Respiratory Disease In Calves Research Articles

Diagnostic and Prognostic Value of Clinical Scoring and Lung Ultrasonography to Assess Pulmonary Lesions in Veal Calves.

This study on veal calf respiratory disease assessed the association between an on-farm clinical scoring system and lung ultrasonography with the postmortem inspection of the lungs. The comparisons allowed the calculation of predictive values of the diagnostic methods. In total, 600 calves on an Austrian veal calf farm were examined at the beginning and the end of the fattening period. Overall, the area under the curve (AUC) for ultrasonographic scores was 0.90 (rsp = 0.78) with a sensitivity (Se) of 0.86. The specificity (Sp) was 0.78, and the positive predictive value (PPV) was 0.74. The AUC for the physical examination was 0.76 (rsp = 0.55) with a Se of 0.64, an Sp of 0.81, and a PPV of 0.69. For the combination of ultrasonography and physical examination, an AUC curve of 0.85 (rsp = 0.69) was calculated. A Se of 0.65 and a Sp of 0.88 with a PPV of 0.73 was calculated. This study concluded that both physical and ultrasonographic examination scoring are reliable examination methods for the detection of lung diseases in veal calves.

A systematic review of the relationship between housing environmental factors and bovine respiratory disease in preweaned calves – Part 1: Ammonia, air microbial count, particulate matter and endotoxins

Bovine respiratory disease (BRD) is one of the leading causes of mortality and morbidity in calves across diverse management systems. Despite expert opinion often citing the influence of housing environment on the level of respiratory disease in calf groups, there have been few reviews of environmental factors that predispose to BRD. This systematic review was undertaken to identify the measurable environmental variables associated with respiratory disease in housed preweaned calves. To achieve this Pubmed, CAB Direct and Scopus databases were searched. To be considered for inclusion, publications had to be fully published in English, published before 24 November, 2022 and include at least one measurable/ manipulated environmental variable and a standardized method of BRD detection.Twelve publications were included in this review. These examined a wide range of risk factors including air microbial count (four publications), air particulate matter (one publication); air endotoxins (one publication) and air ammonia (four publications). From the included publications, a statistically significant relationship to BRD was identified in 2/4 examining air microbial count, 1/1 examining air particulate matter, 1/1 examining air endotoxins and 2/4 examining air ammonia. This review indicated a paucity of evidence from the peer-review literature demonstrating a significant association between the many investigated exposure factors and BRD occurrence. An optimal environment for housed calves could not be clearly identified in this review.

Effect of on-arrival bovine respiratory disease vaccination on ultrasound-confirmed pneumonia and production parameters in male dairy calves: A randomized clinical trial

