Page 31 - Canada Spring 2021

was a clostridial myositis. I didn’t find any gas near the injection site, but finally found a pocket
of gas under the skin by her withers. The gas had travelled
up and along the neck, clear to the withers. I prepped the skin
at the injection area and blocked it with anesthesia as best I could and made incisions through the skin and partway down into the muscle with a big scalpel,” he says.
One of the important aspects of treatment is to open up the area and get oxygen down into the infection. Those bacteria don’t like oxygen. They thrive in damaged tissue with no oxygen supply.
He made several deep incisions and dissected down into the muscle. “Then suddenly my
finger fell into an opening and I thought maybe I’d been unlucky enough to drive my finger into a large blood vessel. I was afraid it might start bleeding, but realized I had to pull my finger out. When I pulled my finger out of the wound, gas rushed out of that hole and the stench was foul. So,
I opened it up even more, grabbed chunks of necrotic muscle tissue and dragged it out. I opened the infected area as best I could,
then packed it with penicillin- soaked gauze and started the
mare on penicillin injections. Another drug that is very effective against clostridia bacteria is metronidazole,” he explains. A horse with this kind of infection would also need a tetanus booster.
“With this mare, I got lucky. She survived, but with large scars on the side of her neck and some atrophy in those muscles, but all in all she did pretty well. The most important thing in dealing with this type of infection is getting oxygen into the affected tissues, and that’s why you see photos of horses with large, gaping incisions into those areas – for oxygen and drainage,” he says.
“If a person has access to a hyperbaric oxygen chamber, that would be ideal, but most people are not close enough to one, and/ or can’t afford those treatments. This type of oxygen therapy is an excellent treatment modality for clostridial myositis.”
If the injection site and subsequent incisions are on the neck, the horse will have a very sore neck for a while and it might be painful to put his head down to eat and drink. “You need to help these horses by placing feed and water a little higher for easier reach. If the horse is in decent body condition to begin with,
even if he can’t eat very well, it will take several days before he starts dropping muscle condition and body weight. But supportive care to help him eat and drink can keep him from losing too much weight. Depending on where the injection was that caused the infection (neck or hindquarters), you may or may not be able to give IV fluids,” he says.
“With this particular mare, with infection in the neck, venous access was not an option because of all the infection and gas under the skin. Trying to get into a vein with a catheter would risk a more serious problem. You can clean the surface of the skin, but you can’t clean out the contaminated subcutaneous tissue. A person can always give fluids and nutrients via stomach tube (nasogastric tube), which would be safer in this situation than an IV. There are some tubes that are designed to be left in place for several days, and the horse could be fed that way,” says Randall.
The mortality rate with this type of infection is fairly high, so it’s important to get your veterinarian involved as soon as possible, to increase the chances of turning it
around quicker.
EQUINE HEALTH
“The most important thing in dealing with this type of infection is getting oxygen into the affected tissues, and that’s why you see photos of horses with large, gaping incisions into those areas – for oxygen and drainage,”
SPEEDHORSE CANADA Spring 2021 31