Early September. Sunday evening. I glance at the clock and sigh. After ten already, dinner dishes still piled in the sink. Not yet adjusted to returning to school schedules, my kids’ voices drift, giggling, from their bedroom. I’m on emergency call. Again. I’ve been doing this for 30 years now, but many such nights I still think of Robby Fair, whom I worked with in the early ’80s at the Vineyard Veterinary Clinic.
In those days, the VVC was the only veterinary facility here and I still treated farm animals as well as dogs and cats. Horses, cows, sheep, goats, the occasional pig, Robby and I rotated covering after-hour farm emergencies. Well, actually, I got delegated more nights, since I was the new kid in town.
Robby had graduated only one year ahead of me from the University of Pennsylvania, but he definitely had more experience and more confidence than me back then. Like one night when a horse got badly hurt at Featherstone. I was pretty sure I had done everything possible, but nagging doubts persisted. It was during the Derby, so I knew where Robby was. Fishing. And I knew where. Out at the gut on Chappy. You fishermen can imagine how thrilled he was when I managed to find someone official with four-wheel drive to track him down and drag him to a telephone (this was before cell phones!) to review the case and reassure me.Robby used to say about his nights on call “I don’t take off my boots until 11:00.”
A lot has changed since then. We have six veterinary practices here, many year-round veterinarians, and I only work with small animals now — but I still don’t take off my metaphorical boots until 11 pm when I’m on call. Good thing, because the phone’s ringing. The answering service reports a couple is here on vacation and their dog, Ulysses, “isn’t acting right.” I call the hotel where they are staying. An anxious young woman answers.
“What kind of dog is Ulysses?” I ask. People often find this question strange but different breeds get different problems. If Ulysses is a great Dane, I may worry about bloat. A dachshund? Back problems. Chihuahua or pit bull? Might need to call in an assistant to help hold them. And so on.
“A Westie mix,” his mother replied. Dogs this size are generally easy enough to handle solo after hours. I mentally went from red alert down to yellow. Then the owner continued, “He’s a rescue. We’ve been working with a behavior specialist on his aggression and anxiety problems.” Uh-oh. Tell me more.
Ulysses had been on fluoxitine for many years. That’s Prozac. Recently the specialist had added a second drug called buspirone or Buspar. But she wasn’t calling about his behavior. “I think he’s hurt his leg or back, ” she said. “I noticed him having a little trouble walking the last few days, but tonight his legs keep going out from under him.”
I tried to persuade her that limping didn’t warrant a late night vet visit, until she added “He almost seems disoriented…and he’s twitchy.”
When Ulysses arrived 20 minutes later, he looked pretty harmless, a disheveled pile of white fluff. But I could tell by his owners’ demeanor that this docile facade was misleading.
“He’s very protective of me,” the woman said nervously. She suggested it would be safer for her husband to wait outside. She carefully slipped a muzzle on Ulysses’s nose.
Very, very slowly, I examined him. His legs and back were fine. Based on his history, altered mental status, and twitching, I suspected something neurological. “This may be serotonin syndrome,” I concluded.
Serotonin is a neurotransmitter produced by certain neurons in the central and peripheral nervous system. These neurons are involved in regulating many functions including wakefulness, appetite, thermoregulation, behavior, pain perception, vascular and muscle tone, and gastrointestinal motility. Psychoactive medications can affect serotonin levels in many ways. Drugs like cocaine and amphetamines increase serotonin release. Some antidepressants block serotonin from being removed from synapses (called “reuptake inhibition”), while others decrease metabolic breakdown or stimulate serotonin receptors. On rare occasions, too high a dose or mixing of two such drugs can lead to too much serotonin in the system, and that’s bad news. Ulysses had been on fluoxitine for several years, but the buspirone had just been added.
In people, serotonin syndrome manifests with three categories of symptoms. Signs related to the autonomic nervous system include diarrhea, dilated pupils, elevated heart rate, rapid breathing, hypertension, sweating and fever. Neuromuscular signs include tremors, muscle rigidity, twitching, and seizures. Behavioral signs include agitation, confusion, disorientation, vocalization, and excitement. Dogs can display any of these symptoms. Serotonin syndrome can become life-threatening because the thermoregulatory center of the brain can be affected. Combined with the excessive muscular activity, body temperature can rise dangerously, leading to seizures, multi-organ failure, coma, and death.
There was no way Ulysses was going to let me check his temperature. Luckily, his symptoms were not severe. There is an oral “antidote” that can counteract the excessive serotonin. Luckily, I had some. “Give him these pills,” I instructed. “Repeat in six to eight hours, if he’s still showing signs. Hold off on his behavior meds until you call your specialist in the morning.”
That night I slept fitfully, anticipating another call if Ulysses got worse, but I didn’t hear back from them until a week later when a thank you note arrived with an update. Their regular veterinarian initially concurred with the diagnosis of serotonin syndrome, but then Ulysses had developed facial paralysis and a head tilt. After evaluation by multiple neurologists, CSF tap, and MRI, the final diagnosis was dysfunction of his seventh and eighth cranial nerves of unknown cause that might resolve over time.
Ulysses will continue his behavior therapy. Derby fever will continue to define autumn on the Vineyard. And I’m on call tonight. Again. What time is it? And where are my metaphorical boots?