OBJECTIVES

Bone turnover reflect changes of bone remodeling and are essentials in the biochemical evaluation of most human osteopathies. These markers, measured in blood and urine, have divers levels of specificity and sensitivity, estimating the excess of bone resorption or formation. Serum markers of bone formation from osteoblasts as osteocalcin (BGP) or extension peptides of collagen such as procollagen type I carboxy-terminal propeptide (PICP, CICP) and enzymes as total alkaline phosphatase (ALP) are indicatives of bone synthesis. Urinary markers of bone resorption included calcium (uCa) or collagen degradation products as pyridinoline (Pyd) and deoxypyridinoline (Dpd). Bone markers has been described in dogs but some controversial aspects exist. In this study, all bone markers cited previously in healthy dogs according to skeletal radiographic findings are presented and discussed.

MATERIALS

 Two groups of dogs are studied.

 Group 1: Fifty healthy adult (> 2 years old) dogs, 10-30 kg, males and females from different breeds were selected from patients of the Animal Hospital Of Zaragoza Veterinariry School (Spain). Group 2: Eleven 2-years old females Beagles housed under standard experimental conditions at the Research Services of Zaragoza Veterinary School (Spain).

 Mineral (serum and urinary Ca, serum P, urine Ca/Crea, FECa) muscular (serum and urinary Crea) and bone turnover profiles (BGP, PICP and ALP in serum, Pyd and Dpd in urine) were determined in all dogs except Dpd studied in Berger dogs and Beagles.

 Mineral, muscle profile and total alkaline phosphatase were performed by colorimetry method at the Veterinary School of Zaragoza and BGP, PICP, Pyd and Dpd determinations by ELISA assays at the Miguel Servet Universitary Hospital of Zaragoza (Spain).

 Laterolateral and ventrodorsal views of lumbar and dorsal spine and hip were determined to find focal osteophytes, laminar sclerosis or hip osteoarthritis.

 Statistical study was based on variance, not parametric and multiple regression test. Significant differences were considered if p< 0,05.

RESULTS

 Dogs free of abnormal skeletal findings in conventional radiographies presented the higher serum levels of serum P (p< 0,05), BGP and PICP. In urine parameters, Crea, Pyd and Dpd/Crea were also high.

 Dogs with a little number of spondylosis lesions (1-4 pics) presented the higher urine levels of Ca/Crea and serum Ca/P ratio (p< 0,05). In urine parameters, besides Ca/Crea, calcium, FECa and Pyd/Dpd ratio were high.

 Dogs with more than four spondylosis lesions presented higher levels of total serum alkaline phosphatase and Dpd and %Dpd in urine.

 Vertebral sclerosis dogs presented higher serum levels of Ca/P ratio and significant (p< 0,05) lower levels of phosphatemia.

 Hip osteoarthritis dogs presented significant (p< 0,05)higher serum levels of Ca/P and PICP, and Dpd and Crea in urine. Levels of total calciuria were the minor registered.

CONCLUSION

Dogs with spondylosis and vertebral sclerosis had significant lower levels of phosphatemia and high levels of serum Ca/P ratio. The serum Ca/P ratio was direct and significantly related to hip lesions. Regarding to the mineral changes, they could reflect some skeletal degenerations in older dogs as well as bone turnover markers in hip osteoarthritis dogs. Dogs with hip lesions presented high levels of serum BGP and PICP maybe due to the higher bone metabolic rate despite serum PICP is not validated for dogs and future studies are need to confirm our results.

In our study, as well as the excretion of deoxypyridinoline is increased in human patients, urine Dpd are higher in hip osteoarthritis dogs. Considering levels of bone markers in geriatric dogs, it could be demonstrated an uncoupled turnover in favor of faster renovation of cartilage collagen particularly such as active rheumatoid arthritis and osteoarthritis where cartilage degradation is faster. In conclusion, bone markers can reflect bone metabolic changes as well as mineral parameters, but future investigations should confirm this idea.