Enteritis In Calves Research Articles

The influence of a phytobiotic with <i>F. ulmaria</i> extract and lactobacilli on the clinical and physiological status of calves

Purpose of the research: to study the effect of a phytobiotic additive on some clinical and physiological parameters of the body of calves during the dairy period (biochemical and morphological blood parameters, live weight gain and disease resistance). The subject of the study was a phytobiotic with the code name Fitostim, which is based on an extract of meadow-sweet (Filipendula ulmaria (L.) Maxim.) and a lyophilized culture of lactic acid microorganisms. The experiment used Holstein calves, divided into experimental (Fitostim + traditional diet) and control (traditional diet) groups of 12 animals each. Starting from 4 days of age, calves in the experimental group were administered Fitostim daily, individually, orally for 30 days at a dose of 3 grams per head, after dilution in milk. Blood tests for morphological (erythrocytes, leukocytes, hemoglobin, leukoformula) and biochemical parameters (IgG, total protein, albumin, ALT, AST, creatinine) were carried out on the 10th and 30th days of the experiment. By the end of the experiment, in the experimental group of calves, compared with the control, there was an increase in ALT (8.0±0.01 units/l) by 19.4 %, total protein (51.4±0.07 g/l) by 14.7 %, albumin (44.0±0.01 g/l) by 15.4 %, creatinine (41.5±0.001 µmol/l) by 10.9 %, immunoglobulin G (5.9±0.01g /l) by 18 %, leukocytes (7.1±0.02×109/l) by 31 %. The studied morphological blood parameters (leukocytes, erythrocytes, hemoglobin, leukoformula) did not go beyond the reference values. Recovery from enteritis in calves in the experimental group occurred earlier by 1.8±0.3 days than in calves in the control group. Safety of calves is 100 %. The average daily increase in body weight in calves in the experimental group was 0.811±0.12 kg, which was 17.1 % higher than the result in the control.

Specific features of distribution and manifestation of cryptosporidiosis of calves on dairy complexes in Siberia

The results of the study of specific features of distribution and clinical manifestation of bovine cryptosporidiosis in association with pathogens of viral and bacterial nature are presented. From 2014 to 2023, 666 samples of biomaterial (tracheal mucosa, lungs, mediastinal and mesenteric lymph nodes, contents of rennet and intestine) collected from fallen and forcefully killed calves under 6 months of age with signs of enteritis and respiratory diseases were examined. 94 farms of six regions, two territories of the Siberian region and the Republic of Kazakhstan were surveyed. The findings confirm the widespread prevalence of Cryptosporidium in calves. Cryptosporidium parvum oocysts were most frequently detected and were present in 34 (5.1%) samples of biological material from calves in 22 (23.4%) of the surveyed farms. It was found that oocysts were rarely (22.7%) present in monovariant in animals, more often (77.3%) they were found in associations with viruses and bacteria during outbreaks of viral-bacterial infections. Young animals under 30 days of age are most susceptible to infection. Newborn calves are most susceptible to infection with oocysts, and those animals that have had the disease become lifelong sources of the pathogen for susceptible animals. Cryptosporidiosis is an independent disease and runs independently of the presence of the viruses and bacteria in the body and has no synergistic interaction with them, but the presence and multiplication in the body of animals of this pathogen contributes to the severity of the course of enteritis in calves and leads to difficulties in the treatment and preventive measures. The presence of Cryptosporidium in animals should be taken into account when carrying out complex anti-epizootic measures.

Moringa oleifera leaf polysaccharide regulates fecal microbiota and colonic transcriptome in calves