The high degree of commingling and accumulation of stressors during and after transport makes prevention of bovine respiratory disease (BRD) extremely challenging in the veal and dairy beef industry. Upon arrival, vaccination for agents involved in BRD is practically most achievable, but its efficacy under such conditions in dairy veal calves is unknown. Given the high prevalence of subclinical pneumonia in these settings, the primary objective of the present study was to determine the effect of 2 vaccination protocols administered upon arrival against bovine respiratory syncytial virus (BRSV), bovine parainfluenza type 3 virus (BPI-3), and Mannheimia haemolytica on clinical BRD and lung ultrasonographic findings in dairy veal calves. In addition, the effects of vaccination on average daily live weight gain and cold carcass weight were determined. In this randomized clinical trial, 443 male dairy calves were assigned to one of 3 groups: a negative, placebo-controlled group (n = 151), a vaccination group with 2 subcutaneous injections 4 wk apart with an inactivated vaccine containing BRSV, BPI-3, and M. haemolytica (parenteral [PE] group; n = 149) and a second vaccination group receiving an intranasal live-attenuated vaccine containing BRSV and BPI-3 and 2 subcutaneous vaccinations with the same inactivated vaccine as the PE vaccination group (intranasal-parenteral [IN-PE] group; n = 143). Clinical scoring and quick thoracic ultrasonography (qTUS) were performed on all calves on arrival (wk 0), at the peak of respiratory disease (outbreak; wk 1), at the end of the first antimicrobial group treatment (wk 3), and at a long-term evaluation point (wk 10). Culture and nanopore sequencing on nonendoscopic bronchoalveolar lavage (nBAL) samples were used to identify pathogens involved in the outbreak. Upon arrival, 15.1% of the calves had lung consolidation ≥1cm and incidence quickly rose to 42.8% during the outbreak. In both the PE and IN-PE group, the odds of pneumonia in wk 10 were reduced by 62% (odds ratio [OR] = 0.38; 95% confidence interval [CI] = 0.23-0.64) and 41% (OR = 0.59; 95% CI = 0.37-0.96), respectively. Short-term cure rate (50.3%), as determined immediately after the first group antimicrobial treatment, was not influenced by vaccination. In contrast, long-term cure rate, determined at wk 10, was affected by vaccination with higher cure in the PE group compared with the control group (69.4% vs. 51.2%; OR = 2.2; 95% CI = 1.1-5.0). Average daily gain in the first 10 wk of production was not affected by vaccination. Vaccination resulted in an increase in cold carcass weight of 3.5 and 4.3 kg in the PE (95% CI = -0.9-7.9) and IN-PE group (95% CI = -0.17-8.7), respectively. In conclusion, under the conditions of the present study, vaccination upon arrival resulted in a reduced prevalence of pneumonia at wk 10 of production, likely caused both by an improved cure rate of secondary infections and a reduced incidence of new cases between outbreak and long-term evaluation. The present protocol, using qTUS for pneumonia detection and nBAL diagnostics for pathogen identification adds a new dimension to randomized clinical trials on respiratory disease in calves.

Etiology of gastrointestinal and respiratory diseases of calves in the conditions of farms of the Vologda region

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Prevalence of respiratory disease in Irish preweaned dairy calves using hierarchical Bayesian latent class analysis.

Bovine respiratory disease (BRD) has a significant impact on the health and welfare of dairy calves. It can result in increased antimicrobial usage, decreased growth rate and reduced future productivity. There is no gold standard antemortem diagnostic test for BRD in calves and no estimates of the prevalence of respiratory disease in seasonal calving dairy herds. To estimate BRD prevalence in seasonal calving dairy herds in Ireland, 40 dairy farms were recruited and each farm was visited once during one of two calving seasons (spring 2020 & spring 2021). At that visit the prevalence of BRD in 20 calves between 4 and 6 weeks of age was determined using thoracic ultrasound score (≥3) and the Wisconsin respiratory scoring system (≥5). Hierarchical Bayesian latent class analysis was used to estimate the calf-level true prevalence of BRD, and the within-herd prevalence distribution, accounting for the imperfect nature of both diagnostic tests. In total, 787 calves were examined, of which 58 (7.4%) had BRD as defined by a Wisconsin respiratory score ≥5 only, 37 (4.7%) had BRD as defined by a thoracic ultrasound score of ≥3 only and 14 (1.8%) calves had BRD based on both thoracic ultrasound and clinical scoring. The primary model assumed both tests were independent and used informed priors for test characteristics. Using this model the true prevalence of BRD was estimated as 4%, 95% Bayesian credible interval (BCI) (1%, 8%). This prevalence estimate is lower or similar to those found in other dairy production systems. Median within herd prevalence varied from 0 to 22%. The prevalence estimate was not sensitive to whether the model was constructed with the tests considered conditionally dependent or independent. When the case definition for thoracic ultrasound was changed to a score ≥2, the prevalence estimate increased to 15% (95% BCI: 6%, 27%). The prevalence of calf respiratory disease, however defined, was low, but highly variable, in these seasonal calving dairy herds.

