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Mimic “CH” Symptoms

Cerebellar Hypoplasia is a condition where parts of the cerebellum are underdeveloped before birth causing the coordination & fine motor skills to be effected which may cause stumbling/falling, goose stepping & head bobbing.

A cerebellar hypoplasia cat in the traditional “stance” that is wide & unsteady

Mostly Caused By:

  1. Mother contracting panleukopenia while pregnant
  2. Mother being vaccinated with the modified-live virus FVRCP vaccine while pregnant
  3. Genetics (inbreeding etc.,)
  4. Trauma to the mother while pregnant
  5. Kitten contracting panleukopenia & surviving, while the cerebellum is still developing (the virus interrupts cerebellum development, leading to the stunting of the cerebellum’s growth).

It is VERY important to look at all symptoms your kitten displays! Before you automatically assume your pet has a neurologic disorder, it is extremely important to rule out illness as the cause of symptoms. This can be the difference in suffering/death and living a normal, happy & healthy life!

CH Symptoms Include:

  • Head/Body Tremors
  • Unsteady Gait/Wide Range Stance
  • Falling/Stumbling
  • Shaking/Tremors (seems worse when excited/aggravated)
  • Non-Progressive Condition (does not worsen or improve over time)

When dealing with neurological symptoms, you must ALWAYS rule out illness especially with problems that mimic “CH” such as (but NOT limited too!):

  • Toxoplasmosis
  • Rabies
  • Vestibular Disease
  • Brain Trauma/Tumors
  • Epilepsy
  • Inner Ear Infections
  • Spinal Cord Issues
  • Nutritional Deficiency
  • Brain Lesions
  • Hydrocephalus

REMEMBER, just because your pet shows symptoms of one (or more) of the listed conditions as a result of an underdeveloped cerebellum/brain, this does NOT mean that it is solely the only thing going on! Again it is very important to NOT assume it is CH at first! Rule of thumb when dealing with pets with neurologic symptoms is ALWAYS to rule out illness/injury as the cause.

There is no simple test to diagnose cerebellar hypoplasia in cats. However, your veterinarian may recommend a series of tests to rule out more serious conditions. Your veterinarian will likely start with routine lab work like blood chemistry, complete blood count, and urinalysis and potentially radiographs. These tests may reveal metabolic problems, organ dysfunction, or abnormal cells in the blood or urine and other infection/abnormalities.

Your primary veterinarian may refer you to a veterinary specialist, like a neurologist, to pursue further testing. The best way to rule out other major neurological conditions is for a veterinary specialist to conduct a CT or MRI scan. A cerebrospinal fluid tap may also be recommended to look for bacterial or viral infections. The CT or MRI may show brain abnormalities including but not limited to cerebellar hypoplasia.

Advanced diagnostics are not always necessary. Perhaps your budget is tight or you don’t want your cat to undergo a lot of testing. Your veterinarian may be able to make a presumptive diagnosis based on your cat’s symptoms, then offer options for helping your cat life a wonderful life.

Speak with your veterinarian as a neurologist if you suspect ANY kind of neurologic disorder.

Swimmers:

Congenital pelvic and pectoral laxity is a relatively common problem in kittens. These ‘swimmer’ kittens are often diagnosed at 4 – 6 weeks of age, showing an inability to stand and move about with a characteristic swimming like motions. This abnormality is usually due to laxity in the pelvic and pectoral girdles, and most invariably rectify themselves with minimal intervention. Appropriate use of carpeted surfaces for the kitten to maneuver upon and use of bandaging usually rectifies the problem within 4 – 6 weeks of therapy[2].

Cerebellar Ataxia:

The cerebellum regulates the rate, range and force of a movement and is involved in the patient’s balance. Affected cats often stand and walk with their limbs far apart. As they walk, there will be a delay in the onset of protraction which is then followed by an exaggerated response and often a misdirected termination. The movement has a bursty quality which may be described as a high-stepping gait or goose stepping. Dysmetria and hypermetria are preferred terms to describe this gait. Cats with cerebellar problems find it difficult to make accurate calculations when jumping and often do this in a very exaggerated way. Tremors, which in some cats get worse when they go to do something such as eating may also be seen. These are referred to as intention tremors.

