Dental disease is a common presenting issue of small companion mammals, perhaps because the unique anatomy of herbivorous small mammals predisposes them to several dental issues not seen in canine and feline patients.
In particular, constantly growing elodont molar and incisor teeth require appropriate occlusion in order to wear down at a constant rate. Malocclusion of these teeth, or an inappropriate diet that prevents normal chewing patterns and, therefore, normal dental wear, can predispose these animals to dental overgrowth. Rodents such as rats, mice, hamsters and gerbils have elodont incisors that continuously erupt but anelodont premolars and molars, which means their incisors constantly grow while the premolars and molars do not (Mancinelli and Capello, 2016).
In some rodent species, such as rats, the mandibular symphysis is not fully ossified, which means that a small amount of movement between the two hemimandibles is normal (Jekl, 2009).
The full dental examination in small companion mammals
The value of a full dental examination in small companion mammals cannot be understated as signs of dental disease can be subtle, even with extensive dental pathology.
Common clinical signs of dental disease include hyporexia or anorexia, dysphagia, an inability to pick up or chew food, and smaller or absent faeces. In rabbits, epiphora can indicate blockage or compression of the nasolacrimal duct by tooth roots (Reiter, 2008).
A conscious dental examination can be performed to gain a general idea of the overall dental health of an animal; however, a detailed dental examination can only be performed with the use of chemical restraint
A conscious dental examination can be performed to gain a general idea of the overall dental health of an animal; however, a detailed dental examination can only be performed with the use of chemical restraint (Fecchio et al., 2019). This can be achieved by sedation only; however, care must be taken when placing a dental gag on patients that still have jaw tone.
It is never appropriate to carry out dental treatment in a conscious patient. In 2023, the British Veterinary Zoological Society and the Rabbit Welfare Association and Fund released a joint statement detailing that conscious dental procedures are stressful, likely to cause trauma and less clinically effective than treatment under general anaesthesia (BVZS and RWAF, 2023).
Safe anaesthesia to carry out dental burring or extractions is achievable in all patients and should not be avoided under the misguided idea that conscious dental procedures are safer or improve patient welfare.
Dental examination under anaesthesia
The author’s preference is to perform dental examinations under full general anaesthesia as it allows for dental treatment to be carried out at the same time (Figure 1).
Handheld and tabletop dental gags are available for small mammals (Figures 2 and 3), along with cheek dilators that allow full visualisation of the oral cavity by retracting the buccal mucosa (Figure 4). The author recommends the gag be relaxed for up to a minute approximately every five minutes when this equipment is used for an examination or dental treatment.
The reasoning behind this is reports of cases where the masticatory muscles have stretched due to tooth elongation, and as a result, the muscles have difficulty contracting even after the molar crowns have been burred (Legendre, 2003); some anecdotal cases exist where prolonged stretching of the temporomandibular joint with a mouth gag during dental procedures has resulted in a similar syndrome, where the jaw then “hangs open” and the patient cannot close it, preventing normal mastication (Capello, 2006).
Common dental procedures and pathologies in small companion mammals
Molar burring
Molar burring can be performed with either a hand rasp or a mechanical dental burr. However, the use of hand rasps is discouraged as they can result in molar fractures or damage to the soft tissues of the mouth (Capello, 2006). A specialised straight, low-speed dental handpiece is required to access the narrow mouth of small herbivorous mammals (Capello, 2006). Several different burr tips are available, and the author recommends the use of a guard cover in order to protect the soft tissues of the mouth.
Clipping, trimming and “snapping off”
Coronal height reduction of incisors should never be performed by “clipping” with clippers or trimmers. Molar crowns should never be treated by “snapping off” sharp points, as this can result in tooth fracture, tooth damage and pulp exposure (Capello, 2016).
Extraction
Incisor malocclusions should be treated with extraction if corrective incisor burring is unsuccessful in the earlier stages of the disease. All incisors should be removed to prevent overgrowth of the remaining teeth that have no occlusal surface following extraction. Animals are able to eat following incisor extraction as they use their lips and tongue to manipulate food that has been sectioned to the appropriate size (Lennox, 2008). Extraction of molar teeth is indicated in cases of tooth root abscessation, molar tooth fractures, severe malocclusion and loose teeth (Lennox, 2008).
Specific instruments for rabbit and small herbivorous mammal tooth extractions have been designed by a veterinarian, Dr David Crossley. The Crossley incisor luxators and Crossley molar luxators are designed to be used within the confines of a small mammal mouth and for the anatomical characteristics of the teeth of these species (Capello, 2006) (Figure 5). In rodents and herbivorous mammals that are smaller than rabbits, hypodermic needles can be used to extract incisor teeth.
The problem with ferrets and dentistry – what do vets need to know?
When discussing dental disease in small companion mammals, it is also important to discuss ferrets as they are a common species to be presented to a veterinary clinic. Unlike our previously discussed herbivorous species, ferrets have only two sets of teeth: deciduous “baby” teeth and “adult” teeth. The deciduous set of teeth contains only incisors, canines and molars, with no pre-molars present (Church, 2007). However, the adult set of teeth has the dental formula I3/3 C1/1 PM3/3 M1/2.
A recent study of 57 companion ferrets showed that periodontal disease, dental attrition and dental fractures, particularly of the canines, were the most commonly encountered dental changes in this species (Nemec et al., 2016). This same study showed that all ferrets included had periodontal disease of some description, and a similar study of rescue ferrets showed periodontal disease in 65.3 percent of the assessed ferrets (Eroshin et al., 2011).
Common dental pathologies and procedures in ferrets
Plaque and calculus build-up
Several factors influence the growth of plaque and calculus on the teeth of ferrets. Plaque and calculus form regardless of the diet consistency; however, commercial diets lack the components that prevent plaque and calculus build-up in wild ferrets (Johnson-Delaney, 2008).
Plaque and calculus are visible on the teeth with a physical examination – the same as is expected in canine and feline patients. It is important to identify and manage these cases early, as these build-ups can extend into the gingival sulcus and between teeth, resulting in gingivitis or periodontitis (Johnson-Delany, 2016). In the author’s experience, extensive calculus build-up and the resultant gingivitis can become so painful that some ferrets become anorexic.
Plaque and calculus form regardless of the diet consistency; however, commercial diets lack the components that prevent plaque and calculus build-up in wild ferrets
Treatment for this includes analgesia, scaling the calculus under general anaesthesia and antibiotics for infection if indicated. During general anaesthesia, it is recommended to probe all the gingival sulci and obtain dental radiographs to assess for pathology below the gum line (Johnson-Delaney, 2016). Surgical extraction of any fractured teeth can be performed under general anaesthesia in the same way canine and feline teeth are extracted. Smaller dental luxators will be required, depending on the size of the tooth being extracted.
Dental prophylaxis is possible in ferrets and follows a similar process to canine and feline patients. Some ferrets can be trained to accept tooth brushing with a finger brush or cotton bud using enzymatic toothpaste. Anecdotally, PlaqueOff or similar products can be used on food, although no studies have been performed on the efficacy of these products in ferrets.
Acute fractures
In acute fractures of viable teeth with exposed pulp, a pulpectomy can be performed (Johnson-Delaney, 2016). In the previously mentioned study of dental disease in rescue ferrets, 31.7 percent of the fractured teeth identified were canines (Eroshin et al., 2011). The maxillary canines are reported to be the teeth most commonly found to be fractured in ferrets (Johnson-Delaney, 2016).
