Excerpt From:
The Veterinarian
Common problems in rabbits and ferrets
http://www.theveterinarian.com.au/clinicalreview/article500.asp
MARK SIMPSON
Of all the gastroenteric problems we see in rabbits, dental disease is the most common. And while dental problems are occasionally due to congenital (possibly inherited) malocclusion, the vast majority of cases are a result of a progressive syndrome caused by poor diet.
Inappropriate levels of dietary protein, calcium, and vitamin D, coupled with inadequate dental wear are strongly implicated in the aetiology. The syndrome of acquired dental disease is characterised by an alteration in the orientation, then shape, and possibly structure of the teeth and the consequent development of malocclusion. It is my opinion that the altered wear (leading to altered pressure at the tooth roots) and generous supply of protein and calcium in inappropriate diets, permitting ready remodelling of the bones of the jaw, are causative factors in the majority of rabbit dental disease.
As a result of this re-orientation, sharp spurs can develop on the cheek teeth that penetrate surrounding soft tissues of the cheek or tongue. In particular I find lacerations and ulcerations of the tongue are intensely painful and affected rabbits do not eat or groom effectively.
Though the incisors are most commonly treated dental problem in rabbits, I believe they constitute only a small proportion of problems - most rabbit teeth problems are associated with the cheek teeth. I have seen several rabbits with bilateral, medially directed spurs of the cheek teeth of the lower jaw literally trapping or skewering the tongue in an immobile position.
Rabbits with spurs are often salivating, which gives rise to the lay term slobbers. Gut stasis is, for multiple reasons, a common sequelae. In some cases the appearance of the teeth in the mouth is normal, and the roots are the site of the pathology. In cases where the clinical sign indicate dental problem but oral examination is within normal limits, radiographs of the head, to assess the tooth roots, are indicated.
The tooth roots are significant as they are frequently the site of abscessation, which may be the first clinical sign the owners identify as a problem. These abscesses will lead to severe osteomyelitis, with draining sinuses on the face, and are an absolute disaster. While occasional anecdotal stories of resolution are told, the vast majority of these abscesses require intense and complicated debridement and the use specialised treatments such as antibiotic-impregnated methyl methacrylate pellets or Consil[sup]â[/sup] to have even a hope of remission.
There is a constant risk of recurrence with these abscesses, and anything that can be done to avoid them is preferable to trying to treat them. One of the factors that we associate with these abscesses is the use of nail clippers to effect trimming, predominantly of the incisors. This technique has been associated with longitudinal microfractures of the tooth, which provides an excellent avenue of access for bacteria of the mouth to enter the tooth apices and begin a problem. For this reason we strongly recommend avoiding the use of nail clippers to trim the teeth.
Once there are spurs affecting the mucosa of the oral cavity the only successful treatment is removal of the spurs under general anaesthesia. It must be emphasised however that this is a temporary measure, and that trimming the teeth will need to be repeated once every six to 16 weeks for the rest of the rabbits life.
To anaesthetise these patients I use the protocol developed by Dr Ron Rees-Davies that I call rabbit DTK: Domitor[sup]â[/sup] (medetomidine 1mg/mL) at 30ug/kg, Torbugesic[sup]â[/sup] (butorphanol 10mg/mL) at 0.10mg/kg, and ketamine (100mg/mL) at 1mg/kg, which gives about 0.10mL Domitor[sup]â[/sup], 0.03mL Torbugesic[sup]â[/sup] and 0.03mL ketamine for a 3kg rabbit, which I inject intravenously as a single bolus. This usually allows enough anaesthesia for cheek tooth examination and burring.
I then intubate the rabbit and provide supply oxygen, and then I am in a position to provide additional gaseous anaesthesia if the need arises
My experience with local anaesthetic blocks in rabbits has not been as good as those used in cats and dogs. This is not totally surprising, as the sites, especially that for mandibular blocks, are much more difficult to access than in other species. I no longer attempt regional blocks for this purpose in rabbits.
Some specialised equipment is necessary to trim the cheek teeth of rabbits. There are many rabbit mouth gags, and some of these may be viewed at Dr David Clarkeâs web page at
http://www.k9gums.com.au/page7.html. I find the concept of two-way action to be critical so that the jaws are opened and then the cheeks are effectively âdilatedâ one side at a time. I therefore have the jaws held open with a standard small animal gag.
I then have an assistant use wooden tongue depressors to expose each part of the cheek teeth. A Dremel[sup]â[/sup] tool with a long bit is then used to burr all the cheek teeth to about a millimetre above the gum line. I find that if I slide off the tooth I do not damage the mucosa, (nor any expensive gags), but simply the wooden tongue depressor.
There is some controversy about how much to remove from the teeth. Some practitioners remove only the offending spur. It is not my aim to restore normal occlusion. By the time these procedures are required any return to normal occlusion is impossible as there have been irreversible changes to the tooth roots and dental disease will be permanent.
Some reports suggest burring will lead to heat necrosis of the tooth roots but I have seen no evidence in the many cases I deal with to support that contention. However there is good evidence to suggest that occlusive pressure will drive affected teeth back into their sockets, and this disrupts the normal anatomy of the tooth apex. The gingival attachment and the periosteum are damaged.
Once again, as in the case of microfractures of the incisors, bacteria of the oral cavity can reach the tooth root and surrounding bone.
By burring to within a millimetre of the gingival margin some of this occlusal pressure is relieved, and the likelihood of tooth root abscesses and associated osteomyelitis decreased. My clinical impression has been that rabbits that have their teeth shortened this way also return to eating more quickly, possibly because the root elongation has been painful.
