Cellulitis in Horses

Every heard or used the phrase stovepipe leg? That’s about the best way to describe cellulitis in a horse’s leg, where it usually happens.

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***** WARNING! This article has some graphic photos. I have put them at the bottom of the article, so you can look at them if you want, or not. *****

What is cellulitis?

To be boring and technical, cellulitis is when the tissue layers under your horse’s skin become infected and inflamed. Hence, the -itis part of things. Cellulitis also goes by the name of phlegmon, which is more fun to say but not as widely recognized.

Unfortunately, cellulitis can stay superficial or go deep into tissues, as well as moving up and down the leg.

Thanks, Kelly, for this photo of your lovely horse and his even lovelier butt.

How is cellulitis different from stocking up?

Stocking up in a horse’s hind leg, or legs usually, is just the collection of normal fluids that usually travel up the leg. This typically happens when a horse doesn’t move around a lot. The muscles of a horse, or human for that matter, help move blood and fluids against gravity. No movement means little muscular support for the lymphatic system to do its job and keep the legs taut.

Stocking up is fairly common, typically not painful, and will resolve itself when your horse starts to move around again. Stocking up typically affects both hind legs more or less equally, while cellulitis is an infection and can just attack one leg.

Both cellulitis and stocking up are more common in the hind legs.

What are the signs?

Your horse’s leg will tell you. The infection below the skin is warm, sometimes even hot. The leg(s) are usually quite swollen and it’s quite painful for you to touch your horse’s legs.

The swollen, hot, and painful leg can also get even more out of hand and cause lameness, sometimes to the point of not putting any weight on that limb. Then your horse is at risk of supporting limb laminitis since he’s shifted his weight to a healthy leg.

Another problem with cellulitis is the potential for your horse’s skin to crack open. So much swelling will literally tear the skin as it can’t stretch anymore. These cracks can seep, and create the perfect entry point for more bacteria to enter your horse, compounding the problem.

The skin can also die, in which case it will slough off. The infection can travel up the legs, your horse can have a fever which is a whole other problem, and then there’s that pesky laminitis.

Cellulitis is also FAST. Lightning fast. Legs can go from normal to huge and cracked in a few hours.

This small cut above the knee created quite the hot swollen leg! Lauren shared this photo with us.

What is cellulitis? A one-minute summary.

Helping your horse – call the vet!

How does cellulitis happen in horses?

If only there was a definitive answer here – but there’s not. There are known factors that can contribute to cellulitis, some of which we can’t do anything about.

There’s an entire world of bacteria that essential coat everything on the planet, your horse’s legs included. It just is. Wounds of any size, depth, location and severity can create even the tiniest of openings for any of that bacteria to enter the leg. Staphylococcus bacteria, which are everywhere and normally live on the skin, are the most likely culprit. When they enter the leg, or anywhere else in the body, the surrounding tissues can get infected. The bacteria themselves, as well as the toxins they release (bacteria poop), create an inflammatory response in your horse. This is the swelling! This can lead to vessels and tissue that leaks, causing more trouble.

When you think about any type of equine pastern dermatitis where the skin is compromised, scabby, and raw, this can be cellulitis waiting to happen. Those butt head bacteria are just looking for a way in.

This challenging case of EPD can end up as cellulitis.

There’s also a component of circulation, both blood circulation and lymphatic circulation. Muscles in your horse’s legs and the plantar surface of your horse’s hoof push blood up the leg into the body. When this system doesn’t quite work so well, cellulitis may have a better chance of taking hold. The mechanism isn’t really clear.

Some horses with cellulitis just show up with it. No rhyme, reason, or easily discernible wound. Old wounds and scar tissue can also influence circulation, which may or may not help cellulitis take hold.

But what about systemic issues with your horse? A virus can create the perfect storm for cellulitis to take over. Viruses can affect the blood vessels, which can lead to vasculitis which makes it’s cousin cellulitis come on over.

