A hospital-based case-control study was conducted to evaluate and compare risk factors for abomasal volvulus (AV) and left displaced abomasum (LDA) in cattle. Medical record abstracts were derived from 17 North American veterinary schools by the Veterinary Medical Data Program for all cattle admitted between Jan 1, 1977 and Dec 31, 1986, and for those with a diagnosis of AV or LDA. From a total of 108,956 individual cattle records, 1,036 cases of AV and 7,695 cases of LDA were identified, with a ratio of LDA to AV cases of 7.4 to 1. In-hospital mortality was 23.5% for AV and 5.6% for LDA. Age, breed, gender, and season each had significant (P < 0.05) effects on risk for AV and LDA. Risk for AV and LDA increased with increasing age, with greater risk in cattle aged 4 to 7 years. Dairy cattle were at higher risk of developing AV (adjusted odds ratio, 36.4) and LDA (adjusted odds ratio, 95.2) than were beef cattle. The odds of AV in Brown Swiss cattle were significantly (P < 0.0001) lower, and the odds of LDA in Guernsey cattle were significantly (P < 0.0001) higher than those in Holstein cattle. Female cattle were also at higher risk of developing AV (adjusted odds ratio, 3.3) and LDA (adjusted odds ratio, 29.1) than were male cattle. The odds of AV and LDA varied considerably throughout the year, with the lowest number of cases observed in autumn. Seasonal development of AV differed significantly (P < 0.0001) from that Of LDA, with the odds of AV and LDA being highest in January and March, respectively. The medical records for all cattle with AV and LDA examined at the teaching hospital over a 10- and 5-year period, respectively, were reviewed, and the time interval since parturition, as well as the existence and nature of concurrent disease, were recorded. Proportionately fewer cases of AV than LDA developed during the first 2 weeks after parturition (28.3% of AV cases vs. 57.0% of LDA cases). Concurrent disease existed in 30.4% of AV cases and 53.6% of LDA cases, with the rates of concurrent disease differing significantly (P < 0.0001) between the 2 groups. The misclassification rate for data generated at the teaching hospital was estimated to be 6.5% for AV and 5.3% for LDA. On the basis of the findings of this study, we hypothesize that: abomasal atony is a prerequisite for AV and LDA; existence of an abdominal void immediately after parturition facilitates development of AV and LDA; normal rumen volume provides a moderately effective barrier against LDA; risk of LDA does not increase appreciably with advancing pregnancy; and the direction of abomasal displacement (AV or LDA) after abomasal atony and dilation is influenced principally by rumen volume.

Sixteen nonsibling sheep, approximately 12 months old, that were raised in a helminth-free environment, were used for 2 protection studies 6 months apart. Sheep were vaccinated weekly for 5 weeks by IM injection of fibrinogen-degrading proteins derived from the intestinal tract of adult Haemonchus contortus. Ten days after the last vaccination, sheep were given 2,500 infective H contortus larvae by intraruminal injection. Vaccinated sheep produced specific antibodies, and were protected from the worm challenge. Significant differences in mean fecal worm egg counts for 56 days after worm challenge, in mean numbers of H contortus worms, and female fecundity ratios at necropsy were detected in vaccinated sheep, compared with those in control sheep. These data suggest that the fibrinogen-degrading proteins have a protective role in vaccination of sheep against H contortus.

The abomasa of 1,949 slaughtered feedlot cattle, 45 necropsied feedlot cattle that died 2 to 45 days after arrival, and 45 necropsied pastured cattle were opened and examined. Of these organs, 484, 1, and none, respectively, contained erosions. The slaughtered cattle were fattened at 3 locations: 1,305 with 430 eroded abomasa were fed a ration of corn in northeastern Colorado; 144 cattle with 4 affected abomasa fed a ration of milo in south-central Arizona; and 500 cattle with 50 affected abomasa fed a ration of milo and corn in northwestern Texas. The redbrown lesions developed late during the second semester of fattening and were located mostly on fundic folds. Those on fold edges were linear and were 2 to 15 cm long, whereas those on fold sides were punctate and were 2 to 15 mm in diameter. Normal fold edges contained fewer goblet cells and less surface mucus than did fold sides. Eroded folds had disruption of surface epithelium, damage to endothelial cells, and dilated, thrombosed, congested, and ruptured capillaries. Mean pH values of 16 normal and 17 eroded abomasa were 4.7 and 3.9, respectively. Necrosis of all tissue toward the mucosal surface of erosions was extensive. The cause of gastric erosion in cattle is not known.