Cerebellar hypoplasia (non-human)


Cerebellar hypoplasia is a neurological condition in which the cerebellum is smaller than usual or not completely developed. It has been reported in many animal species.
This article has some general information, but focuses primarily on CH in the domestic cat.
In cats, this condition is also called "Wobbly Cat Syndrome." An animal with CH may be called ataxic or be described as a "bobble-head."

Function and development of the cerebellum

The cerebellum is the brain's main control center for planning, adjusting, and executing movements of the body, the limbs and the eyes. It plays a major role in several forms of motor learning, including balance and posture.
In the past, the evidence for a role for the cerebellum in cognitive functions was rather weak. However, investigations into the cognitive neuroscience of the cerebellum are rapidly advancing, extending far beyond the traditional view. For humans, current theories support that what the cerebellum does to sensorimotor and vestibular control, it also does to cognition, emotion, and autonomic function.  How it functions in cognition, emotion, or autonomic function in animals is still largely unknown. In 2012, a study in mice provided direct evidence that subtle disruptions in cerebellar architecture can have pronounced effects on behaviors typically associated with autistic-like behavior.
Development of the cerebellum starts in a fetus in utero and, depending on the species, may continue for some period after birth. Postnatal development periods vary by species including: dogs up to 75 days, cats to 84 days, calves up to 6 months.

Causes

A hereditary link to CH has been established in some animals, including certain breeds of cows and dogs. It has not been established in cats.
There are numerous other potential causes for CH. It is suspected that the most common cause is animal parvoviruses.
Feline panleukopenia virus has long been known to cause cerebellar hypoplasia in neonatal kittens through in utero or perinatal infection. In utero, the virus can pass from the dam to the developing fetus and may then disrupt the development of its cerebellum by hindering cell division. This can happen when the dam is actively infected with the virus or given a modified-live FPV vaccine when pregnant. If young kittens are infected by this virus during or after birth, and survive, the active virus can disrupt the postnatal cerebellum development. If kittens are given a modified-live FPV vaccine too early, while their cerebellum is still developing, it may cause CH.
In most cases the cause is unknown. However, in dogs and cats it is thought to be most likely related to in utero viral infections, toxins or genetic disorders.
Other possible causes, if they occurred during the development period of the cerebellum and inhibit its growth, include:
Depending on the specific area and amount of cerebellum affected, the severity at which the animal displays problems varies.
Some signs may be seen immediately after birth. Perinatal kittens with CH may have difficulty getting to the mom's nipples, competing with siblings, and problems suckling and/or swallowing.
As a kitten ages, signs may become apparent when it starts to become mobile and attempts to stand/and or walk. It may display jerky movements, tremors, rolling around instead of starting to stand and walk, swerving, head bobbing, falling, and generally uncoordinated motion. Some animals may never be able to walk.
Sometimes signs are so subtle they are not noticed except under careful observation and as the animal becomes more mature.
Cerebellar hypoplasia may be exhibited by some or all of these, at various levels of severity:
There is a very active U.S.A-based Facebook page for Cerebellar Hypoplasia Cats and Kittens. It has well over 10,000 members from locations all around the globe. The originating organization, chcat.org has been instrumental in introducing a rating scheme for CH cats that is widely accepted and used among its members.
What follows is based primarily on their rating scheme and on an adult cat's ability in its living environment. It does not reflect a neurological assessment of the actual damage to the cerebellum. Temporarily, during growth periods or when ill, stressed, or tired, a cat may seem slightly "worse" than usual.
This mild-to-severe rating should be viewed as a general guide and a scale. Cats may be described as very mild, mild, mild-moderate, moderate, moderate-severe, severe, extremely severe, and may, or may not, exhibit some or all of the following.

Mild

Very capable. Requires little to no extra care. Some home accommodations may be helpful.
Can get around on their own. One end of their body may appear to be doing something else than the other end. A modified living area to prevent injuries from stumbles and falls may be necessary. Some aids to assist in accomplishing essential daily tasks may be helpful or necessary.
Cannot stay standing or walk on its own, except for maybe a few steps. Requires significant adjustments in their living area to protect them from getting hurt when they move around and to accomplish essential daily tasks.
A definitive diagnosis of CH can only be made with brain imaging. A clinical evaluation is necessary to rule out other, contributing, or confounding factors and to establish that the presenting signs are stable. CH is not a progressive disease, so the presenting clinical signs and history should not indicate an overall worsening of the animal's abilities.
Due to the cost and risks factors of having an MRI done, or a lack of access to adequate veterinary services, many owners opt for a probable diagnosis based on observation and/or clinical evaluations.
General practice Veterinarians may or may not be familiar with CH. It is not uncommon for it to be misdiagnosed, with numerous unrelated ailments being attributed to it or when the neurological problem is clearly progressive. Consultation with a Vet Neurologist is advisable; they specialize in disorders of the nervous system: diagnosing and treating diseases of the brain, spinal cord, peripheral nerves, and muscles.
Numerous problems can be mistaken for CH. These include :

Treating CH

There is no standard course of medical treatment for cerebellar hypoplasia; it cannot be cured. Generally, treatment is symptomatic and supportive. When the CH is severe and supportive home care is not available, or is not sufficient, or the quality of life would be poor, affected animals are euthanized.

