Seriously Swollen – Lymphangitis and Cellulitis in Horses
- What is Cellulitis in Horses?
- Causes of Cellulitis in Horses
- Signs and Symptoms of Cellulitis
- Lymphangitis vs Cellulitis
- Treatment of Cellulitis in Horses
- Preventing Bouts of Cellulitis
- Recovery and Prognosis
- Evidence-Based References
Updated October 16, 2024 | By: Andris J. Kaneps, DVM, PhD, DACVS, DACVSR
What is Cellulitis in Horses?
Cellulitis is a painful swelling of the horse’s limb that can result in severe lameness, extreme sensitivity to touching the swollen area, fever, and depression. Horses’ hind limbs are most commonly affected by cellulitis with only one leg involved at a time in most cases.
The pain and swelling are caused by an infection or inflammation of the subcutaneous tissues beneath the horse’s skin. Inflammation leads to extra tissue fluid (edema), which causes swelling. The normal outflow of fluids from the affected leg is reduced because of the fluid overload and infection/inflammation, so the edema progresses significantly.
The lymph nodes that drain the affected region of the leg may also be overwhelmed with fluid and bacteria, resulting in swollen areas high up the leg.
Ask the Vet Video on Cellulitis
Dr. Lydia Gray gives an overview of cellulitis in horses in this Ask the Vet video, including how to recognize this versus other types of swellings and what immediate actions you should take.
DAN: "Cellulitis, and how to bring more circulation to the legs?"
DR LYDIA GRAY: Oh, that's it?
DAN: Ashley is to the point.
DR LYDIA GRAY: OK.
DAN: She knows what she wants.
DR LYDIA GRAY: I have a lot to say about cellulitis. So we should probably define it first.
DAN: OK.
DR LYDIA GRAY: And not to be confused with cellulite.
DAN: Yes. Yes.
DR LYDIA GRAY: So cellulitis. I mean, the itis gives it away - it's inflammation.
DAN: Yeah.
DR LYDIA GRAY: Right. And specifically, it's under the skin, and sort of between the skin and the next layer, which is fatty tissue and connective tissue. And it's sort of a deep seated infection. And usually in horses it's legs. It's hind legs. And it's one hind leg. And only in about half the cases do we know what caused it.
DAN: Of course. Horses.
DR LYDIA GRAY: Hey, half is good. When we do know, it's from a wound, an injury, a break in the skin. Could be there was a surgery, and it just allowed bacteria to go in. But it is a bacterial infection.
And the thing about cellulitis is, one day your horse is totally fine. And the next day he's three-legged lame. The leg is blown up.
DAN: I was going to say, usually.
DR LYDIA GRAY: We call it a stovepipe leg, because from the hoof to could be the hock or knee, could be higher, it is like one thing. It's excruciatingly painful to the touch, but also to stand and move on.
So it would be an emergency, because you don't know that it's cellulitis. And even your vet looking at it is not going to know. So they might do some imaging. They might do some blood work to see if there is an infection going on, to see if it's a local infection, or to see if it's a body wide infection.
Because this all tells them how to treat it. If everything points to cellulitis, then we do try to find out what the cause is, because you have to get rid of that. But aggressive antibiotics.
DAN: I was going to say. Yeah.
DR LYDIA GRAY: And then painkillers, pain relief. And anti-inflammatory. So non-steroidals, like your butes and banamines and firocoxib, which is Equioxx.
And it comes down pretty quick. Now, the things that the owner is going to have to do is cold hosing or icing.
DAN: I was just going to say, it sounds like you're going to do some time cold hosing.
DR LYDIA GRAY: Oh, yeah. And you would like to use something like a game ready or an ice horse that has the cold and compression. But it's so painful, you're not going to be able to do that right away.
DAN: Well, that's what I was just going to ask. As far as poulticing or things of that nature to help...
DR LYDIA GRAY: No. Cause it's open.
DAN: But you don't want to touch anything.
DR LYDIA GRAY: It might be open.
And the other thing is, when the body swells, skin has only so much room to expand.
DAN: Elasticity.
DR LYDIA GRAY: Yeah. Whew. That's a big word.
DAN: I tried.
DR LYDIA GRAY: And when it swells more than it has elasticity for, there can be microscopic breaks in the skin. And then you'll see a yellowish-- the serum of the blood is oozing out. And it even gets crusty.
So you don't want to put a poultice on it. You don't want to put a liniment. You don't want to put anything on it. You let the antibiotics do the work, let the non steroidals, the cold hosing or icing. You will eventually be able to bandage it. Bandaging and application of cold are tremendous for it.
There are things you may have to do well beyond the medication. And even because when a horse has cellulitis in the leg, that leg is more susceptible to it in the future.
DAN: Oh, really?
DR LYDIA GRAY: Yeah.
DAN: Even if you get rid of the infection?
