The anatomy of the area to be injected should be reviewed in order to assure that the suspension is properly placed and to determine that large blood vessels or nerves are avoided. The injection site is located where the synovial cavity is most superficial. The area is prepared for aseptic injection of the medicament by the removal of hair and cleansing of the skin with alcohol.
A sterile 18- to 21-gauge needle for horses, 20- to 22-gauge needle for dogs, on a dry syringe is quickly inserted into the synovial space and a small amount of synovial fluid withdrawn. If there is an excess of synovia and more than 1 mL of suspension is to be injected, it is well to aspirate a volume of fluid comparable to that which is to be injected.
With the needle in place, the aspirating syringe is removed and replaced by a second syringe containing the proper amount of suspension which is then injected. In some animals a transient pain is elicited immediately upon injection into the affected cavity. This pain varies from mild to severe and may last for a few minutes up to 12 hours. After injection, the structure may be moved gently a few times to aid mixing of the synovial fluid and the suspension. The site may be covered with a small sterile dressing.
Areas not suitable for injection are those that are anatomically inaccessible such as spinal joints
and those like the sacroiliac joints, which are devoid of synovial space. Treatment failures are most
frequently the result of failure to enter the synovial space. If failures occur when injections into
the synovial spaces are certain, as determined by aspiration of fluid, repeated injections are
usually futile. Local therapy does not alter the underlying disease process, and whenever possible
comprehensive therapy including physiotherapy and orthopedic correction should be employed.
The single intrasynovial dose depends on the size of the part, which corresponds to the size of
the animal. The interval between repeated injections depends on the duration of relief obtained