Internet Article:
Referenced: 02/24/08
Author: David Crossley, DVM, and associates
The following are the chinchilla-related article abstracts from David Crossley’s page,
“Abstracts of clinical and scientific research articles”
CLINICAL ASPECTS OF RODENT DENTAL ANATOMY
David A. Crossley
Summary: The order Rodentia is vast, encompassing a large number of species with significant anatomical variations developed during natural adaptation to differing habitats. Many veterinarians have little knowledge of the a natomy of species other than the commoner domestic large herbivores and small carnivores. Clinicians require a basic knowledge of the relevant anatomy of species they are likely to be asked to treat. This article provides sufficient working knowledge of the oral and dental anatomy of those rodents commonly kept as pets to enable veterinarians to interpret clinical and radiographic findings when investigating suspected dental disease.
Journal of Veterinary Dentistry, 12(4): 131-136, 1995
CARIES AND ODONTOCLASTIC RESORPTIVE LESIONS IN A CHINCHILLA (Chinchilla lanigera)
Crossley DA, Dubielzig RR, Benson KG
Summary: It is well recognised that domesticated chinchillas (Chinchilla lanigera) suffer from a range of dental problems, the most frequent of which is the result of reduced and uneven coronal wear of the premolar and molar (cheek) teeth with resultant root elongation and secondary malocclusion (Crossley 1995 + 1997). Although rarely detected clinically, destruction of dental hard tissue can often be recognised at post-mortem and in prepared skulls. This paper reports the histological confirmation of caries and odontoclastic resorptive lesions in a chinchilla.
Veterinary Record, 1997, 141:13 337-9
USE OF COMPUTED TOMOGRAPHY TO INVESTIGATE CHEEK TOOTH ABNORMALITIES IN CHINCHILLAS (Chinchilla lanigera)
Crossley DA, Jackson A, Yates J, Boydell IP
Abstract: Computerised tomographic scanning was used to investigate tooth structure in chinchillas (Chinchilla lanigera), both cheek tooth crown and root abnormalities being common in this species. This paper describes a common form of dental disease affecting species with continuously growing teeth, with particular reference to the chinchilla, and confirms the potential role of computed tomography (CT) in its early diagnosis. CT imaging is compared with previously available methods of investigation which frequently fail to detect early pathological changes.
Journal of Small Animal Practice, 1998, 39:8 385-9
ANATOMY OF THE CHINCHILLA (Chinchilla lanigera) LACRIMAL DRAINAGE SYSTEM
Crossley DA, Roxburgh G,
Introduction: Chinchillas (Chinchilla lanigera) are becoming popular as pets. A common clinical sign seen in chinchillas is "wet eyes" due to lacrimal overflow.
Aim: To investigate the normal anatomy of the lacrimal drainage system in the chinchilla to enable further study into the causes of lacrimal overflow.
Method: Clinical examination, radiography and CT scanning, plus anatomical dissection, histological examination and photography of available post-mortem specimens.
Results: There are two lacrimal punctae at the medial canthus of each eye. After a short distance these drain into the single lacrimal duct that enters a bony lacrimal canal. The lacrimal duct is lined by epithelial cells including a proportion of mucus secreting goblet cells. The bony lacrimal canal passes diagonally rostro-ventrally past the root apices of the more rostral cheek teeth, continues towards the root apex of the incisor tooth. The lacrimal canal narrows and passes medial to the incisor then alters direction, continuing a short distance rostro-dorsally with the lacrimal duct continuing several millimetres to enter the nasal chamber just inside the nares.
Conclusions: Lacrimal drainage in chinchillas appears similar to that in other rodents and the rabbit. The point most likely to become obstructed appears to be adjacent to the incisor tooth root, as occurs in rabbits. A further study is investigating the site of obstruction in animals with "wet eyes".
Clinical research abstract, Proceedings,
British Small Animal Veterinary Association Congress 1999
THE SITE OF OBSTRUCTION OF THE LACRIMAL DRAINAGE SYSTEM
IN CHINCHILLAS (Chinchilla lanigera) WITH "wet eyes"
Crossley DA, Roxburgh G
Introduction: A common clinical problem seen in chinchillas (Chinchilla lanigera) is "wet eyes" due to lacrimal overflow.
