Cerebellar hypoplasia (non-human)

Cerebellar hypoplasia ("CH") is a neurological condition in which the cerebellum is smaller than usual or not completely developed. It has been found 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 spastic 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 unknown.

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

Animal parvoviruses have been identified as a cause of cerebellar hypoplasia in felines, rodents, and ferrets; they are suspected of being one of the most common causes among animals.

The Feline panleukopenia virus ("FPLV" aka: Feline Distemper or Feline Parvo) has long been known to cause CH 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 when she is given a modified-live FPV vaccine while pregnant. If young kittens are infected by this virus during or shortly after birth, and survive, or are given a modified-live FPV vaccine too early, it can disrupt the postnatal cerebellum development.

A hereditary link to CH has been established in some animals (certain breeds of cows and dogs ), but has not been established in cats.

In most cases the cause of CH is unknown. In dogs and cats it is thought to be most likely related to in utero viral infections, toxins or genetic disorders.

Possible causes, if they occurred during the development period of the cerebellum and inhibit its growth, include:

• malnutrition (either from a of lack of adequate critical nutrients or an inability to absorb them, either in the dam or the fetus/kitten)
• hypoxia
• traumatic brain injury
• toxins
• viral infections (e.g: Feline infectious peritonitis)
• protozoal infection (e.g: Toxoplasmosis)
• rickettsial infection (most are spread through ticks, mites, fleas, or lice)
• mycotic infection

Signs

Depending on the specific area(s) 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 dams nipples, competing with its 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 kitten becomes more mature.

Cerebellar hypoplasia may be exhibited by some or all of these, at various levels of severity:

• reeling, wide-based gait (ataxia)
• inability to correctly sequence fine, coordinated acts
• inability to vocalize correctly
• inability to perform rapid alternating movements
• inability to control range of movement
• decreased muscle tone (muscle hypotonia)
• involuntary, rapid oscillation of the eyeballs in a horizontal, vertical, or rotary direction (nystagmus)
• tremors (rhythmic, alternating, oscillatory movement of a limb as it approaches a target ("intention tremor") or of proximal musculature when fixed posture or weight bearing is attempted ("postural tremor"))

Levels of severity

There is a very active U.S.A based Facebook page for Cerebellar Hypoplasia Cats and Kittens ("Dogs and Puppies, too"). 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.

• Unusual gait. A high step or waddle.
• Occasional balance loss.
• May have subtle head tremors when focused, excited or stressed.

• Can walk, run, jump, and climb.

Moderate

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 (eating, drinking, voiding, staying clean) may be helpful or necessary.

• Walk with legs splayed in a wide stance.

• May have a notable "bunny hop" with the back legs when running.

• Frequent balance loss and falls.
• Noticeable head tremors, especially when focused, excited or stressed.
• Can usually climb, but uses claws to latch on and pull up.

Severe

Cannot stay standing or walk on its own, except for maybe a few steps. Requires significant adjustments in their living area(s) to protect them from getting hurt when they move around and to accomplish essential daily tasks (eating, drinking, voiding, staying clean).

• May flip and flop to get around.
• May not be able to get to, or use, a litter box. Some may need bladder manually expressed.
• May be able to use claws, by latching onto fabric/carpet, to move around or up.
• Constant head tremors.

Diagnosis

A definitive diagnosis of CH can only be made with brain imaging (MRI). A clinical evaluation is necessary to rule out other, contributing, or confounding factors and to establish that the presenting signs are stable. CH it 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 (but are not limited to):

• Exposure to toxins
• Nutritional deficiency
• Hydrocephalus
• Physical trauma, traumatic brain injury
• Inner ear infection
• Ear polyps
• Feline Vestibular Syndrome
• Toxoplasmosis
• Feline Infectious Peritonitis (FIP)
• Lysosomal Storage Diseases
• Cancer
• Brain or spinal tumors or lesions
• Cerebellar abiotrophy. This can easily be mistaken for CH if it manifest early in the life of an animal. It has been identified in numerous animals, including: cats, dogs, horses, cattle, and sheep. Cerebellar abiotrophy occurs when Purkinje cells in the cerebellum start to die. Unlike CH, however, this occurs after the animal is born, causing normally developed cells to die. It is a genetic disease and may be hereditary in some species.

Treatment

Treating CH

There is no standard course of medical treatment for cerebellar hypoplasia. It can not 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 than for a non-CH cat. They can breed and are susceptible to the same diseases, infections and parasites. Normal preventative care applies for:

• Vaccinations
• Spay or Neuter
• Dental care

CH cats should NOT be declawed. Their claws are essential aids for mobility and stability. It is usually OK to trim the tips of their claws, although some owners have reported that even this causes a notable decrease in ability.

Anesthesia Considerations:

In 2004, a study was published that linked ketamine to post-anesthetic cerebellar dysfunction in cats. 11 cats that did not have any indication of cerebellar deficits before surgery, did after. All of these cats were Persian cross breeds. Ketamine can cause erratic and spastic, jerky movements and muscle tremors and is slow to be metabolized out of the system. Members of the CH Cat Facebook group routinely advise against its use.