Genetic diversity of Siberian bovine coronavirus isolates (Coronaviridae: Coronavirinae: Betacoronavirus-1: Bovine-Like coronaviruses)

Bovine coronaviruses (BCoVs) are causative agents of diarrhea, respiratory diseases in calves and winter cow dysentery. The study of genetic diversity of these viruses is topical issue. The purpose of the research is studying the genetic diversity of BCoV isolates circulating among dairy cattle in Siberia. Specimens used in this study were collected from animals that died or was forcedly slaughtered before the start of the study. The target for amplification were nucleotide sequences of S and N gene regions. Based on the results of RT-PCR testing, virus genome was present in 16.3% of samples from calves with diarrheal syndrome and in 9.9% with respiratory syndrome. The nucleotide sequences of S gene region were determined for 18 isolates, and N gene sequences - for 12 isolates. Based on S gene, isolates were divided into two clades each containing two subclades. First subclade of first clade (European line) included 11 isolates. Second one included classic strains Quebec and Mebus, strains from Europe, USA and Korea, but none of sequences from this study belonged to this subclade. 6 isolates belonged to first subclade of second clade (American-Asian line). Second subclade (mixed line) included one isolate. N gene sequences formed two clades, one of them included two subclades. First subclade included 3 isolates (American-Asian line), and second subclade (mixed) included one isolate. Second clade (mixed) included 8 sequences. No differences in phylogenetic grouping between intestinal and respiratory isolates, as well as according to their geographic origin were identified. The studied population of BCoV isolates is heterogeneous. Nucleotide sequence analysis is a useful tool for studying molecular epidemiology of BCoV. It can be beneficial for choice of vaccines to be used in a particular geographic region.

Genetic Organization of Acquired Antimicrobial Resistance Genes and Detection of Resistance-Mediating Mutations in a Gallibacterium anatis Isolate from a Calf Suffering from a Respiratory Tract Infection

Gallibacterium (G.) anatis isolates associated with respiratory diseases in calves and harboring acquired antimicrobial resistance genes have been described in Belgium. The aim of this study was to analyze the genetic organization of acquired resistance genes in the G. anatis isolate IMT49310 from a German calf suffering from a respiratory tract infection. The isolate was submitted to antimicrobial susceptibility testing, and a closed genome was obtained by a hybrid assembly of Illumina MiSeq short-reads and MinION long-reads. Isolate IMT49310 showed elevated MIC values for macrolides, aminoglycosides, florfenicol, tetracyclines, and trimethoprim/sulfamethoxazole. The acquired resistance genes catA1, floR, aadA1, aadB, aphA1, strA, tet(M), tet(B), erm(B), and sul2 were identified within three resistance gene regions in the genome, some of which were associated with IS elements, such as ISVsa5-like or IS15DII. Furthermore, nucleotide exchanges within the QRDRs of gyrA and parC, resulting in amino acid exchanges S83F and D87A in GyrA and S80I in ParC, were identified. Even if the role in the pathogenesis of respiratory tract infections in cattle needs to be further investigated, the identification of a G. anatis isolate with reduced susceptibility to regularly used antimicrobial agents in cases of fatal bovine respiratory tract infections is worrisome, and such isolates might also act as a reservoir for antimicrobial resistance genes.

A field study on the effects of inactivated bacteria vaccine for respiratory diseases in Japanese Black calves.

This study evaluated the effects of vaccination for Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in young Japanese Black calves at an ordinal farm, where respiratory diseases frequently occur at a young age. In total, 105 calves were divided into the vaccination group (n = 52), which received inactivated combined vaccine at 0 and 2 weeks of age, and the control group (n = 53), which received no vaccine. From both groups, eight calves each were randomly selected to determine the antibody titers. And, the incidence of respiratory disease and medical costs (treatment plus vaccination costs) were recorded for each group from birth to 16 weeks of age. In the vaccination group, the antibody titers against P. multocida, M. haemolytica, and H. somni were significantly higher than those in the control group after 8, 12, and 4 weeks of age, respectively (p < 0.05). The incidence of respiratory disease was significantly lower in the vaccination group compared to the control group (p < 0.01), and the medical costs per calf in the vaccination group were 46.4% lower than in the control group. These results might contribute to establishing an effective vaccination program against respiratory diseases in calves at each farm.