This study investigated the effects of Moringa oleifera polysaccharide on growth performance indicators, serum biochemical indicators, immune organ indicators, colonic morphology, colonic microbiomics and colonic transcriptomics in newborn calves. 21 newborn calves were randomly divided into three groups of 7 calves per treatment group: control group (no Moringa oleifera polysaccharide addition); low-dose group (Moringa oleifera polysaccharide 0.5 g/kg); and high-dose group (Moringa oleifera polysaccharide 1 g/kg). This trial used gavage to feed MOP to calves. The test lasted 8 weeks. Calves were humanely electroshocked on the last day of the trial and slaughtered afterwards. Thymus, spleen, blood and colonic contents were collected for further testing. The results of this trial showed that MOP significantly increased the body weight of newborn calves and reduced the rate of calf diarrhea, thus promoting calf growth. Fecal scores showed a linear decrease with the addition of MOP. In terms of serum biochemistry, feeding MOP significantly increased serum ALB levels in a linear fashion. In terms of serum antioxidants, feeding MOP linearly increased CAT and T-AOC levels and decreased MDA concentrations, and in terms of serum immunity, feeding MOP linearly increased IgA, IgG, and IgM levels. At the same time, MOP regulated the abundance of Firmicutes and Bacteroidetes in the intestinal tract of calves, which reduced the occurrence of diarrhea. In addition, moringa polysaccharide could regulate genes related to inflammatory signaling pathways such as MAPK signaling pathway, TGF-beta signaling pathway, PI3K-Akt signaling pathway and TNF signaling pathway in calves' intestine to reduce the occurrence of intestinal inflammation. In conclusion, MOP can be used as a novel ruminant additive for the prevention of enteritis in calves.

The in vitro effect of lactose on Clostridium perfringens alpha toxin production and the implications of lactose consumption for in vivo anti-alpha toxin antibody production.

Necro-hemorrhagic enteritis in calves, caused by Clostridium perfringens type A, is a fatal disease, mostly affecting calves in intensive rearing systems. The lack of development of active immunity against α toxin, an essential virulence factor in the pathogenesis, has been proposed as a main trigger. In this experimental study, the effect of a set of milk replacer components on α toxin production, and the effect of lactose on in vivo antibody production, were investigated. For the latter, Holstein-Friesian bull calves (n = 18) were fed an all liquid diet that contained either a milk replacer with high-lactose content (45% DM) or the same milk replacer that was lactase treated, resulting in a lactose-free equivalent. Antibody levels against α toxin were monitored from 2 to 12 wk of age. In the in vitro part of the study, a concentration-dependent inhibitory effect of lactose on in vitro C. perfringens α toxin activity was observed, whereas protein did not influence α toxin activity. The in vivo experiment then showed from the age of 10 wk onwards, that anti-α toxin antibody levels of high-lactose animals declined, whereas antibody levels of the animals consuming lactose-free milk replacer remained the same throughout the trial. This points to a natural decline in maternal immunity of lactose-consuming animals, that is not compensated by the development of an active immunity, resulting in inferior protection. This study suggests that dietary lactose reduces C. perfringens α toxin production in vivo, which may lead to a decreased antigen presentation and thus lower serum antibody levels against the toxin. Consequently, any event causing massive α toxin production puts lactose-consuming calves at higher risk of developing necro-hemorrhagic enteritis.

Effect of spraying chlorpyrifos on green weeds and its relationship to bacterial enteritis in calves: Case study

Effect of spraying chlorpyrifos on green weeds and its relationship to bacterial enteritis in calves: Case study

Evaluation of the cellular and extracellular fluid of the body of calves using bio impedancemetry

Currently, non‐invasive animal research methods continue to develop, one of which is bioelectrical impedance analysis to determine the body's water, fat, fat‐free, and cell mass, which reflects the assessment of the body's liquids. The electrical and biological significance of impedance analysis lies in the fact that the measurement of the resistance (impedance) of the body's tissues or fluids changes during exposure to alternating currents of different frequencies and makes it possible to take into account the totality of resistance or the actual difference between two measurements taken in succession. The research object was newborn calves, healthy (G1) and with enteritis (G2), selected according to the principle of analogs, 15 animals in each group. The impedance measurements were studied using the “BICA” device (body impedance composition analyzer). Enteritis in calves is accompanied by a significant loss of electrolytes and free fluid, affecting normal metabolic processes. In this regard, the study of the liquids of the body of healthy and enteritis‐sick calves was the main goal of the research. The first signs of enteritis appeared more often on the second and third days of life. In G2: a decrease in motor activity, hunchback (calves do not lean well on the chest limbs, the head is lowered down) were shown, a decrease in the sucking reflex, retraction of the eyeballs into the orbits, low skin turgor, a red border on the gums under the arcade of the incisors. Feces in sick calves are unformed, watery, gray‐yellow in color, with a pungent, sour odor. On the tenth day of life in calves with enteritis, the total body fluid decreased, and this indicator was 1.5 times lower than in healthy calves (P <0.01). The decrease in the total body fluid volume mainly occurred due to a decrease in the level of intracellular fluid, which in sick animals was 2.8 times lower than in healthy animals (p <0.001). At the same time, the level of extracellular fluid in calves from the G1 and the G2 did not differ significantly and amounted to 7.9 ± 0.8% and 6.28 ± 1.0%, respectively. After the treatment (diet therapy and enroxil 5%, intramuscularly, at a dose of 1 ml per 20 kg of body weight once a day for 3 days) by the age of twenty days, the volume of total body fluid in calves with enteritis recovered and did not significantly differ from the level in healthy animals. There were no significant differences in the volume of extracellular fluid in the calves of both groups. However, as for the intracellular fluid volume, this indicator in recovered calves was still significantly lower (P <0.05) than in healthy animals and amounted to 12.14 ± 1.0% and 15.48 ± 0, 7% respectively. Thus, from the data obtained, it can be seen that fluid loss occurs mainly due to the intracellular fluid with enteritis in calves. Complete recovery of the liquid sectors in calves was observed only by the age of one month.

Results of using probiotic based on Enterococcus Faecium L‐3 strain for enteritis of calves

Diseases of the digestive system of calves, including enteritis, are an urgent problem in dairy farming. The disease occurs under the influence of various causes and often has a mixed etiology. The use of veterinary bacterial drugs today has found its application in preventing and treating many animal diseases. At the same time, valuable microorganisms of the digestive system of animals ‐ lactic acid and bifidobacteria, play the role of an immunomodulator by synthesizing their antibiotic substances that stimulate the work of the organism's defenses. Thus, in the prevention and treatment of enteritis in calves, it is essential to use new effective probiotic drugs, taking into account their effect on the microflora of the digestive tract of calves. Two groups of black‐and‐white calves were formed: experimental (G1, n=20) and control (GC, n=20). The selection of animals was carried out according to the principle of analogs. Calves from the G1 were given a probiotic based on the Enterococcus Faecium L‐3 strainfrom birth to 45 days of age, 0.5 g with feed once a day. The probiotic was not fed to the calves of the GC. The tendency towards an increased level of bactericidal (BAS) and lysozyme activity (LAS) of serum was revealed in the calves of G1. Thus, at 14 days of age, the level of BAS in calves receiving the probiotic was significantly higher by 27% (P <0.05), and LAS by 21% (P <0.05) than in calves from the GC. This result was also noted at 30 and 45 days of age. BAS was significantly higher by the 30th day of life in the G1 (P <0.05) than in GC: 13.12 ± 1.95% and 9.68 ± 0.60%, respectively. The LAS level was significantly higher (P <0.01) in calves from G1 by 26% than in animals of the GC: 5.8 ± 0.43% and 4.3 ± 0.20%, respectively. At 45 days of age in animals of the G1, the level of BAS was significantly (P <0.001) higher by 61%, and LAS by 34% (P <0.001) than in GC. In the study of the intestinal microflora, it was noted that the calves of the GC had a significantly higher amount of total bacterial mass, Escherichia coli and Bacteroides fragilis group, which indicates the development of opportunistic microflora. Thus, regular feeding of a probiotic based on the Enterococcus Faecium L‐3 strain to calves of the early postnatal period contributes to better resistance to gastrointestinal disorders and indicators of nonspecific body defense, creating favorable conditions for the development of representatives of normal flora and limiting the growth of opportunistic microflora.

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.

