Evaluation of Blood Lactate, Heart Rate, Blood Pressure, and Shock Index, and Their Association with Prognosis in Calves.

Diseases in young calves received as emergencies are often associated with hypovolemic and/or septic shocks. The objectives of our study were to (1) assess the correlation between clinical hemodynamic parameters and blood L-lactates (LAC), systolic blood pressure (SBP), and the shock index (SI) recorded upon arrival; and (2) to evaluate how these parameters were related to short-term outcomes in calves under 4 months of age presented as emergencies. We conducted a single-observer prospective observational study on calves aged from 1 day to 4 months, presented to the Veterinary Clinic for Ruminants of Liège from December 2020 to May 2022. Forty-five calves were included in the study. The statistical analysis revealed a significant correlation between LAC and heart rate (r = 0.570; p < 0.05) and LAC and SI (r = 0.373; p < 0.05). A high LAC value at admission was significantly associated with a negative outcome (death) (p < 0.05). In calves suffering from obstructive digestive diseases, the SI was related to the outcome and the analysis indicated a cut-off value of 1.13 (Se = 0.77, Spe = 1). In conclusion, in our study, the initial blood L-lactate value was correlated with heart rate, the shock index, and the clinical shock score, and admission hyperlactatemia was associated with a poor prognosis in calves under 4 months of age. In this cohort, the shock index in calves suffering from digestive diseases was linked with mortality.

Oak Acorn Poisoning in Cattle during Autumn 2022: A Case Series and Review of the Current Knowledge.

Oak poisoning is a known intoxication in grazing animals, but is slightly described in the literature. This case report describes 7 cattle from 3 different farms admitted to the clinic for ruminants of the University of Liège for suspected acorn poisoning in the autumn of 2022. The clinical signs were, anorexia, apathy with polyuria with low density. Further investigations led to the diagnosis of renal failure (blood urea 162 ± 88 mg/dL; blood creatinine 12 ± 4 mg/L). Supportive treatment, based on infusions (NaCl 0.9%) and electrolyte rebalancing, was administered and renal values were assessed every 24-48 h. Of these animals, 5/7 were euthanized. At necropsy, digestive erosions and ulcerations, oedema and renal hemorrhages, between the pyloric/caliceal cavity and the medulla were observed. Histopathological examination revealed necrosis of the renal tubules. The renal values of the two remaining animals were reduced, their general condition improved, and they were discharged. Acorn poisoning is a serious disease with no specific antidote or characteristic symptoms. Animals are identified as sick too late, when renal failure is already established. Farmers should be made more aware in order to prevent exposure, especially in years when acorns are abundant. Furthermore, there is no antidote for this intoxication.

Bacterial Contamination of the Surgical Site at the Time of Elective Caesarean Section in Belgian Blue Cows-Part 2: Identified by 16Sr DNA Amplicon Sequencing.

This study aimed to describe the bacterial composition of the surgical site during elective caesarean sections (CSs) using the 16Sr DNA amplicon sequencing performed in parallel to bacterial culture. The study involved 13 Belgian blue cows of a previous dataset of 76 animals. Bacteriology was performed on swabs sampled from visceral and parietal peritoneum during the CS. Amplicon sequencing was performed in six samples chosen randomly among the swabs positive for bacteriology and seven among the culture-negative swabs. A total of 2542 bacterial operational taxonomic units belonging to 567 genera were identified. The most often identified genus and species were Mycoplasma (44%) and Mycoplasma wenyonii (36%), respectively. Results showed no difference in microbiota composition between the culture-positive and -negative samples. However, a difference was observed between the bacteriology and amplicon sequencing results. Indeed, seven out of nine cultured strains were not identified by amplicon sequencing in the samples in which they were cultured. In contrast to bacteriology, amplicon sequencing unveiled the presence of bacterial DNA in all elective CSs. The most identified DNA is most likely derived from the haematogenous spread of bacteria to the surgical site. Furthermore, the cultured bacteria were not the dominant species in the sample from which they were cultured.

Bacterial Contamination of the Surgical Site at the Time of Elective Caesarean Section in Belgian Blue Cows-Part 1: Identified by Bacterial Culture.

