Case Study

CT Congenital Oligodactylic Malformation of Rear Limb with Phalangeal Aplasia and Hypoplasia of Metatarsal Bones in a 4 year old FS Labrador Retriever Dog

The patient was recently relinquished by breeder to Lab rescue. There is a deformity of the distal LTL of unknown cause. Physical Exam: wt 78#, BAR-H, sweet/nervous. The patient was recently spayed. Heart and lungs show no murmur, reg rhythm, clear bvx4. PLN: WNL. GI: WNL, MS/NS: Mentally appropriate, no overt NS deficits, Distal LTL deformity – distal to tarsus, callus formation at distal end of limb. The patient is being evaluated for future prosthetic placement. CT was done of both limbs – (Left) vs. unaffected/normal limb.

DX

Congenital oligodactylic malformation of the left distal rear limb with complete phalangeal aplasia and hypoplasia of the third to fifth metatarsal bones.

Image Interpretation

CT of the left ad right distal hind limbs – A full set of metatarsal bones 2 to 4 were present. The second metatarsal bone appeared to be regular for length and shape when compared with the unremarkable
right rear. The total length of the second metatarsal bone was 6 cm. There was mild
diaphyseal medullary sclerosis and bony modeling at the distal end of the second
metatarsal bone. The third to fifth metatarsal bones were shortened and thin with distal
penciling. Paired plantar metatarsophalangeal sesamoid bones were present at the
second to fourth metatarsal bone. At the fifth metatarsal bone there was only one small
and malformed plantar metatarsal sesamoid bone. Regular dorsal
metatarsophalangeal sesamoid bones were not seen.
There was mild lateral rotation and bending of the limb distal to the tarsometatarsal
joint emphasizing the second metatarsal bone.
There appeared to be one foot pad. Regular toe pads and claws were not seen.
The length of the metatarsal bones could not be compared with the left rear limb since
these were not entirely included in the scan.