Risk factors for lower respiratory tract disease in a cohort of feedlot cattle

Using data collected from company lot records, potential risk factors related to feedlot management, the cattle, and climate were determined. The risk factors were analyzed by use of weighted multiple regression techniques to determine their effects on the incidence of lower respiratory tract disease in a cohort of 95 lots containing 17,696 cattle. The gender of the cattle, the number of days that groups of cattle filled a lot, pregnancy checking of heifers, and the average temperature change in the first 14 days in which the cattle were on feed significantly influenced the incidence of lower respiratory disease. The incidence of lower respiratory tract disease was most influenced by risk factors in the first 30 days on feed.     

Field trial of theophylline in cattle with respiratory tract disease

A field trial was conducted to determine the efficacy of theophylline in relieving respiratory distress associated with bovine respiratory disease complex (shipping fever). Theophylline (as aminophylline capsules) was administered PO at a dosage of 28 mg/kg of body weight daily for 3 days to 20 calves with naturally acquired disease. Twenty similarly affected calves from the same group were given a placebo, and all calves were administered antibiotics concurrently. Respiratory rate and rectal temperature decreased and physical appearance improved in both groups of calves and was attributed to antibiotic administration or to natural remission of the disease. Five of the calves administered theophylline died; however, no calves administered the placebo died. Plasma theophylline concentration was greatly increased, compared with that determined in clinically normal calves in a pilot study. Bovine respiratory tract disease and/or concurrent antibiotic administration appear to cause such a rapid accumulation of lethal concentration of theophylline that its use should be restricted to hospitals capable of monitoring plasma theophylline concentration.     

Isolation of Staphylococcus species from the tonsils of healthy cattle and phage patterns of isolates

Staphylococci were found in the tonsils of 121 (75.2%) of 161 cattle. There were 15 different species, 10 belonging to novobiocin-sensitive species. The most predominant species was S. simulans (79.3% of the 121 carriers), followed by S. aureus (20.7%), S. chromogenes (10.7%) and S. epidermidis (8.3%). The other 11 species were present in 0.8 to 5.8%. Twenty-six unidentifiable isolates were isolated from 26 (21.5%) carriers. Sixty-two (51.2%) of the 121 carriers yielded two to five Staphylococcus species together while only one species could be found in each of the other 59 (48.8%). Combinations of S. simulans and other species were most frequently encountered in 50 (41.3%) of the 121 carriers. Twenty-four (96.0%) out of 25 S. aureus isolates, 3 (42.9%) of 7 S. hyicus isolates and 45 (25.4%) of 177 coagulase-negative staphylococci (13 species and unidentifiable isolates) isolates were phage typable. Most of S. aureus isolates were lysed by bovine phages 119 (n = 16) or 116 (n = 5). Thirty-three (25.4%) of 45 coagulase-negative staphylococci typable isolates with Pulverer's phage set showed the phage pattern ph5/ph9/ph10/ph12/ph13/U4/U14/U16/++ +U20/U46. The tonsils of cattle thus appear to be a suitable environment for Staphylococcus species, particularly novobiocin-sensitive species.     

Scanning electron microscopic study of the lower respiratory tract in calves and adult cattle

The surface characteristics of the lower respiratory tract of two groups of cattle were studied with the scanning electron microscope. Group A comprised six one-week-old calves and group B four adult cows. None of the animals had overt respiratory disease or gross morphological evidence of pulmonary lesions. The trachea, bronchi, bronchioles and alveoli of the cranial and the caudal lobes of the right lung were examined. In both groups the luminal surface of the trachea and large bronchi were completely covered by cilia, apparently forming an efficient mucociliary escalator. In the adult animals there were some patchy areas in the trachea and large bronchi devoid of ciliated cells; these were considered abnormal. In the bronchi, non-ciliated cells, mainly mucus-secreting, were not easily identified unless they were discharging secretion. In small bronchi, non-ciliated cells were more evident and easily seen. The bronchioles had many non-ciliated cells and very few ciliated cells capable of forming a complete carpet for a mucociliary escalator. Types 1 and 2 alveolar epithelial cells and alveolar macrophages were identified in both groups. Pores of Kohn were found in the alveolar walls in all animals.     

