Visiting Vet: When all four legs are compromised

Visiting Vet: When all four legs are compromised

We may never have a definitive answer. We’re just glad she’s back on her feet and hope she stays that way.

Michelle-JasnyMichelle 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 drjasny@comcast.net.

Stormy is an Australian shepherd in the prime of her life. Last winter at her annual physical examination, her owner mentioned she had been limping recently. Watching her walk, she was a little gimpy on her right front leg, but I couldn’t find any obvious explanation. “Probably a strain or sprain,” I said. Stormy was also significantly overweight, an extra stress on her joints and muscles. “Try to get a few pounds off her,” I advised, sending home pain medication and instructions to rest.

The foreleg lameness resolved quickly, but three months later, Stormy returned. She  had lost three pounds (though still more than pleasantly plump) but there was another issue. She had suddenly developed marked weakness in her hind end. “She just flops over while she’s walking,” her owner said.

Stormy was bright, alert, and responsive. She’d pull herself to her feet and walk willingly, but then her caboose would start swaying and finally she’d drop to the floor. Her temperature was normal and other than the gait abnormality everything looked fine.

“She seems a little tender here,” I said tentatively, palpating her lower back, but it wasn’t definitive. Could be fibrocartilaginous embolism ( a neurological deficit caused by a little plug of stuff occluding the blood supply to the spinal cord) or intervertebral disk disease (a disease in which the little shock absorber between two vertebrae protrudes and presses on the spinal cord.) “She seems stable,” I concluded. “Let’s try rest and anti-inflammatories.”

Two days later, Stormy’s mom called. The dog was no better. Should we be doing something more?

“We can take X-rays,” I offered, though neither of the two diseases on our differential would necessarily show up on radiographs. “Really an MRI would be the next best test, but maybe she just needs a little more time,” I suggested.

I was wrong. Stormy’s condition continued to deteriorate. By the next day she could barely stand, her front legs now almost as weak as her hind.  She spent most of her time lying flat on her side unless her owner hoisted her up with a sling, then she would try to ambulate. Stormy came for a recheck. Dr. Buck did a careful neurologic exam. Stormy could still move all four legs, but that was the only good news. Some of her reflexes were exaggerated while others were diminished. She was trembling all over and had severe neck pain. It was now clear the location of the lesion was not in her lower back. It had to be either in her neck, or even her brain. It was time to consult a neurologist.

Up at VCA South Shore Animal Hospital, Stormy underwent a battery of tests. Blood work, urinalysis, chest X-rays, abdominal ultrasound, then finally MRI and a spinal tap under anesthesia. The MRI confirmed meningomyelitis in her neck. This means there was  inflammation of the spinal cord and surrounding membranes, but it does not identify the cause. She was started on corticosteroids, called prednisone.

Many readers may have taken prednisone yourselves if you’ve ever had a bad allergic reaction, like to poison ivy, or any significant inflammatory disease or auto-immune issues.

She also got gabapentin, a medication currently in vogue for animals with “neuropathic” pain.  But what was causing the problem? The specialists listed possible diagnoses including Steroid-Responsive Meningitis Arteritis (SRMA) and Granulomatous Meningioencephalomyelitis (GME.) Wow. Those are some big words.

Let’s start with SRMA, a disease of unknown cause, thought to be immune-mediated. In other words, for some reason Stormy’s immune system starts attacking her own nervous system. There are two reported forms, acute and chronic. The acute form comes on fast with a stiff neck, pain, fever, and characteristic changes found in the cerebral spinal fluid. The chronic form has a more protracted course with more neurological deficits.

SRMA strikes young adult dogs, like Stormy. Breeds thought to be predisposed to the condition include Bernese mountain dogs, boxers, German short-hair pointers, Norwegian duck tolling retrievers, and beagles. In fact another name for SRMA is Beagle Pain Syndrome.   There is no way to make a definitive diagnosis in a living dog. Basically, if an individual fits the clinical picture and no other explanation can be found, then it’s time to try corticosteroids. If the dog gets better, Bingo! It’s “steroid-responsive.”

GME is an “aseptic inflammatory disease of the central nervous system.” Just like SRMA, the cause is unknown, it can be acute or chronic, and definitive diagnosis is only made on postmortem, although MRI and CSF taps can be helpful in ruling out other disorders. GME has three forms — focal ( affecting one location in the nervous system), disseminated (involving many locations in the nervous system), and ophthalmic (affecting the optic nerve and eye). Symptoms vary depending on location and severity of lesions. Progressive loss of use of the legs is frequently seen. Other signs may include seizures, head tilt, lethargy, blindness, facial abnormalities, walking in circles, and balance disorders. Middle-aged,small breeds, especially terriers and toy poodles, are most commonly affected. GME also may respond to corticosteroids, but sadly, most dogs do not survive more than one to five months, even with treatment.

The neurologists admitted that Stormy did not exactly fit the picture for any one disease. Her CSF tap did not show the changes typically seen with SRMA. On the other hand, she is not a breed in which GME is usually reported. Another possibility was cancer lurking somewhere in the central nervous system, but none could be found on any of the tests. We know so little about these types of progressive neurological diseases, that it can be both frustrating and heartbreaking for owners, but Stormy responded well to the prednisone and within a few weeks was walking almost completely normally. She will be on steroids for several months, gradually weaning down the dose and watching closely for signs of relapse.

We may never have a definitive answer. We’re just glad she’s back on her feet and hope she stays that way.

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