| Rabbit
Dental Disease
From the House
Rabbit Society, San Diego Chapter
Dental disease in the pet rabbit remains one of the
most common problems seen by veterinarians. In recent
years we have come to a better understanding of causes,
prevention and treatment of these diseases.
Anatomy of rabbit teeth
Rabbits are herbivores that are designed to eat a diet
comprised of a wide variety of vegetation from succulent
to tough, dry material. All of the rabbit's teeth grow
continuously throughout its life to compensate for the
pronounced wear created by long periods of chewing on
abrasive foods.
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| Healthy teeth |
Rabbits have a total of 6 incisors (the teeth you see
in the front), two sets upper and one set lower, and
no canine teeth. The cheek teeth consist of three upper
premolars and three upper molars, and two lower premolars
and two lower molars on each side. The teeth are worn
down at a rate of approximately 3mm per week.
The normal structure of the jaw AT REST allows the
incisors to touch, but not the cheek teeth. A rabbit
can use its incisors to cut food material without interference
from the cheek teeth. Food is taken into the mouth with
the prehensile ("grasping") lips and incisors
and then moved via the tongue to the cheek teeth. When
ready to chew, the rabbit changes the position of the
jaw and brings the cheek teeth into contact. At this
time the incisors are no longer in contact allowing
the rabbit to chew without interference.
Rabbits chew their food with a wide side to side movement.
A normal shape to the jaw is very important to the normal
wearing of the teeth. It is important to note that dental
disease can start in either the cheek teeth or incisors,
but over time will ultimately involve both sets of teeth.
The lesson here is that we must always be concerned
with the health of ALL the teeth, even when we initially
see disease in only a few.
The top part of the tooth that is visible to us is
called the crown and the bottom is called the root.
The root is only visible with the aid of a X-ray. Improper
wear of a rabbit's tooth can lead to overgrowth or crooked
growth of either the crown or the root. Overgrown crowns
are generally easy to see, but overgrown roots can be
overlooked. Severely overgrown roots in the lower jaw
can cause a lump to form along the bottom edge of the
jawbone. Overgrown roots in the upper jaw can block
the drainage of tears through the tear duct and cause
lumps behind the eyes.
Rabbit teeth have a natural curve as they grow. If
the crown of a cheek tooth becomes overgrown it can
come into contact with either the inside of the cheek
or the edge of the tongue resulting in painful ulcers.
These ulcers can be painful enough to cause the pet
to stop eating.
Causes of dental disease
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| Malocclusion |
* Genetics - Unfortunately human interference in the
breeding of rabbits has often resulted in anatomical
changes that can lead to disease. In the case of dental
problems, changing the shape of the skull can drastically
change how the teeth contact and wear on each other.
The most obvious example is the lop-eared rabbit, in
which the length of the jaw has been shortened. The
changed the jaw structure results in malocclusion of
the teeth and ultimately elongated teeth (because they
are not being worn down) that must be trimmed or removed.
This type of dental problem is usually seen in young
rabbits before one year of age and is often first noted
in the incisors. However, if left untreated, the cheek
teeth will also be affected in due course. There is
no cure for this problem other than life-long control
and maintenance of the abnormal tooth growth. The ultimate
solution is to breed rabbits with normal jaw anatomy.
* Trauma - Trauma to the face can result in changes
in the jaw or malocclusion of the teeth. If the jaw
is broken it may heal in an abnormal position. If the
teeth are broken (most typically the incisors) and they
grow in at an improper angle, it will throw off the
anatomy of the mouth and lead to multiple tooth problems.
One of the most common incisor traumas is caused when
a tooth breaks off below the gum line as a result of
trimming the incisors with dog nail trimmers. (See the
section on Treatment for safer methods of trimming incisors).
However, accidents do occur and it is essential to get
immediate care for you pet should a facial trauma occur
to provide the best possible chance for a normal recovery.
* Systemic disease - Some systemic diseases can result
in a change in dental health. For example, diseases
that alter calcium levels in the body can cause a change
in the bone surrounding the tooth, which will cause
the tooth to shift its position and lead to malocclusion.
Rabbits too weakened by disease to chew on solid food
can develop overgrown and malocclused teeth due to improper
wear. It is important for your veterinarian to monitor
the dental health of your pet while it is experiencing
any serious systemic disorders because dental disease
may occur as a secondary problem.
* Dental infections - Dental infections are not a common
cause of dental disease. More often, abscesses of the
tooth roots are the result of long term dental problems,
particularly where the tooth root has overgrown and
resulted in inflammation.
* Diet - Next to genetics, this is probably the most
common cause of dental disease in the pet rabbit. In
our modern world, we were trained to believe that a
commercial pelleted diet is the best diet for a rabbit.
After all, it is convenient, tidy and contains all the
nutrients that the rabbit needs. The commercial rabbit
diet was originally developed for the "production
rabbit," meant for a short life ending in the meat
or fur market, or for laboratory rabbits who also experience
a shorter life span. For these purposes it is an efficient
means of growing a rabbit quickly, but is a poor diet
for rabbits kept as pets for the full span of their
life.