Isolation of a paramyxovirus-3 from turkeys with respiratory tract disease in Germany]

In fattening turkeys 2.5 weeks of age a respiratory disease associated with coughing, nasal discharge and swelling of the infraorbital sinus was seen. Pathological findings in diseased turkeys were sinusitis, tracheitis, pneumonia and aerosacculitis. Virological investigations of trachea, kidney and intestine in SPF-chicken embryos resulted in the isolation of a virus, that could be identified as a paramyxovirus type 3 due to chemical-physical, biological, morphological and immunological properties. The pathogenicity of the isolate 324/86 to turkeys was shown in a test with three weeks old turkey poults. This is the first isolation and identification of a paramyxovirus-3 of turkeys in Germany.     

Prevalence, enumeration and strain variation of Arcobacter species in the faeces of healthy cattle in Belgium

Arcobacter species were isolated from faeces of healthy cattle on three unrelated Belgian farms, using a quantitative isolation protocol. Isolates were identified by m-PCR and characterized by modified ERIC-PCR. The Arcobacter prevalence on the three farms ranged from 7.5 to 15%. The prevalence in dairy cattle ranged from 5.9 to 11% and for young cattle and calves, the prevalence was determined as 18.9 and 27.3%, respectively. Of the 276 animals examined, eight had a bacterial load of more than 10(2) cfu/g faeces and low levels were detected in 22 animals using enrichment. The Arcobacter excretion ranged from 0 to 10(4) cfu/g faeces. Arcobacter cryaerophilus was the dominant species isolated from cows, but co-colonizations occurred in 26% of the Arcobacter excreting animals. Characterization of the 164 isolates showed a large heterogeneity and animals could be colonized with more than one genotype.     

肉牛上呼吸道肺炎克雷伯菌的分离鉴定及耐药分析

为研究重庆地区规模化肉牛场肉牛上呼吸道中肺炎克雷菌的带菌状况及耐药性。本研究从重庆荣昌、丰都两地肉牛上呼吸道分离细菌,采用形态学观察、生化鉴定及16SrRNA分子方法鉴定,获得12株肺炎克雷伯菌,分离率为19.7%,表明肺炎克雷伯菌是肉牛上呼吸道中主要的一种条件致病菌;分离菌株对庆大霉素,丁胺卡那霉素,头孢他啶,妥布霉素等药物敏感,对乙酰螺旋霉素,氨苄西林,苯唑西林耐药率达到100%,分离株存在多重耐药,但两个地区的分离株在耐药性上存在一定差异。     

Immunofluorescent evaluation of the lower respiratory tract of healthy horses and of horses with chronic bronchiolitis

Pulmonary parenchymal tissues from 6 healthy horses and from 9 horses with chronic bronchiolitis were evaluated by use of an indirect immunofluorescent technique. In horses of both groups, the diffuse interstitial immunofluorescence was most intense for immunoglobulin (Ig)G, moderate for IgA, and minimal for IgM. Intensity of fluorescence was increased markedly in diseased lungs exposed to anti-IgA and anti-IgG. Around small bronchi and large bronchioles of healthy horses, IgA-containing cells generally were more numerous than were IgG-Fc fragment (Fc)-containing cells; in small bronchioles, however, IgA-containing cells and IgG (Fc)-containing cells were identified with approximately equal frequency. Immunoglobulin-containing cell types usually were located in the lamina propria and submucosa of airways, with occasional Ig-containing cells seen interepithelially and intraluminally; IgG (T)- and IgM-containing plasma cells were observed infrequently in the same regions. The number of Ig-containing cells became fewer as the diameter of the airway decreased; therefore, at the level of the terminal bronchiole, Ig-containing cells only were observed occasionally. This pattern of Ig-containing cell distribution was similar in horses with chronic bronchiolitis; however, horses with chronic bronchiolitis had more IgA-containing cells forming perivascular and peribronchiolar cuffs than did healthy horses. The number of IgG (Fc)-containing lymphocytes and non-Ig-stainable lymphocytes also were higher in horses with chronic bronchiolitis than in healthy horses, but the number did not approach the magnitude of that observed for IgA-containing cells. One horse had deposits of complement C3 and IgG (Fc) within alveolar septa.     

