Salmonellosis in Sheep: Diarrhea, Septicemia, and Abortion

Salmonellosis is an infection caused by Salmonella bacteria. In sheep, it can affect the intestinal tract, the bloodstream, or the reproductive tract. That means one flock may show diarrhea and dehydration, while another may have weak lambs, septicemia, or a cluster of late-gestation abortions.

Clinical signs can develop quickly. Merck notes that salmonellosis in sheep can cause diarrhea in animals of any age, and outbreaks may occur late in pregnancy with abortion as a common feature. Some serotypes are more closely linked with abortion, while others are more often associated with enteritis and systemic illness.

This is also a public health concern. Salmonella can spread to people through manure, contaminated bedding, feed areas, placentas, fetal tissues, and birth fluids. For that reason, sick sheep and any aborted materials should be handled carefully, and your vet may recommend immediate isolation and flock-level biosecurity steps.

Salmonellosis is caused by infection with Salmonella enterica bacteria. In sheep, reported abortion-associated serotypes include S Abortusovis, S Dublin, S Typhimurium, and S Arizona, with S Abortusovis reported in Europe but not reported in the United States in Merck's review. Other serotypes can also cause intestinal disease and septicemia.

Sheep usually become infected by swallowing bacteria from contaminated feces, feed, water, bedding, or the environment. Aborted fetuses, placentas, and uterine discharges can contain large numbers of organisms, so lambing areas can become heavily contaminated during an outbreak. Rodents, wildlife, contaminated equipment, and movement of animals between groups may also contribute.

Stress matters. Merck notes salmonellosis is more common when sheep are intensively congregated or stressed, including after shipping. Late pregnancy, poor weather, nutritional strain, overcrowding, and concurrent disease can all lower resistance and make an outbreak more likely.

Not every exposed sheep becomes obviously ill. Some animals may shed bacteria and contaminate the environment before the problem is recognized, which is why flock-level management is often as important as treating the individual patient.

Your vet will start with the history, the number of animals affected, pregnancy status, recent stressors, and the pattern of diarrhea, fever, weakness, or abortion. Because salmonellosis can look like coccidiosis, listeriosis, campylobacteriosis, clostridial disease, grain overload, or other causes of enteritis and abortion, testing is important.

Diagnosis is usually based on culture or detection of Salmonella from feces, blood, or tissues in an animal with compatible signs. In abortion cases, Merck and Cornell both emphasize submitting placenta, fetal tissues, uterine discharge, and blood from the dam when possible. Your vet may also recommend CBC/chemistry testing to assess dehydration, inflammation, electrolyte changes, and evidence of sepsis.

A single test does not answer every question in a flock outbreak. Your vet may advise testing more than one animal, especially if some have diarrhea and others have aborted. Necropsy of a freshly dead lamb or fetus can also be very helpful when the diagnosis is unclear.

Because Salmonella is zoonotic and may have flock-wide implications, your vet may pair diagnostic testing with immediate isolation, manure control, and handling precautions rather than waiting for final culture results.

Prevention starts with biosecurity and sanitation. Keep feed and water as clean as possible, elevate feeders when practical, reduce fecal contamination in high-traffic areas, and clean lambing spaces between animals. Cornell also recommends isolating aborting females and completely disposing of materials associated with aborted and normal births, including placentas and dead lambs, using appropriate local methods.

Try to reduce predictable stressors. Overcrowding, shipping, abrupt grouping changes, poor weather exposure, and nutritional strain can all increase risk. Late-pregnant ewes deserve especially careful management because salmonellosis outbreaks in this group may be accompanied by abortion.

Rodent control, equipment hygiene, and traffic control matter too. Buckets, boots, sleeves, and handling tools can move manure and birth fluids from one pen to another. If one sheep aborts or develops severe diarrhea, separate that animal promptly and contact your vet before the problem spreads.

Because Salmonella is zoonotic, people should wear gloves when handling sick sheep, manure, placentas, or aborted fetuses, then wash hands thoroughly afterward. Pregnant people, children, older adults, and anyone with a weakened immune system should be especially cautious around suspect cases and contaminated lambing areas.