Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

542 Small Animal Radiolo g y and Ultrasono graphy
A B C
D
Fig. 4-87 A 4-month-old female Labrador Retriever with a history of apparent blindness. The dog
managed well at home but seemed lost in new surroundings. The dog appeared smaller than anticipated.
A and B, There is a bowing deformity of the radius with irregularity of the distal ulnar metaphysis.
The foot is slightly laterally deviated. C and D, At 9 months of age the angular limb deformity
has increased. The distal ulnar metaphysis remains irregular and the physis has partially closed.
Diagnosis: Skeletal dysplasia of Labrador Retrievers.
Retarded epiphyseal ossification results in stippled, patchy densities in the epiphyses. The
skull is not affected.
Epiphyseal Dysplasia. Epiphyseal dysplasia has been reported in Beagles and Poodles. 355
The dogs showed hind limb dysfunction at birth and osteoarthrosis as adults. Punctate calcifications
with irregularly stippled epiphyses were described in the humerus, femur,
metacarpals, metatarsals, carpal and tarsal bones, and vertebral bodies (Fig. 4-88). The disease
may be recognized up to 4 months of age, after which the irregular calcifications
become incorporated in the ossified bone. Nonspecific osteoarthritic changes persist in
the adult. These cannot be distinguished from other causes of secondary degenerative joint
disease.
E C T R O DAC T Y LY
Ectrodactyly, or split-hand deformity, is an abnormal limb development with separation
between metacarpal bones, digit contracture, digit aplasia, metacarpal hypoplasia,
and metacarpal fusions (Fig. 4-89). 367-369 Unilateral involvement is most common.
In dogs, there is equal involvement of left and right limbs and no breed or sex predisposition.
In the cat, ectrodactyly is caused by a dominant gene with variable expression.
H E M I M E L I A
Hemimelia is a rare disease in which one bone in a paired set is partially or completely
absent. This usually affects the radius of the radius and ulna, or occasionally affects the tibia
of the tibia and fibula. 370-372 The bone of the affected pair that is present usually is