General Medical Care and Treatment of the CH Cat

Except as noted below, if otherwise healthy, general medical care for a CH cat is no different from that for a non-CH cat. They can breed and are susceptible to the same diseases, infections and parasites. Normal preventive care applies for:
Cats, especially CH cats should never be declawed. Their claws are essential aids for mobility and stability. It is usually OK to trim the tips of their claws, although some members of the CH Cat Facebook group have reported that even this causes a notable decrease in ability.
Special considerations:
CH cats may benefit from acupuncture, manual or massage therapy, hydrotherapy, and/or aquatic therapy.

Prognosis

The physical deficit of the cerebellum does not get better or worse with age. Mild-to-moderate CH cats can usually learn to compensate for some or all of the associated mobility issues. Very young cats can appear to make dramatic improvements as they mature, but this is primarily due to them developing their muscles and stamina, and from learning and adjusting.
Physical therapy may help a cat develop and maintain muscle tone and stamina, in turn enabling it to achieve and maintain more mobility and flexibility than it might have been able to achieve if left to develop on its own. In addition to the CAVM treatments listed above, support harnesses or slings and mobility carts may be helpful. There are numerous types and styles available commercially. There are also good do-it-yourself tutorials and pictures on-line.
Providing that the root cause of the CH did not affect other parts of the developing animal, it can, in theory, lead a fairly normal life and have a normal life-span if special considerations for its disability are taken by the owner. However, secondary complications, such as accidental injuries that occur as a result of the condition, or complications from a sedentary lifestyle for mobility-limited cats, may affect their overall health and lifespan. CH cat owners can be proactive to help prevent these secondary complications and to integrate exercise into the daily routines.
If the root cause of the CH impacted other parts of the developing brain and/or body, the overall health and life-span may or may not be impacted. For instance, fetuses infected in utero by FPLV that survive, and kittens less than a few weeks of age that become infected with it, can also have retinal dysplasia, and optic neuropathy.

Home Care Considerations and Accommodations

Some CH cats do just fine without any extra care or special home accommodations. Others need a little help to navigate the home without getting injured or to accomplish their daily living tasks. As the level of severity increases, so does the intensity of care that may be required. This includes not only help with getting around, or getting around safely, but also cleaning up their messes and their body.
For mild-to-moderate CH cats, it is important to know that their ability to respond "instinctively" to a threat may not be inhibited. Bolting, biting, scratching and clawing when scared or startled are instincts, and are controlled by a different portion of the brain. A mild-to-moderate cat that can't walk a straight line, could dart straight away in a flash.
CH cats don't understand that they are disabled, so they will not be self-inhibited from trying to climb or descend. Prevention of injuries requires careful consideration of the specific hazards posed by where they live and their potential abilities. Some cats that cannot walk well or jump, can still climb extremely well. Don't assume a CH cat can't or won't try to get up on something; it is in their nature to explore, jump, and climb. A cat can grip with its claws to get where it wants to go.
There is no "one size fits all" answer for how to address and help the unique needs of a specific level of CH cat.

Tips for Caring for CH Cats

For the Room, House, or Home

Most CH cats are at a significant disadvantage when it comes to protecting themselves from other animals or predators. They can't fight, climb, or flee well; nor can they, if they get lost, fend for themselves adequately. If they are going to be allowed outside an enclosed safe area is strongly advised. CH cats that are impounded as strays are at risk of being mistaken as being injured and subsequently euthanized. Some ideas for keeping the cat safe when outside include:
Caring for a mostly immobile cat can be a significant challenge, but it is doable. There are some very specific care practices that need to be instilled into a daily schedule to help keep the cat healthy.
If the cat cannot, or does not, get regular daily exercise by itself, therapeutic massage is incredibly important. Massage helps to promote normal fluid flow throughout the body - improving circulation, encouraging lymphatic drainage, reducing lactic acid build up in muscles, and helps prevent digestive issues like constipation.
Some tips and techniques that may help care for these cats, include: