Last week I wrote about my beloved Arabian gelding’s surgery at Colorado State University. I am very happy to report that as of this post, two weeks post-op, he is doing great. His leg is soft-splinted from his hoof to his chest. He moves around his tiny living space with ease. I was even able to get his very long and off-balance hooves trimmed recently.
In last week’s post, I alluded to two state-of-the-art treatments used to deliver high concentrations of antibiotics directly to the infected tissue. One method is regional perfusion, and the other is the placement of antibiotic-impregnated beads in the area of infection. I referred my readers to this article, co-written by one of my professors when I was in veterinary school at Purdue University.
The technique of regional perfusion was originally used in human medicine to deliver anti-cancer medications to a region impacted by cancer cells while minimizing the negative impact of the drug on the rest of the body. In the case of Kadeen and his bone infection, regional perfusion was used to get high levels of an antibiotic directly to the area of his wound infection.
The technique involved placing a tourniquet above the infected splint bone. It is not something that horses are terribly happy about; therefore, Kadeen was sedated. A butterfly catheter was placed in a vein directly below the tourniquet. The antibiotic was then injected into the vein.
The concentration of antibiotic and the volume of fluid injected directly into the vein are high enough that the drug is actively forced out of the vein and into the infected tissues. This approach results in much higher bone and joint fluid antibiotic concentrations than can be achieved by normal intravenous delivery.
Kadeen received his first regional perfusion while still under general anesthetic in the operating room. He was discharged 48 hours after his surgery, but not before undergoing regional perfusion two more times.
Antibiotic impregnated beads
The second technique used to increase the concentration of antibiotic in and around the infected bone was the placement of beads that were saturated with the same antibiotic used in the regional perfusion. The antibiotic is mixed with bone cement (PMMA) and then formed into small beads strung on a piece of suture material. There are molds available to create this “string of beads.”
The rate of drug release depends on the surface area of the beads. There is an initial spike in the release of antibiotic during the first 24 hours. After that initial burst, the antibiotic is released at a lower, more consistent level. The beads are not biodegradable, and the surface area is rough. Therefore, they are not typically left in place. On the day this blog posts, my regular equine vet will be out to our place to pull the beads. Currently, 2 small sutures in Kadeen’s skin hold the beads in place. The beads are visible in the radiographs depicted on last week’s post.
Kadeen’s surgery under general anesthetic followed our initial attempt to clean out the infection when he was standing and sedated. After the initial wound and following our first attempt at treatment, the skin wound closed over before the infection was eradicated next to his bone and vital ligaments. The two methods described above are designed to insure that the wound will heal from the inside out.
The first day post-op
The morning after Kadeen’s surgery, I arrived at CSU to see my buddy. I had to wait about 30 minutes as they were just finishing up his regional perfusion. Next, I waited about 30 minutes in his stall while he shook off the sedation.
However, when he did wake up, he was more than happy to kiss me for treats! It totally made my heart sing!
On the second day after surgery, I arrived in time to watch and film the regional perfusion. Additionally, I received my marching orders as far as how to bandage him for the next 6 weeks. Once again, I waited for him to shake off the sedation before we were able to load him into the trailer and head home. He never hesitates to jump into the trailer. However, this time he was still not quite himself, and it took him a few moments to process what I was asking him to do.
Sadie was so happy to see him. She started running around the pasture as soon as she heard and saw the horse trailer.
As I mentioned in last week’s post, Alan and I were planning on being in Arizona by now. Ahh… the best laid plans. Our horse facilities here were not designed for either winter weather or rehabilitating a horse. We have more “typical” facilities in Arizona.
Nevertheless, we have made some modifications that should work just fine. Kadeen is enclosed in a 10 by 11 foot stall. One wall consists of our round pen panel with the integrated gate. More than once, Kadeen has contemplated “making a break for it!” Poor guy… what a small world for at least 6 weeks. Alan erected plywood wind breaks to compensate for the north-facing opening he cut into our run-in shed.
Kadeen stands like a statue when I change his bandage. It consists of gauze and elastic tape around the wound itself. Next is a layer of cotton wraps… three of them to encompass his entire leg. My neighbor, a surgical nurse, provided me with a stockinette used in human medicine. It runs from his hoof to the top of his leg and serves to hold the cotton pads in place. I cover that with three rolls of brown gauze applied with some pressure. A layer of Vetrap follows, topped off with elastic tape on the top and bottom of the bandage. I change it every few days.
Many thanks to CSU
Alan and I are immensely appreciative of the stellar care provided by Colorado State University Equine Hospital. It was a banner day when we were allowed to load our boy and bring him home. The resident assigned to our case, Dr. Charlie Barton, and our student, Teresa Le, gave us a wonderful send-off.
I will continue to provide regular updates as his wound and fracture heal. Presumably, barring any more “surprises,”, next week I will resume my regularly scheduled posts. I will tell you about the places we visited on our most recent equitrekking trip.