"The venogram is the ticket to fixing all those laminitis cases you’ve been missing," Amy Rucker, DVM, said at the Bluegrass Laminitis Symposium (held Jan. 25-28 in Louisville, Ky.). Rucker, a practitioner with Midwest Equine in Columbia, Mo., discussed how to use the digital venogram (a radiograph or X ray of the foot taken with contrast media injected into the blood vessels to visualize any blood flow problems) in clinical situations.
She began by listing the phases of laminitis: Developmental, acute and subacute (some mechanical collapse), and chronic. "Each phase has different degrees of damage, and they can bounce between the chronic and acute stages (chronic with flareups)," she said. "When you start thinking about the phases of disease and classifying horses into these groups, it tells you a bit more about what’s going on and you can decide what to do a little easier." The results of a venogram help her determine which phase a horse is in, she noted.
She described the phases of laminitis and their venogram characteristics as follows.
Developmental phase–This begins with exposure to causative factors and triggering of laminar separation, and it lasts 24-30 hours. Lameness is not apparent. Venograms taken during this phase should be normal, but if there is leakage of contrast from the vessels or if the papillae (tiny "fingers" of blood vessels pointing down from beneath the bottom of the coffin bone) are beginning to fold, or if they are compressed and not visible, then laminar separation has begun (and the horse has moved on to the acute or chronic phase).