Гематологические и биохимические показатели при респираторных и желудочно-кишечных заболеваниях телят после применения иммуномодулятора «АНАНДИН®» 10 %

The purpose of the research was to study the effectiveness of the drug ANANDIN 10 % (LLC «AVZ S-P») in respiratory and gastrointestinal diseases of young cattle in comparison with the complex antibacterial drug Sulteprim. To implement the main tasks after the use of the immunomodulator, clinical and laboratory (hematological, biochemical) studies of animals were carried out. Experiments on the study of the immunomodulator were carried out on 52 Holstein calves 1–1,5 months of age in a large dairy complex in the Central region of the Russian Federation. Based on the results of the clinical examination, five experimental and two control groups of eight calves each were formed. Symptoms of respiratory and gastrointestinal diseases were detected in most of the animals selected for the experiment. Based on the results of the studies, it was found that ANANDIN 10 % injection solution (LLC «AVZ S-P») has a pronounced immunomodulatory and immunostimulating activity in doses designed for cattle. The drug is recommended for prophylactic use in cattle at a dose of 0,02 ml/kg twice with an interval of 48 hours before primary, re-vaccination or in the same way before revaccination against infectious diseases. In the complex therapy of severe forms of respiratory diseases in calves, the immunomodulator should be administered at a dose of 0,08 ml/kg three times at intervals of 3 and 10 days.

Developing a tool to assess the health-related quality of life in calves with respiratory disease: content validation

Bovine respiratory disease (BRD) is a major welfare and productivity issue for calves. Despite the extensive negative impacts on calf welfare and performance, BRD remains challenging to detect and treat effectively. However, the clinical signs of disease are only one aspect of the disease that is experienced by the individual. The assessment of emotional experience in animals is not straightforward, but it is increasingly recognised that the quality of behaviour and demeanour of an individual is a reflection of their internal emotional state. The aim of the present study was to complete the content validation stage of the development process for a health-related quality of life (HRQOL) tool. This was based around indicators from an existing conceptual framework containing twenty-three indicators in two domains (clinical signs and behavioural expression). The content validation stage involves engaging with key stakeholders. For this study, this took the form of a survey and discussions with focus groups, which are standard methods in this field. A survey and stakeholder focus groups were conducted to assess the usefulness of each indicator and its relevance for inclusion within a HRQOL tool. In the survey, participants were asked to rate the usefulness of each of the indicators using a 4-point scale which were then dichotomised into ‘useful’ and ‘less useful’. Based on the ‘useful’ result, each indicator within the domains was ranked. A similar approach was taken with the responses from the focus groups. Focus group participants were asked to select indicators that they felt were of use and the result of this was used to rank each of the indicators. The ranks of the indicators from both the survey and the focus groups along with the transcripts from the focus groups were used to determine the indicators from each domain to include within the HRQOL tool. Indicators within the clinical signs domain that were included were nasal discharge, cough, respiratory effort, ocular appearance (discharge and vibrancy), body and head posture and ear carriage. For the domain of behavioural expression, the indicators included were movement to feed, responsiveness, spatial proximity, volume of feed intake, motivation at feed and vigour. The next stage will be to validate the construction of the HRQOL tool through its use in practice. The inclusion of indicators that allow the experiential aspects of disease to be recorded in health assessments will likely increase the ability of farmers and others to detect respiratory disease in calves.

The Effect of Pegbovigrastim Injection on Phagocytic and Oxidative Burst Activities of Peripheral Blood Granulocytes and Monocytes in Calves Challenged with Mycoplasma bovis.

