Bone resorption markers and dual-energy x-ray absorptiometry in dogs with avascular necrosis, degenerative joint disease, and trauma of the coxofemoral joint.

OBJECTIVES

To compare the ability of N-terminal telopeptide (NTx) assays and dual-energy x-ray absorptiometry (DEXA) to detect bone resorption in dogs with nonneoplastic bone lysis and evaluate the correlation between these diagnostic tools.

STUDY DESIGN

Prospective, cross-sectional clinical study.

ANIMALS

Dogs (n = 35; 39 femoral heads) that had femoral head and neck ostectomy and 6 cadaver specimens from healthy immature small dogs.

METHODS

Small dogs with avascular necrosis (n = 12), a reference group of small dogs (7), large dogs with degenerative joint disease (DJD; 10), and large dogs with trauma (10) were studied in addition to 6 femoral heads harvested from 6 small immature and healthy dogs euthanatized for reasons unrelated to this study. Densitometric measurements of femoral heads, urine NTx excretion, and serum NTx concentration were compared between groups.

RESULTS

Avascular necrosis resulted in a decrease in bone mineral density (BMD) (0.18 ± 0.01 g/cm(2;) P < .01) of the femoral head and elevation of serum NTx (159.3 ± 59.4 nM; P = .03) compared to small dog controls (0.28 ± 0.02 g/cm(2) ; 18.7 ± 1.83 nM, respectively), but did not seem to affect urine NTx. DJD in large dogs did not seem to affect any of the densitometric parameters evaluated. BMD (P = .03) and serum NTx (P = .04) were lower in small compared to large dogs. Serum NTx and densitometric measurements correlate inversely with each other (P = .001) but neither test correlated with urine NTx (P = .8-.9).

CONCLUSION

Serum NTx levels vary with dog size but seem to correlate better with BMD better than urine NTx excretion in dogs with nonneoplastic bone resorption.