The problem is that rabbits were never designed to
eat a diet that is essentially already "chewed
up" or pulverized. A pellet breaks apart easily
in the mouth and there is little work for the teeth
to do and thus little wear. In addition, because pellets
are a concentrated nutrient source, the VOLUME of food
is a fraction of what a rabbit would be eating in the
wild and therefore the actual amount of time a rabbit
spends chewing in a day is drastically reduced. Both
the small volume and composition of an exclusively pelleted
diet are both adversely affect proper tooth wear. We
do not recommend commercial pellets as a main source
of food for any pet rabbit for this reason.
Disease caused by an improper diet may not be evident
for many years. Affected rabbits are usually 3 years
or older. Dental changes may be very subtle at first,
but if the situation is not quickly corrected, advanced
dental disease can occur.
Signs of dental disease
There are a variety of signs associated with dental
disease ranging from almost undetectable to severe.
If the disease is mild, the rabbit may not show any
obvious problems and the problem may only be discovered
on a routine physical examination. However, most dental
problems eventually become painful and the rabbit will
give some obvious indications of discomfort or inability
to eat properly.
* Anorexia (loss of appetite)- This is a common finding
because of the pain of either a tooth spur causing an
ulcer of the cheek or tongue, an elongated tooth root
or because the teeth are so out of alignment the rabbit
can't pick up or chew food. There are many other causes
of loss of appetite.
* Being more selective about the food - As rabbits
start to develop malocclusion of the teeth or dental
pain they may stop eating certain items such as carrots,
pellets and occasionally hay. They will continue to
eat soft foods like fruits and some leafy greens, but
cannot eat the harder foods.
* Dropping food out of the mouth - The rabbit still
tries to eat, but can't completely chew the food and
some of it falls back out of the mouth.
* Excessive tear production - This is a common sign
of dental disease that involves the upper incisors.
The tip of the upper incisor root is in close proximity
to the tear duct. Inflammation or elongation of the
root can partially or totally block the tear duct. The
tear gland will still produce tears but they spill over
onto the face as opposed to going down the duct. The
corners of the eyes appear wet or accumulate a crusty
white material that is an accumulation of salt and mucous.
Secondary bacterial infections cause inflammation of
the tear duct as well as the production of pus.
* Nasal discharge - If the roots of the upper incisors
are inflamed or elongated there may be irritation to
the sinuses and with resultant nasal drainage. This
can be difficult to differentiate from true upper respiratory
disease, and it is essential to have a high detail X-ray
to aid in the diagnosis.
* Salivating excessively - This can happen because
of pain or the inability of the rabbit to properly close
its mouth due to overgrown teeth. The saliva accumulates
on the fur in the corners of the mouth, the chin and
the dewlap.
Other causes of excessive salivation include overheating,
eating something that has an unpleasant taste, foreign
bodies in the mouth and extreme general weakness.
* Tooth Grinding - This is more often seen with abdominal
discomfort, but some people have noted that rabbits
with dental disease may grind their teeth more frequently.
Occasional tooth grinding can be normal, but if it is
heard continuously there may be a problem.
* Bulging of the eye - Abscesses of the upper premolars
or molars can lead to pressure behind the eye. The eye
will be pushed slowly out until the optic nerve is stretched
and damaged and the pet loses its sight. Tumors behind
the eye can also cause a similar sign.
Diagnosing dental disease
* History - The history of the rabbit may reveal changes
in eating habits that indicate dental disease. As I
have said many times, it is vitally important that you
observe your pet closely and share your observations
with your veterinarian.
* Physical examination - Every rabbit should have a
thorough mouth examination done at least once a year.
It is my opinion that every rabbit should have a mouth
examination performed each time it comes into the veterinary
clinic. The earlier we can detect dental disease the
greater the chances for success of treatment. The examination
is usually performed without anesthesia in the healthy
pet. There are a number of instruments that can be employed
to examine the cheek teeth without discomfort in the
conscious pet. In cases where the pet is difficult to
handle or where dental disease is difficult to see due
to its position, it will be necessary to use sedation
for the mouth examination.
In addition to the mouth examination, a complete physical
examination is vital to determine any other disease
problems that might be present.
* Radiographs (X-rays) - Rabbits that have dental disease
need to have radiographs taken of the skull to determine
the extent of the disease and to determine the appropriate
treatment approach. Without a radiograph, it is impossible
to assess the condition of the tooth roots. Several
views of the head need to be taken in order to see all
the teeth. It is necessary and also much less stressful
to the rabbit to use anesthesia for this diagnostic
procedure.
* Blood tests - If the rabbit is suspected of having
concurrent disease that may have lead to the dental
disease, your veterinarian will recommend that certain
blood tests be performed.
Treatment of dental
disease
The most valuable key to treatment and management
of dental disease is EARLY DETECTION. This is why a
thorough mouth exam coupled with your keen observations
of your pet are critical.