Mycoplasma bovis (M. bovis) is an important pathogen affecting cattle, causing various diseases including pneumonia which mainly occurring in calves. Control of M. bovis infections is difficult due to the lack of commercial vaccines in most parts of the world and increasing trends of antimicrobial resistance in field isolates of the pathogen; therefore, it seems reasonable to look for new solutions for the prevention of the infection. Pegbovigrastim is a pegylated form of naturally occurring circulating cytokine in cattle that affects bovine leukocytes and some cell functions. Most studies on pegbovigrastim have focused on reducing the occurrence of mastitis and other diseases occurring during the periparturient period in cows, while this study attempts to use pegbovigrastim in the prevention of respiratory diseases in calves, which are largely caused by M. bovis. Based on previous observations on the immunostimulatory properties of pegbovigrastim in cattle, for the first time, the effect of its injection on the number and phagocytic and oxidative burst activities of peripheral blood granulocytes and monocytes in calves experimentally infected with M. bovis was investigated. Pegbovigrastim administration in the calves significantly stimulated an increase in peripheral blood granulocyte and monocyte counts and phagocytic activity of the cells, especially granulocytes, which was also generally expressed in the course of M. bovis infection. In response to pegbovigrastim administration, a general increase in the oxygen burst activity of the cells was observed. This effect was also shown despite ongoing infection with M. bovis which, taken together, may indicate a beneficial effect of pegbovigrastim injection on the immunity of the affected animals.

Early Detection of Respiratory Diseases in Calves by Use of an Ear-Attached Accelerometer.

Simple SummaryBovine respiratory disease is one of the most important diseases in group-housed calves worldwide, with impacts on calf welfare and farm economics. Early detection of the disease is important for the well-being of the animals and a targeted treatment. Therefore, tools for an automated monitoring of individual calves would be a breakthrough in health management. In this study, we used an ear-attached accelerometer to evaluate its potential for the early detection of behavioral changes related to respiratory disease in calves. Our result showed that accelerometers are able to detect changes in activity and lying times that can be used to predict respiratory disease before clinical diagnosis.Accelerometers (ACL) can identify behavioral and activity changes in calves. In the present study, we examined the association between bovine respiratory disease (BRD) and behavioral changes detected by an ear-tag based ACL system in weaned dairy calves. Accelerometer data were analyzed from 7 d before to 1 d after clinical diagnosis of BRD. All calves in the study (n = 508) were checked daily by an adapted University of Wisconsin Calf Scoring System. Calves with a score ≥ 4 and fever for at least two consecutive days were categorized as diseased (DIS). The day of clinical diagnosis of BRD was defined as d 0. The data analysis showed a significant difference in high active times between DIS and healthy control calves (CON), with CON showing more high active times on every day, except d −3. Diseased calves showed significantly more inactive times on d −4, −2, and 0, as well as longer lying times on d −5, −2, and +1. These results indicate the potential of the ACL to detect BRD prior to a clinical diagnosis in group-housed calves. Furthermore, in this study, we described the ‘normal’ behavior in 428 clinically healthy weaned dairy calves obtained by the ACL system.

Genetic diversity and distribution of bovine pestiviruses (Flaviviridae: Pestivirus) in the world and in the Russian Federation

The genus Pestivirus of the family Flaviviridae includes 11 species. Bovine pestiviruses are the causative agents of viral diarrhea/mucosal disease and include three genetically distinct species: pestivirus A (BVDV-1), B (BVDV-2), and H (BVDV-3). The number of BVDV-1 subtypes is 21, BVDV-2 - 4, and BVDV-3 - 4, which complicates the diagnosis of associated diseases, reduces the effectiveness of vaccination and control programs.We performed the search in the PubMed, Web of Science, Scopus, eLIBRARY.RU databases for articles published in 2000-2021.Pestivirus A is distributed everywhere, although the largest number of subtypes was found in cattle in Italy and China. The virus is widespread in the Central region of the Russia (subtypes 1a and 1m). In Siberia, eleven subtypes circulate among native and imported animals: 1a (5%), 1b (35%), 1c (5%), 1d (10%), 1f (20%), 1g, 1i (both 2.5%), 1j, 1k, 1p, and 1r (all for 5%). Pestivirus B subtype is more virulent, found less frequently and mainly in the North and South America, in some European countries, and in Asia. Three subtypes have been identified in Siberia: 2a (25%), 2b (10%), and 2c (5%). Pestivirus H circulates in Europe, Asia and South America. The main route of entry is contaminated biological products. In Russia, BVDV-3 of the Italian-Brazilian group (3a) was detected in 7 lots of fetal bovine serum.The role of the virus in the occurrence of respiratory diseases in calves, abortion, systemic infection and enteritis in calves and adult animals has been established. The source of the virus in such cases was a contaminated modified live vaccine.

