Onset of epiphyseal mineralization and growth plate closure in radiographically normal and dysplastic Labrador retrievers.
OBJECTIVE
To determine whether onset of mineralization of the femoral and proximal tibial epiphyses and age at closure of the femoral and acetabular triradiate growth plates was different for Labrador Retrievers that were radiographically normal or that had canine hip dysplasia (CHD).


METHODS
Cohort study.


METHODS
36 Labrador Retriever puppies.


METHODS
Puppies were radiographed every other day from the time they were 8 to 10 days old until ossification of the femoral heads was apparent. Radiographs were then obtained weekly until puppies were 1 month old and then monthly until puppies were 8 to 12 months old. Age at which mineralization was first observed in the proximal and distal femoral and proximal tibial epiphyses and at which the femoral capital, triradiate acetabular, and distal femoral growth plates were no longer radiographically visible were recorded. Fifteen dogs were euthanatized and necropsied to determine whether dogs had CHD.


RESULTS
There were 26 radiographically normal left and right hip joints and 10 dysplastic left and right hip joints. Onset of mineralization of the proximal femoral epiphyses and of the right proximal tibial epiphysis was significantly later in dysplastic than in radiographically normal puppies. The left femoral capital growth plates closed significantly later in dysplastic than in radiographically normal joints, but other differences in growth plate closure were not detected.


CONCLUSIONS
Endochondral ossification may be abnormal in dogs with CHD. The disease appears to affect multiple joints, even though it is most evident clinically in the hip joint.
Todhunter
R J
RJ
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Zachos
T A
TA
Gilbert
R O
RO
Erb
H N
HN
Williams
A J
AJ
Burton-Wurster
N
N
Lust
G
G
D000375:Aging / Q000502:physiology; D000818:Animals; D001947:Breeding; D002113:Calcification, Physiologic / Q000502:physiology*; D015331:Cohort Studies; D004285:Dogs; D005269:Femur / Q000000981:diagnostic imaging* / Q000473:pathology; D006132:Growth Plate / Q000473:pathology / Q000502:physiology*; D006619:Hip Dysplasia, Canine / Q000000981:diagnostic imaging* / Q000473:pathology; D006621:Hip Joint / Q000000981:diagnostic imaging; D011859:Radiography; D013264:Stifle / Q000000981:diagnostic imaging; D013977:Tibia / Q000000981:diagnostic imaging* / Q000473:pathology