Abomasitis in Sheep: Stomach Inflammation in Lambs and Adults

Abomasitis means inflammation of the abomasum, which is the "true stomach" in sheep. This part of the digestive tract produces acid and enzymes to break down milk in lambs and feed in older sheep. When the abomasum becomes inflamed, it may fill with fluid or gas, stop moving normally, and become painful. In severe cases, toxins from bacteria can enter the bloodstream and cause shock or sudden death.

In lambs, abomasitis is often discussed alongside abomasal bloat or clostridial stomach disease. These cases may be linked to overfeeding, inconsistent milk replacer mixing, poor feeding hygiene, or bacterial overgrowth. In adult sheep, inflammation of the abomasal wall can also occur with clostridial disease such as braxy, a rapidly fatal form associated with Clostridium septicum.

This is not a condition pet parents should try to sort out alone. Several other sheep diseases can look similar at first, including enterotoxemia, watery mouth in newborn lambs, coccidiosis, intestinal obstruction, and severe parasitism. Your vet may need to examine the sheep, review feeding and flock history, and sometimes recommend necropsy or lab testing to identify the cause and protect the rest of the flock.

The outlook depends on how fast signs are recognized and what is driving the inflammation. Mild cases may respond to supportive care, while toxin-producing bacterial disease can progress within hours.

Abomasitis has more than one cause, and the age of the sheep matters. In young lambs, one major pattern is bacterial overgrowth in the abomasum with gas buildup, often called abomasal bloat. Risk factors include large milk meals, infrequent feeding, poor nipple or bucket hygiene, improperly mixed milk replacer, and feeding systems that let lambs gulp too much milk too quickly. Merck notes that feeding small amounts more often helps reduce bloat and diarrhea risk in lambs.

Another important cause is clostridial disease. Clostridium perfringens is associated with enterotoxemia in lambs, especially when there is heavy milk intake or sudden access to rich feed or grain. Merck also describes braxy in sheep, a highly fatal disease caused by Clostridium septicum that involves inflammation of the abomasal wall and toxemia. Although braxy is classically described in some grazing systems, clostridial disease remains part of the differential diagnosis whenever sheep show sudden digestive collapse or unexplained death.

Less common contributors can include parasites, other bacterial infections, severe dietary upset, and management stress. In some sheep, abomasal inflammation may be part of a broader digestive disease rather than a stand-alone diagnosis. That is why your vet will usually look at feeding practices, age group affected, vaccination history, recent ration changes, weather stress, and whether deaths are isolated or happening in a cluster.

Because several causes overlap, treatment is not one-size-fits-all. A lamb with feeding-related abomasal bloat may need a different plan than an adult sheep in a flock with suspected clostridial disease.

Your vet usually starts with the basics: age, feeding program, vaccination status, recent ration changes, and how quickly signs developed. On exam, they may look for abdominal distension, dehydration, pain, weakness, temperature changes, and evidence of shock. In lambs, the feeding setup matters a lot, including milk replacer type, mixing accuracy, meal size, and sanitation of bottles, nipples, or automatic feeders.

Diagnosis is often based on a combination of history, physical exam, and response to treatment, but testing may be needed when the case is severe or multiple sheep are affected. Depending on the situation, your vet may recommend fecal testing, bloodwork, or sampling for bacterial culture. In sudden-death cases, necropsy is often the most useful tool because it can show an inflamed or gas-distended abomasum, excess feed or milk in the stomach, intestinal lesions, or changes that support clostridial disease.

Merck notes that clostridial causes may be supported with tissue smears, fluorescent-antibody testing, PCR, immunohistochemistry, or anaerobic culture, especially when Clostridium septicum is suspected. Timing matters. Postmortem bacterial invasion can make late samples harder to interpret, so fresh samples and prompt necropsy improve the odds of a useful answer.

A clear diagnosis helps your vet do two things at once: treat the sick sheep in front of you and reduce risk for the rest of the flock. That may mean changing feeding practices, reviewing vaccination timing, or watching closely for additional cases.

Prevention starts with consistent feeding management. For bottle or artificially raised lambs, avoid oversized meals, abrupt formula changes, and poorly mixed milk replacer. Clean bottles, nipples, buckets, and mixing tools thoroughly. Merck advises feeding small quantities more often, and notes that calf milk replacer can increase digestive problems in lambs because it has more lactose than sheep milk. Fresh water and age-appropriate creep feed should also be introduced thoughtfully.

For older lambs and adults, make ration changes gradually. Sudden access to rich milk, lush pasture, or high-carbohydrate grain can increase risk for clostridial digestive disease. Keep feed storage dry and clean, reduce crowding and stress where possible, and work with your vet on parasite control and general flock health planning.

Vaccination is an important prevention tool for clostridial disease. Merck recommends that breeding ewes receive a booster for type D toxoid 4 to 6 weeks before lambing after the initial series is established. Cornell sheep resources also support vaccinating ewes in late gestation so lambs receive better early protection through colostrum. Your vet can help tailor the schedule to your flock, local disease patterns, and the products you use.

If you lose a lamb or ewe suddenly, consider prompt necropsy rather than guessing. A fast answer can help protect the rest of the flock and may prevent repeated losses during the same lambing or feeding season.