CHANGES IN THE BLOOD BIOCHEMICAL VALUES OF CALVES IN THE TREATMENT OF RESPIRATORY PATHOLOGY

Respiratory diseases of calves cause a great damage to cattle breeding. Various medications are used to cure animals. The objective of the work was to study the effect of the drugs sulfetrisan and gentaaminoseleferon on metabolic parameters in the treatment of calves. Upon the recovery of animals of the experimental group, normalization of blood biochemical values was registered in the animals of the experimental groups, that indicated a decrease in the inflammatory process in the respiratory organs. The use of gentaaminoseleferon provided a more intensive restoration of metabolism and, as a result, a high therapeutic efficacy.

Cross-sectional study of antimicrobial use and treatment decision for preweaning Canadian dairy calves

Antimicrobials should be used prudently in farm animals to prevent the development of resistant bacteria in both humans and animals. The objective of this study was to investigate Canadian dairy producers' practices for antimicrobial use in the treatment of disease in preweaning dairy calves. In-person questionnaires were administered to 144 dairy producers across 5 provinces in Canada between July 2019 and August 2020. Almost all (96%) producers used antimicrobials to treat calves with respiratory disease, but only 27% indicated they had a written treatment protocol for respiratory disease. Most (95%) of these protocols for respiratory disease were developed with input from the herd veterinarian. Seventy-four percent of producers used antimicrobials to treat calf diarrhea, with 37% of producers having a written treatment protocol for calf diarrhea with input from the herd veterinarian. The combinations of signs adopted by the producers for antimicrobial treatment in calf respiratory disease and diarrhea were evaluated based on findings from other studies. More than half (56%) of producers who used antimicrobials for calf respiratory disease decided to use antimicrobials by evaluating multiple clinical signs. Eighty-two percent of producers who used antimicrobials for calf diarrhea made decisions based on systemic signs of disease, presence of bloody stool, no response to previous treatment, or on the recommendation from the herd veterinarian. Producers with a written treatment protocol had 3 to 7 times greater odds of using antimicrobials based on multiple signs or systemic signs of disease compared with those without a protocol. Further research may investigate other calf management practices related to decision-making by producers in using antimicrobials to improve antimicrobial stewardship on dairy farms.

Use of thoracic ultrasound on Scottish dairy cattle farms to support the diagnosis and treatment of bovine respiratory disease in calves.

Bovine respiratory disease (BRD) is common in cattle youngstock on UK dairy farms. The current diagnostic methods lack sensitivity and specificity. Thoracic ultrasound (TUS) is a relatively new BRD diagnostic tool with increased accuracy. Data were collected from TUS examinations of 347 calves on Scottish dairy farms and compared to farmer BRD treatment rates. A calf health scoring tool was used to collect information on youngstock health and management on these farms. Of 347 ultrasonographic examinations, 53 (15.3%) were classified as abnormal and 294 (84.7%) as normal. Of the 53 calves classified as abnormal, only 13 (24.5%) were treated by the farmer; however, of the 294 classified as normal, 22 (7.5%) were treated. The results indicated farmers were misdiagnosing BRD in youngstock. Use of TUS on UK farms may improve diagnostic rates and accuracy, reduce the unnecessary use of antimicrobials and demonstrate the value of preventive healthcare programmes.