BACTERIAL INTESTINAL INFECTIONS OF YOUNG CATTLE

Gastrointestinal infections of bacterial etiology occupy one of the main places in the pathology of young cattle. The article presents a literature review on the etiology, pathogenesis and clinical diagnosis of major bacterial intestinal infections in young cattle.
 The body of animals is constantly affected by a set of causes, which, due to violations of the technology of maintenance, care and feeding, playing the role of stress factors, leading to reduced nonspecific resistance, increased reactivity and bacteriosis in animals associated with gastrointestinal lesions. Up to 75 % of diseases of the digestive tract of young cattle are more likely to occur as associated infections caused by both viruses and bacteria. Viruses, multiplying in the mucous membrane of the gastrointestinal tract, cause dystrophy, necrosis and desquamation of epithelial cells, what promotes the colonization and penetration into the blood of pathogenic bacteria or their metabolites and the development of severe pathological processes.
 Bacterial agents that cause diarrhea or complicate viral infections include pathogenic Escherichia coli, Salmonella, Clostridium, Citrobacter, Enterococci, Yersinia, Pseudomonas, Campylobacter and others. A special role in the occurrence of diseases of the digestive tract in young cattle is played by opportunistic pathogens, which include bacteria of the family Enterobacteriaceae.
 The main intestinal infections of bacterial etiology of young cattle are colibacillosis, salmonellosis, anaerobic enterotoxemia of calves and campylobacteriosis. Calf colibacillosis is an acute infectious disease caused by enteropathogenic Escherichia coli, which is characterized by profuse diarrhea, septicemia, intoxication, dehydration and significant animal death. The causative agents of salmonellosis are bacteria of the family Enterobacteriaceae Salmonella dublin, S. enteritidis and S. typhimurium. Calves suffer from salmonellosis from the first days of life and up to 6 months of age, with a characteristic acute fever and diarrheal symptom complex. Anaerobic enterotoxemia of calves is an acute toxic-infectious disease of mainly newborn young, caused by the obligate anaerobic bacterium Clostridium perfringens, characterized by hemorrhagic-necrotic inflammation of the intestine, diarrhea and intoxication of the body. Campylobacter jejuni can cause diarrhea in calves. Campylobacteriosis with symptoms of enteritis mainly affects dairy calves, although C. jejuni can also cause enteritis in ruminant calves.
 Other bacteria that can cause enteritis in calves are Bacteroides fragilis, Chlamydophila psittaci, Klebsiella spp., Proteus spp., Yersinia enterocolitica and others.

Differentiating causes of neonatal calf enteritis to enhance management and prevention

There are numerous different agents that cause infectious enteritis in neonatal calves. Although each of these agents have some unique features, the pathophysiological effects on calves can be grouped into 2 categories that are useful in establishing appropriate treatment protocols and management guidelines. One group includes the viral pathogens rotavirus and coronavirus plus the protozoal agent Cryptosporidium. These are non-invasive, cause diarrhea with associated fluid and electrolyte loss that responds well to fluid therapy and are not affected by antibiotic treatment. The other group includes bacterial pathogens that cause different pathophysiologic changes including significant inflammatory response and invasion beyond the intestinal lining. The differences between these groups should guide treatment methods and help establish realistic prognostic expectations and preventive practices. Most affected calves are treated by the workers on a cattle operation. Educating these workers about clinical signs of disease that distinguish between causes of neonatal enteritis could help guide more successful treatment and more judicious antibiotic use.

Long-term production effects of clinical cryptosporidiosis in neonatal calves

Cryptosporidiosis can have a devastating effect in neonatal calves, resulting in diarrhoea, dehydration and, in severe cases, death of the animal. The disease is caused by Cryptosporidium spp. and is one of the most common causes of calf enteritis in the UK. The parasite is very difficult to remove from the farm, as the oocysts have a tough outer wall which enables the parasite to survive for several months in moist temperate environmental conditions and it is difficult to kill oocysts with common disinfectants used on a farm. If appropriate management practises are applied, the disease is usually self-limiting and most calves will recover. It has been shown, in studies with children and in lambs, that severe clinical cryptosporidiosis can result in long-term growth and cognitive impairment compared with individuals with no obvious signs of the disease. This study measured the long-term growth rate of beef calves on farm by comparing groups of animals that had suffered differing degrees of clinical severity of cryptosporidiosis as neonates. A group of 27 beef calves were enrolled in the study and monitored from birth to 6 months of age. The calves were scored for severity of cryptosporidiosis and weighed at regular intervals. The average difference in weight gain, at 6 months, between a group of calves that had severe cryptosporidiosis as neonates and a group of calves with no clinical signs of infection was 34 kg. Those calves that had experienced severe cryptosporidiosis as neonates showed a significantly reduced live weight gain compared with those calves showing no clinical signs of infection (P = 0.034). Therefore, the impact of severe cryptosporidiosis in neonatal calves has longer term effects on weight gain and production efficiency, resulting in the parasite having a greater impact on cattle production than previously thought.