* Diet - A diet full of food items that require chewing
is essential. A healthy diet is necessary in the treatment
of dental disease to minimize further damage and to
attempt to prevent reoccurrence.
* Grinding/cutting overgrown teeth - Incisors should
not be cut with side cutters or dog nail trimmers. Although
there are individuals who have employed these methods
for years with success, it only takes one occurrence
of breaking off an incisor below the gum line that leads
to a lifetime of dental problems. It is not worth the
risk. Overgrown incisors are best cut with a dental
burr or a small grinding attached to a low or high-speed
motorized handle. In this way teeth can be trimmed without
fear of breakage. This procedure can be performed at
a veterinary clinic or by a person experienced in this
technique. It is generally performed painlessly and
quickly while your pet is awake. Occasionally, a very
nervous rabbit is difficult to handle and may have to
be sedated for this procedure.
Overgrown cheek teeth are more difficult to trim in
the conscious pet. The rabbit has a narrow mouth opening
making it difficult to access all areas easily in the
conscious pet. It is usually necessary to anesthetize
your pet to properly manage all but the mildest cheek
tooth overgrowth. The treatment that has been used for
years is to simply cut back the overgrown crowns with
a bone-cutting instrument. The problem with this treatment
in all but the mildest of dental disease is that it
does not allow for correction of the alignment of ALL
the cheek teeth. It is rare that only one or two teeth
are malaligned. Although this procedure can often be
done without anesthesia, the likelihood of rapid (4
to 6 weeks) reoccurrence of the overgrowth is high.
In addition, some rabbits object vigorously to this
procedure and because it is often being performed blindly,
there is a possibility of injury to the cheek, gums
or tongue. In cases of moderate to severe disease it
is preferred to anesthetize the pet and use a dental
burr to grind and reshape all the cheek teeth at the
same time to encourage proper realignment. This treatment
addresses the entire anatomy of the mouth rather than
just one or two teeth. In early cases, this treatment
may be curative. In chronic or more severe disease,
the procedure will need to be repeated, but the length
of time between treatments is much longer than with
a simple clipping. Your veterinarian can advise you
on the best treatment regimen for your pet.
* Extracting teeth - Extraction of abnormal teeth,
either cheek teeth or incisors, is a viable and often
more humane option for your pet than frequent trimming.
Rabbits can successfully live without their incisors
because they can use their prehensile lips to move food
into the mouth. Rabbits can also live and eat without
one or more cheek teeth. We have helped many rabbits
that otherwise would not have been able to survive by
removing the abnormal teeth permanently. Diet modifications
may have to be made in these cases. Specifics should
be discussed with your veterinarian.
* Treating abscesses - The treatment of abscesses of
the face is a topic for an entire column, so I will
not attempt to go into it here in detail. Suffice it
to say that dental disease must be considered anytime
a rabbit develops an abscess on the face or jaw and
X-rays should be taken to assess the problem. There
are many options now available for the treatment of
dental abscesses including complete surgical excision,
antibiotic bead impregnation, and various injections
into the wall of the abscess. Please discuss these options
with your veterinarian.
Prevention of dental disease
* Diet - It is obviously not possible to prevent all
types of dental disease. Dental problems caused strictly
by diet, however, can be avoided. Your rabbit should
be fed a diet of unlimited grass hay and a good amount
and variety of fresh leafy greens daily. Avoid feeding
an exclusive diet of commercial pellets. You can find
specific information on the healthy diet of the House
Rabbit in our Care Of Rabbits handout. In addition offer
other items to chew upon such as fresh tree branches
(from trees that are NOT sprayed with chemicals), untreated
wood pieces and unvarnished, unpainted wicker baskets.
Providing a healthy diet will ensure adequate wear of
all the teeth.
IT IS NEVER TOO LATE TO CONVERT A PET TO A HEALTHY
DIET. A natural diet has a myriad of benefits beyond
just good teeth; it is literally the foundation for
good health.
* Examinations at home - Be familiar with the appearance
of your pet's teeth. You will only be able to see the
incisors, but take a good look at least once a month.
Your veterinarian or experienced rabbit friend can help
show you how to perform the exam. Report any changes
in shape, color or texture of the teeth to your veterinarian
as soon as possible.
* Veterinary examinations - As mentioned, your veterinarian
should examine your pet at least once a year. Part of
a thorough physical examination on a rabbit is a dental
exam. Merely examining the front teeth is not sufficient.
Cheek teeth may have early disease that will be missed
so the entire mouth needs to be examined.
Conclusion
Dental disease is common in the pet rabbit. Diet is
the best means of prevention and is essential as well
in treatment. Your pet's teeth should be thoroughly
examined at least once a year. If your pet does develop
dental disease, there is a good possibility it can be
controlled effectively if diagnosed early.
By Susan Brown, DVM, Midwest Bird
& Exotic Animal Hospital
Westchester, IL 60154
From Pet Care Forum/Veterinary
Hospital on Veterinary information network (www.vin.com)
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