rumen, reticulum, omasum

keratinizing stratified squamous epithelial lining

• protects ruminant forestomach from xenobiotics and coarse ingested materials

• unlike the abomasum, these forestomachs lack a secretory apparatus but still absorb volatile fatty acids

• the presence of “normal” flora and alkaline pH helps prevent pathogen colonization and growth

primary (frothy) bloat/tympany

• persistent foam traps fermentation gases in the rumen, preventing normal eructation

• develops after dietary change, especially with lush legumes or highly fermentable feeds

• lesion often difficult to detect if there is interval between actual death and postmortem examination

bloat line

• most reliable postmortem indicator of ante-mortem bloat

• caused by compromised venous return due to a distended rumen

• displaces diaphragm cranially, increasing intrathoracic pressure

• prevents venous blood flow into the thorax

secondary (free-gas) bloat/tympany

• gas accumulates as free gas separate from the ingesta because the animal cannot eructate normally

• result from physical obstruction of the esophagus, such as foreign bodies, papilloma, lymphoma, or enlarged lymph nodes, or from functional disorders such as vagus indigestion and other neurologic or motility disturbances

rumenitis

• inflammation of the rumen, synonymous with lactic acidosis with rumen overload, carbohydrate engorgement, and chemical rumenitis.

• death due to dehydration, acidosis, and circulatory collapse

• bacteria

  • Actinobacterium pyogenes

  • Fusobacterium necrophorum

mycotic rumenitis, rumen, calf

numerous well demarcated red foci of necrosis and hemorrhages (infarcts) in the ruminal mucosa that can be caused by angioinvasive fungi such as Aspergillus, Mucor, Rhizopus, Absidia, and Mortiriella sp.

paramphistomiasis

• fluke infection of ruminants

• adult flukes are usually harmless, but heavy larval infection in the small intestine can cause anemia, hypoproteinemia, and death