Abomasal erosions in feedlot cattle.

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 red-brown 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.

Association of bovine respiratory syncytial virus with atypical interstitial pneumonia in feedlot cattle.

Thirty-three cattle with fatal respiratory tract disease were examined for gross and histologic lesions and for the presence of viral and bacterial agents in the lungs. Fifteen cattle had lesions characteristic of atypical interstitial pneumonia (AIP), and 18 had other respiratory tract diseases, including infectious bovine rhinotracheitis, shipping fever pneumonia, bronchopneumonia, pulmonary abscess, and edema of the trachea. Gross necropsy findings in the cattle with AIP were uncollapsed and emphysematous lungs; histopathologic findings included interstitial edema, thickening of alveolar walls, hyaline membrane formation, and hyperplasia of type-II pneumonocytes. The infective agents found in the lungs of the 33 cattle included bovine respiratory syncytial virus, bovine herpesvirus type 1, Pasteurella sp, mycoplasmas, and Corynebacterium pyogenes. Bovine respiratory syncytial virus was detected by use of immunofluorescence and immunoperoxidase on lung tissue sections; bovine herpesvirus type 1 was detected by these techniques and by isolation of the virus. Bovine respiratory syncytial virus was significantly (P = 0.01) associated with lesions of AIP (11 of 15), compared with those of other respiratory tract diseases (5 of 18).

Eosinophilic myositis and muscular sarcocystosis in the carcasses of slaughtered cattle and lambs.

Fifty-three bovine and 7 ovine carcasses condemned for having eosinophilic myositis were evaluated. Four (7.3%) of the bovine carcasses had a few, large local lesions in skeletal muscles (category A), and 49 (92.7%) of the bovine carcasses and 7 (100%) of the ovine carcasses had multiple, small, disseminated lesions in tongue, esophagus, heart, diaphragm, or skeletal muscles (category B). Tissue from carcasses of category B were evaluated for bacteria, viruses, selenium, and pathologic changes. Pathogenic bacteria and viruses were not isolated and selenium concentrations were normal. In category B, all carcasses had granulomas; of the 49 bovine carcasses and 7 ovine carcasses, 38 (77.6%) and 7 (100%), respectively, had one or more granulomas with opened dead sarcocysts. The data indicated that opened sarcocysts killed the host myocyte and adjacent myocytes and stroma, thereby initiating granuloma formation.

Cause and pathogenesis of middle ear infection in young feedlot cattle.

Two populations of feedlot cattle--weaned calves and yearlings--suffered otitis media. In calves the disease was acute and epizootic and had a prevalence of about 400 cases per 2000 cattle, whereas in yearlings, it was chronic and sporadic and had a prevalence of 1 case per 2000 cattle. Clinical signs were facial paralysis, otorrhea, and head tilt. The middle ears from 64 dead calves and 22 dead yearlings were examined. Calf ears had acute infection, with exudate in air cells and rupture of tympanic membranes. Yearling ears had chronic infection, with exudate in air cells, rupture or destruction of tympanic membranes, and necrosis of air cell partitions. Mixtures of Pasteurella multocida and Corynebacterium pseudotuberculosis were isolated from diseased ears, but Pasteurella multocida predominated in acute infections and Corynebacterium pseudotuberculosis predominated in chronic infections.

Ischemia: a cause of hepatic telangiectasis in cattle.

We histologically examined (i) 73 bovine livers condemned by packing house inspectors for telangiectasis, (ii) 15 bovine livers passed by the same inspectors as normal, and (iii) 8 livers from cattle given an injection into their mesenteric veins: 6 with a suspension of agar particles containing viable Haemophilus somnus and 2 with diluent only. The injected cattle were killed and necropsied 2 to 12 days after the inoculations. Of the 73 telangiectatic livers, 57 (78%) had thrombosed and occluded or contracted and empty portal veins (venopathies), whereas 1 of the 15 normal livers contained one microscopic focus of telangiectasis and nearby venopathy. Of the 6 livers injected with suspended particles, all had venopathies and telangiectasis and the 2 control livers had neither.

Osteochondrosis in feedlot cattle.

Beginning in summer 1977 and continuing through four consecutive seasons, we examined lame limb joints from 106 partially fattened cattle and 28,235 pairs of occipital condyles from fully fattened cattle for osteochondrosis. Of the 106 lame cattle, nine (8.5%) had characteristic lesions, usually in their stifle joints, and of the 28,235 atlanto-occipital joints, 1063 (3.8%) had lesions on their condyles. Slices of affected articular cartilage and subjacent bone were studied radiographically and histologically. Radiographs showed subchondral defects and epiphyseal "cyst-like" lesions, and histologic sections showed disarrayed and degenerated chondrocytes. Splits occurred along osteochondral junctions or in adjacent cartilage or bone. Some bone trabeculae had been replaced by fibrous tissue that, in some areas, extended deep into epiphyses.

Laryngeal diphtheria and papillomatosis in feedlot cattle.

In a random sample of 30,444 larynges from slaughtered beef cattle, 441 (1.4%) had chronic diphtheria and 1,345 (4.4%) had papillomatosis. Both types of lesions were centered in mucous membranes over the vocal processes and medial angles of the arytenoid cartilages. Since they are found in the same anatomical locations as laryngeal contact ulcers, we hypothesize that ulcers are primary and diphtheria and papillomatosis are secondary.

Laryngeal contact ulcers in feedlot cattle.

Of 30,444 larynges from fattened cattle at three companies, 3,985 (13.1%) had contact ulcers or ulcer scars in the mucous membranes over the vocal processes and medial angles of the arytenoid cartilages. The incidence was higher in cattle fed during fall than in cattle fed during other seasons. We hypothesize: 1. that some feedlot cattle develop acute mucositis from mixed infections with species of Pasteurella, Haemophilus, Mycoplasma, and viruses in the nose, pharynx, and larynx; 2. that reflex coughing and swallowing accelerate the rate of larynx closure; and 3. that the closures erode the swollen membrane over the vocal processes and medial angles of the arytenoid cartilages and thus produce primary contact ulcers.

Limb arthropathies and periarticular injuries in feedlot cattle.

Beginning summer 1977 and continuing through 4 consecutive seasons, we examined samples of at least 25, and a total of 106, lame limbs or joints from slaughtered beef cattle. Of this number about 64 (60%) were articular and 42 (40%) periarticular lesions. Fifty-three were caused by trauma and 9 by osteochondrosis. Stifle joints (40) and digital joints (19) were the most frequently affected articulations, and the humerus and femur were the most frequently fractured bones. Twenty joints, mostly stifles, had fibrinous arthritis, and Mycoplasma spp. were isolated from 11.