Cerebellar hypoplasia (non-human)

Cerebellar hypoplasia ("CH") is a neurological condition in which the cerebellum is smaller than usual or not completely developed.[1] It has been reported in many animal species.[2]

For the condition in humans, see Cerebellar hypoplasia.

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.[3] 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.[4][5]  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.[6]

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.[7]

Causes

A hereditary link to CH has been established in some animals, including certain breeds of cows[2] and dogs.[8] 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 ("FPLV" a.k.a.: Feline Distemper or Feline Parvo) virus has long been known to cause cerebellar hypoplasia in neonatal kittens through in utero or perinatal infection.[9] 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.[10] 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.[11]

Other possible causes, if they occurred during the development period of the cerebellum and inhibit its growth, include:[12]

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 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,[13] at various levels of severity:

  • Decreased muscle tone (muscle hypotonia)
  • Inability to control range of movement
  • Inability to correctly sequence fine, coordinated acts
  • Inability to perform rapid alternating movements
  • Inability to vocalize correctly
  • Involuntary, rapid oscillation of the eyeballs in a horizontal, vertical, or rotary direction (nystagmus)
  • Reeling, wide-based gait (ataxia)
  • Tremors (Intention tremors are alternating, oscillatory movement of a limb or the head as it approaches a target. Postural tremors are tremors in the body or extremities when a fixed posture or weight bearing is attempted.)

Levels of Severity

There is a very active U.S.A-based Facebook page for Cerebellar Hypoplasia Cats and Kittens ("Dogs and Puppies, too").[14] It has well over 10,000 members from locations all around the globe. The originating organization, chcat.org [15] 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 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):

Treatment

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:

  • Vaccinations
  • Spay or neuter
  • Dental care
  • Parasite prevention (with the exception of some flea/tick agents that are contraindicated for cats with neurologic abnormalities)

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:

  • Anesthesia: In 2004, a study was published that linked ketamine to post-anesthetic cerebellar dysfunction in cats.[19] 11 cats that did not have any indication of cerebellar deficits before surgery, did after. All of these cats were Persian crossbreeds. 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[14] routinely advise against its use. The 2018 American Association of Feline Practitioner's Feline Anesthesia Guidelines[20] lists numerous alternatives. Gas anesthesia offers a number of advantages in many circumstances. In CH cats the rapid recovery is its primary advantage.[21]
  • Medications: Medications that may cause 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. Some medications are specifically contra-indicated in cats with neurologic deficits/disease.

Complementary and Alternative Veterinary Medicine (CAVM)

CH cats may benefit from acupuncture,[22] manual or massage therapy,[23] 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 (a.k.a.: quad wheelchairs) 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.[24]

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 (scare/startle) 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.

For the Room, House, or Home
  • 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.
  • 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 to go up and down, may be necessary, as might denying access to the stairs. (Baby gates with vertical-only bars.)
    • Banisters and balustrades are another big concern. Nets or guards can be added to protect a cat from going between the vertical posts and falling.
    • Being able to get up on things may necessitate putting pillows or cushions on the ground to catch them if they fall off.
    • Cats like to perch and laze on top of things and look out windows. Adding protected ledges and perches, by using side-boards to prevent the cat from falling off over the edge, can allow it to relax and stretch out safely.
  • Climbing aids. Many CH cats use their claws to help pull them up on things.
    • Draping blankets or towels on furniture, so they hang down low enough for the cat to catch onto to climb up, not only helps the cat, but can protect the furniture. These need to be tucked in tight, or secured, so it doesn't tumble down while the cat is pulling itself up.
    • Ramps with carpet or grip-strips and side-walls are good aids to let them get up and down safely from furniture, beds, window perches, etc. A cat may need a few lessons to learn to use these.

Eating and Drinking
  • Elevated food/water bowls. Having these at chest level, based on whatever position the cat eats/drinks in, may help reduce head bobbing, chin bops, and nose dunks.
  • Soft, silicone bowls. Toddler training bowls help prevent chipped teeth and mouth/chin bruises.
  • Chute-like feeding stations. DIY innovations include padded or non-padded vertical walls that "hug" the cat as it goes into the chute and either stands to eat or eats in a sphinx-like position.
  • Drinking aids. CH cats may avoid drinking water from bowls because of nose dunks. Adequate water intake daily is a critical component of staying healthy. Some helpful ideas include:
    • Adding water to their food by giving wet/canned food, making food a soup or slurry consistency with water, or floating dry food in water.
    • Pet water fountains. There are numerous styles and sizes.
    • Non-spill water bowls
    • Giving water with a dropper or syringe
    • Rabbit water bottles