To improve the efficacy of preoperative antibiotics used in elective caesarean section (CS), we aimed to identify the bacteria contaminating the surgical site during this surgery. A study was conducted on 76 Belgian Blue cows. Bacteriology was performed on cotton swab sampled from the visceral and parietal peritoneum of each cow during the CS. Most of samples showed a negative culture (55/76; 72.37%), 19/76 (25%) were positive (p < 0.0001) and two samples were contaminated. In total, 32 isolates belonging to 18 species were identified. Most of them are aerobic (17/18; 94.44%) and half of them were gram-negative (G-). The most encountered bacteria were Acinetobacter sp. (6/32; 18.75%), Pseudomonas sp. (4/32; 12.5%), Aerococcus viridans (4/32; 12.5%), Psychrobacter sp. (3/32; 9.37%), and Escherichia coli (2/32; 6.25%). Among the identified isolates, 31/32 (96.87%) were aerobic and 1/32 (3.12%) was anaerobic (p = 0.0001). Furthermore, 20/32 (62.50%) strains were G− while 12/32 (37.5%) were gram-positive (G+) (p = 0.012). In fact, most of cultured strains were aerobic G− (20/32), 11/32 were aerobic G+ and 1/32 is anaerobic G+ (p < 0.0001). In conclusion, most of samples showed a negative bacteriology; however, aerobic G− strains were the most identified in positive swabs. Therefore, preoperative antibiotics should be aimed against these bacteria.

Blood Inflammatory, Hydro-Electrolytes and Acid-Base Changes in Belgian Blue Cows Developing Parietal Fibrinous Peritonitis or Generalised Peritonitis after Caesarean Section.

This study aimed to describe the inflammation, hydro-electrolyte and acid-base imbalances caused by generalised peritonitis (GP) and parietal fibrinous peritonitis (PFP) after caesarean section. After clinical examination, blood was sampled from 11 cows with PFP, 30 with GP and 14 healthy cows. Serum and plasma refractometry and glutaraldehyde tests were used to evaluate the inflammation level, while hydro-electrolytes and acid-base parameters were assessed using an EPOC® device. In addition to clinical signs of dehydration (>10%), blood analysis showed a high fibrinogen concentration (PFP: 8.64 ± 8.82 g/L; GP: 7.83 ± 2.45 g/L) and fast glutaraldehyde coagulation (<3 min) indicative of severe inflammation in both diseases compared to the control group (p < 0.05). Moreover, a severe decrease in electrolytes concentration (Na+: 126.93 ± 5.79 mmol/L; K+: 3.7 ± 1.3 mmol/L; Ca++: 0.89 ± 0.12 mmol/L; Cl−: 82.38 ± 6.45 mmol/L) and a significant increase in bicarbonate (30.87 ± 8.16 mmol/L), base excess (5.71 ± 7.42 mmol/l), L-lactate (8.1 ± 4.85 mmol/L) and creatinine (3.53 ± 2.30 mg/dL) were observed in cows with GP compared to the control group (p < 0.05). In contrast, few major perturbations were noticed in PFP, where only K+ (3.64 ± 0.25 mmol/L) and Ca++ (1.06 ± 0.09 mmol/L) were significantly modified (p < 0.05). In conclusion, a high dehydration and severe inflammation are induced by PFP and GP. Nevertheless, GP causes more electrolytes and acid-base disturbances than PFP.

Antimicrobial Susceptibility Profile of Several Bacteria Species Identified in the Peritoneal Exudate of Cows Affected by Parietal Fibrinous Peritonitis after Caesarean Section.

