Rodents include: the Chinchilla, Gerbil, Guinea Pig, Hamster and Rat
As stated above, teeth evaluation is the basis for the differentiation between rabbits and rodents. Rodents only have one set of incisor teeth and rabbits have the "peg teeth" as the second set.
Guinea pigs and chinchillas have continually growing and erupting incisors and cheek teeth, which also occurs in the rabbit. This dentition has been called elodont.
Hamsters, gerbils, mice, rats and other small rodents have continually growing and erupting incisors; however, their cheek teeth are brachyodont. They have a short crown and a well defined root. These brachyodont teeth do not grow continually.
Chinchillas: Kirby and his brother eating.
Dental formula for guinea pigs and chinchillas; 2(I2/1 C0/0 PM1/1 M3/3) = 20
The guinea pig and chinchillas have incisors and cheek teeth that continually grow.
Dental formula for the gerbil, hamster, mice and rats is; 2(I2/1 C0/0 PM0/0 M3/3) = 16
The gerbil, hamster, mouse and rat, have continually growing incisors however, the cheek teeth are not continuously growing and are classified as short (hypsodont) teeth.
Additionally, some hamsters only have 12 teeth as they may have 2 molars (as opposed to 3) on the top and the bottom dental arches.
Dr. Kressin performing a brief facial evaluation.
As the incisors elongate, they tend to twist.
A speculum is used to get an initial overview.
Rodents have continuously growing teeth. The number of teeth vary between species of rodents. The diet is fundamental to dental and overall health for these animals. Continuous growing teeth remain functional as a result of the normal wear from chewing feeds. Every time a rodent stops eating, reduces feed intake or becomes anorexic, the teeth may overgrow. The result is a painful mouth and in some cases the inability to eat. This becomes a life threatening problem very rapidly. Early presentation of rodents for a dental evaluation may be life saving.
Sammy, a beautiful 9 month Guinea Pig
A routine radiograph to evaluate the occlusion.
A routine radiograph to evaluate for tooth root elongation. Tooth roots appear normal in the radiograph above.
Chinchilla dropping feed and eating less than normal.
Chinchilla dental care
Dental radiograph shows uneven upper dental arcades due to coronal elongation. Mandibular cheek teeth have unequal coronal height creating a "wave" appearance. Kirby left lateral view prior to operative dentistry!
Dental radiograph from opposite side consistently demonstrates coronal length disparity between left and right upper dental arcades. Kirby right view.
Kirby after operative dentistry. This was the initial occlusal adjustment to reduce the "wave" occlusion. One large spike was removed from lower right second molar tooth. The teeth require periodic occlusal adjustment.
Computed tomography (CT scan or Cat scan) was suggestive of mandibular brachygnathism to the veterinary radiologist. These chinchillas must be fed a diet that will maximize dental wear and periodic professional occlusal adjustments will be required.
The owner reported rapid return to normal eating of a diet with long stem hay. The large spur on the lingual aspect (tongue side) of the lower right second molar was causing a deep laceration into the palate. This resulted in pain and discomfort as well as an innefective dental occlusion and abnormal tooth ware.
Kirby is back to eating hay!
Kirby is eating and quite playful.
Rabbit & Rodent Dental Care
A comprehensive oral health assessment for rabbits therefore must be performed under anesthesia. Assessments are made for periodontal disease (radiographs and probing), tooth irregularities (tooth spikes or waves of the dental arcades), tooth infection (dental abscesses) soft tissue injuries or for oral tumors.
The veterinarian may need to provide occlusal adjustments (grinding teeth down) to imporve the occlusal relationships between the upper and lower dental arcades (arches). Endodontic (vital pulpotomy) therapy can be used to save tooth that are fractured and have pulp exposure. Oral surgery may be required to extract teeth, to treat dental abscesses or to excise oral tumors.
Sedation and general anesthesia for rabbits
Performing dental procedures, such as "teeth trimming" without anesthesia is often ineffective and can be dangerous for the rabbit and for the operator. Dr. Kressin discourages this practice. It is stressful at a minimum and can easily result in injury!
Rabbits can be safely sedated and anesthetized. We prefer not to withold feed from rabbits in an attempt to avoid bloat. We also do not withold water to avoid dehydration. It is very important to provide great care with patient warming during the anesthesia and during the recovery period.
