Treating Chronic Laminitis

Indepth Equine Podiatry Symposium Notes Written and presented Summer 2010 by R.F. (Ric) Redden, DVM

Frequently, the chronic laminitis horse is confused with the acute case, and is often treated the same way. This misunderstanding and misconception continues to stifle progress in the field of podiatry. Many definitions of acute and chronic have been proposed, however when we have working knowledge of the sequence of events that can be clearly identified by a physical exam, radiographs and venograms we can formulate a treatment regimen tailored not only for this stage of the syndrome but for each foot involved. Personally I consider cases to be in the chronic stage after the acute phase has passed through the largest window of response, which normally occurs 4-6 weeks from onset. An exception is the high scale case that goes off the radar screen within the first few days of the syndrome. The feet are physiologically dead within hours of onset and slough in a matter of days. The window of response for these cases is extremely short relative to the average acute case.

Chronic cases suffer from the cumulative damage that is caused by compromised blood flow to the vital areas of the hoof. Chronic sole compression thins the sole and erodes the apex. Toe growth all but stops due to dorsal coronary plexus compromise, and the ever increasing PA prevents heel loading, which causes excessive heel growth. The cumulative effects are the result of a cascading series of events that is relative to the damage at onset or efficiency of the emergency treatment and the mechanical protocol that follows. The chronic case is no longer considered a red alert, but certainly demands prompt attention as many cases remain very painful even months to years from onset. Regardless of the stage presented, it behooves us to follow a disciplined, methodical discovery protocol that helps define the degree of vascular, soft tissue and bone damage; determine soft tissue parameters and establish client goals as we formulate a treatment protocol.

Case 1: Show horse with pre-symptomatic chronic laminitis

This case may have a history of intermittent soreness, though not necessarily lameness, scoring less than Obel grade 1 of 5. The foot may have increased heat and often pulse, usually in one foot, and often stands with the affected foot positioned forward of the other. However, the horse warms out of soreness and continues to compete.

This could describe many different problems and is often thought to be quite insignificant when there are no other findings. The lateral low beam, soft tissue radiograph will help confirm that very low grade laminitis is present. There will be no signs of rotation or sinking, but a close look at the HL zone reveals it is 2-5mm wider than it is on the opposite foot. When both front feet are involved, the HL zones can be compared to the hind feet, which will normally be the same as the front feet unless pathology is involved. To further confirm that the wider L side is evidence of low grade laminitis, perform a venogram and compare the findings to that of other healthy feet. The vascular pattern will be quite different.

Treatment: Depending on the degree of vascular alteration and the length of time that has passed since the first indications that there was a problem, I treat cases such as this with a medium score rocker rail that provides a 12-15 degree PA and recommend very light exercise and a follow up venogram in 30-45 days. At that time the vascular pattern should be improved, revealing demonstrable solar papillae; a tighter, denser dorsal supply; good medial/lateral coronary and quarter supply and a continuous flow over the extensor process. Sole depth should have increased by several millimeters and horn growth should be accelerated, evidenced by a new growth pattern that should be equal at the medial and lateral quarters unless prior growth history produced otherwise.

These cases can respond well to this method of treatment, though several resets using moderate mechanics to aid vascular and soft tissue repair may be required for the best long term results. The training schedule should be kept light until the new horn has grown to the level of the apex, which takes approximately 4-6 months. Closely monitor the soft tissue parameters as the new hoof grows out. The L side measurement should return to normal and the new horn will show a distinctly tighter growth pattern that can continue provided the mechanics that release DDF tension are maintained.

Same case, 30 days later. Note HL zone, 20/18mm. This is evidence of the mechanical action of the Ultimates.

Case 2: Low scale chronic laminitis

This case presents weeks to months from onset with lameness grade 2/5 or less and the following soft tissue parameters: distal HL zone widening of 3-5mm, PA 5-10 degree (depending on prior history when a club foot is present) sole depth 15+mm and no lucent zone along the endodermal/ectodermal junction. Why is the timing of onset important here? Though the same radiographic signs can be visible in the first few days to weeks of onset, the mechanical plan for the acute case will be totally different from the chronic case, as two to three months from onset the acute stage has passed. Capsular rotation and other parameters have basically become static.