by Carole Machery DVM

This orthopedic problem can mimic other hip and rear-end diseases, but it is unquestionable a prevalent disease in its own right among greyhounds.  It’s not just a Greyhound problem, though,  as it is found in many other large-breed, athletic dogs.  Afflicted dogs can begin showing signs as young as 5 years or less but, as the disease progresses, veterinarians are often presented with a wobbly and weak aging greyhound.

WHAT IS CAUDA EQUINA?

This disease goes by several names – cauda equina, lumbosacral instability, lumbosacral stenosis.  It’s a compression of the nerves in the spinal canal near the hip.  This can be from arthritic changes, disc rupture, or tumor.  When nerves are pinched you feel pain, numbness, or a stimulation, and the range of possible signs with CES (cauda equina syndrome) come from one of these effects.

Here are some remarkable pictures to illustrate what happens.  These are MRI’s of a 7 year old Labrador Retriever named Trapper.  Trapper lived in Alaska, and was diagnosed with CES, and treated surgically at the Washington State Veterinary Teaching Hospital.  Many MANY thanks to Bob Shem for sharing these images.  They clearly show the compression of the nerves:

This is a side view of Trapper’s spine.  In this image, Trapper’s legs are in their normal standing position. You can clearly see the marked compression of his nerves.

1 = pinching or compression of the spinal nerves

2 = healthy spinal discs of the lumbar vertebrae

3 = collapsed disc space between the last lumbar and first sacral vertebrae (the lumbosacral junction).  Note the rounded bony arthritic bridging that has developed under the joint

In this image, Trapper’s legs are drawn forward, changing the position of the vertebrae and opening up the spinal canal, relieving the pinching (#4). This is the inherent “instability” that defines this problem.  The movement leads to pressure on nerves.

This is how this same area would look on a simple x-ray.  The nerves are not visible, and the only visible sign of a problem is the collapse of the LS disc space (# 5)  and the visible bone proliferation beneath the LS space (# 6).

SYMPTOMS

AN AFFECTED DOG WILL PROBABLY NOT DISPLAY ALL THESE SIGNS.

DO NOT RULE OUT CAUDA EQUINA  BECAUSE YOUR DOG ISN’T DOING ALL THESE THINGS.

• Sharp pain – remember dogs don’t cry out with every pain, especially chronic pain that develops slowly and they can adjust to it.  DON’T EXPECT THEM TO CRY OUT CONSTANTLY!!!
• Slow to rise – again, related to pain
• Changes in posture and gait – how they place their rear legs or stand or their posture laying down
• Unwillingness to exercise, or significant discomfort after exercise
• Unwillingness to use stairs, or noticeable change in speed and skill using stairs
• Poor coordination
• Shuffling gait
• Weakness in the back end
• Urinary or fecal incontinence
• Chewing at feet or tail
• Less tail movement
• Worn rear nails due to dragging the paws
• Intermittent lameness
• Partial rear-end paralysis (paresis)
• Complete rear-end paralysis

DIAGNOSIS

This is a surprisingly difficult disease to prove.  Frequently mistaken for hip dysplasia, the nerve injury is not visible on plain x-rays and to be able to “see” the problem, the patient must submit to a myelogram, epidurogram, or if feasible, a CT or MRI (as illustrated above).

It is possible to make a presumptive diagnosis of CES based just on a physical exam.  Dogs with cauda equina are very sensitive over the LS area.  Your veterinarian may test your dog by applying targeted pressure to the affected LS area.  Also, many dogs with CES are very uncomfortable when their tail is lifted or hyperextended.  A careful patient history, a good physical exam, and probably plain x-rays to rule out other problems are likely to be suggested.

Remember, if your dog tests “positive” to the exam described above, we must also consider other diseases that cause pain or nerve compression – spinal tumors, prostatic disease, bone infection, etc – in the differentials.

TREATMENT

• Avoid strenuous exercise, or even lighter exercise if it causes your dog visible discomfort afterwards.
• Oral NSAID’s like Rimadyl®, Deramaxx®, and Metacam®, and oral steroids, sometimes provide some relief, but it may be minimal depending on the level of pain.
• Tramadol (Ultram) can be a helpful analgesic.
• An injection of 20 mg DepoMedrol® on either side of the LS midline can be very helpful to affected dogs.  Here is a diagram to illustrate the location:

• Surgery to remove herniated disc material and open the compressed areas can be attempted.  Results vary with the individual case and should only be done by a surgeon experienced in this area.

PROGNOSIS

This is a progressive and debilitating disease, and one that can become a legitimate cause for euthanasia if the terrible pain and disability cannot be relieved.

The speed and extent of progression will vary from dog to dog.  Some may never develop symptoms severe enough that their owner must make major treatment decisions.  Many dogs, however, face a difficult future and if this happens to yours, you must discuss your options with your veterinarian, based on your individual dog’s symptoms, age, and general health.

Some dogs have made a complete recovery with surgery.  Others recover briefly and then relapse.  Some do well with the DepoMedrol® injections.  Whatever you decide, you must be fully informed about this disease and its effects on your dog.

This page last updated 12/09/2007

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