Any issue that starts as long term swelling, such as after a wound or even a tendon or ligament issue, can open the door for cellulitis as well.

The swelling involved

Edema is the official term for swelling, and it comes in two forms. Pitting edema is when you squish a bit into the swelling, and your thumb dent remains.

Interstitial edema is swelling that happens between the cells of your horse’s legs or other body part. It won’t leave a dent when you squash it.

The swelling during a bout of cellulitis can become so severe that skin cracks or you might see the skin sweating or weeping a bit. This is serum, and it will leak from the skin.

It looks like Ellie, shown here, has some pitting edema in the leg. It also could be hair loss from a sore. Hard to say, but this is basically what pitting edema looks like. Your thumbprint remains.

How do you help the horse with cellulitis?

First things first – take your horse’s temperature and call your vet. You may want to be able to describe the following to your vet as well:

Is the leg hot, swollen, painful, causing lameness, or affecting his appetite or routine. Are there any obvious wounds? Is the swelling in one leg or both? Hind or front?

It’s not usually wise to ask your horse to jog to check for lameness at this time. Some other conditions, like fractures and severe soft tissue injuries, can look like cellulitis.

Follow your vet’s instructions until they can arrive.

The plan to combat cellulitis

The bacterial infection needs antibiotics.

No natural herb or spell or internet remedy can do this, your horse needs a prescription. In some cases, your vet may need to do a culture and sensitivity at the lab. A sample of tissue or fluid from your horse is collected and the lab will grow the bacteria in a culture to determine what type it is. It’s usually a strep variation. Then the sample is tested against antibiotics to determine which is the most effective.

The swelling needs to be addressed.

For most horses, this means moving around. Motion is lotion and can help the muscles of the leg massage the lymphatic system and vessels to draw out the fluid naturally.

Cold therapy may also be a good idea for some horses. Cold hosing can help in a pinch, ice boots are likely to be easier to apply and may provide more cold.

Anti-inflammatory medications can help with pain levels and help reduce the swelling, as can diuretics and some steroids. But each case is different and your vet needs to come up with the “cocktail” of meds.

There may be a poultice or sweat that is appropriate for your horse. This may not be the case if the skin is in danger of being open, or if it’s cracked already.

You and your vet should decide if wrapping is right for your horse’s case. There are too many moving parts to just guess. Thanks, Liz, for the photo and the perfect wrapping job!

Bandaging with standing wraps is often not indicated as the swelling will just settle higher in the leg, potentially causing more problems. Some horses absolutely need to be wrapped.

In some cases, clipping the area is warranted, to deliver topical meds or to better a better understanding of the leg, especially in winter if there’s a thick coat to contend with. In some cases, clipping just makes things worse.

Prevention of cellulitis in horses

Some things about horses JUST ARE, and there’s not a lot we can do about it. With cellulitis, it’s partially just circumstance, and partially just active prevention. Things to keep in mind:
Since this is a bacterial infection, keeping your horse’s skin healthy is key.

Lots of regular grooming.

Not stripping your horse’s sebum from his skin with detergents.

Keeping mud at bay around the farm.

Using clean bedding.

Daily leg inspections to be sure there are no new wounds or irritations.

Getting your vet involved early.

Using physical barriers, like Sox for Horses, can help keep bacteria from the legs. This is especially useful in muddy conditions and when a horse has some dermatitis going on.

Keep your horse moving

Turn out

Exercise

Movement!

There is the possibility that some cases of cellulitis can create permanent damage. Scarring within the leg can weaken your horse’s ability to drain the area in the future, possibly leading to repeat cases. It also might be that the leg just remains larger most of the time even without another cellulitis occurrence.

What about lymphangitis? Or vasculitis?

All of these conditions manifest themselves with swelling, it’s just a matter of where. Lymphangitis happens in the lymphatic system, vasculitis in the blood vessels. Just one more reason to get your vet in the loop sooner, rather than later!

For more on lymphangitis, read this amazing page turner. Or scroller-downer.

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