Dental Disease in Rabbits

Click to access Rabbit-dental-information-pre-dental-website-information.pdf

 

Dental disease is one of the most common health issues affecting rabbits. Although your rabbit’s teeth may appear
healthy from the outside, there’s a lot going on beneath the surface. Unlike humans, rabbit teeth continue to grow
throughout their life. In humans, the crown of the tooth is what we see above the gumline, and there is only a short
root below. In rabbits however, the crown extends deep below the surface of the gums (as depicted in the image
below), and what we see above the gumline is called the occlusal surface. Overgrown teeth do not just protrude into
the mouth; the elongated crown also grows in the opposite direction into the jawbone. As a result, overgrown teeth
can cause significant damage to the surrounding bone, as well as the nasal sinuses, nasolacrimal (tear) ducts, eye
sockets and even the eyes.

Figure 1: comparison of a human tooth vs a rabbit tooth1. The occlusal surface of the rabbit teeth is the only portion
of the tooth that we can see when looking inside the rabbit’s mouth. The crown of the tooth extends far below the
gumline, the root located at the base of this.

The primary cause of dental disease in rabbits is a lack of dietary fibre; as rabbits’ teeth are constantly growing, they
need to constantly chew to grind their teeth down. A lack of fibre means that they do not have adequate roughage
to chew on, and subsequently, their teeth become overgrown. The best food to enable adequate grinding down of
teeth is a low sugar grass hay. Foods such as pellets and soft fruit and vegetables are not adequate for grinding down
teeth. Other common causes of dental disease may include genetics or injury to the mouth, however these are less
common.

If adequate teeth grinding is not achieved, the teeth continue to grow and may end up elongating into the mouth
and jawbones (as seen in the radiographs below). This increase in pressure causes the teeth to curve. Over time, this
creates spaces between the teeth and results in infection, which commonly spreads to the jawbones. Additionally,
the upper teeth of rabbits lie very close to their eyes, nasolacrimal ducts (tear ducts), nasal sinuses and the eyes.
When tooth roots overgrow, we commonly see problems associated with these regions, causing significant pain and
discomfort.

The following table shows common radiographic (x-ray) findings of dental disease in rabbits:

Healthy rabbit skull radiographs
Figure 2: lateral radiograph of a rabbit skull2
– Green arrow: note the normal length and curvature of the incisors (front teeth – I1 and I2) creating nice alignment of
the teeth where they meet, and no protrusion of the roots into nasal sinuses (upper) or roots of the cheek teeth
(lower)
– Yellow circle: normal alignment of the cheek teeth (ct) with each other, with no evidence of any malocclusion
(misalignment) where the upper and lower teeth meet. The teeth are all relatively straight.
– Orange arrows: no evidence of protrusion of the tooth roots into the lower jawbone (can clearly see dark regions
between the end of the tooth roots and the lower jawbone).
Early stages of dental disease
Figure 3: lateral radiograph of a rabbit skull with early stages of dental disease3
– Green arrow: note the extended length and curvature of the upper incisors (front teeth), the extended roots of the
upper incisors into the sinuses, and extended roots of the lower incisors into the cheek teeth.
– Yellow arrow: extended length of the cheek teeth has caused curvature, resulting in a malocclusion (misalignment)
where the upper and lower cheek teeth meet. This curvature can be followed along into the roots of the teeth,
where they are now protruding into the sinuses and eye socket (upper) and jaw bones (lower).
– White arrow: increased length of the second cheek tooth has resulted in it growing downwards into the jawbone and
caused secondary malformation of this bone.
– Orange arrows: curvature of the roots of the cheek teeth has resulted in spaces forming between the teeth; this
often results in infection of the jawbone and teeth roots.
Moderate dental disease
Figure 4: lateral radiograph of a rabbit skull with moderate dental disease4
– Green arrow: note the curvature of the incisors (front teeth) resulting in extension of the roots into the sinus cavity
(upper) and roots of the cheek teeth (lower).
– Yellow arrows: the roots of the upper cheek teeth have penetrated the nasal sinuses and eye socket
– Orange arrows: the lower cheek teeth have extended significantly into the lower jawbone causing significant
malformation of this bone.
Severe dental disease
Figure 5: lateral radiograph of a rabbit skull with severe dental disease3
– Green circle: severe malocclusion (misalignment) of where the upper and lower cheek teeth within the mouth.
– Yellow arrow: extensive bone lysis (breakdown of bone) is evident due to infection and malformation of the jawbone
– White arrow: abnormal growth of the extended crown into the mandible (lower jaw)
– Orange arrow: the root of this cheek tooth has penetrated the jawbone resulting in significant structural
malformations
– As in the previous images, this radiograph also shows severe overgrowth and curvature of the incisors, as well as
overgrowth of the upper cheek teeth into the eye socket.
Infection of the jawbone
Figure 6: lateral radiograph of a rabbit with mandibular osteomyelitis
– White arrow: in this radiograph, there is a pocket of osteomyelitis (infection of the bone) that has occurred due to
the overgrown roots of the lower incisors (front teeth). This is a very painful infection and leads to bone loss (an
irreversible change). A dental procedure and subsequent antibiotics is the only way to alleviate this condition,
however this rabbit will likely require ongoing dentals throughout the rest of its life.