Aim: To investigate the site or sites of obstruction of the lacrimal drainage system in chinchillas showing signs of lacrimal overflow.
Method: Radiography, CT scanning, anatomical dissection, and histological examination of affected animals. signs of lacrimal overflow.
Results: The main site of obstruction of lacrimal drainage is in the descending portion of the lacrimal canal between the orbit and the incisor tooth root apex. Bony remodelling around elongating maxillary premolar and first two molar tooth roots intrudes into the lacrimal canal compressing and sometimes occluding or even obliterating the lacrimal canal and duct. No evidence has been found for obstruction adjacent to the incisor root apices in the specimens examined so far.
Discussion: Lacrimal drainage in healthy chinchillas is similar to that in other rodents. This species is adapted to a highly abrasive herbivorous diet, having continuously growing cheek teeth (in addition to the continuously growing incisors). When these teeth are not worn adequately, i.e. when domestic animals are fed commercial diets, the teeth continue to elongate. Eventually occlusal pressure prevents eruption, so the roots intrude inducing remodelling of adjacent tissue including the lacrimal canal.
Conclusions: Chinchillas should be fed a herbivorous diet which requires prolonged chewing in order to wear the teeth adequately.
Clinical research abstract, Proceedings,
British Small Animal Veterinary Association Congress 1999
DENTAL DISEASE IN CHINCHILLAS IN THE UK
David A. Crossley
Abstract: Dental abnormalities are common in chinchillas, however, knowledge of the nature and relative incidence of the lesions responsible for clinical signs is incomplete. Animals, radiographs and/or prepared specimens were examined to gain further knowledge regarding dental anatomy and dental disease in the UK chinchilla population.
Thirty five percent of the apparently healthy chinchillas examined had dental abnormalities detectable on routine examination. The range and relative incidence of different dental abnormalities encountered in these and clinically affected animals are presented. Whilst malocclusion was a common finding, in all but one case this was secondary to crown elongation or absence of opposing teeth, not a primary skeletal problem.
Clinical signs commonly attributed to malocclusion, such as ventral mandibular swelling, weight loss, dysphagia, altered chewing pattern and changed food preferences, are not specific to malocclusion. They are seen associated with tooth root elongation, spike formation on the sides of the occlusal surfaces and advanced periodontal lesions. Caries and odontoclastic resorptive lesions rarely cause obvious clinical signs but were identified regularly. Congenital absence of cheek teeth, true skeletal malocclusion and pathological loss of incisor teeth all resulted in significant clinical signs but were rarely seen.
Lack of dietary abrasion and stress are probably the main aetiological factors for the most prevalent dental problem, cheek tooth elongation. Combination of provision of a diet matching that eaten by wild animals and reducing stress levels of captive chinchillas should reduce the incidence of dental disease in this species.
Journal of Small Animal Practice 2001, 42:1, 12-19
SKULL SIZE AND CHEEK TOOTH LENGTHS IN WILD AND CAPTIVE CHINCHILLA POPULATIONS
David A. Crossley and Maria del Mar Miguélez
Summary: Chinchillas are herbivorous rodents with teeth that all grow continuously. In captivity they are commonly affected by dental disease. Since the range of dental disease occurring in wild chinchillas is unknown, the dentition of museum specimens originally obtained from the wild was assessed and compared with specimens prepared from captive bred animals.
Skulls from wild-caught chinchillas showed minimal evidence of dental disease and the teeth were all short, cheek tooth lengths averaging 5.9 mm. Cheek tooth lengths in zoo specimens (average 6.6 mm), clinically normal (average 7.4 mm) and captive bred animals with dental disease (average 10 mm) were significantly elongated by comparison (p < 0.0001). Captive bred specimens showed a wide range of tooth related lesions.
These results suggest that some aspect of captivity is responsible for the development of dental disease in chinchillas. It is suggested that the diet (its physical form and composition) is the main etiological factor, and that provision of a diet closely matching that of wild chinchillas should significantly reduce the incidence of dental disease in captive chinchillas.
Archives of Oral Biology 2001, 46:10, 919-928