Michelle Gerhard Jasny, V.M.D. has been practicing veterinary medicine on the Vineyard since 1982 and writing the Visiting Vet column for more than 25 years. She lives and works in West Tisbury. She can be reached at: firstname.lastname@example.org.
“If an orange-faced Oompa Loompa and a grey-faced Oompa Loompa have babies, what percentage of their offspring will have orange faces?” my husband asks. My daughter is studying genetics and her homework is full of chromosomes, genes, dominant and recessive traits. I smile as my daughter shouts gleefully, “One-fourth orange faces!”
In veterinary medicine, we deal with genetics daily. What’s the difference between Chihuahuas and Great Danes? They’re both dogs, but selective breeding for particular genes makes one huge, the other teensy. Genetics give us the smooshed faces of bulldogs, the wrinkled skin of Shar-Peis. Even behavior and temperament can be driven by genetics — herding behavior, guard dogs, dogs who like water, or retrieve, or track scents. A dog’s breed strongly influences personality and behavior. It also affects predisposition to certain diseases.
“You should review this record before the appointment,” my secretary suggested, the morning after the Oompa Loompas. “Sounds complicated.” The owner had dropped off a list of concerns about his dog, Aberdeen. Difficulty housebreaking. Not responding to commands. Acting like he’s lost. Odd blank stare. Unusual gait. Hypersensitivity to noise. Trouble gaining weight. I then did what every veterinary student is taught to do first. Look at the signalment. That means breed, age, and gender. All these impact the likelihood of various illnesses. Aberdeen was a 15-month-old intact male Llewellin setter. My first thought was that he was so young I should first consider congenital and inherited problems. My second thought was what the heck is a Llewellin setter? I readily admit I’m kind of lame when it comes to knowing every breed. I have enough trouble remembering where I left my glasses. So I began researching.
The Llewellin setter is a specific “pure” strain of English setter tracing its bloodlines back to a 19th century dog breeder and sportsman named R.L. Purcell Llewellin in South Wales. Ignoring all the doggy politics about whether they are a distinct breed or not, for my purposes the pertinent information was that, medically speaking, they are English setters. Next I researched inherited conditions of English setters. Hip and elbow dysplasia — not relevant. Deafness -— interesting. Hearing-impaired dogs may be hard to train, act lost, not respond to commands. Oh, wait a minute. His owner said Aberdeen was hypersensitive to noise. Scratch deafness.
Then I saw a disease I had never heard of before — neuronal ceroid lipofuscinosis (NCL). An autosomal recessive genetic mutation that causes accumulation of abnormal stuff inside cells in the nervous system, which in turn leads to devastating progressive neurological dysfunction, NCL has been reported in dogs, cats, and humans. (In people it is called Batten disease or Familial Amaurotic Idiocy.) Canine breeds affected include English setters, Tibetan terriers, American Staffordshire terriers and bulldogs, border collies, Australian shepherds, Labrador retriever, Polish Owczarek Nizinnys ( no kidding), and dachshunds.
Age of onset can span from one year in dachshunds to five years in Tibetan terriers but once NCL begins, it is progressive and typically fatal. Symptoms vary, breed to breed. Most develop vision deficits. Almost all exhibit a change in gait, loss of balance, or incoordination. Dementia with confusion, progressive decline in intelligence, and loss of prior training is common, as is hypersensitivity to sound, touch, and movement. Affected dogs may become withdrawn, fearful, or aggressive. Eventually dogs develop severe seizures and either die or are euthanized by two years of age. There is no cure.
When Aberdeen arrived, I didn’t want to unduly upset his owner. NCL is extremely rare. It was probably something else. Something simple. Something curable. I began my exam. Other than being thin, Aberdeen looked physically healthy. He heard when I made a loud noise. He blinked when I poked my finger at his eyes. His retinas looked fine. He had normal feeling and motion in his legs. Perched on my exam table, he seemed pretty normal, maybe a bit bemused.
“Let me watch him walk,” I said. Aberdeen’s hind legs moved a bit stiffly. His front legs lifted too high with each step as though marching to a drum only he could hear. His dad had mentioned that Aby had recently developed an odd way of cocking his head when offered a treat, so I held out a cookie. Aberdeen slowly extended his neck, tilted his head, then very, very slowly took the treat. I did it again. He did it again. I dropped a treat on the floor. I could tell he had seen and heard it drop, but now couldn’t seem to locate it, searching around an unusually long time before finally finding and eating the tidbit.
“I’d like to record all this and send it to the neurologist,” I said, grabbing my iPad. The owner used treats to entice Aby to walk back and forth as I filmed. Then Aberdeen spontaneously started walking in circles. His owner offered another treat. Aby cocked his head, stretched his neck, and suddenly started spinning in tight circles, like a kid break dancing. He was agitated and growling continually with his head held way up in the air. Dogs with ear infections or balance disorders will frequently have a head tilt and circle, but this was different. There was a weirdness to his behavior that we call “altered mentation,” a kind of dissociation that was clearly neurological. It was time to discuss NCL.
There is a blood test available to screen for the NCL genetic mutation in English setters, so we sent a sample to the researchers in Missouri. The doctors there viewed the video and agreed it might be NCL. If the test comes back negative, Aberdeen still clearly has a problem that should be evaluated by a neurologist who can do further testing and brain imaging. If it turns out to be neuronal ceroid lipofuscinosis, then sadly, there is nothing we can do, other than to alert the breeder that his line of dogs is carrying this rare but fatal genetic condition. If only all genetics were as fun and as easy as orange-faced Oompa Loompas.