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Hypermetria and Dysmetria in Cats

Dysmetria and hypermetria describe the incoordination of an animal's limbs during voluntary movement. More specifically, dysmetria is characterized by a cat's inability to judge the rate, range, and force of its movements -- literally, an inability to measure space. Hypermetria, meanwhile, describes the action of overreaching, or high stepping, the intended location.

Symptoms and Types

Signs of cerebellar disease that may be present include:

• Head tilt
• Body swaying
• Body tremors; often more pronounced with movement
• Wide leg stance
• Loss of the menace response – the reflexive closing of the eyes when a finger is stabbed toward the eye
• Unequal pupil size (anisocoria)
• Abnormal, jerky movements

Causes

Trauma to the brain or back is often the primary cause for spinal or brain injury, leading to incoordination or overreaching of the  limbs. Lesions on the cerebellum, the part of the brain that is responsible for coordinating voluntary movements and balance, or on the nerves leading to the cerebellum, are believed to be one of the causes for these symptoms. Lesions can be caused by strokes, or by tumors located near these nerves.

Diagnosis

Your veterinarian will perform a thorough physical exam on your cat, taking into account the background history of symptoms and possible incidents that might have led to this condition. If there are no other signs of cerebellar disease, it will be important to establish whether a high-stepping thoracic limb gait is physically normal for your cat. Diagnostic imaging, such as with X-ray or ultrasound, is generally performed to review possible injury or damage to the brain and spine, and is especially recommended for older animals.

Your veterinarian will check your cat's reactions and responses to stimulus, such as whether your cat responds when your veterinarian stabs a finger toward the its eyes. The reflexive closing of the eyes and jerking away is called the menace response, or menace reflex, and the lack of such of a response is indicative of loss of eye sight, or neurological dysfunction.

Treatment

If the condition is severe and/or rapidly progressive, hospitalization is recommended for an immediate diagnostic work-up and treatment. If the condition is mild or slowly progressive, treatment is often done on an outpatient basis. Generally, cats that are suffering from this condition are confined to ensure that they are not at risk of being injured while they are healing. You will need to set up a place in the house where your cat can rest comfortably and quietly, away from other pets, active children, and busy entryways. Setting the cat litter box and food dishes close by will enable your cat to continue to care for itself normally. You may consider cage rest for a short time, if it is difficult to keep your cat confined to one place.

However, it is important that your cat is not left alone for extended times, as this can be a very stressful time for the cat, and being alone for too long can make the stress, and the healing, worse for the cat.   

Living and Management

It is recommended that periodic neurologic examinations be performed to monitor your cat's progress.