Visiting Veterinarian : A mystery unsolved
By Michelle Gerhard Jasny V.M.D.
Published: March 25, 2010
Baby was an adorable schnoodle puppy - half schnauzer, half poodle. She'd come to the Vineyard in January at ten weeks of age, and appeared a happy, healthy pup. Then, out of the blue, Baby had two seizures one day in March. "Could be epilepsy," I told her dad when he called that Sunday evening. "As long as she's fine now, we can just see her tomorrow during office hours."
At five months old, she was a tad young for idiopathic epilepsy, which typically comes on between six months and five years of age, but it was the most likely diagnosis. "Feed her every few hours tonight in case it's low blood sugar," I concluded. Little dogs, especially when young, occasionally seizure from hypoglycemia. This is easily corrected by frequent meals. I hung up the phone and went off to bed.
Wazzat?? Telephone. What time is it? Midnight. "Baby is worse," her dad reported. "She ate but then threw up. She's twitching all over and covered in drool."
"Come right over," I said groggily, groping around for my clothes. Baby arrived, twitching mightily, her mouth covered in white foam. I reviewed her papers. No rabies vaccination. Donning a pair of gloves, I handed another set to the owner. "Although it's extremely unlikely, we have to consider rabies. Wear these."
Baby had spent her first ten weeks on the mainland, so we couldn't rule out the possibility of exposure to a rabid skunk, bat, or raccoon, and since the rabies incubation period can be as long as six months, well, let's just wear gloves. We ruled out hypoglycemia with a quick blood test.
"Could she have eaten any medications, drugs, poisons?" I asked, racking my brain. Strychnine. Lead. Stimulants like amphetamines or ADHD medications. Rotten garbage. Mushrooms. Anything?
"I really don't think so," her owner replied. Baby's body temperature was very high, probably from the constant muscle spasms. We needed to stop the twitching. With her owner's help, I placed an intravenous catheter and gave anti-convulsant medication, a little at a time, until the twitching ceased. A sponge bath and intravenous fluids cooled her down a bit. She was squirmy, resisting our ministrations, but soon was looking better. I showed the owner how to give additional medication via suppository if needed later.
"Can't you keep her overnight?" he asked. "She needs someone with her constantly in case she seizures again," I sighed, wishing for the billionth time that the Island could support a fully staffed 24-hour emergency clinic.
"It's best if you take her home and call me again later if necessary." I gave strict instructions to keep her confined to her crate, isolated from the family, human and otherwise, and to wear gloves when handling her until we were sure it wasn't rabies.
"Can you at least test her for rabies?" he asked nervously.
Hhmmm. How to explain this tactfully? "If she improves, it's not rabies. The only way to test is postmortem, on the brain," I said, eschewing further details. "She seems stable now. Let's see how she is in the morning."
But in the morning Baby was not better. The twitching, salivation, and fever had all returned in force. Back in vet school we were taught about "chewing gum" seizures associated with canine distemper. Could that be the problem? Distemper is a contagious viral disease that has been mostly eliminated in pet dogs thanks to vaccination but there are still sporadic outbreaks, and the virus can be carried by wildlife including raccoons and skunks. Affected dogs usually present with fever, ocular and nasal discharge, coughing, vomiting, diarrhea, depression, and loss of appetite, but in later stages they may have seizures. Young animals are most susceptible and Baby had not had all her recommended vaccinations. On the other hand, distemper is rare, and Baby had shown few of the other signs we would have expected with distemper.
"I hate to even ask," her owner hesitated, "but should we put her down?" I looked into this sweet pup's face as she spasmed and drooled, and reviewed my differential diagnosis. Could be something congenital like a liver shunt or hydrocephalus. Could be toxic, or an infectious disease like distemper or rabies. Could be something I hadn't thought of yet. Whatever it was, it wasn't good. She needed round-the-clock intensive care. Or to be euthanized.
I imagine all vets struggle with these moments. It's easier with an elderly patient. It's easier when I am confident of the diagnosis and prognosis. "I hate to condemn her without consulting a specialist, in case I'm missing something," I said.
Baby's owners valiantly rushed her off Island, but her condition rapidly deteriorated and she was euthanized only hours later. We gave their other dogs distemper boosters and waited anxiously for the rabies test results. Two days later, the specialist called. It wasn't rabies.
"So," I asked her, now that our biggest fear was laid to rest. "What do you think it was?" Probably not distemper, she ventured, since there were no respiratory or gastrointestinal signs. Probably not a toxin. "Maybe a protozoal brain infection, like Toxoplasma or Neospora," she ventured, "but I'd bet on a liver shunt."
Portosystemic liver shunt is an abnormality of the blood vessels of the liver that affects the body's ability to detoxify the blood properly. It is usually a congenital problem and clinical signs often appear by six months of age, though sometimes not until much later in life. Signs may include loss of appetite, lethargy, vomiting, diarrhea, stunted growth, episodes of weakness, incoordination, head-pressing, disorientation, circling, pacing, behavioral changes, blindness, seizures, coma, hypersalivation, and bizarre aggressive behavior.
Onset may be gradual, with just a few mild symptoms, or more rapid and severe. Prognosis varies greatly case by case. Some may be managed medically but most require surgery to correct the defect.
Yorkies and miniature schnauzers are known to have an especially high incidence. We will never know for sure if Baby had a liver shunt, but she was the right age and the right breed. Her family can rest easy that they did everything they could, and remember that her life, though brief, was happy and she was well loved.
