Managing paraparetic cats (Proceedings)

Paraparesis is a common presenting sign in cats, but the differential diagnoses are less well known than for dogs. In addition, it can be challenging to perform a neurological examination in cats, making it more difficult to accurately localize the problem. This presentation will summarize the diagnostic approach to paraparetic cats and discuss the differential diagnoses, their treatment and prognosis.

Diagnostic approach

Cats are unwilling to walk around a veterinary consulting room and so it is important to take an accurate history, ensuring that you get details of the changes in gait and behavior, such as jumping. Other pertinent information includes the presence of other cats, and in particular the introduction of new cats, vaccination status, diet and environment. A thorough physical examination should be performed, paying particular attention to the cardiovascular system as heart murmurs and gallop rhythms can be significant. Femoral pulses should be palpated and the color of nail beds inspected. Performing a neurological examination is often difficult in a cat and there is frequently only a small window of opportunity. I start by watching them move around the room. While many freeze in unfamiliar surroundings, they will walk towards their carrier if it is placed in a strategic position. Many adopt a crouching, low level posture when walking as a behavioral response to being in the vets office, so interpret this with caution. Following this evaluation of their ability to move around and interact with the environment, I usually test the postural reactions and cranial nerve and then place them in lateral recumbency to test reflexes. Palpation of the spine is the last step and remember that many cats are sensitive in the caudal lumbar region.

Following the physical and neurological examination, blood work and a urinalysis should be performed (the chemistry panel should include creatine kinase). If the signs localize to the spine, spinal radiographs should be obtained and if a diagnosis is not established, referral for advanced imaging (preferably MRI) and CSF analysis is appropriate. If the signs localize to the periphery (nerves, muscle or neuromuscular junction), metabolic causes should be ruled out and then the next step is referral for electrophysiological evaluation, testing for myasthenia gravis and muscle and nerve biopsies.

Vascular events

One of the most common causes of paraplegia in cats is iliac thrombosis and is outside the remit of this talk. However, there are a couple of important points about diagnosing iliac thrombosis. The first is that femoral pulses can be difficult to palpate in a large/overweight cat and so should not be the defining criterion for diagnosing this disease. I like to see cyanotic nail beds, pale paw pads, cold extremities, pain, distal edema, and hard muscles on examination. We do see animals with partial vessel occlusion that have reperfused their hind limbs – measuring blood pressure in the distal limb, measuring the partial pressure of oxygen in the distal limb and measuring CK can also help to establish a diagnosis in these cases. Finally, ultrasound of the distal aorta and following the vessels down the limbs can be very helpful. We do see cats that have thromboembolic events affecting their thoracolumbar spinal cord, although this is unusual. There are also occasional reports of fibrocartilagenous embolism. Diagnosis is established by magnetic resonance imaging (MRI) and CSF analysis and all possible underlying causes should be investigated.

Trauma

Cats can fall from heights, be attacked by dogs and be hit by a variety of objects causing vertebral fractures and luxations. If the cat is paraplegic with no nociception in its hind limbs with a displaced fracture or luxation, then prognosis for recovery is guarded. If the cat still has ncocipetion, it has the potential to make a recovery. Treatment depends on whether there is compression and/or instability that needs to be addressed surgically. Conservative management with strict rest and rehabilitative exercises may also be successful.

Intervertebral disc disease

Degenerative changes of intervertebral discs are very common in old cats, but clinically significant acute or chronic disc herniations are less common. However, they certainly can occur and disc disease should be considered as a differential for any cat with paraparesis or paraplegia. There is a trend for overweight, older cats to acutely herniate low lumbar discs, and disc herniations are also reported at the thoracolumbar junction. Clinical signs relate to the location and severity of the herniation. Referral for advanced imaging and potential surgery is indicated in any cat that is non-ambulatory paraparetic or paraplegic.

Infectious diseases

The most common infectious/inflammatory disease to cause paraparesis in cats is FIP. The typical case is young and has a spinal ataxia. They may also exhibit other neurological signs. Diagnosis can be difficult to establish; serum globulins are usually high, and CSF is typically abnormal with a very high protein and neutrophilia. MRI may show meningitis and ependymitis, and if evaluated, there may be hydrocephalus due to ependymitis. Other infectious diseases to consider include toxoplasmosis, but remember that affected cats tend to be systemically ill as well, and that serum titers can be misleading. CSF analysis should be inflammatory and CSF titers and pcr can be obtained. FeLV has been associated with a viral induced myelopathy in one report, but is usually associated with signs through induction of lymphoma (see below). Discospondylitis has been reported in cats, with a similar course to dogs. Radiographs will aid in diagnosis and urine cultures (+/- blood cultures) should be performed to identify the causative agent.

Neoplasia

Primary or metastatic sarcomas and metastatic carcinomas can involve the vertebral column and cause compression of the spinal cord. They may be identifiable on radiographs if they cause enough bone lysis. Round cell neoplasia is an important consideration in cats, more specifically cats that are infected with FeLV or FIV. There is a well described syndrome of spinal lymphosarcoma in young FeLV positive cats. These cats present with progressive paraparesis that localizes to the third thoracic to lumbar spinal cord segments. They typically have involvement of other organs (e.g. bone marrow, kidneys, liver). Spinal lymphosarcoma is usually extradural in which case lymphoblasts are not found in the CSF. If the tumor is intradural or intramedullary, CSF analysis may be diagnostic. Advanced imaging will identify the location of the tumor, and sometimes it can be aspirated directly to obtain a diagnosis. Round cell neoplasia can be treated with chemotherapy or radiation, although prognosis is poor. Meningiomas and glial cell tumors can also occur within the spinal cord, again diagnosed by advanced imaging. Surgical removal of meningiomas may be possible depending on the location, although there is little information available on prognosis.

Peripheral neuropathies

The most common peripheral neuropathy is associated with diabetes. The distal sciatic is involved first and causes the classic 'dropped hock' plantigrade stance. If allowed to progress the cat will develop both a plantigrade and palmigrade stance. Appropriate control of diabetes will improve the signs. Cats with traumatic tail pull injuries can present with bilateral sciatic deficits causing a plantigrade stance, but these cats will have a paralyzed tail, in addition to an inability to urinate and fecal incontinence. Another differential to consider is bilateral rupture of the Achilles tendon. If it is possible to hold the stifle in extension and flex the hock until the digits touch the tibia, the Achilles tendon is ruptured. This is believed to be an inflammatory disease, and typically the Achilles tendon is thin, and the gastrocnemius muscle is painful on palpation. If the signs are unilateral, consider iatrogenic paresis due to injection into or around the sciatic. Injections should not be made into the biceps femoris because of the risk of injuring the sciatic nerve.

Summary

Paraparetic cats should be evaluated logically starting with accurate neurolocalization and progressing to appropriate imaging or electrodiagnostics. Many causes of paraparesis are treatable although some, such as lymphosarcoma and FIP, carry a poor prognosis.