Vestibular Ataxia:

This is caused by dysfunction of the vestibular receptors in the inner ear, the vestibular portion of the vestibulocochlear nerve (VIII), vestibular nuclei in the pons and medulla or vestibular components of the cerebellum. The vestibular system controls the orientation of the head and eyes with the position of the neck trunk and limbs.

Affected cats may have a head tilt, lean and fall to one side, occasionally circle to that side and exhibit an abnormal nystagmus (flickering of the eyes from side to side or, more rarely, up and down). Signs of motion sickness such as vomiting are noted.

General Proprioceptive Ataxia:

General proprioceptive (GP) ataxia is also referred to as sensory ataxia. This is caused by lesions that involve the brain stem spinal cord or nerves that are involved in detecting the location of the limbs. In the central nervous system this GP system is closely associated with the upper motor neuron (UMN) system and therefore the lesions that affect the GP system also affect the UMN system.

It is not possible to clearly recognize clinical signs only caused by interruption of the GP pathways and it is not necessary in order to make an accurate anatomic diagnosis. The clinical signs that include dysfunction of the GP pathways include a delay in the onset of protraction, excessive medial (adduction) or lateral (abduction) of the affected limbs, a slight delay in the termination of the swing phase of the gait causing it to be prolonged. The affected limb shows a tendency to overreach or float which is easier to see in the thoracic limbs. Occasionally the manus or pes will fail to extend fully resulting in the paw landing on its dorsal surface.

Causes

Developmental

Abnormal development of the brain is an important cause of ataxia in kittens. Abnormalities will be observed as the kitten begins to stand and walk and are usually non progressive. The most common malformation is the cerebellar hypoplasia and atrophy due to the in uterio or perinatal infection with the feline panleukopenia virus. FPV is a virus which has a predilection for rapidly dividing cells and therefore the tissues most severely affected by this virus include the cerebellum (which develops during late pregnancy and early life), the intestinal tract and the bone marrow. Panleukopenia means low white blood cell numbers which occurs as a result of the bone marrow infection with the virus.

Griseofulvin treatment for ringworm in the pregnant queen may result in a number of brain malformations.

Lysosomal Storage Diseases

Lysosomal Storage Diseases re rare inherited diseases where the kitten is born lacking an enzyme required for normal metabolism. Enzymes are required for chemical reactions which convert one substance into another in the body. In cats with storage diseases, metabolites accumulate most commonly in the neurons. Neurologic signs are common since the brain function is affected by this abnormal accumulation.

Metabolic Problems

Metabolic problems describe the category of diseases where problems outside the brain affect how this very sensitive organ is able to work. Porto-systemic shunts  are one example of this where an abnormality of the blood supply to the liver affects how the brain functions. More rare additional examples of metabolic problems in kittens include diabetes mellitus, low blood calcium levels and low blood glucose. For example, very young kittens are vulnerable to having low blood sugar levels (hypoglycaemia) if they are ill for another reason and this can cause weakness, ataxia and seizures in severe cases.

Nutritional

Thiamine deficiency can result in weakness and a wobbly gait – nutritional deficiencies should not occur when commercial cat food is fed.

Infections

The most common viral infection of the CNS of cats including cats only a few months of age is the meningoencephalitis caused by the Feline Infectious Peritonitis virus. Bacterial abscesses can follow bite wounds or otitis media-interna

Head Trauma

Head trauma, such as a kitten falling or being dropped from a considerable height will cause acute cerebellar signs that usually lessen over the ensuing hours.

Neoplasia

 Neoplasias are uncommon in kittens and young cats.

Clinical Assessment

History

Investigation of any ataxic kitten requires a logical and step by step approach. The first important requirement is to obtain a thorough history concerning the cat’s background and breeding.

