Re: Tryst: Questions on vasodilation, please advise
You are getting a really good grasp of things in a very short time - kudos to you.
Any horse who has sinking will have vasoconstriction - it's mechanically impossible not to. You need to address - and remove - the cause(s) to halt any ongoing deterioration and promote healing. Until the trim is corrected there will be no healing of the feet as the mechanics will continue to thwart all efforts to stabilize them. Whether there has been more sinking or not is actually unknown as it is impossible to see where the coronary band is located in relation to the extensor process of the coffin bone as the landmark points on the hooves aren't identified and there is casting material interfering with the views. Because there have been no adjustments to the trim, it is quite possible that any deterioration in the mechanics is due only to the trim itself getting more and more out of whack as the weeks go by.
Although venograms do give you some information, they aren't without risks and repeating them is spending money that could likely be spent in better ways as they aren't going to provide useful information for treating a laminitis/founder/rotation. Well-marked and executed xrays are a better investment. See here for getting the most out of xrays:
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Think of it this way: You wear a size 7A shoe, you are wearing shoes that have good arch support BUT they are size 9E. This places the arch support under your metatarsals and leaves your arch quite strained. Your feet start to hurt so the podiatrist glues platforms onto your shoes that allow you roll over more easily but leaves you in the same shoes. So the raised arch is still under the ball of your foot, your arch is still hyper-flexing, your feet are still killing you and now you are trying to balance on a taller sole while sliding around inside those too big shoes. The hoof capsule is like a shoe for the coffin bone and it needs to have a snug fit in order to do its job well. When the trim is not physiologically correct, the coffin bone slides around inside because it is not well supported.
Vasodilators are appropriate once the inciting cause of the inflammation has been removed. If used before then, they can make the situation worse. It is unclear right now whether or not there is actually more active laminitis going on or if any possible deterioration in the hoof integrity is due to the continuing bad hoof form. If there is no active inflammation, Jiaogulan - an adaptogenic herb - is an effective vasodilator See here for more info:
Although Tryst's glucose hasn't skyrocketed, it has jumped 20 points in the interval between the two Sept tests. Was this the time frame of when the Prascend was introduced? It doesn't appear as if insulin and glucose have ever been tested from the same blood draw. These are numbers that are inter-related and need to come from the same blood pull in order to be relevant to each other.
Because Tryst's ACTH numbers have remained solidly within the middle of the normal range PPID is unlikely so the use of pergolide (Prascend) is not indicated. I don't believe Dr.Kellon was necessarily endorsing the use of pergolide to treat the IR, only that in this instance it may not be having a deleterious effect at this time. Anything that can affect the endocrine system is "powerful medicine" and needs to be used with caution and appropriately. If I'm off base here, I'm sure she'll chime in.
If the only feed Tryst is currently receiving is the TC Safe Starch Forage it may be part of the problem. Although it is generally relatively low in ESC + Starch, there are no guarantees that each individual batch is below the 10% ESC+Starch threshold. It also contains added iron and is 6% fat (added oil), which gives it an inverted omega 3 to 6 profile. Some horses have become footsore on it. Ontario Dehy Balanced Timothy Cubes would be another, better option.
Other variables to check would be possible iron overload, which can drive IR. To test, you need to send blood samples to KSU for serum iron/ferritin/TIBC. KSU is the only lab in US that can test equine ferritin. See here:
Possible Lyme disease, which can result in miserable laminitis and also drive IR. Blood work needs to go to Cornell for the Lyme Multi-Plex test.
Lavinia, Dante, George Too and Peanut
Jan 05, RI
EC Support Team