What is the pathogenesis of traumatic reticuloperitonis in a pregnant cow?

Answer 1

For those of you how don't know and need a layman's term for Traumatic Reticuloperitonis, it's Hardware Disease, where a piece of metal has punctured the wall of the reticulum chamber in the cow's stomach.

From the Merck Veterinary Manual (see link below):

"The initial attack is characterized by sudden onset of ruminoreticular atony and a sharp fall in milk production. Fecal output is decreased. The rectal temperature is often mildly increased. The heart rate is normal or slightly increased, and respiration is usually shallow and rapid. Initially, the cow exhibits an arched back; an anxious expression; a reluctance to move; and an uneasy, careful gait. Forced sudden movements as well as defecating, urinating, lying down, getting up, and stepping over barriers may be accompanied by groaning. A grunt may be elicited by applying pressure to the xiphoid or by elevating this area firmly and then pinching the withers, which causes extension of the thorax and lower abdomen. The grunt can be detected by placing a stethoscope over the trachea and applying pressure or pinching the withers at the end of an inspiration. Tremor of the triceps and abduction of the elbow may be seen.

"In chronic cases, feed intake and fecal output are reduced, and milk production remains low. Signs of cranial abdominal pain become less apparent, and the rectal temperature usually returns to normal as the acute inflammation subsides and peritoneal contamination is walled off. Some cattle develop chronic vagal indigestion, possibly due to the adhesions that form after foreign body perforation, particularly those on the ventromedial reticulum.

"Cows with pleuritis or pericarditis due to foreign body perforation usually are depressed, tachycardic (>90 bpm), and pyrexic (104°F [40°C]). Pleuritis is manifest by fast, shallow respiration; muffled lung sounds; and possibly pleuritic friction rubs. Thoracentesis may yield several liters of fluid. Traumatic pericarditis usually is characterized by muffled heart sounds, possibly with pericardial friction rubs, and occasionally by gas and fluid splashing sounds on auscultation. This has been described as a washing machine murmur. Jugular vein distention with a pronounced jugular pulse is present early in the course, and congestive heart failure with marked submandibular and brisket edema is a frequent sequela. Prognosis is grave with these complications. Penetration through the myocardium usually results in extensive hemorrhage into the pericardial sac and sudden death."

As far as pregnant cows is concerned, a sudden infection like this may either kill the calf, cause the cow to abort her calf, or, as a result of the death of the cow, the calf would die as well from the infection flowing in the blood vessels.