Mycoplasmas isolated from the respiratory tract of cattle and goats in Tanzania

A microbiological study of the mycoplasma flora in the respiratory tracts of cattle and goats in selected regions of Tanzania is described. In the examination of cattle, mycoplasmas were isolated from 60 (17.8%) of the 338 examined lung samples, 8 (47.1%) of the 17 lymph nodes, 4 (13.3%) of the 30 pleural fluid samples and 4 (3.9%) of the 103 nasal swabs examined. All the isolates were identified as Mycoplasma mycoides subsp. mycoides, Small Colony type except for one isolate from pleural fluid which was identified as Mycoplasma arginini. M. mycoides subsp. mycoides, Small Colony type was isolated from samples originating from Dodoma, Iringa, Mbeya, Morogoro and Shinyanga regions where outbreaks of contagious bovine pleuropneumonia had been reported. In the examination of goats, mycoplasmas were isolated from 54 (34.0%) of the 159 examined lung samples, 41 (18.1%) of the 226 nasal swabs and 4 (40.0%) of the 10 pleural fluid samples. The species demonstrated were Mycoplasma capricolum subsp. capripneumoniae, M. mycoides subsp. mycoides, Small Colony type Mycoplasma ovipneumoniae and M. Capricolum subsp. arginini. The isolation of M. capripneumoniae in the Coast and Morogoro regions confirmed the presence of contagious caprine pleuropneumonia in the regions.     

Immune responses to mycoplasma infections of the respiratory tract

Mycoplasmas are capable of causing respiratory disease in a number of species of animals. The pathogenicity of the mycoplasma species ranges from those that cause major disease outbreaks and economic loss to what might be considered the more highly evolved and successful parasites at the other end of the spectrum that survive for long periods in the host without being recognised and evicted. This prolonged colonisation of mucous membranes which is typical of many mycoplasmas is related to certain unique features of the mycoplasma and its interaction with the hosts immune system. An initial step in infection is the attachment of the mycoplasma to the epithelial lining of the respiratory tract. Lack of cell wall confers plasticity and may engender the intimate association of mycoplasma and host cell that has been noted. This in turn may favour persistence of the extracellular parasite. Before the specific immune response is produced avoidance of the non-specific immune mechanisms would clearly aid survival. Both passive (capsules) and active (toxic effects) mechanisms of avoiding phagocytosis have been proposed. Both humoral and cell mediated responses are generated by mycoplasma infections. The serum antibody response follows the usual course IgM, G and A. The indications of cell mediated immunity that have been reported include; delayed type hypersensitivity reactions, lymphocyte transformation responses and inhibition of macrophage migration. The concept that the pathological lesions are in a large part due to host reactivity is well accepted. The lung lesions may contain infiltrating and dividing lymphocytes some of which are producing specific antibody. Evidence for the lung lesion in some animals being partly due to the hosts cell mediated response has also been produced. The local immune response appears to be of greater relevance to immunity to infection than the systemic response, in general the association between local antibody and immunity is much better than for serum antibody. Of particular note is the high contribution of local IgG production, particularly in the lower respiratory tract. Attempts are now being made to use this increased understanding to produce effective killed vaccines that produce immune responses in the lung. Such studies will hopefully lead to the development of 'killed' vaccines that are effective. It can be urged that mycoplasmas would be less pathogenic if they did not produce an inflammatory response and some species have been shown to have an immunosuppressive effect. Such a property could affect the lesion, and hence pathogenicity, and also aid mycoplasma persistence.(ABSTRACT TRUNCATED AT 400 WORDS)