First detection of bovine noroviruses and detection of bovine coronavirus in Australian dairy cattle.

Background and objectiveNoroviruses have been recognised as a significant cause of neonatal enteritis in calves in many countries, but there has been no investigation of their occurrence in Australian cattle. This study aimed to establish whether bovine noroviruses could be detected in faecal samples from Australian dairy cattle. It also sought to determine whether bovine coronaviruses, also associated with neonatal enteritis in calves, could be detected in the same faecal samples.MethodsA selection of faecal samples that were negative for rotaviruses from dairy farms located in three geographically distinct regions of Victoria were pooled and tested by reverse transcription‐PCR for the presence of noroviruses (genogroup III), neboviruses and bovine coronaviruses.Results and conclusionGenetically distinct genogroup III noroviruses were detected in two sample pools from different geographic regions and bovine coronavirus was detected in a third pool of samples. This is the first report of bovine norovirus infection in Australian cattle and suggests that future work is required to determine the significance of these agents as a cause of bovine enteric disease in Australia.

Enteritis infecciosa de los terneros I. Estudio de tres brotes en diferentes localidades del país

Three outbreaks of calf enteritis were investigated. Salmonella typhi-murium was isolated from two of them, and a Salmonella of group E 1 from the third. In no instance was S. dublin found; pending further investigation, therefore, the suggestion is made that calves and pregnant cows should be immunized with vaccine prepared from the isolates of each outbreak, as commercial or other vac­cines prepared from S. dublin are likely to be of little value

SOME RECENT BACTERIOLOGICAL AND BIOCHEMICAL STUDIES ON DIARRHEA IN NEWLY BORN CALVES WITH SPECIAL REFERENCE TO DNA FRAGMENTATION IN BLOOD

Rectal swabs and blood samples were collected from (100) diarrheic calves and (20) apparently healthy contact calves using sterile cotton swabs, at different farms in Sharkia Governorate. For hematological and biochemical investigations, a total of 20 blood samples with and without EDTA from healthy animals showed negative bacterial isolation (group 1) and 50blood samples were selected from collected blood samples (100) from animals showed positive bacterial isolation (group 2). Bacteriological examination of fecal samples revealed that E coli was the most prominent cause of calf diarrhea at an incidence of 54.1 %,followed by Salmonella species at an incidence of 17.5 % then Campylobacter at an incidence of 10.8 %. Proteus valgaris was isolated at an incidence of 10 % then Pseudomonas at an incidence of 6.7 %. Serological identification of 65 E. coli isolates, revealed that the E. coli were typed as O157 (38.5%), O119 (23.1%), O25 (7.7), O111 (7.7%), O186 (15.4%), and untypable E. coli (7.7%). Bacteriological examination revealed the isolation of Salmonella from diarrheic calves as well as apparently healthy contact calves. S. typhimurium was the most predominant serovars (52.4%) which indicates that S. typhimurium is the most predominant serovars causing enteritis in calves. S. enteritidis (33.3%) and 3 strains (14.3%) were untypable. Results of antibiogram revealed that, ciprofloxacin, cephalexin and ofloxacin( were the most effective antibiotics for treatment of diarrheic calves. Most isolated bacteria showed different degrees of resistance to Ampicillin, Cefotaxime, Gentamycine. PCR results revealed that 16 (88.9%) out of 18 examined E coli strains encoding blaTEM gene while only two (11.1%) strains were negative. The hematological changes revealed that there was a significant decrease in total red blood cells count, platelets and hemoglobin concentration (p < 0.05) accompanied by higher values of Total leukocyte count (TLC), neutrophilia with lymphopenia recorded in diarrheic calves in comparison with control.Biochemical analysis of positive cases revealed significant increase (P<0.05) in serum globulin content and decrease in total protein, albumin content, resulting in altered A/G ratio, also there was significant increase in urea, creatinine and potassium accompanied by significant decrease in glucose and sodium. In comparison with control amino acid analysis demonstrated significant (P<0.05) decrease in diseased calves. Inter nucleosomal cleavage of host cell DNA, indicated evidence of apoptosis, there was a direct relationship between DNA fragmentation and malondialdehyde level (MDA) while inverse relation with antioxidants.

