EC January/February, 2007
Septicemia is defined as systemic disease associated with the presence and persistence of pathogenic bacteria and their toxins in the bloodstream. This sometimes occurs when a horse develops a bacterial infection, and can be especially dangerous in young foals. The infection can be anywhere in the foal’s body–the intestinal tract, umbilicus, lungs, etc. Septic Foal Syndrome (a acute and deadly infection) has now been identified as the most common cause of death in young foals.
Nathan Slovis, DVM, Diplomate of ACVIM, an internal medicine specialist at Hagyard, Davidson and McGee in Lexington, Kentucky says that this serious condition is caused by the spread of bacteria throughout the system. The infection is no longer localized. “Bacteremia is the term for bacteria in the blood; septicemia occurs when both the bacteria and their toxins circulate through the body. It is mainly the toxins that do the damage,” he says.
“The only way a foal becomes septicemic is when bacteria gain entry into the body, and the most common entry routes in young foals is orally (intestinal tract), respiratory tract (pneumonia), or through the umbilicus. Puncture wounds are another route, but not as common,” says Slovis. The intestinal tract and the umbilicus are the most common, and that’s why it’s so very important to have the foal checked soon after it is born, he says.
Toxins from certain types of bacteria ingested by the foal can compromise the gut wall and leak through into the bloodstream where they start attacking all the organs of the body. The foal soon goes into shock as various organs shut down, and unless treated in the very earliest stages of shock, he generally dies. Once the foal goes into shock, it is very difficult to reverse the condition and have a good outcome.
PRENATAL INFECTIONS – “A foal can also become septicemic before birth–in the uterus–if the mare has an infection. In the first day of life, the foal may suddenly develop a septic joint and the most common way to get the infection that quickly was before birth. The way an unborn foal becomes septicemic is via the bloodstream from the placenta–if the mare has a placentitis. Infection enters the foal’s bloodstream and can travel wherever it wants to go. Those foals are already sick when they are born. They can be very ill and may even act like dummy foals,” Slovis says.
“They seem worse than a typical dummy foal, however, because they have utilized all their energy stores in the uterus, before birth, trying to fight the infection. They are weak and lethargic. They have low glucose levels because they’ve already used up their sugars and they may be dehydrated and have electrolyte imbalances. If you look at them closely after they are born, they may have white blood cells in their eyes–puss in their eyes,” he says.
“The medical term for this is hyphema. This is what we were seeing with the MRLS (mare reproductive loss syndrome) foals. They had white blood cells in their eyes. You can easily see this if you shine a flashlight in the foal’s eye,” says Slovis. If you get a newborn foal like this, you know you are in trouble. Immediate and proper treatment is crucial to save them. Those foals may have only a 50-50 prognosis for survivial, he explains.
EFFECTS OF SEPTICEMIA – Once bacteria gain entrance into the body, they may start releasing toxins depending on the type of bacteria. “The toxins cause hemodynamics dysfunction, which means that suddenly the foal has low blood pressure and is going into septic shock. The body is doing several things to try to protect itself. The blood pressure drops, the heart rate increases, and temperature rises to try to fight off the infection. The foal starts breathing heavily, because of the high fever, to try to dissipate heat. The body starts using a lot of energy for this and the foal becomes weak,” he says. A young foal does not have energy reserves like an older horse. There is very little body fat in the foal.
“The sick foal becomes acidotic because he can’t get proper blood flow to the organs and muscles. Inadequate blood flow creates lactic acidosis, just like in an athlete that has been running hard. The foal can’t get enough oxygen to those tissues. It’s similar to the condition a human may encounter after running a marathon and pushing the body to the limit. What slows the runner down is the build-up of lactic acid, and he may feel weak and dizzy,” Slovis explains.
The sick foal can’t stop ‘running’ (fighting the infection), however, and the decreased blood flow to organs and muscles and the increase in lactic acid creates acidosis. “This causes weakness, and abnormalities in heart rate and intestinal function. At the same time, there is poor circulation to the gut so it shuts down. The foal doesn’t nurse properly. If he tries to nurse, the stomach just fills up because nothing can move on through, so he quits nursing,” says Slovis.
“These foals become impacted, and may suffer damage to the bowel, which causes release of more toxins into the system (toxins can leak through the damaged gut wall into the bloodstream) so this creates a snowball effect. Regardless of the original cause of the infection, now there is an added effect–more toxins released into the body. Bacterial toxins affect the liver and, eventually, the other organs of the body; there is multi-organ failure,” he says.
DIAGNOSIS – If a veterinarian suspects septicemia, bloodwork may help confirm the diagnosis. “If there is a low white blood cell count, we know those blood cells are going somewhere–fighting a battle. We look for electrolyte abnormalities, and look at glucose levels and whether or not the foal is acidotic. At the same time, we take blood cultures, before we give antibiotics, to determine exactly what kind of bacteria we are dealing with,” says Slovis.
“We ultrasound the foal’s chest, abdomen and umbilicus to get an idea where this infection may be coming from. After we do that, we determine the treatment plan using our experience in these kinds of infections,” he says.
TREATMENT – “Whatever route the bacteria entered, the treatment is similar–except if it’s a really bad lung infection. In that instance we may give the foal inhaled antibiotics. If the entry route was the umbilicus, we surgically remove that. In all cases, we give systemic antibiotics,” he says.