DR LYDIA GRAY: Yeah. Because you have stretched all the tissues, maybe created scar tissue. Now, I say "you." It's not your fault. The circulation is impaired. The lymph drainage doesn't work properly anymore. And so you have to be in the future, to prevent it, I mean, there's things you can do. You closely monitor the legs.
So you have to everyday be looking for cuts, breaks, scabs, abrasions. You can't let your let your horse get scratches.
DAN: OK.
DR LYDIA GRAY: And turnout is great, because when they're in a stall, they swell up.
DAN: So you want a little movement.
DR LYDIA GRAY: But you don't want to turn them out early in the morning when there's wet grass, because you want to avoid that leg getting wet. Can't put it in. You can't turn it out when it's muddy or sloppy.
DAN: The fun parts of horse ownership.
DR LYDIA GRAY: Oh, my goodness. So I don't mean to be discouraging. But there is quite a bit of care in the moment, and then afterwards.
DAN: So that's good to know, though. Cause a lot of times when horse owners do go down, they see that the horse's leg is swelled up. A lot of times, even if it's just the hock and it doesn't seem super dramatic. They do want to wrap, or do something like that to kind of get the compression down.
DR LYDIA GRAY: Yeah. But the horse will tell you. It's so painful.
DAN: So at this point it's like, get the vet out. Make sure. It's important.
DR LYDIA GRAY: Because the horse probably isn't going to be bearing weight. And so you won't know that it's a cellulitis, unless you've been through this with this horse. You don't know. I mean, this looks as bad as a fracture.
DAN: Oh, so it's--
DR LYDIA GRAY: Oh, yeah. It's three-legged lame. It could be an abscess. There's a couple things that make horses-- joint infection. When your joints get infected, the horse is three legged, non weight bearing.
So this is an emergency, not only to make sure it's not one of those things. But you've got to get therapy started right away.
DAN: And get ahead of the infection.
DR LYDIA GRAY: Yeah.
DAN: So then with the follow up question of how to bring more circulation to the legs? Turn out's OK. Hand walking I'm assuming.
DR LYDIA GRAY: Yeah. Exercise is really good to keep things moving as little-- like I don't keep my horse in a stall. Not for this reason, but for others. So if you can find a situation where the horse is not in a stall at night, like it's a run in, run out, that would be ideal. Because when they're stabled and standing still, that leg is just going to stock up.
Trailoring even will cause them to stock up. And you also want to protect the leg. So when you trailer, you'll want to for sure, if you didn't before, use shipping boots, or wraps, however you want to do it. This may be a horse that you now wrap when you exercise, because they can't have a bump or booboo, because then that's going to get the cycle going again.
DAN: Oh.
DR LYDIA GRAY: I know.
DAN: But it sounds like, though, if you get ahead of it, there is at least hope for you. You have some treatment and management.
DR LYDIA GRAY: Yeah. Yeah.
DAN: OK. We don't want to scare people too much.
DR LYDIA GRAY: Well, I want to add that it can be life threatening. But that's why you call your vet right away. And you get on top of it.
DAN: Instantly. OK.
DR LYDIA GRAY: And there are treatments. Yeah.
DAN: Well, that is definitely great to know. And keep us posted with how your horse is doing for sure.
DR LYDIA GRAY: Sorry.
Causes of Cellulitis in Horses
Cellulitis is usually caused by a bacterial infection of the subcutaneous tissue - the deepest layer of connective tissues of the skin. The infection is often due to either gram positive bacteria (Staphylococcus or Streptococcus) which are usually found on the skin, or gram negative bacteria (Escherichia coli). The bacteria may access the horse’s subcutaneous tissue through a wound, scratch, abrasion, or dermatitis such as “scratches” or “greasy heel.”
Other uncommon causes of an infection that leads to cellulitis are surgery or joint injections.
Signs and Symptoms of Cellulitis
- Painful leg swelling
- Moderate to severe lameness
- Fever (greater than 101.5°F)
- As signs progress, skin may break or crack and ooze serum
The most obvious clinical sign of cellulitis is extensive swelling of the leg. Swelling often starts in the lower leg, near the pastern, fetlock, or below the hock, and can quickly spread to involve most of the limb. The horse’s leg may be warm to the touch and is usually very sensitive to pressure.
The horse’s level of lameness varies from moderate to severe, with some horses being non-weight bearing on the leg.
Other Conditions with Similar Signs or Potential Causes of Cellulitis:
- Limb edema, known as stocking up, such as a swelling of the lower leg that happens after stabling overnight. Common edema is not painful to the touch and the horse is not lame as he would be with a case of cellulitis. This kind of swelling usually resolves itself with exercise.
- Trauma to the limb (such as a fracture or strain).
- Joint or tendon sheath infection.
Lymphangitis vs Cellulitis
Lymphangitis is similar to cellulitis, but it is caused by inflammation, not an infection. The lymph system is found under the skin and is like a mesh of small blood vessels, however, lymph vessels carry tissue fluid (lymph), not blood.
Compared to cellulitis, horses affected with lymphangitis usually are not as lame, the leg swelling is not as painful to the touch, and most horses will not have a fever.