Assessment of Adhesins as an Indicator of Pathovar-Associated Virulence Factors in Bovine Escherichia coli.

The CS31A, F17, and F5 adhesins are usually targeted by serology-based methods to detect pathogenic Escherichia coli associated with calf enteritis. However, the virulence traits of the selected isolates are still poorly described. Here, from a set of 349 diarrheagenic E. coli isolates from cattle, we demonstrated a 70.8% concordance rate (Cohen's kappa, 0.599) between serology- and PCR-based approaches for the detection of adhesins under field conditions. A 79% to 82.4% correspondence between the two methods was found for fimbrial adhesins, whereas major discrepancies (33%) were observed for CS31A-type antigens. Various F17A variants were found, such as F17Ac (20K) (50%), F17Aa (FY) (18.9%), F17Ab (8.1%), and F17Ad (111K) (5.4%), including a high proportion (17.6%) of new F17A internal combinations (F17Aab, F17Aac, and F17Abc) or untypeable variants. In addition, the highest proportion of pathovar-associated virulence factor (VF) genes was observed among E. coli isolates that produced F5/F41 adhesins. A specific link between the heat-stable toxins related to the enterotoxigenic E. coli (ETEC) pathovar and adhesins was identified. STa was significantly linked to F5/F41 and EAST1 to CS31A adhesins (P < 0.001), respectively, whereas NTEC was associated with F17 adhesin (P = 0.001). Clustering between phylogroups according to the adhesin types was also observed. Also, few Shiga toxin-producing E. coli (STEC) or enteropathogenic E. coli (EPEC) pathovars were identified. Finally, no statistically significant difference was observed in the occurrence of extended-spectrum beta lactamase (ESBL) production according to the adhesins expressed by the isolates (P = 0.09). Altogether, this study gives new insights into the relationship between adhesins, VF, and antimicrobial resistance in calf enteritis and supports the need for further standardization of methodologies for such approaches.

Patterns of antimicrobial resistance in pathogenic Escherichia coli isolates from cases of calf enteritis during the spring-calving season

Neonatal enteritis is a common condition of young calves and can be caused by pathogenic strains of Escherichia coli. We hypothesised that on-farm antimicrobial use would result in an increased frequency of resistance in these strains during the calving season. We also sought to determine if the frequency of resistance reflected on-farm antimicrobial use. Faecal samples were collected from cases of calf enteritis on 14 spring-calving dairy farms during two 3 week periods: Period 1 – February 11th through March 2nd 2008 and Period 2 – April 14th through May 5th 2008. E. coli were cultured from these samples, pathogenic strains were identified and antimicrobial susceptibility testing was carried out on these pathogenic isolates. Antimicrobial prescribing data were collected from each farm for the previous 12 months as an indicator of antimicrobial use. The correlation between antimicrobial use and resistance was assessed using Spearman's correlation coefficient. Logistic regression analysis was used to investigate the relationship between resistance, sampling period and pathotype. Penicillins and aminopenicillins, streptomycin, and tetracyclines were the most frequently prescribed antimicrobials and the greatest frequencies of resistance were detected to these 3 antimicrobial classes. A strong correlation (ρ=0.879) was observed between overall antimicrobial use and frequencies of antimicrobial resistance on farms. Sampling period was significant in the regression model for ampicillin resistance while pathotype was significant in the models for streptomycin, tetracycline and trimethoprim/sulphamethoxazole resistance. The frequencies of resistance observed have implications for veterinary therapeutics and prudent antimicrobial use. Resistance did not increase during the calving season and factors other than antimicrobial use, such as calf age and bacterial pathotype, may influence the occurrence of resistance in pathogenic E. coli.

