Abstract

In March 2014, a 47-kg calf was rescued due to cold stress syndrome and brought to Tampa's Lowry Park Zoo for rehabilitation. On exam, a large abscess was present on his right pectoral limb between the radius and ulna. Diagnostic radiographs were performed of both limbs. There was no radiographic evidence of osteomyelitis, but a transverse physeal fracture of the proximal ulna was detected on the left pectoral limb. During this radiographic evaluation it was noted that there was a complete lack of ossification of the carpal bones bilaterally. The abscess on his right pectoral was lanced and drained and the fracture was left untreated. This manatee received ceftiofur (7.5 mg/kg Excede® single dose) and tulathromycin (2.5 mg/kg Draxxin® q7d x 3) in addition to ketoprofen (2 mg/kg Ketofen® single dose) during his management of cold stress syndrome and his fracture.

Coagulation tests performed throughout rehabilitation confirmed the presence of raised D-dimers in association with cold stress syndrome;¹ however, these did not remain high throughout the fracture remodelling and inflammation. D-dimers were > 500 ng/ml on arrival, > 1,000 ng/ml one month post-admission and > 1,300 ng/ml two months post-admission. Over the next 3 months, D-dimers gradually returned back to normal < 200 ng/ml. In humans, elevated D-dimers are not only indicators of thromboembolic disease but also indicators of the severity of acute trauma.² The consistently raised levels of D-dimers in this manatee support the profound effect cold stress syndrome can have on D-dimer levels.

To investigate the lack of carpal bones further we performed several radiographs of other pectorals from rehab manatees and carcasses. We found inconsistencies between the presence of carpal bone ossification in manatees of varying ages. We monitored this fracture over the next 9 months and despite this being a now healthy growing individual have yet to observe complete healing of the fracture site or ossification of the carpal bones. We present a series of images documenting the progression of the fracture remodelling and a resulting sequestrum as well as the embryonic development of carpal ossification. Correlation of these data will be useful in estimating the age of manatee calves according to the development of carpal bones as well as assessing the age of a fracture according to the extent of remodelling.

Figure 1. The left pectoral demonstrating the transverse physeal fracture of the ulna and lack of carpal bone ossification

Acknowledgements

The authors would also like to thank the FWC marine mammal pathobiology lab staff Martine De Wit and Anna Panike, as well as the veterinary clinic staff Michelle Devlin and Heather Henry and the Manatee Rehabilitation Team led by Virginia Edmonds at Tampa's Lowry Park Zoo.

* Presenting author
⁺ Student presenter

Literature Cited

1.  Ball RL. Thromboembolic disease as a component of health issues in the Florida manatee (Trichechus manatus latirostris). In: Proceedings from the IAAAM 27th Annual Conference, Sausalito, CA; 2013.

2.  Zhang LD, Liu HB, Li YN, Ma HM, Liu YB, Wang MY. Correlation analysis between plasma D-dimer levels and orthopedic trauma severity. Chin Med J. 2012;125(17):3133–3136.