Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

536 Small Animal Radiolo g y and Ultrasono graphy
Fig. 4-80 A 6-month-old female domestic short-haired cat
with a history of generalized weakness, pain, and reluctance to
walk. A lateral radiograph of the tibia (A) and a follow-up
radiograph 3 months later (B) are illustrated. There is a
decrease in bony density in the radiograph obtained at the
time of admission. The cortices are thin and the leg is bowed.
A pathologic fracture is present in the distal femur, and the
proximal tibia and fibula. On the follow-up radiograph the
normal bone density has returned. The pathologic fractures
have healed; however, a residual bony deformity, a tibial curvature,
is present. Diagnosis: Nutritional secondary hyperparathyroidism.
A
B
H Y P E RV I TA M I N O S I S A
Hypervitaminosis A produces fusion of cervical vertebrae due to bony proliferation along
the dorsal spinous processes, vertebral bodies, and articular facets. 338,339 Bridging exostoses
also may occur across articulations of the appendicular skeleton (Fig. 4-82). Coarse
medullary trabeculation, medullary sclerosis, decreased bony density, thin cortices, and
soft-tissue mineralization have all been described (Fig. 4-83). In affected young growing
dogs, a decrease in long bone length and width, premature physeal closure, transverse
metaphyseal widening, periarticular osteophytes, metaphyseal periosteal proliferation, and
spontaneous fractures have been described. 244 Permanent retardation of growth may
result.
L E A D I N T OX I C AT I O N
An uncommon finding in lead intoxication in the juvenile animal is metaphyseal sclerosis,
or lead lines. Radiographically, bands of increased density adjacent to the physeal growth
plate are identified. 244 A similar finding may be seen in normal individuals. These lines are
referred to as growth-arrest lines and they are usually very thin and further from the physis
than lead lines.
H E R I TA B L E A N D B R E E D -RELAT E D D I S O R D E R S
Several abnormalities have been identified. Many of those that have been reported are listed
below. Some rare disorders are only referenced. 340-344
E RY T H R O C Y T E P Y RU VAT E K I N A S E D E F I C I E N C Y I N B A S E N J I S
An anemia associated with erythrocyte pyruvate kinase deficiency has been described in
Basenjis. 345 A progressive, diffuse osteosclerosis has been associated with this syndrome
(Fig. 4-84).