to confirm addison's disease, called the ACTH stimulation test. Although high potassium and low sodium are enough to suspect Addison's, several other diseases can cause these changes, and ACTH stimulation is the test necessary to confirm its presence.  A blood sample is collected, and injection of a medication to induce secretion of cortisol is administered, and a second blood sample is collected one hour later.  This test will detect the majority of addisonian patients.  This test can be inaccurate if steroids are given prior to collection of both blood samples.

Within 6 hours, Tia was standing, barking, and appeared clinically normal.  She discharged within 24 hours, after confirmation of potassium returned to normal.  Treatment was initiated pending results of her ACTH stimulation test.

Treatment of Addison's disease requires supplementation of the mineralocorticoid hormone that is absent.  This can be performed with an injection (given about once every 25 days) or an oral pill (given every day).  The specific decision about which to choose is case-dependent.  Additionally, supplementation with steroids is often needed to replace the lack of cortisol.  Prednisone is commonly utilized in a daily dose, which should be increased during times of stress (travel, vet visits, addition of new pets, etc.).  Initially, electrolytes should be monitored weekly, but over time, may only be necessary 2-3 times per year while the patient is clinically normal.

Rarely, a less common form of Addison's disease (atypical Addison's) occurs where the patient has normal electrolytes.  These patients only require supplementation with steroid hormones.  Many of them, however, progress to typical Addison's disease with time, and so they require electrolyte monitoring over their lives, espeically in times of illness.  Atypical Addison's disease is also diagnosed with an ACTH stimulation test.

Tia's test confirmed Addison's disease.  She is expected to live a long, healthy life.  With proper monitoring, careful veterinary care, and correct medications, Addison's disease does not affect the lifespan of our canine friends.