Tri-State Neighbor: South Dakota Farm Newspaper

About half of dairy producers across the country have come across at least one case of hemorrhagic bowel syndrome (HBS) in their dairy herd.

That is according to Robert Callan, Colorado State University associate professor in the school's College of Veterinary Medicine and Biomedical Sciences. He recently spoke at the Central Plains Dairy Expo in Sioux Falls, S.D.

"That's consistent with what we see in feedback when we go to meetings as well as feedback on some of the national surveys, that about half of the producers have seen at least one case of hemorrhagic bowel syndrome," he said.

Callan has been researching the disease with other researchers at CSU and says that many questions remain on what exactly causes the disease.

HBS may also be known as jejunal hemorrhage syndrome, bloody gut syndrome or dead gut syndrome. HBS may be segmental or diffuse. Either the animal will have a specific section of bowel or a wider generalized section of the bowel will be affected. The hemorrhage that occurs is an intraluminal hemorrhage in the small intestine.

"This hemorrhage that collects in that area forms a clot and that clot then results in obstruction of the intestinal tract," Callan said. "Then we also see associated necrosis with the intestinal tract."

The incidence of HBS is low in most dairies - generally less than 1 percent of the animals in a herd. It is most often seen in lactating cattle and usually within the first 90 days of lactation. The disease usually comes on fast and is most oftentimes fatal.

The first published report of HBS was in 1991. The number of cases across the country has increased steadily since then.

Animals with HBS usually show abdominal distension because of the obstruction in the GI tract. Callan says fluid builds up in the intestine and the cows start getting some abdominal distension.

"They may have dark or clotted blood in their feces. This is a very helpful sign that helps you differentiate this disease from some other diseases like salmonella," Callan said.

After about 24 hours of the obstruction, feces that are past the obstruction will pass out of the animal, but anything before that obstruction will not pass. Animals with HBS will also be in systemic shock because they are collecting blood in the GI tract. They will appear dehydrated and their extremities will be cool.

"They may have pale mucus membranes. A lot of people think they have pale mucus membranes because they bled into the intestine, but actually their amount of red blood cells in the blood is still up in the normal range," Callan said. "The reason they have pale mucus membranes is because they're in shock."

Oftentimes, veterinarians will do a rectal palpation or ultrasound the animal in these cases. An ultrasound allows them to visualize the small intestine. What will often be seen is the loops of small intestine will be distended to more than 4 centimeters in diameter. Normal bowel should be 1 to 2 centimeters in diameter.

If an animal has HBS, there are limited things that can be done. Surgery is possible but there is still a high mortality rate.

"The reason is is because you go in and try to resolve the obstruction and we clear everything out, suture things back together, close things on up. Often we get hemorrhage back into the same spot or a more proximal spot from the area where we did surgery and it re-obstructs," he said.

In early research performed at CSU, they looked at 34 cases of HBS for organisms that were related to or caused the disease. When they tried to culture Clostridium perfringens, they cultured the organism in 32 out of 34 cases and they cultured it at very high levels.

However, more research at Oregon State University shows that a fungus, Aspergillus fumigatus, may also be associated with HBS. The fungus is an opportunistic pathogen that can generate into an animal's body and multiply, causing considerable disease in those individuals.

Callan says that there may be other contributing factors to the disease as well.

"Fundamentally it is my belief and I think a lot of other people's belief that HBS really is a management and nutritional disease," he said. "The management factors and the nutritional factors that lead to issues with immunal suppression, that lead to issues with GI motility and passage of ingesta, issues with carbohydrate passage into the small intestine that may allow Clostridial growth, could also lead to exposure to Aspergillus fumigatus in feed.

"It is really believed that there's a strong factor of the ration, an effect of possibly pasture grazing, dairy size is involved in this and the type of management practices that they have and how they may effect stress and the digestive properties of cattle as well as the environment. Fundamentally, these are the types of things that really originate the disease of hemorrhagic bowel syndrome," Callan said.