Ischemic myelopathy

Back (spinal) problems are not common in cats. If your cat has a spinal problem they may have neck or back pain or show a variety of signs including difficulty walking, jumping, using one or more legs or even complete paralysis. These signs may occur suddenly (acute spinal problem) or more progressively (chronic spinal problem). Unfortunately signs of spinal problem are not typical of a specific disease and many spinal problems (slipped disk, fractured spine, spinal infection, spinal tumor, ischemic myelopathy) can cause similar signs. If you suspect your cat might have a spinal problem (especially an acute one) you should make sure your veterinarian checks them over as soon as possible. Some conditions may just require rest and pain killers whereas in others your pet may need urgent surgery if they are to recover. Spinal problems in cats include slipped disk, fractured spine and ischemic myelopathy. Ischemic myelopathy is only occasionally seen in cats but comes on very suddenly without warning and can be very frightening.

©Douglas McCallum

Ischemic myelopathy is a disease of the spinal cord (myelopathy) caused by a poor blood supply (ischemia). Like any other part of the body, the spinal cord relies on a permanent blood supply to bring nutrients and remove waste products. Arteries supply defined segments of the cord on each side. If one of these arteries becomes blocked the blood supply to a particular area of the spinal cord is shut off and this causes damage to the nerves running there.

The most common cause of blockage in animals is a fragment of the cushion (disk) between the bones in the back. This disk is made of a tough cartilage (fibrocartilage) and so the term fibrocartilaginous embolism (literally meaning fragment of fibrocartilage blocking an artery) is often used to describe the condition. There are many theories, but no-one really knows how or why this fragment of intervertebral disk suddenly gets into the spinal cord artery. There are many other more unusual causes of blockage (a fragment of tumor or fat).

Ischemic myelopathy is only occasionally seen in cats. This condition can cause paralysis of one back leg, both back legs, all four legs or only one side of the body (depending on which portion of spinal cord is affected). Typically, this paralysis comes on suddenly, is not painful and does not get worse with time (at least after the first 24 hours).

Other diseases that cause sudden paralysis and may be mistaken for ischemic myelopathy include spinal fracture or dislocation (broken neck or broken back), spinal cord bruising (spinal cord contusion) caused by a road traffic accident or a bad fall. Slipped disk (intervertebral disk herniation) is considered rare in cats and often seen as a result of spinal trauma.

A diagnosis of ischemic myelopathy is often made by ruling out other causes of acute paralysis (see above). For this purpose, diagnostic tests such as spinal X-rays, myelography and/or MRI scan are indicated. It is important to rule out other conditions causing pressure on the spinal cord (slipped disk or spinal fracture/dislocation) where an operation might be needed (picture myelogram IVDH). In most animals with ischemic myelopathy the results of these tests come back as normal. Since your veterinarian is relying on absence of findings on X-ray or MRI scan to make a diagnosis it is essential that the correct portion of the spinal cord is checked. Occasionally, swelling of the spinal cord can be detected on X-rays or MRI scan (picture MRI scan ischemic myelopathy).

A definite diagnosis of ischemic myelopathy and identification of its exact cause can only be made by examining the spinal cord after death.

There is no specific treatment for ischemic myelopathy but most cats tend to recover within a few weeks provided they have retained the ability to feel pain in their feet. Good nursing care (physiotherapy, assisted walking, hydrotherapy, adequate bedding to prevent bed sores) is essential for the recovery of the animal. The recovery period may be long and require intensive nursing so can be quite expensive.

If your cat did not lose sensation in its feet then it will probably recover over a few weeks. Most cats will make a full recovery after 8 to 12 weeks but some may keep some residual deficits. In animals where there was complete paralysis, improvement may not be seen for a number of weeks and some animals may never fully recover.