Potty tips and basic hygiene
  • Pee pads. Disposable puppy pee pads or reusable human bed liners are invaluable for catching the occasional misses or to even train cats to potty on.
  • Unscented, alcohol-free, hypoallergenic baby wipes. These are good for cleaning up some of the mushy-face food smears and doing a quick wipe of a messy bottom or paw.
  • Waterless pet shampoo may help keep a messy butt clean. If frequent baths are necessary, it's advisable to use a shampoo specifically formulated for cats. Their skin pH is significantly different from ours; our soaps, shampoos, and detergents may be too harsh and cause dry skin or brittle fur.[25]
  • Extra high litter boxes
    • High-sided litter boxes may help a moderate CH cat stay standing while it leans on one of the sides 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.
  • 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.
  • Some people have trained their cat to go on a pee pad inside a litter box, instead of using any cat litter.
  • A sanitary cut (a.k.a.: sanitary clip or hygiene cut) may help keep the fur on and around the butt from catching poop or litter. The hair around the cat's anus and genital area is shaved short.

Containment
  • A CH cat may need to be contained in CH friendly areas in the home, either when the owner is away or full-time (usually for severe/immobile cats). Options include:
    • A modified room.
    • An enclosed pet play pen.
    • Expandable, small animal plastic playpens (some models have clear plastic, interlocking panels, so a cat can't climb out).
    • A regular playpen (for CH cats unable to climb and with very limited mobility).
    • A kiddie pool (for very limited to no-mobility CH cats).

Outside

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:

  • Enclosed pet strollers. These allow you to take your CH cat outdoors without putting it at risk of escaping or being mauled.
  • Baby strollers for immobile cats - always tethered to keep them inside it.
  • Pet carrier slings or pet backpacks.
  • Special ID tags on the cats identifying it as having CH.
  • Enclosed patios or "catios." Pet screen material/mesh resists tearing from claws.
  • Cat containment yard fencing.

Especially for Moderate-Severe and Severe CH Cats

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.[26]

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.[27]

Some tips and techniques that may help care for these cats, include:

  • 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.
  • Very low soft silicone bowls (toddler bowls and pet travel bowls) that allow a prone cat to get its chin over without bruising it.
  • Disposable, absorbent ‘chucks’ or ‘pee pads,’ Placed under the cat, these may help keep its bedding dry and make cleanup easier.
  • 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 (UTIs).
  • 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, boot-shoe trays, and low big litter boxes designed for senior cats.
  • Some cats can be trained to go potty on schedules. Owners can also learn to recognize certain signs the cat shows that indicate a need to pee or poop, and then take them to their litter box. Caution: cats need to urinate regularly throughout the day to help prevent UTIs and/or uroliths (urinary stones or crystals) blockages.
  • Since a lack of physical activity can also slow down the gastrointestinal system, modifications to a normal cat diet may be necessary. Fiber and liquids play an important role in helping to keep stools consistent and avoid constipation. The fiber and moisture content of cat food varies significantly, so careful consideration of what may or may not be suitable is advisable.

See also

References
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  4. Schmahmann JD (January 2019). "The cerebellum and cognition". Neuroscience Letters. 688: 62–75. doi:10.1016/j.neulet.2018.07.005. PMID 29997061. S2CID 51623392.
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  10. "Feline panleukopenia |". Retrieved 2019-03-01.
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  12. Delauche A, Franklin R, Marsella R, Garosi L (February 2019). "Brain: cerebellar disease". Vet Stream. ISSN 2398-2950.
  13. Gonzalez-Usigli HA (February 2019). "Cerebellar Disorders".
  14. "Cerebellar Hypoplasia Cats & Kittens, Dogs and Puppies too".
  15. "Cerebellar Hypoplasia Cats and Kittens".
  16. Wilson J. "Ataxia (Wobbly Gait) in Cats - Causes, Symptoms & Treatment - Cat World – Cat Health, Cat Care & Cat Advice". Retrieved 2019-03-02.
  17. {{Cite web|url=https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/vestibular-syndrome feline vestibular syndrome|title=Feline infectious peritonitis}}
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  22. "Acupuncture - Management and Nutrition". Merck Veterinary Manual. Retrieved 2019-03-01.
  23. "Manual Therapy - Management and Nutrition". Merck Veterinary Manual. Retrieved 2019-03-01.
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  27. "Caring for a Pet with Limited Mobility" (PDF). Bush Veterinary Neurology Service. 2017.

Further reading
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