Granuloma development in cattle after intratonsilar inoculation with Mycobacterium bovis.

OBJECTIVE: To examine the temporal development of tuberculous lesions in cattle inoculated with Mycobacterium bovis. ANIMALS: 15 mature crossbred cows obtained from a herd with no history of M bovis infection. PROCEDURE: Inoculation of cattle was done by intratonsilar instillation of 1.48 X 10(5) to 5.4 X 10(7) colony-forming units of M bovis strain 2045T. At 3 to 4 hours, 4 weeks, 6 weeks, and 8 weeks after inoculation, tissues were examined for gross and microscopic lesions and processed for isolation of M bovis. RESULTS: Retropharyngeal lymph nodes from cattle examined 4 weeks after inoculation contained microgranulomas consisting of aggregates of macrophages with few neutrophils. Retropharyngeal lymph nodes from all cattle examined 6 and 8 weeks after inoculation contained multiple, large, coalescing granulomas consisting of central areas of necrosis with mild fibrosis, numerous macrophages, lymphocytes, plasma cells, multinucleated giant cells, and neutrophils. Three of 8 cattle examined 6 or 8 weeks after inoculation had lesions in nonretropharyngeal sites with morphologic characteristics similar to that seen in retropharyngeal lymph node granulomas from cattle examined 4 weeks after inoculation. CONCLUSION: Granulomas can develop in draining lymph nodes of cattle in as little as 4 weeks after inoculation via intratonsilar instillation of M bovis. Intralesional morphologic changes between 4 and 6 weeks after inoculation indicate an increase in cellular chemotaxis and differentiation. Dissemination of bacteria to distant sites most likely was by lymphatic and hematogenous routes after establishment of the primary infection in retropharyngeal lymph nodes.

Seminal vesiculitis and orchitis caused by Brucella abortus biovar 1 in young bison bulls from South Dakota.

Specimens of blood, lymph nodes, spleens, and genitalia were collected at slaughter from seven 3- and 4-year-old male bison that had recently become seropositive for brucellosis. The animals were from a captive herd of approximately 3,500 bison located in central South Dakota. Brucella abortus biovar 1 was isolated from 2 or more specimens from each of 6 bison. Severe necrotizing and pyogranulomatous orchitis was present in 1 testicle from 1 bull, and 4 animals had mild to marked seminal vesiculitis. Immunohistochemical staining labeled organisms in seminal vesicles and the testicle with orchitis. Ultrastructurally, intact bacilli were present in cytoplasmic vacuoles of some macrophages; other macrophages contained intracytoplasmic aggregates of calcified coccobacilli.

Survey of free-ranging elk from Wyoming and Montana for selected pathogens.

From December 1991 through January 1995, a disease survey was conducted on herds of free-ranging, hunter-killed elk (Cervus elaphus nelsoni) from three areas in proximity to Yellowstone National Park (YNP), Wyoming (USA), after tuberculosis caused by Mycobacterium bovis was discovered in a captive herd of elk in the area. Complete or partial sets of specimens from 289 elk collected between December 1991 and January 1993 were examined histologically; no mycobacterial lesions were observed. Lesions of tuberculosis were not detected in tonsils or lymph nodes of the head from an additional 99 hunter-killed, adult elk from one area (area 2) collected in January 1995. Neither M. bovis nor M. paratuberculosis were isolated from any of the specimens cultured. Antibodies to Brucella abortus were detected in serum samples from 0%, 1%, and 1% of elk from three areas sampled (areas 1, 2 and 3), respectively. Brucella abortus biovar 1 was isolated from multiple tissues from one seropositive animal from area 3. Larvae with morphology consistent with Dictyocaulus sp. were found in 12%, 14%, and 0% of fecal specimens tested from areas 1, 2, and 3, respectively. Pasteurella multocida and Actinomyces pyogenes were isolated from a lung with purulent bronchopneumonia and abscesses.

