Osteoarthritis of the temporomandibular joint in the Eastern Atlantic harbour seal (Phoca vitulina vitulina) from the German North Sea: a study of the lesions seen in dry bone

Table 6 Frequency and lesion severity of TMJ-OA in different marine carnivorans in relation to age classes

	Individuals examined	TMJ-OA frequency [%]	TMJ-OA severity [%] ^a			Age class ratio		Affected [%]
(Sub)species	Individuals examined	TMJ-OA frequency [%]	mild (1)	moderate (2)	severe (3)	(juvenile:adult)		juveniles	adults
Callorhinus ursinus [10]	145	20.0	43.9	31.6	24.6	1.5	87:58	n/a ^b
Odobenus rosmarus [13]	76	60.5	54.7	30.2	15.1	0.3	18:58	11.1	75.9
Phoca v. richardii [11]	194	34.5	54.1	28.1	17.8	0.9	93:101	n/a ^b
Phoca v. vitulina [this study]	1787	53.9	68.1	26.0	5.9	1.0	910:877^c	24.5 ^c	84.4
Zalophus californianus [12]	497	63.5	82.0	7.0	11.0	0.5	173:324	52.6	69.6
Enhydra lutris nereis [14]	1008	4.1	41.5	19.5	39.0	n/a		n = 6	n = 35
Ursus maritimus [15]	249	9.2	52.9	41.2	5.9	1.0	124:125	1.6	11.3

^a all affected articular surfaces combined, except for Z. californianus (based on individuals affected)
^b the study mentioned that adult individuals were statistically significantly more often affected by TMJ-OA than juveniles
^c to be comparable with the other studies, the individuals of the juvenile/subadult age class of the present study are here listed as juveniles

ISSN: 1746-6148