Important questions include:

  1. How old was the kitten when the ataxia was first seen?
  2. Is this congenital or acquired?
  3. Has there been any possible exposure to toxins?
  4. Was the queen vaccinated when pregnant?
  5. Did the queen receive any veterinary treatment when pregnant?
  6. Any possible exposure to toxins since the kitten was born? (this includes veterinary or pet shop treatments)
  7. What is the kitten’s diet? Any possibility of a nutritional deficiency?
  8. Are the other litter mates normal? Any reports of similar problems? (this would implicate problems such as infectious diseases, problems when the queen was pregnant, exposure to toxins etc.)?
  9. Any reports of similar problems in previous litters (this may indicate a possible inherited problem)?
  10. Any traumatic episode in the kitten’s life which preceded the wobbly gait? (e.g. road traffic accident, falls)?
  11. Any other clinical signs which could be helpful in pointing to a particular diagnosis? For example hypersalivation is commonly seen in cats with portosystemic shunts?

Taking a thorough history should make it possible to rule out some of the possible causes of the ataxia and may highlight areas for further investigation and questioning.

Examination

Physixal and neurological examinations are the next important steps which your vet will perform. A thorough general physical examination may reveal clues as to the cause of the ataxia, for example, in cats with FIP there may be abdominal distension with fluid. A neurological examination enables assessment of the nervous system which helps to locate the exact anatomical site and extent of any abnormality. Some problems are associated with quite specific and localised clinical signs, for example cerebellar hypoplasia/atrophy is usually associated with tremors, a high stepping gait and exaggerated jumping. Other diseases such as feline infectious peritonitis (FIP) can result in several foci of disease which may lead to a number of neurological deficits on examination.

In many cases, a thorough history, physical and neurological examination will be sufficient to reach a diagnosis.

Ancillary Procedures

In some cases further tests are needed in order to reach a specific diagnosis. These tests include:

Blood and Urine Tests:

These can give vital clues as to the cause of the disease and include routine haematology (assesses red blood cells, platelets and white blood cells) and biochemistry (evaluates liver, kidneys etc.). These tests are helpful in the diagnosis of conditions including portosystemic shunts as well as some of the infections that can cause ataxia. Specific tests for infectious diseases (FeLV, FIV, Toxoplasma Gondii) and Lysosomal Storage diseases are also available.

Eye Examination

This is particularly useful in the case of infectious disease (FeLV, FIV, FIP, Toxoplasmosis etc..,) where inflammatory lesions can also be seen in the eyes. Examination of the eyes can also be useful in diagnosing lysosomal storage diseases.

Radiographs (Thorax & Abdomen)

This is useful in screening for abnormalities which cannot be identified on physical examination of the patient and particularly in diagnosis of FIP where fluid production can occur in the thorax and/or abdomen

Ultrasound Examination

This is also helpful in checking for the presence of fluid in the thorax or abdomen (FIP) and can identify portosystemic shunts in affected kittens

Cerebrospinal Fluid (CSF) Analysis

The CSF is the fluid that bathes the brain and spinal cord. This test is especially useful in diagnosing the cause of the problem in cats with inflammatory diseases (such as FIP) or neoplasia (such as lymphoma).

Magnetic Resonance Imaging (MRI) Scan

Specialist imaging techniques have only recently become available but are a very useful, non invasive way of obtaining valuable information about the anatomical structure of the brain and presence or absence of inflammation or neoplasia. Some diseases cannot be diagnosed using this technique and unfortunately it is a very expensive test which generally is only performed in cats that are insured.

Diagnosis and Management

In most cases, a diagnosis can be reached allowing advice to the cat’s owner as to what the best treatment and likely long term outlook is. The prognosis varies hugely from disease to disease and although there are many serious and incurable causes of ataxia, there are also conditions to which the affected kittens can adapt and cope. One common example of such a disease would be cerebellar hypoplasia/atrophy.

References
  1.  Dr Sarah MA Caney, ex-FAB Lecturer in Feline Medicine. FAB Conference October 2002. http://www.fabcats.org/wobbly_kittens.html
  2.  Verhoeven G et al (2006) Swimmer syndrome in a Devon rex kitten and an English bulldog puppy. J Small Animal Pract 47(10):615-619