Jersey is a three-year-old Lab-golden cross who's gotten into a spot of trouble now and then (like the birthday party where he ate the chocolate cupcakes and at least one rubber ball) but in general, he's a typical happy, healthy, dog. Preparing to leave on vacation, his owners noticed that Jersey's appetite was off, but they weren't overly concerned. Maybe he had an upset tummy, or was anxious about their departure. Jersey was staying home with Grandma who would look after him. Several days later Grandma called for an appointment. "He's refusing all food and shivering like he's cold," she said uneasily. "Maybe he just misses the family, but I'm worried."
When Jersey arrived, I could see he was not himself. This usually rambunctious boy sat dully on the exam table, head drooping, body hunched. He had lost ten pounds since his last visit. Because of his penchant for eating the nonedible, my first thought was intestinal obstruction. Dogs with rubber balls stuck in their gut often look like this. "Is he vomiting?" I asked, lifting my stethoscope to my ears.
"No, but he makes an odd gulping noise when he drinks, like it's hard to swallow," Grandma replied.
I was barely listening. I was having trouble finding Jersey's heartbeat. It was muffled and slow. I reached to feel the pulses in his hind legs and could scarcely find them.
"I don't know exactly what's going on," I announced, "but we need to run tests." I advised blood work and radiographs. A few minutes later I had the first chest film in hand. It was definitely abnormal. The heart looked small and was elevated off the sternum in a way consistent with pneumothorax, which means free air trapped between the body wall and the lungs. Pneumothorax will cause muffled heart sounds. The most common cause is trauma - like being hit by a car. But Jersey had no history of trauma or evidence of injury.
I checked his ribs carefully. No fractures. Hhmmmm. What else? A perforation of the esophagus could cause pneumothorax. I scanned the film again. What was that? A thin white line in the area of the esophagus. Could Jersey have swallowed a sharp bit of wire, which lodged in his throat and poked a hole allowing air to leak into his chest? It would explain the discomfort, the trouble swallowing, and the pneumonthorax. If this was the problem, we would need to refer him immediately to a specialist. While I was explaining all this to Grandma, my assistant brought me the blood test results. I glanced down at the paper.
Whoa! Hold the phone! Look at those abnormal kidney tests and that severe electrolyte imbalance. His potassium levels were so high, he was at imminent risk for cardiac arrest. Jersey had hypoadrenocorticism, an adrenal gland disorder also known as Addison's disease.
Hypoadrenocorticism is an uncommon syndrome caused by inadequate production of glucocorticoid (cortisone) and mineralocorticoid (aldosterone) by the adrenal glands. Aldosterone is responsible for maintaining proper balance of the electrolytes sodium and potassium, which in turn are essential for proper neurologic and muscle function. Too little sodium results in low blood pressure, kidney dysfunction, dehydration, and weakness. Too much potassium can stop the heart. Not enough cortisone can cause weight loss, anorexia, vomiting, and an inability of the body to respond properly to stress.
Based on clinical signs and lab work I was pretty sure this was the diagnosis... but what about that pneumothorax? And the white line on the radiographs? Grabbing a textbook, I flipped to the page on Addison's disease. Hey! Right there! "Radiography may reveal microcardia." Microcardia means "really small heart." I slapped my forehead. (Okay, I didn't really, but it was an Aha! moment.) This wasn't pneumothorax. It was microcardia due to circulatory problems due to Addison's. What about that white line? I stared at the x-rays. Sure looked like it was in the esophagus. Then I noticed it was at exactly the same spot on each film. Maybe it wasn't in the dog. Maybe it was on our film. We investigated. Turns out the white lines were being caused by a glitch in our automatic processor.
We immediately began fluid therapy aimed at reversing the circulatory collapse and correcting the electrolyte imbalance, and intravenous cortisone to provide the glucocorticoids his body had stopped making on its own. Oral mineralocorticoids were also started. Within a few hours, Jersey's heart rate had returned to normal and his femoral pulses were strong. We decided he did not need to be transferred off-Island to a 24-hour-care facility. Grandma took him home along with a lot of medication, but two days later, he still wasn't eating and looked a little pale. His electrolytes had returned to normal, but a complete blood count confirmed he was now anemic.
I began to second-guess myself. Was I sure of my diagnosis? Was I missing something? I decided to call in the experts by telephone. Twenty minutes later I felt better. The specialist had agreed with both diagnosis and treatment. The anemia was most likely the result of gastrointestinal bleeding, a common, treatable complication of hypoadrenocorticism.
Addison's disease has been called "The Great Pretender" because the signs can be variable and look like many other problems. In the early stages, symptoms may come and go, mimicking primary kidney or gastrointestinal disorders. Left untreated, it may progress to an acute "Addisonian crisis" which is a life-threatening emergency. Jersey had almost reached that point. Hypoadrenocorticism is usually immune-mediated, i.e., the body's immune system attacks its own adrenal glands, for some unknown reason. It occurs most commonly in young to middle-aged dogs. Females have a slightly higher risk than males and some breeds are reported to have a predilection, including Great Danes, rottweilers, Portuguese water dogs, and standard poodles. Once an animal is stabilized, maintenance therapy consists of lifelong mineralocorticoid replacement with daily oral medication or monthly injectable, and oral cortisone.
The Great Pretender almost fooled me. It wouldn't have been the first time. We are now treating Jersey's gastrointestinal ulcers and maintaining his other medications. He is recovering slowly. He started eating a bit. The rest of the family returned from vacation to a sweet reunion, as we sent Jersey home, maybe a little worse for wear, but alive and wagging his tail.