Muscular and skeletal degeneration in rabbits that lack
exercise.
Kim Chilson
Warning: this page contains pictures that may be distressing for
some persons.
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Wild
rabbits are very athletic animals that are built to move rapidly in order to
find food, water, find or fight mates, or flee predators over greater
distances to find a hiding place. This daily exercise strengthens the
locomotive muscles, fortifies their heart and lungs and increases their
resistance against stress. Regular movement will fortify muscle and bones,
will stimulate the blood circulation, and the activity and functioning of
organs including the digestive system.
House rabbits often do not have the
possibility to develop as their wild brothers and sisters, as they are often
confined in small hutches or cages with poor possibilities to exercise their
muscles and develop strength. This will inevitably lead to systemic
hypoplasia underdevelopment of tissues or organs) and the development of
physiological, physical and/or behavioral disorders. Physical disorders include: ·
Overweight. The lack of exercise
needed to burn calories and a rich diet will undoubtedly lead to overweight
and accumulation of fat in female and male rabbits. This can lead to the
development of (ulcerative) pododermatitis, cardiovascular problems, and skin
problems, due to the inability to groom properly. Physiological disorders include: ·
Gastro-intestinal disorders, e.g.
decreased intestine motility, ·
Cardiovascular disorders, e.g. weak
heart muscle, ·
Urinary disorders, e.g. soiling of
the perianal region, paste-like consistence of urine (sludge) or formation of
kidney or bladder stones, ·
Pulmonary disorders, due to
cardiovascular problems.
Muscular and skeletal problems When a rabbit is not given
opportunities to exercise, the muscle mass will not develop and remain weak.
In terrible cases, a rabbit has been found unable to develop a proper motor
coordination and normal ambulation. The heart is also affected and will
remain weak. Aside problems of proper blood circulation and blood pressure, a
weak heart will lead to problems when a rabbit will face a stressful
situation. While a well-trained wild rabbit can cope with the stressful
event, like being chased or hunted and will flee over a greater distance to
find a shelter, the poorly exercised rabbit, that is confined in a cage, may
not be able to cope with the situation and may faint or die from a cardiac
arrest. Lack of exercise furthermore
influences the vertebral column. The spine possesses 3 types of muscles
connecting the transverse and spinous processes of each vertebra: the
transversospinalis muscles. The function of these muscles is not well
understood, but is believed to be involved in local rotations of the
vertebral column or initiate bending. The fact that some transversospinalis
muscles cross a few intervetebral joints suggests a role in the control of
the vertebral position and the stability of the spine, fore- and hindlimbs. The spine is furthermore connected to
an intricate system of trunk muscles: ·
extensors, which include the back and
gluteal muscles (muscles that form the buttocks.), allowing for instance
hip movement, ·
flexors, which allow the spine to
bend, to control the arch of the lumbar spine, or hip movement, ·
obliques, that stabilize the spine.
The bone structure and density is
often affected in rabbits with lack of exercise and/or a diet deficient in
calcium, mineralization of bones is poor. Weakened bones and bones affected
by osteoporosis are easily injured or broken. The vertebras of the spine
provide support for the back. If this is accompanied by poorly developed transversospinalis
spine muscles and trunk muscles, the normal balance of the spinal structure
and the biomechanics can be altered, which can leads increasingly to
degenerative processes. Deformations appear that will prevent the development
of a good locomotric activity. Intrinsic muscle disbalance furthermore leads
to degenerative changes of the lumbar vertebrae and of the femoral head have
been observed in rabbits that lack exercise. They include: ·
hemivertebrae (abnormal birth defect in which the vertebra fails to
develop completely. As a result of the growth defect of the spine, a
wedge-shaped vertebra develops, and neighboring vertebrae expand or tilt to
fit the deformity) ·
spondylosis (a condition of the spine marked by stiffness of a
vertebral joint) ·
kyphosis (humplike curvature of the spine) ·
lordosis (abnormal, increased degree of forward curvature of any
part of the spine). The severity of the deformations is
shown to depend on the cage size. Rabbits suffering from weak muscles
and poorly mineralized bones and/or bone degeneration are at increased risk
of spine fracture when there is an inadequate support of the heavily muscled
hindquarters, walking on a slippery floor, or twisting of the lumbosacral
junction when frightened or restrained. Fracture is commonly observed at the
level of the 7th (L7) lumbar vertebra. Treatment A radiography will confirm the injury
or fracture the degree of severity of the problem can be assessed. Each case
needs to be evaluated on an individual basis.
Acknowledgement Thanks are due to Dr B. Langhofer (FIRST Regional Animal
Hospital, Chandler, AZ – USA) and to A. Carpenter for sharing their pictures. Further information 1. Katherine E. Quesenberry, James W. Carpenter, Peter Quesenberry Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery
Includes Sugar Gliders and Hedgehogs, Elsevier Health, 2004. 2. Frances Harcourt-Brown Textbook of
Rabbit Medicine, Oxford UK: Butterworth-Heinemann, 2001. 3. Paul Flecknell, editor, BSAVA Manual of Rabbit Medicine
and Surgery Gloucester, UK: British Small Animal Veterinary Association,
2000. and references therein. |
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