Dog Quixote is an 85-pound, senior Labrador retriever. We’ve known for a while about his hip dysplasia and arthritis, but one morning he took a dramatic turn for the worse. He just couldn’t get up. At all. I get millions of calls about old dogs who “can’t get up.” The majority are jauntily trotting around by the time they arrive at my office.
Many geriatric dogs simply get so stiff and achy they have trouble hoisting themselves up and getting their footing and balance, especially after lying down for a long time, after excessive exercise, or on slippery floors. Often all they need is a rubber-backed carpet for traction, a little assistance getting up, and arthritis medications.
But Quixote could barely lift his head. His owners carried him in on a homemade stretcher. When we tried using a sling to help him stand, he collapsed to the floor. His size and the degree of weakness made it hard to effectively evaluate his reflexes, but he did have feeling in all his limbs, and the ability to move them. He cried out when I touched various places, but it seemed more from anxiety than actual pain. Otherwise Quixote was bright-eyed and alert, eagerly eating the liver treat I offered.
Collapse is defined as the inability to support weight and walk without assistance. There is a long list of possible causes. We immediately ruled out respiratory and cardiac disease, and heat stroke, since he was breathing well, heart and lungs sounded fine, temperature was normal. Blood tests quickly ruled out metabolic disturbances that alter neuromuscular function such as low calcium, blood sugar, or potassium levels. That left us three categories of disease that could cause Quixote’s infirmity — orthopedic, neuromuscular, or neurological.
Orthopedic collapse is simply failure of the skeleton and/or joints to support an animal’s weight. In Quixote’s case there were pre-existing problems in his hips and knees, but we had never seen such severe symptoms, nor had his front legs ever been affected.
“His joint disease could certainly be contributing to his difficulties,” I said, “but it’s unlikely that’s the sole cause.” We needed to look further.
Neuromuscular collapse occurs when there is dysfunction in nerve conduction, in transmission of signals from nerve to muscle, or in the muscles’ ability to respond. This includes odd diseases like tick paralysis, myasthenia gravis, and polyradiculoneuritis, a.k.a. coonhound paralysis. Tick paralysis is caused by a neurotoxin in the saliva of certain ticks. It comes on fast, starting with the hind legs and rapidly progressing forward until the dog is completely paralyzed. Diagnosis is made by finding and removing the tick, and seeing if the patient improves. Without removing the tick, dogs may die from respiratory failure. Just what we need, huh? One more tick disease to worry about.
Polyradiculoneuritis is a similar progressive paralysis and is often linked to exposure to raccoon saliva, hence the alternate name “coonhound paralysis,” although many cases have no known initiating cause. Diagnosis is made on history and clinical signs. Most affected dogs spontaneously improve within three weeks and recover completely in two to four months.
One final neuromuscular disease to consider was acquired myasthenia gravis, an autoimmune disease affecting the receptors at the junctions between nerves and muscles, causing extreme muscle weakness.
But Quixote’s presentation did not fit any of the neuromuscular disorders exactly, so our diagnostic process went on to consider neurological diseases in which nerve impulses in the brain or spinal cord either fail to generate or are not communicated properly to the body. “Probably not in his brain,” I thought, since his mental status and cranial nerve functions were all normal. It was time to consider various spinal cord diseases.
Fibrocartilaginous embolism (FCE) occurs when a bit of gelatinous material from inside an intervertebral disc extrudes into an artery supplying the spinal cord. Exact symptoms depend on the exact location of the embolism, though classic presentation is sudden onset of weakness, without pain, often affecting only one side of the body. Definitive diagnosis requires MRI. FCE is most common in large breeds, like Quixote, although it typically affects younger dogs. Treatment is simply supportive care and most dogs improve with time. FCE is usually painless, and not progressive, but by Day Two, Quixote was a bit worse and clearly painful when I gently flexed his neck side to side. Probably not FCE. We were narrowing things down to intervertebral disc disease ( IVD).
Intervertebral discs are little cushions that sit between the vertebrae acting like shock absorbers. As animals age, these discs become less flexible and can push out into areas they shouldn’t, putting pressure on the spinal cord and/or nerve roots. Radiographs can help support a diagnosis, but MRI is often needed for a definitive answer and helps rule out other things like spinal cord tumor. Again, exact symptoms depend on exact location, as well as the severity of the disc herniation. Our radiographs showed an area in Quixote’s neck consistent with IVD. We also saw spondylosis deformans in his back, a non-inflammatory condition in which new bone forms bridging vertebrae together. This is fairly common in older dogs and is often of minimal clinical significance, although Quixote’s was quite extensive. With a presumptive diagnosis of IVD, we gave Quixote intravenous corticosteroids to reduce spinal cord swelling, emptied his bladder with a catheter since we weren’t sure he could urinate, then sent him home with oral steroids, analgesics, and antibiotics to cover for diskospondylitis, a bacterial infection of the intervertebral discs. His mom and I emailed back and forth constantly. Day Three Quixote heaved himself up, ran outside, urinated and defecated, then collapsed again. Same thing next day. His owner sent me video. His hind end staggered. His left front foot knuckled under. But he walked. Quixote is on his way now to an appointment with the neurologist. We hope an MRI and the specialist’s expertise will confirm a definitive diagnosis and treatment plan in hopes that Dog Quixote will soon get his feet solidly back under him.