The aim of this study was to identify the species and antimicrobial susceptibility of bacteria involved in parietal fibrinous peritonitis (PFP). We studied 156 peritoneal fluid samples from cows presenting PFP after caesarean section. Bacteria were cultured in selective media and their antimicrobial susceptibility was tested by disk diffusion assay. Bacteria were isolated in the majority (129/156; 83%) of samples. The majority (82/129; 63%) of positive samples contained one dominant species, while two or more species were cultured in 47/129 (36%) samples. Trueperella pyogenes (T. Pyogenes) (107 strains) was the most identified species, followed by Escherichia coli (E. coli) (38 strains), Proteus mirabilis (P. mirabilis) (6 strains), and Clostridium perfringens (C. perfringens) (6 strains). Several other species were sporadically identified. Antimicrobial susceptibility was tested in 59/185 strains, predominantly E. coli (38 strains) and P. mirabilis (6 strains). Antibiotic resistance, including resistance to molecules of critical importance, was commonly observed; strains were classified as weakly drug resistant (22/59; 37%), multidrug resistant (24/59; 41%), extensively drug resistant (12/59; 20%), or pan-drug resistant (1/59; 2%). In conclusion, extensive antibiotic resistance in the isolated germs might contribute to treatment failure. Ideally, antimicrobial therapy of PFP should be based upon bacterial culture and susceptibility testing.

Parietal fibrinous peritonitis in cattle: A literature review.

BACKGROUND: Parietal fibrinous peritonitis (PFP) is a complication of laparotomy in cattle, consisting of fluid and fibrin accumulation within a fibrous capsule between the parietal peritoneum and the abdominal muscles. Since scientific information on PFP is scarce, we aim to collect available information to help practitioners in its diagnosis and treatment, and to formulate research perspectives. METHODS: PubMed and GoogleScholar databases were scanned using "cattle" or "bovine", and one of the following keywords: "seroma", "parietal fibrinous peritonitis", "retroperitoneal abscess", or "wound infection". RESULTS: Although scientific information is often anecdotal, two recent larger studies shed more light on PFP symptoms, diagnosis and treatment. Symptoms vary according to the cavity's localisation and size, and include anorexia, weight loss and an inflammatory status. Rectal palpation is strongly indicative, but the definitive diagnosis is made by ultrasound. Trueperella pyogenes and Escherichia coli are frequently isolated germs, although it remains unclear whether they are primary or secondary agents. Good survival rates were reported after surgical drainage. CONCLUSION: Although the diagnosis and treatment seem clear, the exact pathogenesis of PFP should be the focus of ongoing research. This can be achieved by epidemiological data analysis focusing on risk factors like surgery technique, housing and ration.

Antimicrobial Susceptibility of Mycoplasma bovis Isolates from Veal, Dairy and Beef Herds.

Mycoplasma bovis is an important pathogen causing mostly pneumonia in calves and mastitis in dairy cattle. In the absence of an effective vaccine, antimicrobial therapy remains the main control measure. Antimicrobial use in veal calves is substantially higher than in conventional herds, but whether veal calves also harbor more resistant M. bovis strains is currently unknown. Therefore, we compared antimicrobial susceptibility test results of M. bovis isolates from different cattle sectors and genomic clusters. The minimum inhibitory concentration of nine antimicrobials was determined for 141 Belgian M. bovis isolates (29 dairy, 69 beef, 12 mixed, 31 veal farms), and was used to estimate the epidemiological cut-off. Acquired resistance was frequently observed for the macrolides, while no acquired resistance to oxytetracycline and doxycycline, minimal acquired resistance to florfenicol and tiamulin, and a limited acquired resistance to enrofloxacin was seen. M. bovis isolates from beef cattle or genomic cluster III had higher odds of being gamithromycin-resistant than those from dairy cattle or genomic clusters IV and V. In this study, no cattle industry could be identified as source of resistant M. bovis strains. A single guideline for antimicrobial use for M. bovis infections, with a small remark for gamithromycin, is likely sufficient.

Comparison between generalised peritonitis and parietal fibrinous peritonitis in cows after caesarean section.