Balanced anesthesia incorporates analgesia (pain prevention) and allows minimization of all drugs for smooth anesthesia and patient recovery. We prefer to premedicate rabbits with ketamine, buprenorphine and midazalam. Meloxicam, a medication the provides anti-inflammatory effects and pain relief is also frequently utilized. Regional anesthesia is also preferred when oral surgery is performed.
Anesthesia induction is by inhalent (Isoflurane or Sevoflurane). We prefer intubation to protect the airway unless a very short anesthesia period is anticipated. It is always preferred to minimize the overall anesthesia time period. For additional information on anesthesia safety see anesthesia concerns. If you have additional concerns regarding pain management, go to pain related concerns.
Regional anesthesia for rabbits
Regional anesthesia or nerve blocks are beneficial when performing oral surgery in rabbits. By blocking the nerve input from the periphery (the teeth and the oral cavity), the general anesthesia levels can be lowered to increase anesthesia safety.
Nerve blocks effectively allow early return to eating and reduces bloating problems after anesthesia.
Veterinarians are encouraged to study "regional anesthesia" provided by Dr. Kressin.
Every opportunity to reduce pain in our patients should be implemented when dental or oral surgery is anticipated.
Diagnosis helps determine the prognosis
Radiographs are fundamental and essential to helping rabbits with dental problems. Non-screened radiographs provide higher detail and help with the diagnosis of the problem(s). I prefer non-screened mamography x-rays taken from various positions to evaluate rabbits. These radiographs are taken with the general anesthesia. Using radiographs and by performing a detailed intraoral exam, the best approach to treatment is established. The stage of disease is determined which offers a long term prognosis.
Grade 1 stage of disease may involve minor malocclusion of incisors. The ventral border of the mandible is smooth and of normal bone density. The roots are of optimal length and appear parallel to adjacent teeth. The occlusal surface of teeth are smooth and linear on radiographs. The prognosis is good after occlusal adjustments are made (if needed) and the rabbit is eating an optimal diet.
Grade 2 stage of disease has early radiographic changes. The ventral border of the mandible is thin. There may be root elongation and root divergence from parallel orientation of adjacent teeth. Enlargements of the face or lower jaw may be palpable and there may also be radiographic evidence of bony growth (enlargement). Occlusal adjustments may be needed and with the appropriate diet, the prognosis is good.
Grade 3 stage of disease may be significant enough to be resulting in eating habits and weight loss. These rabbits may have substantial infectious disease. Radiographs demonstrate further thinning of the ventral border of the mandible and less overall bone density. Root elongation may be significant causing pain and discomfort. There is further deviation from the parrallel arrangement of the teeth. The bony protrusions (face and mandibles) may be very significant with marked densities on radiographs. The prognosis is guarded. Bacterial cultures are indicated in many cases.
Grade 4 is an advanced disease process with obvious clinical signs of poor health. The ventral mandible has perforation of very thin bone. There is significant deviation of adjacent cheek teeth from the normal parallel orientation. The occlusal surfaces appear blurry due to variable cheek teeth length. Soft tissue abscesses are common. Surgical intervention along with occlusal adjustments are indicated. Antibiotic coated beads are chosen based on culture and sensitivity testing to treat the soft tissue infections. Dental extraction is often indicated. Rabbits do well with one or two cheek teeth extraxcted however with multiple extractions, occlusal problems are common requiring periodic 6-12 week occlusal adjustments. The prognosis is guarded to poor based on the individual case.
Grade 5 is the most severe stage of dental disease. These animals have moderate to severe weight loss, excessive salivation, eye and or nasal discharge with chronic pain. Infection of bone (osteomyelitis) and soft tissue is present. Radiographic evidence of bone destruction is severe. The dental arcades align poorly. Fractured and missing teeth are common. Prognosis is poor to grave.
Radiographs help diagnose jaw (mandibular) and tooth fractures
This patient suffered from a traumatic injury. The mandibular symphysis was "separated" or "fractured". The left and right mandibles were mobile and would float independently. The radiograph below demonstrates the rotated mandible and torn symphyseal tissue.
Paddington was injured and his symphysis was separated. The symphysis is joint-like and holds the two lower jaws together. The two lower jaws would move independently.
The symphysis was stabalized and Paddington was immediately eating.
The radiograph below demonstrates abnormal occlusal alignment.
Occlusal adjustments were indicated and performed. Notice that the ventral aspect of the mandible (lower) jaw appears smooth and is normal.
Chinchilla dental care