Incisor Malocclusion in a Specimen of Sylvilagus floridanus 

 (Mammalia: Lagomorpha) from North Carolina 



Gary W. Woodyard 



Wayne Community College, 

 Goldsboro, North Carolina 27530 



ABSTRACT. — A cottontail rabbit with incisor malocclusion was 

 examined, but no clear reason for the unusual dental condition was 

 found. This is only the second report of the phenomenon in wild Sylvi- 

 lagus floridanus; most such reports deal with domestic or laboratory 

 animals. 



Malocclusion, with the consequential overgrowth of incisors, pre- 

 molars or molars, has been reported in rodents and, to a much lesser 

 extent, in lagomorphs. Most reports concerning lagomorph malocclu- 

 sion deal with domestic or laboratory animals (Zeman and Fielder 

 1969). Thorpe (1930), Lincoln (1938), and others, reported malocclusion 

 and overgrowth of incisors in Marmota. In 1968 I collected but have 

 not previously reported a Scuirus carolinensis with incisor malocclusion 

 and hypertrophied incisors. The only prior published report of incisor 

 malocclusion in a wild cottontail rabbit was that of Gregory (1952). 



A female Sylvilagus floridanus, apparently a young-of-the year, 

 was brought from the Seven Springs area of Wayne County, North 

 Carolina, to Wayne Community College for examination because of its 

 unusual dental condition (Fig. 1). It weighed approximately 1 kilogram 

 and had a remarkable amount of body and kidney fat considering the 

 severity of its incisor condition. The lower left incisor extended 1.8 cm 

 beyond the mandible, where it interesected the lower right incisor. The 

 tip of the left incisor was rounded and smooth and the tooth appeared 

 to be correctly positioned relative to the symphysis of the mandibles. 

 Although the incisor rested against the upper lip with the mouth closed, 

 no skin irritation was evident. The lower right incisor extended 2.5 cm 

 beyond the mandible and curved to the left to a point 0.3 cm from the 

 symphysis of the mandibles. Its tip was rounded and rested against the 

 lower part of the left nostril when the mouth was closed, but there was 

 no apparent irritation to the nostril. There was a slight notch approxi- 

 mately 0.7 cm from the tip of the right incisor, caused by the intersec- 

 tion of the lower left incisor. 



The upper left first incisor extended 1.4 cm from the premaxillary 

 and had grown into a short arc. Its tip appeared to have been broken 

 anteriorly at an angle of approximately 20 degrees sometime prior to 

 the animal's death. The smaller incisor was of equal length and lay in a 



Brimleyana No. 7:151-153. July 1981. 151 



