Much can be said about the blood supply to the
bone, but generally speaking the blood flow to the bone is normally centrifugal from the
medulla to the periosteum. In the event the nutrient supply is compromised, the
periosteal system is able to adjust and convey an adequate supply to the compactum.
Fluids delivered bathe the crystalline component of bone and the necessary ion exchanges
occur. Uptake of radionuclide in the bone is directly proportionate to blood flow. That
being said, offers a partial explanation to the seemingly random incidences of poor bone
uptake in the equine patient especially in the cooler weather conditions.
Significant detrimental factors appear to be age, breed, mass, and atmospheric
temperature. Special attention to the these factors can improve the target
background (soft tissue) ratio of a bone scan and subsequently improve the diagnostic
quality of a bone scan. Some suggestions are: (1) to wrap the distal limbs and
blanket the horse 12-24 hours prior to injection of the radionuclide. (2) Hold the patient
in a heated area during colder temperatures for 12-24 hours prior to injection. and/or (3)
exercise the horse to increase the heart rate and encourage profusion immediately prior to
injection of the radionuclide especially for larger breeds and older horses.