A comparison of gross pathology, histopathology, and mycobacterial culture for the diagnosis of tuberculosis in elk (Cervus elaphus).

Using the isolation of Mycobacterium bovis as the reference standard, this study evaluated the sensitivity, specificity and kappa statistic of gross pathology (abattoir postmortem inspection), histopathology, and parallel or series combinations of the two for the diagnosis of tuberculosis in 430 elk and red deer. Two histopathology interpretations were evaluated: histopathology I, where the presence of lesions compatible with tuberculosis was considered positive, and histopathology II, where lesions compatible with tuberculosis or a select group of additional possible diagnoses were considered positive. In the 73 animals from which M. bovis was isolated, gross lesions of tuberculosis were most often in the lung (48), the retropharyngeal lymph nodes (36), the mesenteric lymph node (35), and the mediastinal lymph nodes (16). Other mycobacterial isolates included: 11 M. paratuberculosis, 11 M. avium, and 28 rapidly growing species or M. terrae complex. The sensitivity estimates of gross pathology and histopathology I were 93% (95% confidence limits [CL] 84.97%) and 88% [CL 77.94%], respectively, and the specificity of both was 89% [CL 85.92%]). The sensitivity and specificity of histopathology II were 89% (CL 79.95%) and 77% (CL 72.81%), respectively. The highest sensitivity estimates (93-95% [CL 84.98%]) were obtained by interpreting gross pathology and histopathology in parallel (where an animal had to be positive on at least one of the two, to be classified as combination positive). The highest specificity estimates (94-95% [CL 91-97%] were generated when the two tests were interpreted in series (an animal had to be positive on both tests to be classified as combination positive). The presence of gross or microscopic lesions showed moderate to good agreement with the isolation of M. bovis (Kappa = 65-69%). The results showed that post-mortem inspection, histopathology and culture do not necessarily recognize the same infected animals and that the spectra of animals identified by the tests overlaps.

A comparative study of the histopathologic features of bovine tuberculosis in cattle, fallow deer (Dama dama), sika deer (Cervus nippon), and red deer and elk (Cervus elaphus).

Sections of tuberculous lesions from 23 elk (Cervus elaphus nelsoni) and red deer (Cervus elaphus elaphus), 12 fallow deer (Dama dama), 10 sika deer (Cervus nippon), and 30 cattle were examined and compared. Lesions were scored for caseous necrosis, mineralization, neutrophils, macrophages, giant cells, and acid-fast bacilli. Some differences in lesion morphology between the species were noted. Elk/red deer lesions had marked variation and often differed from bovine lesions in several characteristics; elk/red deer lesions usually had scattered peripheral mineralization rather than central mineralization and contained more neutrophils and fewer giant cells than did bovine lesions. Fallow deer lesions contained more giant cells but were otherwise indistinguishable from elk lesions. Sika deer lesions had more giant cells and fewer neutrophils than did lesions from cattle or other cervid species. Sika deer giant cells were larger and contained more nuclei than did giant cells in the other species.

Comparison of the sensitivity of the caudal fold skin test and a commercial gamma-interferon assay for diagnosis of bovine tuberculosis.

A study to determine and compare the sensitivity of the caudal fold tuberculin test (CFT) and a commercial gamma-interferon (gamma-IFN) assay for diagnosis of bovine tuberculosis was conducted. A dairy herd with approximately a third of the cattle infected with Mycobacterium bovis was chosen for this study. All cattle from this herd were slaughtered, and tissue specimens for bacteriologic culturing and histologic examination were collected. Results of the CFT and gamma-IFN assay were compared with results of bacteriologic culturing and histologic examination to determine test sensitivity. Results were analyzed, using each of the following 4 standards to classify cattle as infected: positive test result by bacteriologic culturing only; histologic examination only; bacteriologic culturing and histologic examination; and bacteriologic culturing or histologic examination. Sensitivity of the CFT ranged from 80.4 to 84.4%, depending on the standard of comparison. Sensitivity of the gamma-IFN assay ranged from 55.4 to 97.1%, depending on the standard of comparison and on the method of interpretation. The CFT was significantly (P < 0.001) more sensitive than the gamma-IFN assay for diagnosis of bovine tuberculosis when the gamma-IFN assay was conducted and interpreted as instructed by the manufacturer. Maximum overall sensitivity was achieved when results of the CFT and gamma-IFN assay were interpreted in parallel.

