Elephant specific information, if available, is in blue.

Chemistry – Hyaluronate sodium (HS) is the sodium salt of hyaluronic acid which is a naturally occurring high-viscosity mucopolysaccharide.

Storage/Stability/Compatibility – Store at room temperature or refrigerate depending on the product used—check label; do not freeze. Protect from light.

Pharmacology – Hyaluronate sodium (HS) is found naturally in the connective tissue of both man and animals and is identical chemically regardless of species. Highest concentrations found naturally are in the synovial fluid, vitreous of the eye and umbilical cord. Surfaces of articular cartilage are covered with a thin layer of a protein-hyaluronate complex, hyaluronate is also found in synovial fluid, and the cartilage matrix. The net effects in joints are: a cushioning effect, reduction of protein and cellular influx into the joint and a lubricating effect. Hyaluronate also has a direct antiinflammatory effect in joints by scavenging free radicals and suppressing prostaglandins.

Uses/Indications – HS is useful in the treatment of synovitis not associated with severe degenerative joint disease. It may be helpful to treat secondary synovitis in conditions where full thickness cartilage loss exists.

The choice of a high molecular weigh product (MW >1 x 106) versus a low molecular weight one is quite controversial. One author (Nixon 1992) states that “…low molecular weight products (which tend to be less expensive) can be equally efficacious in ameliorating signs of joint disease. When synovial adhesions and pannus are to be avoided (as in most surgeries for carpal and fetlock fracture fragment removal), higher molecular weight preparations are recommended because they inhibit proliferation of synovial fibroblasts.”

Pharmacokinetics – No specific information located.

Contraindications/Precautions/Reproductive Safety – No contraindications to HS’s use are noted on the label. HS should not be used as a substitute for adequate diagnosis; radiographic examinations should be performed to rule out serious fractures. Do not perform intra-articular injections through skin that has been recently fired or blistered, or that has excessive scurf and counterirritants on it.

While HS would unlikely cause problems, safe use in breeding animals has not been established and most manufacturers caution against its use in these animals.

Adverse Effects/Warnings – Some patients may develop local reactions manifested by heat, swelling and/or effusion. Effects generally subside within 24-48 hours; some animals may require up to 96 hours for resolution. No treatment for this effect is recommended. When used in combination with other drugs, incidence of flares may actually be higher. No systemic adverse effects have been noted.

Overdosage/Acute Toxicity – Acute toxicology studies performed in horses have demonstrated no systemic toxicity associated with overdoses.

Drug Interactions/Laboratory Considerations – None noted.

Doses –

Horses: Because of the differences in the commercially products see each individual product’s label for specific dosing information.

Client Information – HS should be administered by a veterinarian only using aseptic technique.

Dosage Forms/Preparations/FDA Approval Status/Withholding Times –

Veterinary-Approved Products:

Hyaluronate Sodium (average MW of 500,000 – 730,000) 20 mg/ml in 2 ml disposable syringes; Hyalovet®  (Fort Dodge); (Rx)

Hyaluronate Sodium Injection Legend® (Bayer) (Rx); 2 ml vial for IA administration; 4 ml vials for IV administration. Approved for use in horses.

Also available Hyvisc ® (Boehringer Ingelheim) (Rx)

Hyaluronate Sodium 10 mg/ml (MW 3.5 x 106) in 2 ml disposable syringes; Hylartin® (Pharmacia & Upjohn); (Rx)

All the above products are approved for use in horses. Not for use in horses intended for food.