Equine Neonatal Septicemia

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Equine Neonatal Septicemia

By: Dr. Mary Rose Paradis

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Section: Overview

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Septicemia is a systemic disease associated with the presence and persistence of bacteria and their toxins in the blood eventually leading to septic shock. The word septicemia literally means bacterial invasion of the blood, and it arises from a seat of infection somewhere in the body. Once a local infection opens the door for bacteria to enter the bloodstream, they travel throughout the body. This widens the circle of infection and tissue damage.

For instance, infection of the navel (umbilicus) facilitates the movement of bacteria into the blood, which then relocate to the lung causing pneumonia. Bacteria also release toxins (chemical poisons) that cause further complications, on their own. Thus, septicemia is a complex process initiated by bacterial infection and perpetuated by the spread of those bacteria and toxins to cause dysfunction and even failure of multiple organs, including the kidneys, liver, joints and lungs.

Septicemia is an important disease of neonatal (less than 14 days of age) foals. Thirty-three percent of neonatal deaths can be attributed to septicemia. In one study of 160 neonatal foals hospitalized for various reasons, septicemia was the second most common problem diagnosed. It was surpassed only by the problem of inadequate transfer of maternal antibodies from the dam's colostrum.

The foal can be exposed to bacteria in many ways. The exposure may take place while the foal is still in the mare's uterus. This is generally a consequence of the mare developing an infection of the placenta near the end of her pregnancy. Infection can also come through the blood of the mare to the fetus if the mare is severely ill (e.g. with septicemia) before birth or parturition. The foal can also get infected when exiting the birth canal. Infections that occur after the foal is born are commonly promoted by failure of the foal to get antibodies from the mare. This is called failure of passive transfer. The bacteria gain entry to the foal by inhalation, ingestion, and contamination of the umbilical stump and through wounds.

The clinical signs of septicemia are variable. They range the full spectrum from mild depression to shock and death. It is often difficult to identify the foal in the beginning of the illness. Early identification is essential in the prevention of the progression of the problem into irreversible shock. Foals usually start out with mild to moderate depression, decreased suckling frequency, and sleepiness, loss of energy, or weakness.

Because the bacteria are in the bloodstream, they can travel and settle in various organ systems causing local system infection or failure. One foal may have more than one system affected at the same time. Some of the body systems that are most affected include the following:

Respiratory system. Pneumonia is one of the most common sites of infection with approximately 50 percent of the septic foals presenting with respiratory signs.

Gastrointestinal system. Enteritis/diarrhea is the second most common manifestation of sepsis.

Musculoskeletal system. Bone (osteomyelitis) and joint infection (septic arthritis) occur when the bacteria invade the growth plate of the bone or the lining of the joint (synovial membrane).

Nervous system. Meningitis (infection of the meninges of the brain) has a very poor prognosis for life.

Umbilical structures. Infections of the umbilical structures are often not apparent from the exterior of the body.

What to Watch For

It is not difficult to diagnose the foal that is in septic shock. These young animals are generally severely depressed to comatose. Their legs are cold and it is difficult to find a pulse. The challenge comes in diagnosing foals that are only beginning to show subtle signs of depression. Early signs include:

Signs of depression

Foal lying down more than normal

Mare's udder is distended with milk

Diagnosis

To recognize the early stages of sepsis, your veterinarian will attempt to get clues from a thorough perinatal history, that period shortly before and after birth, and a physical examination. This information is supplemented with some blood work, which will include a complete blood count, a serum immunoglobulin level and blood glucose. Additional blood work that is helpful if available is a blood culture, an arterial blood gas analysis, serum electrolytes and chest radiographs.

Treatment

Once septicemia is suspected then treatment should start immediately. Care can be quite intensive and may require that the foal be sent to a hospital that has the ability to monitor the foal 24 hours a day. The general treatment of a septic foal should include:

Immunologic support. Foals with failure of passive transfer of maternal antibodies need to be provided with some protective antibodies. This is usually accomplished through a plasma transfusion.

Antibiotic support. Antibiotics are used to help kill the bacteria that are causing the signs of septicemia. Any number of bacteria in the foal's environment can cause septicemia. Because you can't delay treatment until you identify causative bacteria, your veterinarian will place the foal on an antibiotic or combination of antibiotics that will kill the majority of bacteria involved.

Shock treatment. Foals that are already in shock will need intravenous fluids to support their circulation.

Nutritional support. Many septic foals are too depressed and sick to eat. Your veterinarian may need to feed the foal hourly or every two hours through a nasogastric tube.

Home Care and Prevention

Home care begins with prevention of septicemia. Because the largest risk factor for the development of septicemia is failure of passive transfer, owners should be extremely observant of the late pregnant mares. Any leakage of milk from the udder before the foal is born is cause for concern. High quality colostrum gives the newborn foal the tools to fight most normal bacterial contamination at birth.

It is important for owners to be present at the time of foaling as well. The mare may have excellent colostrum, but if the foal does not stand and nurse within three hours of foaling, the bacteria will have a chance of establishing residence before the foal has a chance to build his defenses. At the time of foaling, owners should disinfect the foal's umbilicus. The umbilicus can be a portal of entry to the environmental bacteria. Because ingestion is also a way that bacteria can invade a foal's systems, cleaning of the mare's udder and hind legs with a light disinfectant or soap may reduce the number of bacteria that the foal's are exposed to at birth.

Next to prevention, early recognition of septicemia is the next best thing that owners can do. The first sign of a bacterial infection in a foal may be that he is not as active as other foals. You may see him lying down more than he should. The mare's udder may be distended indicating that he is not drinking as much milk as he should. If you have any concerns about the health or behavior of the foal, insist that your veterinarian check the foal out as soon as possible. Septicemia is an emergency.

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