Numerous agents are available to Veterinarians for sedation and anesthesia. Gas anesthesia offers a number of advantages in many circumstances. In CH kitties the rapid recovery is the primary advantage.

Medications

Medications that that may induce ataxia or have other possible neurological side-effects should be carefully considered before being used. Those side-effects may be extra difficult for a cat that is already wobbly.

Prognosis

Afflicted animals can, in theory, lead a fairly normal life and have a normal life-span if special considerations for the animal's disability are taken by the pet's owner. However, secondary complications, such as accidental injuries that occur as a result of the condition, may lead to a shorter lifespan. CH cat owners can be proactive to help prevent these secondary complications.

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 miild-to-moderate CH cats, it's important to know that their ability to respond "instinctively" to a threat (scare/startle) may not be inhibited. Bolting, biting, scratching and clawing when scared or startled are instincts, which are controlled by a different portion of the brain. A mild-to-moderate CH cat that can't walk a straight line could dart straight away in a flash.

CH cats don't understand that they are special-abled, so they will not be self-inhibited from trying to climb or descend. Protection and 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 even jump on target, can still climb extremely well. Don't assume a CH cat can't or won't try to get up on something; a cat can grip with its claws and do a pull-up.

There is no "one size fits all" answer for how to address and help the unique needs of a specific level of CH cat. Some general aids that apply to most include:

• Carpet or rugs. The pile allows a cat to get better traction or to use its claws to get around.
• Pool noodles and/or pipe insulation tubes. These are great for padding wall corners and furniture edges.
• Foam floor tiles (kiddy play mats). The soft rubber helps with floor traction and is good for lining flat vertical surfaces. Caution: some cats like to tear and nibble on these, posing a possible ingestion hazard.
• Pee pads. Disposable puppy pee pads or reusable human bed liners are invaluable for catching the occasional misses or to even train cats to go on.
• Elevated food/water bowls. Having these at chest level, based on whatever position the cat eats/drinks in, helps reduce head bobbing.
• Fall prevention or protection. Always remember, what goes up, must come down!
  • Stairways pose a significant hazard, especially if not carpeted. Keeping them from tumbling down is essential! Adding carpet, building a U-shaped ramp, or teaching the cat, may be necessary, as might denying access to the stairs. (Baby gates with vertical-only bars.)
  • Being able to get up on fabric furniture or carpeted cat trees may necessitate putting pillows or cushions on the ground to catch them if they tumble. If access to a specific place is desirable (e.g.: a bed), a carpeted ramp with side walls works well

For the moderate to severe cat, these may be helpful:

• Soft, silicone bowls. Toddler training bowls help prevent chipped teeth and mouth/chin bruises. These are low bowls, so prone cats can put their chin in them, too.
• Chute-like feeding stations. DIY innovations include padded or non-padded vertical walls that "hug" the cat as goes into the chute and stands to eat.
• Baby play mats with hanging toys. These are good for engaging play in cats that are not very mobile. Replace the hanging baby toys with cat toys.
• Extra low or extra high litter boxes.
  • Tall high-sided litter boxes may help a moderate CH cat stay standing while it leans on a wall as it pees or poops. Common DIY solutions use big plastic totes with an entry-way cut into it, or an entry and exit for a "drive-thru" solution.
  • Very low, or almost flat, litter boxes. Some severe CH cat are able to navigate into and out of these. Options include potting trays, disabled-rabbit litter boxes and low, big litter boxes designed for senior cats.
• Pelleted cat litters. These may help prevent clumping messes in its fur if the cat lays to potty or frequently falls down in the litter box.
• Cat diapers. There are several options for these: custom made-to-fit, washable or disposable, and DIY modifications of baby diapers. It is important to have a very proactive hygiene routine for keeping cats that wear diapers from getting urine scald or urinary tract infections.
• Unscented, alcohol-free, hypoallergenic baby wipes. These are good for cleaning up some of the mushy-face food smears and doing a quick wipe up of a messy bottom.

See also

• Cerebellar hypoplasia - article on the condition as it occurs in human beings

Further reading

• Schatzberg SJ, Haley NJ, Barr SC, Parrish C, Steingold S, Summers BA, deLahunta A, Kornegay JN, Sharp NJ (2003). "Polymerase chain reaction (PCR) amplification of parvoviral DNA from the brains of dogs and cats with cerebellar hypoplasia". Journal of Veterinary Internal Medicine. 17 (4): 538–44. doi:10.1111/j.1939-1676.2003.tb02475.x. PMID 12892305.
• Sharp NJ, Davis BJ, Guy JS, Cullen JM, Steingold SF, Kornegay JN (July 1999). "Hydranencephaly and cerebellar hypoplasia in two kittens attributed to intrauterine parvovirus infection". Journal of Comparative Pathology. 121 (1): 39–53. doi:10.1053/jcpa.1998.0298. PMID 10373292.

External links

• This Is Charley Video of a cat with cerebellar hypoplasia
• Samson: Lessons From A Blind Dog Video of a dog with cerebellar hypoplasia
• Cat Cerebellar Hypoplasia Symptoms and Treatments