Hyaluronan in horses: physiological production rate, plasma and synovial fluid concentrations in control conditions and following sodium hyaluronate administration.
BACKGROUND
Hyaluronic acid (HA) is an endogenous glycosaminoglycan used in the treatment of joint diseases, but medication control is required by horseracing authorities. Therefore, a medication control policy needs to be established.


OBJECTIVE
To establish physiological plasma HA concentrations in post race horses, determine the HA endogenous production rate and document the disposition of HA after i.v. and intra-articular hyaluronic acid administration at recommended therapeutic doses.


METHODS
Hyaluronan concentrations in plasma were determined using an ELISA specific test; concentrations in synovial fluid were determined using a radiometric binding assay.


RESULTS
The overall mean plasma HA concentration in 120 post competition horses was 89 ng/ml. In a group of 6 experimental horses, synovial fluid control concentration was 328+/-112 microg/ml. After i.v. sodium hyaluronate administration (37.8 mg in toto), the terminal half-life was very short (43+/-29 mins) and after a delay of 3 h, the plasma concentration returned to control values. The endogenous HA production rate was 33-164 mg in toto per day, i.e. 1-4 times the recommended i.v. daily dose. Twenty-four hours after intra-articular administration, HA concentration was not significantly different from control values (328+/-112 microg/ml).


CONCLUSIONS
Due to the rapid disappearance of HA from plasma after i.v. administration and from the joint after intra-articular administration, long-term detection needs a more appropriate approach to be developed.
Popot
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Laboratoire des Courses Hippiques, 15 Rue de Paradis, 91370 Verrières le Buisson, France.
Bonnaire
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Guéchot
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Toutain
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PL
D000704:Analysis of Variance; D000818:Animals; D018592:Cross-Over Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D006736:Horses / Q000097:blood / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000096:biosynthesis / Q000097:blood / Q000493:pharmacokinetics; D007270:Injections, Intra-Articular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology; D011874:Radiometry; D011897:Random Allocation; D012016:Reference Values; D013582:Synovial Fluid / Q000737:chemistry*
D006820:Hyaluronic Acid