“With some foals, we may also give plasma because it is high in antibodies. This might help fight the infection. We also put them on supportive fluids and care. We feed the foal via nasogastric tube or I.V,. giving nutrients and fluid orally or intravenously depending on whether the bowel is functional or not. If the bowel is not working, we feed the foal through the vein (total parenteral nutrition). The fluids will also help reverse shock. Sometimes we give additional medication to try to help increase the blood pressure. It all depends on the individual case, and it’s a very fine line,” he explains.
Antibiotics and supportive care are crucial to recovery. “You just try to keep the body going. But if the infection has a head start and you are behind the 8-ball, it may be a losing battle.”
PREVENTION – “The main thing we recommend for preventing septicemia is a clean environment. This is VERY important. Clean foaling stalls, clean mare, clean hands. Wear gloves when handling foals, wash your hands before handling foals. Don’t let a foal start sucking your clothes. Wash the mare’s udder and hindquarters after foaling. The foal will go right to her hind end and start sucking everything in his search for the udder. When a mare is foaling, she defecates a great deal; there is usually feces all over her hind end. So clean her up and clean her tail,” says Slovis.
Make sure the foal nurses very soon after birth. The mare’s colostrum is very important, to give the foal the antibodies he needs to combat common infections. If the mare has been leaking milk beforehand, have a bottle of good colostrum ready, says
Slovis. Have an emergency supply of frozen colostrum, so that if a mare leaks milk, you can give the foal colostrum by bottle within an hour of birth–to ensure he gets adequate antibodies. A veterinarian can also do a blood test to determine whether or not the foal received enough antibodies or whether his passive immunity should be augmented by other means (such as plasma).
We used to think that a foal could obtain adequate antibody protection if he nursed within the first 2 to 4 hours following birth, but recent studies have shown that this may not be quick enough to protect them from Septic Foal Syndrome (SFS). Dr. John Madigan (UC-Davis) has been studying septic foals for a number of years and has come to the conclusion that foals should have colostrum BEFORE they even try to nurse the mare–to give the best protection against SFS.
“On a farm where we had a large salmonella outbreak, we began this process of getting colostrum into the foals before they nursed the mare, along with washing the mare so she has a clean udder before the foal nurses,” says Madigan. “Having a clean area for the foal to nurse is very important. Once the udder is cleaned up, we milk the mare to get some colostrum, and feed it to him from a bottle while he’s still lying there. Foals take a bottle very readily before they stand up,” he says.
This does not confuse them or keep them from going ahead in their urge to stand up and go find the udder. In fact, having a taste of colostrum stimulates them to want to go find some more.
They don’t know where the milk came from. It stimulates them to get up and go look for the udder. So this was part of our treatment and prevention strategy to protect these foals from early infection with salmonella and it was very effective,” says Madigan.
Don’t get the mare up too soon; let her lie there quietly until she wants to get up. Then, as soon as the mare gets up, go ahead and milk her to feed the foal, he advises. A mare can be very swiftly and easily milked (with less stress on the mare and less risk for being kicked) with the new Udderly EZ© milker pump. Many breeding farms are now using this hand-held trigger operated pump for milking mares since it gets the milk out much more quickly and more comfortably (no friction on the teats) than hand milking, and it keeps the milk a lot cleaner. The collection bottle under the pump can then be poured into a nursing bottle, or a nipple can be put onto the collection bottle to feed the foal.
The studies at UC-Davis showed that early administration of a small amount of colostrum (2 to 8 ounces depending on the size of the foal) before the foal gets up will protect him from SFS. In their studies, the researchers had an 85 percent reduction in death rate in the foals that were given colostrum immediatly after birth.
So Dr. Madigan began recommending hand feeding colostrum before a foal gets up. “This was based on evidence that foals, as they seek the udder, may acquire bacteria that go into the intestinal tract and cross what we call the open gut,” he says. The intestinal lining is permeable for a short time, to allow the large molecules of antibodies in colostrum to slip through, but it also enables bacteria to go through. When a foal is born, it’s a race between the pathogens and the antibodies. This simple act of feeding him colostrum before he gets up and starts nuzzling around the mare or the stall walls gets the colostrum into the gut ahead of the bacteria. The antibodies stimulate systemic immunity and also give local protection within the gut to fight off the pathogens ingested by the foal in his attempt to find the udder.
If the “good guys” (antibodies) get to the gut first, they close the door to the pathogens that cause disease preventing the penetration of the gut lining by bacteria and their toxis. “It has been shown in experimental models in other species that absorption of antibodies from colostrum inhibits what’s called bacterial translocation (movement of bacteria through the gut lining and into the bloodstream),” explains Madigan. “Colostrum not only supplies IgG antibodies that go through into the bloodstream but also provides a local antibody, IgA, which stays in the gut to give local protection. There’s enough evidence in experimental literature to say that colostrum prevents and reduces bacterial translocation in foals as well,” says Madigan.
The protective antibodies shut down the permeability of the gut to any other large molecules so the bacterial toxins can’t get through. Mother Nature has things pretty well-programmed to protect the newborn foal. “If, however, the foal is slow to nurse (or licks the ground or contaminated objects before he nurses), he’s at risk,” says Madigan.
“If he is weak or short on oxygen at birth, or has angular limb problems or any other situation that makes him slow to get up, or the mare has a tender udder and kicks at him–anything that delays his first nursing–this can interfere with protection. If the foal is slow to find the udder and is hungry and licking on everything, he is at risk for bacterial translocation,” explains Madigan. “It pays to intervene–and feed the foal colostrum immediately.”
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