Ask Horse Journal: 10/07

I have a healthy 21-year-old gelding. For no known reason, he presented one morning with four stocked-up legs and a very swollen, dangling sheath. The vet felt he needed to be cleaned, despite my statement that he was on a regular sheath-cleaning schedule and wouldn’t be exceptionally dirty. She cleaned him and admitted that wasn’t the problem, We attributed it to two weeks of mistakenly being fed alfalfa, which I prefer he not be fed as he is such an easy keeper.

After a day or two, his legs returned to normal and his sheath greatly improved, although it’s never returned to normal. He’s now on his fifth episode of sheath swelling over several months’ time. The sheath never returns to normal but does improve and then swells again. It’s chronically enlarged/thickened.

We’ve tried dexamethasone, antihistamines and Azium. My vet is perplexed. She can offer possibilities ranging from allergies, to age, to melanomas. We ran a blood panel and all results were normal. He runs no temperature. He urinates normally. He is normal in every other way. He does have melanomas under his tail, some of which have been there since he was six. Other than increasing in number they have caused us no issues. Can you help me with any thoughts, ideas or resources’

Horse Journal Response

The sheath can be swollen because of local inflammation (you ruled that out with the sheath cleaning/inspection), with a more generalized allergic/inflammatory process, by fatty deposits or because of interference with the drainage of blood or lymph. 

The first episode you describe does sound like a generalized process, either allergic or infectious, because all four legs were also involved and there’s no way to explain that anatomically by a local drainage problem.

Easy keepers do often accumulate fat in their sheath, and when insulin resistance is involved, the sheath size can vary depending on how well (or not) the IR is controlled. However, in this case, it really sounds like more of a local circulatory problem.

The sheath is drained partially by veins and lymphatics that travel through the inguinal ring in the horse’s groin, and partially by vessels that run up the perineum (the space between the anus and the sheath) before entering the pelvis.

Since the hind-leg vessels and lymphatics also go through the inguinal ring, and he’s not stocking up anymore, the problem might lie deep in the perineum or in the pelvis. Your vet’s suspicion of melanomas being involved might be right. 

A rectal exam and ultrasound of the perineum, or transrectally if anything is felt on examination, might give you some answers. Treatment options would depend on what you find, e.g. antibiotics if a lymph-node abscess seems likely or local cisplatin-impregnated beads if it’s a melanoma and is accessible.

If he has abnormal fat deposits elsewhere (e.g. crest, tail head), and especially if these change in size the same time as the sheath, it would also be worthwhile checking him for insulin resistance and treating that with controlled diet.


I was given a bag of whole flaxseeds last year. I stored them in a metal bin with a secure lid. How much do I feed’ Is it still safe’

Horse Journal Response

As long as the flax wasn’t subjected to temperatures above normal room temperatures or high moisture, it should be safe to feed. Flax is high in protein, high in plant anti-inflammatory compounds and high in fat, predominately the omega-3 essential fatty acids. Most of its carbohydrate is in the form of highly digestible soluble fiber. Flax is primarily used as an omega-3 fatty-acid supplement, as it is one of the few seeds that can provide omega-3 and omega-6 fatty acids in a ratio that is similar to that found in fresh grass. There’s not much point in feeding it to horses on good pasture, but it’s a good additive for horses not on pasture or over the winter months.

Diet: Know What You Need

I have a nine-year-old Percheron gelding. I’ve been feeding him the EPSM diet, assuming this is what he has had the past several years. I recently had him tested for Cushing’s, and he had a high ACTH level. He’s lethargic and his coat is the color of toast even though he’s really a black. I think he needs a supplement. What should I give him’

Horse Journal Response

You didn’t mention what his problems have been, but if his history dates back several years before the age of 9, Cushing’s is unlikely. Things like acute stress/pain, transport or another illness might give you a false positive ACTH. You could also be seeing a seasonal rise. It’s important to try to determine if he really does have Cushing’s because the pergolide could make him even more lethargic. More sophisticated testing could help sort through this.

EPSM should be diagnosed by biopsy. It’s important to do that, too, since high-fat diets also cause sluggishness. If he hasn’t responded to the current diet symptomatically, it may be time for a change.

We agree the condition of his coat could be related to his diet. Inadequate or poor-quality protein and trace-mineral imbalances could be involved. Hay as the cornerstone of his diet is fine, but you need to know what’s in it so that you can properly supplement him.


My horse has been looking jaundiced for the last three weeks. The vet said he has a low blood count, negative Coggins and high bilirubin. I want to find out more about what could be wrong, but I’m not finding any articles on jaundice. Can you help’

Horse Journal Response

Jaundice is a yellow discoloration of the whites of the eyes, skin and mucus membranes. Bilirubin is what makes bile a yellow color and also what causes jaundice when it is at high levels in the blood. Bilirubin is hemoglobin with the iron stripped out of it.

The horse’s spleen is constantly removing old or damaged blood cells from the circulation, removing the iron from the hemoglobin, then releasing the iron-free hemoglobin back into the blood as bilirubin. Bilirubin is then processed by the liver and excreted into the bile.

High bilirubin levels can be caused by either high levels of red-cell destruction (several possible causes for this include EIA, which is why your vet checked a Coggins), or by liver disease, or blockage of the bile ducts that prevents the bile from being excreted so that it basically ”backs up” into the blood. Because there are so many possibilities, any of them potentially serious, your horse really needs a thorough medical work-up to get to the bottom of the problem and treat it. Infections and toxins top the list of possibilities.