Prevention of Dental Disease

The best way to manage your rabbit’s dental health is to provide a diet high
in grass hay (high in dietary fibre) to enable adequate chewing and grinding
down of their own teeth. It is also important for your rabbit to have regular
dental health checks. This allows a vet to identify any dental issues early on
and treat accordingly, helping prevent irreversible changes to your rabbit’s
teeth and jaw and maintain a healthy mouth.

Below is a rough guide to rabbit nutrition. We recommend Oxbow nutrition
as this is a nutritionally balanced formula that will provide your rabbit with
the essential nutrition and fibre required for a healthy mouth and gut.

Additional information can be found at:
“Caring for your rabbit” Guide by Oxbow
https://www.oxbowanimalhealth.com/uploads/files/Rabbit-Care-Guide.pdf

Resources

  1. Stromberg, C 2006, ‘Evolution of hypsodonty in equids: testing a hypothesis of adaptation’, Paleobiology,
    vol. 32, no. 2, pp 236-258.
  2. Van Caelenberg, A, De Rycke, L, Hermans, K, Verhaert, L, van Bree, H, Gielen, I 2008, ‘Diagnosis of dental
    problems in pet rabbits (Oryctolagus cuniculus)’, Flemish Veterinary Magazine, vol. 77, pp. 386-394.
  3. Capello, V 2016, ‘Diagnostic imaging of dental disease in pet rabbits and rodents,’ Veterinary Clinics: Exotic
    Animal Practice, vol. 19, pp. 757-782.
  4. Radiograph taken by The Wild Vet

Rabbit Anaesthetic Procedures at The Wild Vet

Rabbit anaesthetics are typically riskier than cat and dog anaesthetics for a number of reasons. These include:

  • Greater difficulty in maintaining body temperature: rabbits have a greater surface area to body weight
    ratio, meaning that they lose heat more quickly. As such, it is vital that their body temperature is managed
    throughout the procedure, from pre-medication right through until recovery.
  • Stress: rabbits are typically more prone to stress than many other species. Additional stress increases their
    risk of developing gut stasis (which can be fatal) and can make anaesthetic procedures unpredictable.
  • Rabbits process medications differently: certain medications that are commonly used in cats and dogs are
    unable to be used in rabbits.

At The Wild Vet, we have a highly trained team of staff who are well versed in each of these risks. While no
anaesthetic is risk free, we take a number of measures to ensure that we provide the safest anaesthetic we possibly
can. This includes:

  • Thorough pre-anaesthetic assessment: each rabbit is carefully assessed by one of our experienced vets.
    Factors such as age, weight, body condition, and other health issues are considered, and blood tests may be
    recommended depending on the health status of your rabbit. An individual plan is developed for each rabbit
    based on these factors.
  • Intravenous catheter placement: every rabbit will have an IV catheter placed prior to their anaesthetic
    procedure. This means that we can quickly administer emergency medications if needed, and easily maintain
    their hydration status by administering IV fluids.
  • Intubation: every rabbit is intubated at the onset of their procedure. We have specialised equipment
    enabling us to safely intubate your rabbit. This means that we can maintain oxygen throughout the
    procedure and enables us to carefully adjust anaesthetic doses as required. It also means that we can
    ventilate the patient if required.
  • Multiparameter monitoring system: each rabbit is carefully monitored throughout their procedure. We are
    constantly monitoring their:
    • Heart rate and rhythm with an ECG à this allows us to detect any arrythmias or changes in heart
      rate
    • Respiratory rate, oxygenation levels and end-tidal carbon dioxide à this enables us to ensure that
      your rabbit is maintaining good oxygen perfusion throughout their body
    • Body temperature à we use an oesophageal probe to maintain constant monitoring of body
      temperature throughout the procedure. We also use heat pads or a heated table, as well as a Bair
      Hugger, to ensure temperature is maintained.
    • Blood pressure à this provided additional insight into how well the cardiovascular system is
      functioning throughout the procedure. If this drops or increases outside of the healthy range, we can
      intervene immediately to restore adequate cardiovascular function.
  • Fluid therapy: intravenous fluids are administered throughout the procedure. This not only helps to
    maintain their hydration status (subsequently reducing the risk of gut stasis), but also helps us to maintain
    adequate blood pressure for your rabbit. Additionally, fluids help the liver and kidneys to clear the
    anaesthetic drugs more quickly, meaning that your rabbit will have a faster recovery time.
  • Pain relief: this is an integral component to any invasive procedure. Pain significantly increases stress in all of
    our patients; by providing the appropriate analgesia (pain relief) before, during and after the procedure, we
    are minimising the stress levels of each patient. We also opt for multi-modal pain relief; this means that we
    use a combination of medications specifically tailored to the needs of each patient, and reduces the overall
    amount of medication required to meet the same outcome. All of our patients will be sent home with pain
    relief if required.
  • Assisted feeding: one of the major contributors to gut stasis is a lack of food intake. We always ensure our
    rabbit patients are happily eating independently before they return home. Until this occurs, we assist feed
    them with Oxbow Critical Care. This is a nutritionally balanced formula that minimises the risk of developing
    gut stasis. It’s also important to note that rabbits should never be fasted prior to any anaesthetic procedure.
  • Post-operative care: included in the cost of a rabbit anaesthetic procedure is an additional 24 hours of
    hospitalisation. We like to keep all rabbits in overnight following their procedure. This enables us to assist
    feed them if needed, monitor their faecal output and hydration status, and ensure they are receiving
    adequate pain relief. We always like to see them eating independently and passing faeces normally before
    they return home.