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Incisor Malocclusion and Overgrowth in Rabbits

A rabbit's teeth usually grow throughout its life, and a high fiber diet, with foods that warrant heavy chewing, are required for proper alignment and functioning, as the coarse foods help to keep the teeth at a manageable length. Occlusion, the fitting together of the teeth of the upper and lower jaws when the mouth is closed, can be hampered by overgrowth of one or more of the teeth, a condition referred to as malocclusion (where the prefix mal- joined with -occlusion refers to the ill-fitting shape of the teeth).

If elongation of the cheek teeth occurs, complete closure of the mouth cannot be achieved, and the upper incisor teeth are prevented from coming into contact with the lower incisors, leading to excessive growth of the incisors. The incisor teeth can grow as much as one mm a day if left unopposed by the opposite jaw – the meeting/occlusion of the teeth, along with a diet high in roughage, acts as a natural inhibitor of the tooth's growth.

Symptoms and Types

• Readily visible teeth
• Excessive drooling
• Tooth grinding
• Nasal discharge
• Food drops out of mouth
• Preference for softer foods
• Preference for a water bowl over a sipper bottle
• Decreased appetite or complete loss of appetite (anorexia)
• Weight loss
• Excessive tear production
• Facial asymmetry or exophthalmos (protrusion of eyeball)
• Pain (i.e., reluctance to move, depression, lethargy, hiding, hunched posture)
• Unkempt hair coat due to lack of self grooming

Causes

There are many factors that can lead to cheek teeth overgrowth. The most significant contributing or exacerbating factor is a diet that contains inadequate amounts of the coarse roughage material that is required for properly grinding the tooth's surface, allowing the incisors to grow into the surrounding soft tissues, damaging the tissue and even leading to secondary bacterial infections in the mouth. Dwarf and lop breeds have been found to be at an increased risk for congenital malocclusion, as they are more prone to skeletal abnormalities.

Diagnosis

Your veterinarian will perform a thorough physical exam on your rabbit, differentiating between overgrown incisors and other tumors of the mouth of skull. Visual diagnostics will include skull and face X-rays, and computed tomography (CT) for better viewing of abnormalities. A fine needle aspiration (drawing and analyzing the fluid from swelling) will be taken for laboratory testing. A complete blood profile will be conducted, including a chemical blood profile, complete blood count, urinalysis, and a bacterial culture to determine the exact strain of bacteria so that the appropriate antibiotics can be prescribed.