Genetic parameters of calf morbidity and stayability for US organic Holstein calves

The objectives of this study were to estimate genetic parameters of calf health in organic US Holstein calves. Calves were born on farms across the United States from 2006 to 2019. Three calf health traits were evaluated in the study: calf respiratory disease until 365 d of age, calf scours until 60 d of age, and heifer stayability until 365 d of age. For respiratory disease and scours, animals were assigned a phenotype of 0 if they were healthy and a phenotype of 1 if they were diseased. For stayability, animals were assigned a phenotype of 0 if they were removed from the herd by 365 d of age and 1 if they remained in the herd at 365 d of age. Genetic parameters were estimated from threshold models that included the fixed effects of mean, year-season of birth, and dam age (respiratory disease and scours only) as well as the random effects of herd-year of birth and additive genetics. Heritability estimates were 0.100, 0.075, and 0.085 for respiratory disease, scours, and stayability, respectively. Solutions for estimated breeding values for respiratory disease and scours were transformed from disease risk to disease resistance by reversing the signs before calculating genetic correlations such that higher values of scours, respiratory disease, and stayability were favored. There was a moderate favorable genetic correlation estimate between respiratory disease resistance and stayability of 0.675. However, genetic correlation estimates between respiratory disease resistance and scours resistance (0.148) and between scours resistance and stayability (0.165) were low. Estimated breeding value correlations between calf health traits and other traits evaluated nationally were generally low in magnitude. The strongest correlation estimates were with longevity, particularly between stayability and heifer livability (0.217) and between stayability and cow livability (0.288); respiratory disease resistance was also favorably correlated with heifer (0.190) and cow (0.178) livability. Correlations with cow health traits were generally low and unfavorable. Linear models including the random effect of herd-by-sire indicated that herd-by-sire accounted for approximately 2% of phenotypic variance for scours and stayability, which may indicate a genotype by environment interaction effect for these traits. In conclusion, there is significant genetic variation in organic calf health, and there was evidence of genotype by environment interaction.

Decision tree analysis for pathogen identification based on circumstantial factors in outbreaks of bovine respiratory disease in calves

Respiratory tract infections continue to be a leading cause of economic loss, hampered animal welfare and intensive antimicrobial use in cattle operations, worldwide. To better target antimicrobial therapy, control and prevention towards the involved pathogens, there is a growing interest in microbiological tests on respiratory samples. However, these tests are time consuming, cost money and sampling might compromise animal welfare. Therefore, the objective of the present study was to develop immediately applicable decision trees for pathogen identification in outbreaks of bovine respiratory disease based on circumstantial factors. Data from a cross sectional study, involving 201 outbreaks of bovine respiratory disease in dairy and beef farms between 2016 and 2019 was used. Pathogens were identified by a semi-quantitative PCR (polymerase chain reaction) on a pooled non-endoscopic broncho-alveolar lavage sample from clinically affected animals. Potential risk factors of involved animals, environment, management and housing were obtained by enquiry. Classification and regression tree analysis was used for decision tree development with cross-validation. Different trees were constructed, involving a general 3-group classification tree (viruses, Mycoplasma bovis or Pasteurellaceae family) and a tree for each single pathogen. The general 3- group classification tree was 52.7 % accurate and had a sensitivity of 81.5 % and a specificity 52.2 % for viruses, respectively 51.7 % and 84.4 % for M. bovis and 28.9 % and 93.6 % for Pasteurellaceae. The single-pathogen trees were more specific than sensitive: Histophilus somni (Se = 25.8 %; Sp = 94.5 %), Mannheimia haemolytica (Se = 69.2 %; Sp = 70.6 %), bovine coronavirus (Se = 42.2 %; Sp = 89.6 %) and bovine respiratory syncytial virus (Se = 34.0 %; Sp = 96.6 %). For Pasteurella multocida, M. bovis and parainfluenzavirus type 3 no meaningful tree was obtained. The concept and trees are promising, but currently lack sensitivity and specificity in order to be a reliable tool for practice. For now, the obtained trees can already be informative for decision making to some extend depending on the end node in which an outbreak falls.

