Gas Gangrene Up Close And Personal

By Janet Forster

Gas gangrene, or clostridial myonecrosis, is a rare and serious bacterial infection of anaerobic (without oxygen) muscle tissue. The bacterium produces gas and releases toxins that destroy the surrounding muscle and other tissues. It is a medical emergency requiring immediate treatment, and the outcome is often fatal.

The bacteria responsible for the infection usually live in soil, but can also be found in wounds, infected surgical sites, or other areas affected by trauma. They likely arrive there via external contamination. In horses, Clostridium perfringens type A is the commonest gas gangrene causing bacteria, although several others have also been known to cause it.

Equine Gas Gangrene

Equines most commonly develop gas gangrene after an intramuscular (IM) injection of a tissue irritating substance. Flunixin meglumine AKA Banamine® or Finadyne® is the most common culprit because it is not specifically designed for IM administration. However, IM injections of phenylbutazone, ivermectin, vaccines, vitamins, antihistamines, and prostaglandins have also been known to bring on gas gangrene.

It’s not known exactly how the bacteria spores reach the infection site. Intestinal populations of Clostridium perfringens type A are reasonably common in humans and other mammals, including horses. Thus, the spores may already be present in the intestinal system of the horse and reach the injection site via the blood stream, or they may be introduced into the muscle by the needle. There also appears to be no correlation between cleaning and not cleaning the skin prior to injection.

Symptoms of gas gangrene include severe pain, swelling, and discoloration of the infected area, along with a smelly discharge. If not treated promptly, the infection can spread to other parts of the body, leading to tissue death and organ failure.

My Experience With Gas Gangrene

I was unfortunate enough to have a run-in with gas gangrene with one of my horses in 2015. It started, sure enough, with an IM Finadyne® injection in the chest muscle late one afternoon. Within 12 hours, his entire off fore leg was swollen [photo 1]. I called the vet, suspecting a broken leg. It turned out it wasn’t so the next likely scenario was an abscess from the injection.

He was started on penicillin and gentamicin, which in hindsight almost certainly saved his life. Also in hindsight, it was probably lucky we didn’t realise at the time what we were dealing with!! In fact, it wasn’t until several years later when I read an article about gas gangrene that the penny dropped. Lucky certainly was one very lucky lad. In 2015, though, gas gangrene in horses was rare enough that it obviously didn’t occur to the vet either.

Treatment Begins

Alongside the antibiotics and pain relief, I hosed his leg down several times a day to reduce the swelling. Surprisingly (in hindsight), it came down within a day or 2.

Around day 3 or 4 the ‘abscess’ ruptured so I could now keep it flushed it out. The small patch of black skin to the right of the rupture hole is the site of the original injection. It subsequently blew open as well. The yellow is discharge.

One Week Later

About day 7, the skin over the infection site broke away to expose a gaping hole in his chest muscles. Between weeks 2 and 3, the hanging skin flap dried out and fell off. Incidentally, the pink around the edges of the wound is a hospital grade antiseptic antibacterial product (not Centrigen!). He was also still getting his penicillin and gentamicin jabs plus I was hosing it out 3 or 4 times a day, and pumping antibiotic powder in there.

At Two Weeks

I noted much of his muscle tissue had disappeared. The hole towards the middle of his chest was particularly deep and the infection by now had almost completely ‘dissolved’ his nearside chest muscles.

The yellow paste I used was made from natural healing oils and various other antibacterial botanicals mixed with sulphur powder. I started using it when it became apparent a bulk product that could literally be ‘shovelled’ into the hole was in order! One that would keep the flies out at the same time because it was the middle of summer in the fly capital of Australia! Did it work? I’ll let you be the judge of that!

By Three Weeks

Between weeks 2 and 3, some pretty amazing healing happened. It is incredible how fast the offside muscle tissue grew back once the infection was knocked on the head. The proud flesh also disappeared of its own accord as everything healed over. His skin also grew back at a phenomenal rate.

One Month And Counting

A month after it happened and it’s around a third of the original size. The muscles on the offside chest have grown back nicely but you can still see a large gap where they’re meant to be on the nearside!

At 5 ½ weeks [photo 8] it’s down to about an eighth of the original size and the nearside muscles have finally begun regenerating. The following photos were taken at weekly or fortnightly intervals after that [photos 9 – 12].

Three Years And Eight Years

And finally, just on 3 years later – [photos 14] there’s only a small indent and insignificant looking scar to tell the tale. Eight years later (2022) and there is just a tiny scar and a small depression when viewed at certain angles [photos 16]. Interestingly he did develop a slight swing in his off fore leg afterwards.

Clostridium perfringens type A And Other Gas Gangrene Causing Bacteria

One of the most important things to consider when dealing with gas gangrene is that these bacterial spores attack anaerobic muscle. They don’t like oxygen at all because exposure to it kills them! Therefore, standard treatment protocol for gas gangrene includes allowing oxygen to get into the site.

Most horses unfortunately develop gas gangrene in the neck muscles because that’s a common injection site. The infection then rapidly travels up and down the major muscles there, requiring multiple surgical incisions to let oxygen in. It’s also often fatal because it’s just too hard to control the spread.

In Lucky’s case, the location in his chest allowed for easy drainage so infected tissue wasn’t sitting there festering away and spreading. The infection site also completely opened up, allowing plenty of oxygen to get in. These factors plus the regular hosing and aggressive antibiotic treatment, almost certainly are what saved him. I also believe the oxygen in the water (it is after all made from 2 hydrogen molecules plus an oxygen molecule i.e. H2O) helped too.

About the author:

Janet Forster hails from sunny Perth in Western Australia. During a lifetime spent with horses, she has bred, competed, loved and written about them. She owns a collection of high percentage Tb crossbreds, most of which are palominos and registered Australian Stock Horses.