A serious pediatric disease, joint ill requires immediate veterinary attention

by Denise Steffanus

JOINT ILL can ruin a foal's chances for an athletic career and oftentimes threatens his life. Technically called septic arthritis, the disease occurs when bacteria invades one or more of the foal's joints as a result of a systemic infection.

In neonates, infection may gain entry to the foal's body via the umbilical stump, which is a pathway for invasion of bacteria for several days after birth until it shrinks closed. In slightly older foals (up to two months of age), a bacterial infection in the respiratory or gastrointestinal tracts may migrate to one or more joints via the bloodstream. In most cases, the infection tends to progress rapidly and in a few days can cause irreparable damage to the joint and a lifetime of painful lameness.

"The infection can be a swollen umbilicus that you will see externally, or it can be the internal structure of the umbilicus that is infected, and you will not even know," said William Bernard, D.V.M., a practitioner at Rood & Riddle Equine Hospital in Lexington who is board certified in internal medicine. "We call it navel ill or joint ill, but the most common source of infection is the gastrointestinal tract," he said. "Don't think if you don't have a navel infection, you won't get joint ill. Most cases we see are secondary to enterocolitis or diarrhea. So, many foals that get diarrhea, particularly those that are less than a couple weeks of age, end up with joint infections."

Keep it clean

Good hygiene is the best prevention for septic arthritis and other diseases of young foals because the heavier the bacterial load in the environment, the more pathogens the foal's body has to fight off.

"A clean foaling environment is critical to avoid some of those early infections," Bernard said. "Passive transfer of maternal antibodies is also important. There is no question that antibody protection is important in early life, but I think we've overplayed that a little bit. If you have a clean environment and failure of passive transfer, you're probably not going to have problems."

Some horse owners have drawn a link between wood shavings and navel ill and joint ill, but Bernard said, "There is a possibility that there may be a link there, but if so, it is probably just the fact that the navel is not clean. Obviously, shavings are going to stick to a navel more than a long piece of straw is going to. If you have a clean, dipped, healthy navel, I don't think shavings are going to cause more of a problem than straw. But to me, what sounds like a better environment to be born in: a stall full of dusty shavings or one with clean straw?"

Soon after birth, the foal's umbilical stump should be dipped in a 1:4 dilute solution of chlorhexidine (Nolvasan). Researchers at the University of California at Davis discourage the old practice of dipping a navel in a dilution of strong iodine because it can damage sensitive tissues and cause the umbilical stump to dry prematurely, thereby trapping bacteria.

Some practitioners recommend dipping the navel twice a day for the first three days of life, but Bernard said that might not be necessary.

"If you get that navel clean and dipped early, sometimes you only need to dip it once, and if it's clean and dry and healthy looking, that's all you need," he said. "If it looks like there is a problem or if it's dirty, you may want to dip it a few more times."

On farms where navel ill, joint ill, or other pediatric infections have become a problem, Bernard urges assessment of the overall herd health program and disinfection of areas that house foals.

"It is very important to review all your newborn-foal processes if you have a problem like that," he said. "Some people have found that the foaling man is dipping the umbilicus with dirty hands. If you grab the umbilicus with a dirty hand, you've seeded it with bacteria before you dip it. Wear gloves or dip the umbilicus without touching it."

Antibiotics and lavage

The first line of defense against joint ill is administration of broad-spectrum antibiotics. The veterinarian may draw fluid from the infected joint for a culture to see what type of antibiotic is most effective against it. A foal's health can deteriorate rapidly from any disease or injury, so horsemen should seek veterinary care as soon as they notice any sign of illness, even something as subtle as lethargy.

"If you wait on a joint infection, your chances of success decrease quickly," Bernard said. "If you have multiple joints involved, the prognosis is worse than if you just have one involved. Certain bacteria, Salmonella, for example, are very aggressive in bone destruction. If you get bone destruction, the prognosis is poor."

"With every foal that has a swollen joint, you should consider it septic until proven otherwise," advised Steeve Giguere, D.V.M., Ph.D., director of the University of Florida's neonatal intensive care unit, the only neonatology center in Florida where a board-certified internal medicine specialist is on call 24 hours a day, 365 days a year.

"The way to diagnose that is to do a joint tap for culture and cytology," Giguere said. "Once confirmed that the joint is septic, we also [further investigate] that because sometimes the joint is septic because the bone is actually infected, which makes the prognosis even worse. Usually, antibiotics alone are not sufficient for joint infections or bone infections. So if we have a joint infection, we're going to lavage the joint."

"Lavage is critical because what you do is flush out not just the bacteria but the cells that are there to fight bacteria that can degrade the joint surface and cartilage," Bernard said. "The joint lavage helps reduce the inflammatory response, which is very beneficial."

Joint lavage entails putting a catheter the size of a large needle into two sides of the joint and then flushing the joint by forcing sterile saline solution into one catheter and allowing the excess fluid to exit the other. The joint is flushed until the fluid leaving it is free of debris. Treatments are repeated over several days until the joint fluid appears clear. Lavage is most effective if used as soon as the first sign of joint inflammation is detected.

Navel ill and joint ill are life-threatening illnesses that require quick and sometimes drastic measures to pull the foal through, according to Kenneth Hinchcliff, B.V.Sc., Ph.D., one of the veterinarians who helped to develop the Kick Start program at Ohio State University's Galbreath Equine Center in Columbus that offers a quick solution for foals that simply are not doing well. The aim of the program is to provide 36 hours of initial care and stabilization of sick foals so they can be returned to the owner and continue to recover under the care of the farm's local veterinarian.

"One new thing we are doing for joint ill is called regional perfusion of antibiotics," Hinchcliff said. "You clamp off the blood supply on either side of the joint and inject the antibiotic into a vein in that area so that you get a very high concentration. You leave it for 30 minutes with the tourniquets on it--but you are still getting blood to it--and we get really high direct concentrations of antibiotics to the joint."

"By putting on a tourniquet, you basically prevent the antibiotic from diffusing throughout the whole body, so high concentrations of the antibiotic stay in that limb," Giguere added. "The other approach is to infuse the antibiotic into the bone itself if it is infected. In some cases where the bone is severely infected, we have to go in and surgically debride the affected area and remove the infected bone."

Bernard emphasized prevention as the best weapon against septic arthritis because he said the prognosis typically is only fair, especially for a foal that is expected to go on to a successful athletic career.

"A lot of them will recover with antibiotics and a couple of joint lavages," Bernard said. "There are some that just go on and on with a sort of chronic infection. You may get it resolved, but then you have damage to the joint."