http://horsesidevetguide.com/drv/Observation/469/swelling-under-belly-or-lower-abdomen/
Congestive heart failure would be a concern if legs and the sheath (or udder) area was swollen. Not a given, but fairly high on the list, and something you’d at least want to be aware of.
But sometimes, it can actually all be related to a recent deworming (rare, but it happens, happened to one of mine when I had to deworm him while he was on stall rest, never before or since), or it can be symptoms of some VUO - Virus of Unknown Origin
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We have a horse in he barn with recurring lymphangitis and his sheath is usually the first part to swell. It’s one of our early warning signs that help us keep on top of it with him.
Disclaimer:
I am not a vet, and I make no claims that the information I’m providing below is accurate. It is based on my own experience working with horses for many years, and is my own opinion.
When in doubt, call your vet.
Please correct me or add your own views if you think I’m wrong.
Nothing below is meant to be taken as any all-inclusive advice for any particular person diagnosing their own horse.
My intent is solely to offer some of what I’ve learned and share it, with hopes that it might inspire others to delve deeper into these subjects, form their own opinions, and learn more about equine health care.
Stocking up occurs due to an accumulation of excess interstitial (between the cells) fluid that leaks from blood vessels into the tissues of the leg, causing edema. The horses lymphatic system is responsible for the reabsorption of that fluid, channeling it back into the horses circulatory system. The lymphatic system in the legs functions with the help of leg movement. The leg movement causes a pumping mechanism to occur in the lymphatic vessels helping excess fluids to be drawn up and out of the horse’s legs. When certain horses stand for long periods, the lack of leg movement causes excess interstitial fluid to accumulate in the horse legs. Gravity then pulls that fluid down, and that is what causes the edema of the lower leg that we call stocking up. When the horse moves and uses their legs, the fluids are then pumped back into the lymphatic system, and the edema goes away.
Regarding your question about swelling (actual edema) in the sheath (or edema along the horse’s ventral midline. Those areas are low areas of the horses body where gravity will also cause excess interstitial fluid to collect and pool.
There’s a form of therapy that was developed in Europe called “Equine Manual Lymphatic Drainage” (EMLD). I hope these these articles might offer some insights into how the equine lymphatic system functions for anyone interested:
http://www.vetclick.com/directory/eq…nage-p3339.php
http://www.equicrown.com/uploads/tx_…ter2011_01.pdf
A key point to understand is that the horses lymphatic system is a network of lymph vessels that runs throughout the horse’s body. The lymphatic system of the right rear leg is connected to the lymphatic system of the left rear leg, and is also connected to the area of the horse’s groin, and ventral midline. The lymphatic system of the horse is divided into regions, each region being primarily responsible for the absorption of interstitial fluid in different parts of the horse body.
Because the horses rear legs and ventral midline are all of the same lymphatic region. Pathology that effects one area, may have the potential to effect other areas located in the same lymphatic region.
Examining these other areas for signs of edema, may offer a clues to the potential severity of what may be causing edema at the primary site.
A typical example could be a horse that is developing a case of bacterial lymphangitis /cellulitis.
Example…In the morning the examiner notices some stocking up in one of the horse’s hind legs while he’s in his stall. There’s some pitted edema and maybe a little heat but it’s hard to tell. there is no edema in the horses sheath. Examiner wonders if the horse banged his leg in the field yesterday, is it an insect bite, or could the horse just stocking up? The examiner doesn’t know the cause. Pulse and respiration are normal, horse is moving fine on the leg. But horse’s temperature is 101.
The examiner puts horse out in small paddock for the day to keep an eye on the horse. Examiner brings horse in at noon for a follow up, but now swelling is up to the hock, horse is now noticeably off on that leg, and temp is now closer to 102.
Examiner knows to check sheath again for edema, and the other leg. There is now edema developing in the sheath, and a slight amount of edema is now forming in the other hind leg.
Examiner suspects a case of lymphangitis is developing and calls the vet.
By the time the vet arrives leg is more swollen, horse is more lame on the leg, and the other hind leg has more swelling in it.
Vet agrees it looks like a case of bacterial lymphangitis, but because the horse care giver noted the progression, vet believes an infection is migrating through the horse’s lymphatic system. With the horse’s temperature now at 102, and due to the rate the the symptoms have progressed, the vet deems it wise to begin treating the horse with an IV antibiotic.
Some cases of cellulitis never progress beyond the single leg, and many resolve with time all on their own. Sometimes a course of SMZ’s may be all that’s required.
But a progression of leg edema into the horses sheath (groin), is a presentation that every horse owner should be aware of.
Ventral midline edema, or sheath swelling all on it’s own, is a different presentation. There can be many causes, some serious, and it’s probably wisest to have a horse checked by a vet when there’s a “sudden” presentation of ventral midline edema.
A sheath swelling on it’s own can be different. Some geldings develop swollen sheaths just as other horses stock up. But the horse’s sheath should be examined for heat and/or pain. If heat and/or pain are present, and the cause is not known, it may be wise to call the vet.
A bug bite, a bee sting, an allergic reaction, or irritation from a dirty sheath, can cause sheath swelling.
A horse sheath should be cleaned and the beans removed on a yearly basis. But cleaning the sheath too often can actually cause irritation and sheath swelling in some horses. I once had a horse that was sensitive of ivory liquid, and excalibur was fine. Some use KY for sheath cleaning as a less irritating alternative to soaps.
Googling: horse ventral edema, will bring up many sources of information about it, and the diseases and disorders that can cause ventral edema.
Hope this was helpful.
Sudden onset of ‘stocking up’ (edema) can definitely be a sign of something systemic happening. My mare had gradually increasing stocking up in hind legs, no apparent cause, got suddenly worse in all 4 after a bout of mild colic. Turned out to be an intestinal infection causing low protein in the blood leading to fluid leaking into the tissues. Stocking up resolved completely after treating the infection.
Prolonged swelling in the legs stretches the tissues and can leading to persistent swelling (similar to after a bout of lymphangitis). Better to control with wraps while you figure out the cause.
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