Pathogenic studies and antigenic and sequence comparisons of A/equine/Alaska/1/91 (H3N8) influenza virus.

An influenza virus, A/equine/Alaska/1/91 (H3N8), was isolated from horses from Alaska with an acute respiratory infection. Pathogenic and serologic studies revealed that this virus is similar to previously isolated equine H3N8 influenza viruses. Antigenic analyses utilizing hemagglutination inhibition and neuraminidase inhibition assays indicated an antigenic drift from the prototype equine H3N8 influenza virus, A/equine/Miami/1/63. Partial sequence analysis of the A/equine/Alaska influenza virus indicated that each of 8 gene sequences are of equine origin.

Gross and microscopic lesions of naturally occurring tuberculosis in a captive herd of wapiti (Cervus elaphus nelsoni) in Colorado.

A Mycobacterium bovis-infected herd of captive wapiti (Cervus elaphus nelsoni) in Colorado was depopulated after lesions of bovine tuberculosis were confirmed in 8 of 10 tuberculin skin test reactors. Of the 43 animals > 1 year of age, 26 had gross lesions suggestive of tuberculosis, 24 had microscopic lesions of tuberculosis, and 23 had acid-fast bacilli associated with the lesions. Lungs and retropharyngeal lymph nodes were the most frequently affected sites. Most lesions grossly and microscopically resembled tuberculosis in cattle; however, some lesions resembled abscesses or ovine caseous lymphadenitis lesions. Special stains and immunohistochemical techniques labeled few to numerous mycobacteria associated with the lesions.

Shipping fever pneumonia in yearling feedlot cattle.

During each week of 1974, we surveyed, for illnesses and deaths, a continually changing population of yearling feedlot cattle that, for the year, totaled 407,000 animals. About 5.1% of the cattle sickened and, of these, 18.9% died. From the 3,943 fatalities, 1,988 necropsies were made. About 75% of the clinical diagnoses and 64% of the necropsy diagnoses were respiratory tract diseases; of the fatalities from respiratory tract diseases, 75% were attributed to shipping fever pneumonia. Nearly 72% of fatal cases of shipping fever pneumonia occurred during the first 45 days on feed. In the lungs of most cattle with shipping fever pneumonia, bronchiolitis, fibrinous exudate, colonies of microorganisms, lymphatic clots, intravascular clots, thromboses, and foci of necrosis were found. Pasteurella spp, Mycoplasma spp, and infectious bovine rhinotracheitis virus were isolated from pneumonic tissues. It was hypothesized that pathogenic Pasteurella spp and other microorganisms in nasal secretions transfer from the nasopharynx into the lungs by draining along the tracheal floor into ventral bronchi, bronchioles, and alveoli, and that pasteurella endotoxin, formed in infected lobules, thromboses and occludes lymphatics, capillaries, and veins and thereby causes ischemic necrosis.

Embolic pulmonary aneurysms in yearling feedlot cattle.

Throughout all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. Of 1,988 cattle necropsied, 25 (1.3%) had ruptured pulmonary aneurysms and an additional 4 had gross pulmonary emboli without rupture. The emboli originated from thrombi in the caudal vena cava where that vessel closely applies to the left border of the liver and where parenchymal abscesses had developed. The emboli had lodged in the pulmonary artery, weakened its wall, and led to saccular aneurysms. Infection weakened and blood pressure ruptured the saccule and opened the adjacent bronchi. Extravasated blood dissected the tunica adventitia, formed hematomas, poured into the bronchus, and was expelled from the larynx. A portion was swallowed into the rumen, and some was coughed and blown from the nose and mouth. Deaths were attributed to exsanguination and pulmonary incapacitation.

