There are several conditions involving infection of limb structures that have historically been catastrophic and carried a very poor prognosis.
These include infections following deep-puncture wounds involving the navicular bursa, tendon sheaths or joints and coffin, sesamoid or navicular bone infection (osteomyelitis). Even intravenous antibiotics may not reach adequate concentrations in these structures. Horses with these injuries have usually been euthanized because of uncontrolled infection and unrelenting pain. Now there’s hope for, at the very least, a life at pasture.
Over the past 10 years, reports have appeared describing excellent results in these tough to treat conditions using a technique called regional limb perfusion. The procedure can be done on the farm under heavy standing sedation and using local nerve blocks. It is performed in the same way as a venogram.
If possible, a sample from the infected area (e.g. joint fluid from an infected joint) should be cultured prior to starting the treatment. This allows the vet to also do antibiotic sensitivity testing to determine the best antibiotic to use to treat the infection.
For conditions involving the leg below the level of the hock or carpus/knee, a tourniquet or other pressure bandage, such as an Esmarch, is placed on the leg above the level of the infection. A catheter is then placed into a vein. A full IV dose of antibiotic is diluted in a suitable volume of saline and injected into the venous system under pressure. This is sufficient to fill both the veins and arteries. The tourniquet is left on the leg for 20 to 30 minutes, which allows time for the antibiotic to diffuse out of the vascular system and into the tissues. For treatment of hock or carpal joint infections, a tourniquet is placed both above and below the joint. This results in antibiotic concentrations in the local tissues up to 100 times higher than it is possible to achieve by IV, intramuscular or oral antibiotics.
Protocols for repeating the treatment vary from every other day to daily. Progress is followed both by clinical signs of heat, pain and swelling as well as repeat cultures to confirm the infection has been eliminated. From three to seven treatments are required on an average. Reported success rates are very high, from 75% to around 90% with as many as 60% returning to their original or less demanding athletic careers in some reports.
While this treatment obviously entails veterinarian-visit charges, it is actually less expensive in the long run than previous options, which required hospitalization, insertion of permanent catheters for flushings, often surgery, or very prolonged courses of antibiotics. Best of all, the prognosis is good for at least pasture soundness and often return to full use.
Many individual factors will also influence prognosis, such as extent of pre-existing damage and how long the infection has been present so your precise situation will need to be discussed with your vet. If your horse seems like a good candidate, we’d say go for it.