Objective—To determine the relationship between
parturition date and fetal skeletal mineralization
detected radiographically in cats.
Design—Prospective clinical trial.
Animals—31 queens and their 49 pregnancies.
Procedure—Seventeen pregnant queens were
radiographed with a computed radiography system
every 2 to 3 days from 1 week after pregnancy was
identified by abdominal palpation until parturition.
Radiographs were evaluated to determine the first
identifiable mineralization of 16 bony structures
and teeth during each pregnancy. This information
was used to establish a table of expected parturition
dates on the basis of fetal mineralization.
Single radiographs from an additional 32 pregnant
cats were evaluated, and predictions of parturition
dates were made on the basis of the mineralization
Results—Mineralization was first detected 25 to 29
days prior to parturition (dpp). Mineralization was
determined for the spinal column (22 to 27 dpp), skull
(21 to 27 dpp), ribs (20 to 25 dpp), scapula (17 to 24
dpp), humerus (20 to 24 dpp), femur (19 to 23 dpp),
radius (15 to 22 dpp), tibia (15 to 21 dpp), ulna (5 to 21
dpp), pelvis (8 to 20 dpp), fibula (0 to 17 dpp), tail (8 to
16 dpp), metacarpals and metatarsals (3 to 14 dpp),
phalanges (0 to 11 dpp), calcaneus (0 to 10 dpp), and
teeth (1 to 6 dpp). Date of parturition was predictable
within 3 days in 75% of cats.
Conclusions and Clinical Relevance—Identification
of bony structures in the fetus is useful in estimating
the time to parturition in queens. (J Am Vet Med