Fetal Horse Rad Study Maps Ossification Timelines to Predict Limb Deformities

Anatomo‐Radiographic Study on the Osteogenesis of Carpal and Tarsal Bones in Horse Fetuses

S. Soana, G. Gnudi, G. Bertoni, P. Botti

Background:
Angular limb deformities in foals are linked to multiple factors, including delays or abnormalities in enchondral ossification of carpal and tarsal bones. Identifying the prenatal timing and sequence of bone ossification may improve understanding of these deformities. This study aimed to radiographically document the chronology and morphology of osteogenesis in carpal and tarsal bones of horse fetuses from 70 to 340 days of gestation.

Methods:
The right carpal and tarsal regions of 140 equine fetuses (71 males, 69 females) from slaughtered work and meat breeds were examined radiographically. Fetal age was estimated using crown-rump length, bone measurements, and dental development. Radiographs (mediolateral and dorsopalmar/dorsoplantar views) of intact and disarticulated joints were analyzed to detect and chronologically sequence the earliest ossification sites.

Results:
The first carpal bone to ossify was the accessory carpal bone at approximately 254 days. This was followed by the radial carpal (274 days), intermediate carpal (278 days), and ulnar carpal bones (310 days). Ossification of third, fourth, and second carpal bones was hypothesized to occur between 285 and 295 days. For the tarsus, the calcaneus ossified first at about 125 days, followed by the astragalus at 220 days, with a secondary center appearing around 260 days. Central, third, fourth, first, and second tarsal bones ossified between 280 and 330 days. Ossification patterns were consistent across fetuses, though minor individual variability in size and presence of centers was noted.

Limitations:
The study's population was limited to slaughtered work and meat horse breeds, limiting extrapolation to other breeds such as Thoroughbreds. Gaps in gestational ages between 280 and 310 days made precise timing for some bones approximate. The study relied on radiographic estimation of fetal age, which carries inherent inaccuracies.

Conclusions:
Osteogenesis of carpal and tarsal bones in equine fetuses follows a consistent chronological pattern, with all critical centers present and developed at birth under normal conditions. Recognizing deviations from this sequence may aid in early detection of developmental orthopedic diseases such as angular limb deformities. These findings offer baseline data for future studies and clinical assessment of skeletal development in equine neonatology.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.