Mycobacterium aviumSubsp.aviumInfection in Four Veal Calves: Differentiation from Intestinal Tuberculosis

Mycobacterium avium subsp. avium (Maa) is an intracellular pathogen belonging to the Mycobacterium avium-intracellulare complex (MAC). Reservoirs of MAC are the natural environment, wildlife and domestic animals. In adult bovine, MAC infections are typically caused by Mycobacterium avium subsp. paratuberculosis (Map). Maa infections in bovine are rarely reported but may cause clinical disease and pathological lesions similar to those observed in paratuberculosis or those induced by members of the Mycobacterium tuberculosis complex (MTBC). Therefore, differentiation of MAC from MTBC infection should be attempted, especially if unusual mycobacterial lesions are encountered. Four veal calves from a fattening farm dying with clinical signs of otitis media, fever, and weight loss were submitted for necropsy. Samples from affected organs were taken for histologic investigation, bacteriologic culture, and bacterial specification using PCR. Macroscopic thickening of the intestinal mucosa was induced by granulomatous enteritis and colitis. Intracytoplasmic acid-fast bacteria were detected by Ziehl-Neelsen stains and PCR revealed positive results for Mycobacterium avium subsp. avium. Clinical and pathological changes of Maa infection in veal calves had features of Mycobacterium avium subsp. paratuberculosis and the MTBC. Therefore, Mycobacterium tuberculosis complex infection should be considered in cases of granulomatous enteritis in calves.

Characterisation of bovine viral diarrhoea virus (BVDV) isolates from an outbreak with haemorrhagic enteritis and severe pneumonia

During 2007 a disease outbreak occurred in cattle in the Marmara region of western Turkey characterised by severe pneumonia and haemorrhagic enteritis in calves. Cases from three farms at different locations were examined and bovine viral diarrhoea virus (BVDV) isolated in all cases. Phylogenetic characterisation of the virus isolates allocated them in a new cluster tentatively named as BVDV-1r.

Lesion Development in a New Intestinal Loop Model Indicates the Involvement of a Shared Clostridium perfringens Virulence Factor in Haemorrhagic Enteritis in Calves

Clostridium perfringens-associated enterotoxaemia is a fatal disease in fast growing suckler and veal calves. An intestinal loop model was developed to study the pathogenesis of the disease. Loops were injected with stationary and logarithmic C. perfringens cultures with or without, a milk protein-based commercial milk replacer for calves. Isolates tested were from cases of bovine enterotoxaemia and from calves without signs of enterotoxaemia, in addition to netB-positive and -negative isolates from poultry, a type C isolate from piglets and the human isolate JIR325. All isolates induced necrohaemorrhagic lesions in combination with milk replacer, while all control loops (i.e. medium plus milk replacer) remained histologically normal. In addition, time-course experiments were conducted using an isolate from an outbreak of bovine enterotoxaemia. Histological examination showed that the earliest lesion was congestion of the capillaries, starting within 30min of inoculation. Haemorrhage and mucosal necrosis began at the tips of the villi 3-4h after bacterial inoculation. These lesions are similar to those observed in natural cases of bovine enterotoxaemia. Therefore, in this model, necrohaemorrhagic lesions can be induced by C. perfringens isolates from diverse origins, suggesting that the lesions may be caused by one or more virulence factors that are shared by these isolates.

Necrotic Enteritis in Young Calves

Non-enterotoxin (CPE)-producing Clostridium perfringens type A has been associated with enteritis in calves. Recent evidence has suggested that a novel toxin, named beta2 (CPB2), is implicated in the pathogenesis of this disease, although there is little evidence supporting this. In the current study, the role of C. perfringens type A in an outbreak of enteritis in calves was studied. Two 20-day-old dairy calves exhibiting apathy and reluctance to eat, with paresis of the anterior limbs, were euthanized for postmortem examination. Gross and histological changes compatible with acute enteritis, rumenitis, meningitis, and pneumonia were seen in both calves. Clostridium perfringens type A non-CPE, non-CPB2 was isolated from the abomasum and the small intestine. Escherichia coli ONTH8 (with cdtBIII and f17 virulence genes detected by polymerase chain reaction) was also isolated from the brain, abomasum, and intestine from both calves. All the samples were negative for Salmonella spp. When the C. perfringens strain was inoculated into bovine ligated small and large intestinal loops, cell detachment, erosion, and hemorrhage of the lamina propria were observed, predominantly in the small intestine. The results suggest that non-CPE, non-CPB2 C. perfringens type A is able to induce pathologic changes in the intestine of calves, probably enhanced by other pathogens, such as some pathogenic E. coli strains.