THE RESULTS OF THE USE OF BIOTECHNOLOGICAL DRUGS IN VETERINARY MEDICINE, PROMISING FOR MEDICINE (PART 1)

Cell and serum nucleases are considered as a natural biological barrier, one of the first links in the body’s antiviral defense: nucleases act on viruses that the usual immunological barrier cannot resist. Inactivation of the enzymatic properties of nucleases also leads to the loss of their antiviral activity. It was found that the nucleases do not inactivate the native virus outside the cell and act mainly on the virus that multiplies in the cells. There is a direct dependence of the antiviral activity of endonuclease on the concentration of the enzyme in the medium. The first antiviral drug created on the basis of the Serratia marcescens endonuclease was called bacterial endonuclease. Its technology was developed by joint research of NIKTI BAS of the Ministry of Medical Industry (Berdsk, Novosibirsk region) and ICIG SB of the USSR Academy of Sciences in 1973–1984. Serratia marcescens endonuclease is capable of cleaving the nucleic acids of both RNA and DNA-containing viruses. The enzyme inhibits the reproduction of vesicular stomatitis and smallpox vaccine viruses in chicken fibroblast cell culture, respectively. It was the first antiviral drug in the history of beekeeping, designed to prevent acute and chronic paralysis and other viral diseases of bees. The drug was also intended as an antiviral agent for a wide range of diseases in various organisms. The effectiveness of bacterial endonuclease as a means of prevention and treatment of respiratory viral diseases in calves was studied. The research was carried out at the industrial complex for growing heifers of the Gosnensky state farm in the Leningrad region on calves of a black-and-white breed of 20–60 days old. For the experiments, we used bacterial endonuclease produced by the Vyshnevolotsky Plant of Enzyme Preparations or NICTI BAS of the Ministry of Medical Industry. In the future, NIKTI BAV together with Diafarm LLC developed a second – generation antiviral drug, endoglucin, based on bacterial endonucleosis. Production experiments to study its effect as a therapeutic and prophylactic agent for respiratory diseases of calves were conducted during 2007– 2011. in the agricultural complex «Prichulymsky» of the Achinsky district of the Krasnoyarsk Territory with the participation of the Department of Epizootology and Parasitology of the Faculty of Veterinary Medicine of KrasGAU and in CJSC «Suzdalskoye» of the Dovolensky district of the Novosibirsk region. Prophylactic use of endoglucin in calves with bronchopneumonia can reduce the incidence from 2.2 to 3.1 times. The drug endoglucin in combination with drugs indicated for the treatment of pulmonary pathology, has therapeutic effectiveness in bronchopneumonia of calves.

PRESENCE OF MOLLICUTES AND MYCOPLASMA BOVIS IN NASAL SWABS FROM CALVES AND IN MILK FROM COWS WITH CLINICAL MASTITIS

Mycoplasma bovis is part of the bovine respiratory tract microbiota but is considered an opportunistic pathogen of extreme importance in respiratory diseases of calves. It causes to the herd several diseases such as mastitis, polyarthritis, pneumonia and endometritis. This pathogen is highly contagious and animals with mastitis are potential disseminators of infection to the herd since they release from 106 to 108 CFU per mL milk. Similarly, animals with pneumonia eliminate, through respiratory secretions, high microbial loads of the agent. The present study aimed to perform molecular detection of Mycoplasma bovis in 185 milk samples from cows with clinical mastitis, as well as in 50 nasal swab samples from healthy calves with or without signs of pneumonia and born from cows with mastitis, all belonging to four dairy farms in Paraná State, where cases of mastitis had beendiagnosed. DNA extraction from both secretions was carried out according to the thermolysis method. For polymerase chain reaction (PCR), generic primers were employed to amplify the Mollicutes DNA and positive samples were subjected to PCR with primersspecific for M. bovis. Positivity for M. bovis was 3.78% in milk samples, regardless of the farm, and 20% in nasal swabs.