Diseases of yearling feedlot cattle in Colorado.

During all of 1974 we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. The morbidity was 5.1%, with a case mortality of 18.9% and a population mortality of 1.0%. Both morbidity and mortality were higher during fall and winter than during spring and summer. Of the 3,943 dead cattle, 1,988 were necropsied. The most prevalent diseases were: pneumonia, 48%; diphtheria, 6%; brisket disease, 6%; hemorrhagic colitis, 5%; riding injury, 4%; bloat, 3%; calculosis, 2%; endocarditis, 2%; abomasal ulcers, 2%; bovine viral diarrhea, 2%; embolic pulmonary aneurysm, 1%; and pulmonary edema, 1%.

Atypical interstitial pneumonia in yearling feedlot cattle.

During each week of 1974, we surveyed, for illnesses and deaths, a constantly changing population of yearling feedlot cattle that, for the year, totaled 407,000 animals. From 3,943 fatalities, 1,988 necropsies were made; of this number, 106 (5.3%) had atypical interstitial pneumonia. The death rate was higher during summer and fall than during the other seasons and was evenly distributed throughout each of the 4 stages of fattening. Gross pulmonary lesions involved both lungs and were prominent throughout the caudal (diaphragmatic) lobes. Epithelialization, hemorrhage, fibrin, hyaline membranes, emphysema, bronchiolitis, and interstitial edema were common, whereas chromatin strands, bronchiolar edema, interstitial emphysema, and obliterating bronchiolitis were less common histopathologic features.

Brisket disease in yearling feedlot cattle.

During all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle maintained at 1,600 m altitude. Of 1,988 cattle necropsied, 116 (5.8%) had brisket disease. The malady occurred during all seasons but was most common throughout fall and winter. The gross changes were hypertrophy and dilatation of the right ventricle and generalizaed passive congestion. The postulated causative factors were high genetic susceptibility, rapid growth rate, previous mountain grazing, and hypoventilation with airway hypoxia.

Fetal abomasal ulcers in yearling feedlot cattle.

During all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. From the 3,943 dead cattle, 1,988 necropsies were made; of this number, 31 (1.6%) had ulcers with fatal perforations or hemorrhages; a similar additional number of necropsied cattle had innocuous ulcers as incidental findings. Ulcers developed during all seasons and all stages of fattening, but were more common during the first 45 days of winter-initiated fattening than during other times. Perforations of the abomasal wall resulted in spillage of abomasal contents into the abdominal cavity and the development of peritonitis.

Sudden deaths in yearling feedlot cattle.

A survey of the causes for fatal diseases of yearling feedlot cattle was conducted on more than 407,000 cattle during a 14-month period. Of the 4,260 (1%) cattle that died during this period, 1,358 (32%) were categorized as cases of "sudden death syndrome." Of the 11 most frequent causes of the syndrome, as determined at necropsy, only 4--bloat, pulmonary aneurysms, riding injury, and hemopericardium--were considered as short-course problems and true causes of sudden death. The largest number of cases of sudden death were attributed to pneumonia (113 animals). Consequently, the sudden death syndrome is a misnomer for many long-course diseases and, in some instances, a mask for neglect because, as clinically used, the name frequently includes cattle that have been sick, often with pneumonia, for several days.

Bronchiectasis in yearling feedlot cattle.

Thoughout all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. From the 3,943 dead cattle, 1,988 necropsies were made; of the cattle necropsied, 32 (1.6%) had bronchiectasis. In this disease, the permanently dilated small bronchi and bronchioles, located in ventral parts of the lungs, were filled with accumulations of exudate and microorganisms, including Pasteurella hemolytica, Pasteurella multocida, Corynebacterium pyogenes, Escherichia coli, Salmonella anatum, Staphylococcus spp, and Mycoplasma arginini.