Hereditary Myopathy (formerly known as "spasticity")
by Helen Bryant


Hereditary Myopathy (formerly known as "spasticity") is a disorder that results in
muscle weakness and is a form of muscular dystrophy affecting young Devon Rex
cats and kittens. The condition has now been proven to be hereditary and
transmitted recessively (i.e. both parents have to carry the gene before an affected
kitten can be born).

The following symptoms have been compiled from the description of many owners
of affected kittens, however not all kittens will show all the symptoms, as not all
are affected to the same degree - but it has been noted that owners' descriptions
of affected kittens are very similar, so much so, that there is no doubt the kittens
are all suffering from the same disorder.

ONSET:
The onset of symptoms has been reported at different ages varying between 2 and
25 weeks (6 months). This could depend in part on how observant the breeder is, and on
other things such as stress on the kitten, plus severity of the condition in
individuals. Some have first been noticed as "different" at weaning time. They may
appear frightened and back away from food be it solid of liquid, or adopt unusual
positions for eating, or even have difficulty/be unable to eat at all.

Perhaps one of the earliest indication that a kitten might be affected is a
reluctance to come out of the nest and play with the other kittens. They are
noticeably quieter than normal Devon hooligans and will invariably adopt the role of
spectator rather that participator. This behavioral tendency becomes more marked
as they get older and they are often described as "so good" when compared to
their normal littermates of the same age. Their reactions have also been noted as
being marginally slower than those of kitten the same age.

Some affected kittens have been noted when learning to use the litter-tray - (see
below). They have also been reported as having difficulty in washing themselves,
this is thought to be due to the constriction of their neck muscles making the
movement of washing themselves very difficult, of in badly affected kittens,
impossible. Others have first shown symptoms after the stress of being
vaccinated, or following an illness or move to a new home. Some have not been
recognized as being "different" at all and sold to new homes at around 3 months
and later diagnosed as "affected". Often, with information and hindsight, both the
breeder and the owner have realized later, perhaps months/years after its death
that a particular kitten was affected.

SEVERITY:
There does seem to be wide variation in the degree to which kittens are affected.
Some are severely disabled and have died very young, or had to be euthanased
because they were unable to eat of drink. It is possible that some die
undiagnosed in the first few weeks of life. Some are less severely affected,
although an observant owner will be able to notice some symptoms. Most affected
kittens do not have a very long life expectancy. The average life span being
between six months and 2 years, only one has been known to live longer than 3
years.

HEAD AND NECK:
The typical affected kitten develops and arched neck and the head gets lower and
lower, often until the chin is almost permanently tucked into the chest. At first this
may be noticed by the kitten's head swaying from side to side, or the head being
held sideways. Some kittens will rear up on hind legs, or adopt a begging position
in order to be able to look around without difficulty. Others use furniture or a wall
for support. It has also been reported that affected kittens have very prominent
shoulder blades, one breeder describing them as like "angel's wings". Affected
kittens are invariable long and thin in type, they rarely put on a lot of weight.

WALKING:
These kittens are described as walking with a stiff legged high stepping action.
After any physical exertion such as eating or using the litter tray, the kitten may
remain "stiff legged" for a time. Running, which seems to take a lot out of them, is
often in a rabbit hopping fashion.

TOILET:
With the concentration and effort of using a litter tray, many kittens heads sink
lower and lower, until they are resting in the litter. Sometimes they almost appear
to be asleep, them will suddenly get up and out of the tray. some experience
difficulty getting into the tray in the first place.

SHAKING:
Though no affected kittens have been reported as being nervous per se, most have
periods of trembling or shaking uncontrollably, often when in unfamiliar
surroundings or under other forms of stress. Quiet, gentle reassurance is often all
that is needed to bring these bouts of trembling to an end.

CO-ORDINATION AND BALANCE:
Those who have mentioned this, say the kittens have good co-ordination (if
sometimes a bit wobbly) often better than their normal littermates. However most
do have difficulty with balance, and for them, falling over can be something of a
panic situation, with them wildly waving their paws in the air in an effort to regain
balance. Many also display a marked reluctance to jump down from even the
lowest height (a footstool) but seem to have to difficulty in climbing.

EATING:
Because of the bent neck and position of the heat (tucked under) most affected
kittens have great difficulty in eating. They cannot eat from a normal dish, but
some can eat from a flat plate or from the floor. Their method of getting food into
their mouths has been described as a "snatching action", often missing the food
more times than not. Bowls of liquid seem to terrify most of them, and some never
drink at all. Some adapt by tucking their paws under the body and eating the food
from their paws, and drink by licking fluids from their paws also. Most owner of
affected kittens, actually hand feed them for the whole of their life time.

RESTING:
Affected kittens seem to need frequent rest periods during play. They will lie in
unusual positions with their heads resting either on their front paws, the arm of a
chair, or some other object. While resting they are usually alert, watching
everything that is going on around them. Some also sit in "human" positions, the
only way they can be comfortable and breathe without difficulty.

EYES:
Most, but not all owners, report that affected kittens have something different
about their eyes - an indefinable expression which has been described as a "far
away gaze", "dreamy", "dazed", and "looking into the middle distance". It has
also been observed that several affected kittens have round eyes, noticeably
different from the normal oval shape of most Devons. Their sight however appears
to be perfectly normal.

TEMPERAMENT:
Without exception owners of affected kittens have said how loving/loveable they
are - far more so than is normal even for Devons. They tend to be "one man" cats,
and can become very dependent, demanding a great deal of attention.

MANAGEMENT:
Most owners say that their kittens need constant vigil for fear of choking - and not
just at meal times, several owners have had to remove food from the mouths of
choking kittens - sadly this is how many of them die.

A number have found to have heart defects and/or underdeveloped lungs and they
do seem particularly prone to respiratory infections - the second most common
cause of death. Some owners say massaging helps strengthen the limbs and
vitamin supplements seem to generally help the overall condition, which
incidentally is irreversible.

GENERAL:
It has been noted that affected kittens often seem unaware of the pain they are
inflicting on littermates during play. It is believed they have less control over their
jaw movements than normal kittens which can sometimes result in painful bites
for littermates and owners alike.

Many people expect these kittens to look mongoloid in appearance - this is not
the case. Apart from the physical disabilities described above, affected kittens
look exactly the same as other Devon kittens and they are not in any way
mentally deficient - far from it in fact, as many owners will testify.

FINALLY:
If you have been unfortunate enough to breed an affected kitten it is vital to have it
properly diagnosed by a Veterinarian Surgeon who may well refer you to one of
the Universities who are familiar with this problem. It should be noted that its
parents will be proven carriers and could be valuable to the breed in any test
mating program that may be in progress at the time.