Swelling on Belly (Ventral Edema) Unknown Cause

[GretaJeane]

Hello, I’m hoping to get some ideas for my 2 horses. The vet and I are stumped as to what’s causing the bread dough like swelling (ventral edema) on their bellies. It’s both of my horses and the swelling comes and goes. Bloodwork/temperature/heart are normal, they are the only two here at my house and they haven’t been off the property in 3 months.

They are generally healthy horses otherwise, eating, drinking normally. The vet had me switch one of them to another hay source from a different region but it hasn’t made a difference. The vet checked my hay and paddocks for anything that might cause this but nothing seemed like a good culprit. I’ve kept them in their small sacrifice paddocks with just hay (no winter grass) while we’re doing the hay trial to keep the feed very controlled.

Any ideas? No tick bites that I can find (also it’s January in Massachusetts), and they are turned out separately so no kicking injuries.

Thank you!!

[Bluey]

How large their pastures/pens, are they being ridden or exercised and how much?

Especially in the winter, if horses stand around too much, some may stock up behind and, more rare yet, get ventral edema.
That is fluids accumulating by gravity on the lower parts without sufficient regular movement.

That would be more of a zebra cause, especially with both horses affected.

Since it seems that you are down to looking for zebras …

[NancyM]

When you get ventral edema, it is fluid dropping from somewhere up high from some issue. Can be from inflammation in gut or organs. Can be from ulcers. Can be from cancer. Can be from allergy. Multiple possibilities. With both being effected, feed may well be the issue, as your vet has suggested. But it will take a while for it to dissipate. Light exercise will help dissipate, if possible.

[Fharoah]

Make sure there is no toxic weeds in there hay Or forge that could affect their liver. My horse has a lump on his belly my vet refers to it as a fat pad. My horse had a large haematoma on his right side of his flank from a Trumatic injury last summer. The swelling moved down to the lowest part of his belly I never completely disappeared.

[fjordmom]

I was going to say possible irritation to fly/gnat bites if you were down south, but I see you are in MA. Still, here in the upper Midwest, we’ve had a totally crazy, mild winter. It hasn’t been quit warm enough for flies, but is that a zebra worth considering?

I have one horse with sweet itch who also has a habit of sleeping in his pee spot. Sometimes that will irritated his skin enough to cause a reaction. Have you considered giving them both a sponge bath with warm water to make sure any skin irritants are washed off? Then rinse with witch hazel to calm any possible irritation.

[dotneko]

I was going to say ticks. They are still active in MA in Jan - especially with our mild winter. Have you pulled a lyme titer? How big is the swelling? Entire midline or apple sized in one area?