Since so many of the signs of cellulitis and lymphangitis are similar, making a diagnosis may not be possible in the early phase of either condition. Veterinarians usually recommend treatment for the worst-case scenario, which would be cellulitis.
Treatment of Cellulitis in Horses
If your horse has the signs of cellulitis described above, call your veterinarian for specific advice. Your vet will ask several questions that may help identify the potential cause of the swelling and help them make appropriate treatment recommendations.
Veterinary Care is Critical
When your veterinarian arrives to examine your horse, they will conduct a full examination by taking vital signs (rectal temperature, heart rate, breathing rate, gum color and refill time).
Your veterinarian will watch your horse walk to determine the level of soundness and palpate the affected limb(s) to determine sensitivity to touch, warmth of the limb, and if any wounds or dermatitis may have contributed to the infection. In many circumstances, blood and tissue samples will be taken for analysis and an effort to culture potential causative bacteria.
In most cases of cellulitis, your horse will be treated with broad-spectrum antibiotics and non-steroidal anti-inflammatory medication. In certain cases, advanced methods of antibiotic delivery, such as limb perfusion, may be necessary. If the leg swelling has resulted in oozing of serum through the skin, topical antibacterial agents such as silver sulfadiazine cream are often applied. Complications may include extensive sloughing of the skin or laminitis.
Pain management is critical for severe cases of cellulitis. Non-steroidal agents alone are often not enough to relieve your horse’s pain. Other pain relief options include using opiates and various other pain-relieving medications that are administered via a continuous rate intravenous infusion or through an epidural.
Secondary Care Horse Owners Can Provide
Cold hosing the leg with a high-pressure spray may be recommended to decrease the swelling.
Dry, cold therapy ice boots with compression are very useful for horses with cellulitis or lymphangitis. Look for compression boots that have adjustable compression pressure. This is important when the limb is very sensitive to the touch, and sequentially pressurizes a lower section of the leg, then the next higher section, and so on up the limb.
Your veterinarian may recommend wrapping the leg with a poultice or sweat is to help reduce swelling. Leg sweats reduce swelling by increasing blood flow to the treated limb, thus helping to resolve edema. Sweats may include topical agents such as nitrofurazone with or without DMSO, mineral oil, or glycerin.
Depending on your horse’s unique case of cellulitis or lymphangitis, you will want to work closely with your veterinarian and not put products, ointments, or wraps on their legs without your vet’s advisement.
Exercise and Riding a Horse with Cellulitis
If your horse is comfortable enough to take a walk, then regular hand walking several times daily may be suggested as movement helps resolve the severe edema. Therapeutic exercise starts with hand walking and gradually progresses to under saddle work based on the horse’s level of comfort. Changes in your horse’s exercise regime should only be made after speaking with your veterinarian.
Preventing Bouts of Cellulitis
Horses that have a case of cellulitis are predisposed to future repeat episodes because of potential damage to the circulatory and or lymphatic system. Here are some tips to help prevent future bouts of cellulitis in your horse:
- Maintain a regular schedule of active exercise, such as riding or groundwork (longeing).
- Provide access to daily turn out and/or regular hand walking.
- Pay close attention to your horse’s skin. Treat conditions that could cause a skin infection, like scratches, right away to prevent a bout of cellulitis. Muddy, wet conditions can lead to skin issues on the lower legs, which can then be entry points for bacteria.
At the first sign of recurrence, start treatment as recommended by your veterinarian – for example, high-pressure cold-water therapy, bandaging, and increased exercise.
Recovery and Prognosis
Recovery from a bout of cellulitis may require days to weeks and recovery time varies depending on the extent of the infection or inflammation. Rates of a full recovery are reported to be guarded (55-89%), yet most horses with cellulitis will have a return to their previous level of work.
Some horses will continue to have a thicker limb after the cellulitis. This is because there can be scarring of the subcutaneous tissues and damage to their circulatory and/or lymphatic system. Swelling may persist for a lengthy period, even when the infection is completely resolved, due to the horse’s circulatory and lymphatic systems being impaired.
As previously mentioned, horses that have cellulitis once may, unfortunately, have it again.
Evidence-Based References
- Adam EN, Southwood LL. Primary and secondary limb cellulitis in horses: 44 cases (2000- 2006). J Am Vet Med Assoc 231:1696-1703, 2007.
- Fjordbakk CT, Arroyo LG, Hewson J. Retrospective study of the clinical features of limb cellulitis in 63 horses. Vet Record 162:233-236, 2008.
- Getman LM. Alternative therapies for cellulitis. Proceedings, American College of Veterinary Surgeons, 585-587.
- Duggan M, Mair T, Fews D. Equine cellulitis/lympangitis resulting in distal limb ischaemia and avulsion of the hoof capsule. Equine Veterinary Education, 2021.
- Keckler, K. Lymphangitis: a frustrating condition. In: Horse Health. American Association of Equine Practitioners.