BACKGROUND: Parietal fibrinous peritonitis (PFP) and generalised peritonitis (GP) are two postoperative complications in cows, characterised by fluid and fibrin accumulation throughout the peritoneum (GP) or in an encapsulated cavity (PFP). Unlike GP, PFP is scarcely documented. METHODS: Twenty-one GP cases and 12 PFP cases were confirmed by ultrasound in cows referred to the Veterinary Clinic (Liège University) for complications after caesarean section. All cows underwent a standardised examination protocol. Blood samples were analysed for metabolic and inflammatory markers. Bacteriology was performed on peritoneal fluid samples. Treatment consisted of surgical drainage of the abdominal cavity (GP) or the encapsulated cavity (PFP). Variables concerning anamnesis, clinical findings and treatment outcomes were compared. RESULTS: Perioperative complications had occurred in 9/21 GP cows but 0/12 PFP cows (P<0.05). Biochemical analysis indicated pronounced inflammation and did not differ between groups. Peritoneal fluid samples of both groups were contaminated and contained similar bacteria (Trueperella pyogenes and Escherichia coli). While 11/12 PFP cows were discharged, all patients with GP died or were euthanased (P<0.05). CONCLUSIONS: We hypothesise that PFP and GP are two different manifestations of perioperative peritoneal contamination. The severity and spread of the contamination determine the clinical presentation and the prognosis.

The presence of Mycoplasma bovis in colostrum.

In herds with Mycoplasma bovis circulation, colostrum is often considered infectious. However, in contrast to milk, the presence of M. bovis in colostrum was not previously evidenced. In this survey, the presence of M. bovis DNA was determined with real-time PCR in 368 colostrum samples from 17 herds, recently infected with M. bovis. Only 1.9% of the samples tested positive, with 13 herds having no positive samples and an overall within-herd prevalence of 3.2% (SD: 4.9%; Range: 0-30.0%). These results show that in infected herds M. bovis DNA can be retrieved in colostrum. To what extend colostrum is infectious remains to be determined.

Optimizing identification of Mycoplasma bovis by MALDI-TOF MS.

Fast and accurate identification of Mycoplasma bovis in cattle samples is of great importance for rational treatment and control of pneumonia, arthritis and mastitis. However, which growth conditions will allow the fastest identification of M. bovis with MALDI-TOF MS remains unclear. Therefore, growth conditions and incubation time were investigated to optimize identification of M. bovis with MALDI-TOF MS and an in-house library was constructed. Nine different M. bovis strains were inoculated in triplicate in three liquid media (B1-3). Basic broth (B1) consisted of pleuropneumonia-like organism broth, enriched with 25% horse serum and 0.7% yeast extract. B2 and B3 were additionally supplemented with 0.5% pyruvate or 520 µg/mL ampicillin, respectively. Protein extraction was performed after 24, 48, 72, 96 and 120 h of incubation (37 °C, 5% CO2) and processed with Autoflex III smartbeam. Identification scores ≥1.7 were interpreted as reliable. The present study showed reliable identification of M. bovis with MALDI-TOF MS as early as 24 h after inoculation, and in broth supplemented with pyruvate, up to 120 h after inoculation. Serial dilutions showed improved survival of M. bovis in broth with pyruvate. The addition of ampicillin to prevent contamination, did not impair identification of M. bovis and state-of-the-art in-house libraries contributed to higher identification scores for M. bovis with MALDI-TOF MS.

Factors associated with lung cytology as obtained by non-endoscopic broncho-alveolar lavage in group-housed calves.

BACKGROUND: Respiratory infections are the main indication for antimicrobial use in calves. As in humans and horses, studying inflammation of the deep airways by lung cytology raises the possibility of preventing respiratory disease and targeting its treatment in the future. Whether lung cytology findings coincide with clinical signs and lung ultrasonographic findings is currently unknown. Therefore, the objective of the present study was to determine the association of lung cytology with clinical signs, lung consolidation and broncho-alveolar lavage fluid (BALf) characteristics (including bacteriology). A total of 352 indoor group-housed calves aged between 1 and 6 months from 62 conveniently selected commercial herds were included in this cross-sectional study. Clinical examination, thoracic ultrasound and bacteriology and cytology on non-endoscopic broncho-alveolar lavage (nBAL) samples were performed. RESULTS: Pneumonia, defined as presence of ultrasonographic lung consolidations ≥1 cm in depth, affected 42.4% of the calves. Mean BALf neutrophil percentage was 36.6% (SD 23.8; R 0-97.4) and only a positive induced tracheal cough reflex (P = 0.04), standing posture (P = 0.03) increased breathing rate (P = 0.02) and isolation of Pasteurella multocida (P = 0.005), were associated with increased neutrophil percentage. No significant associations between lung ultrasonographic findings and cytology results were present, except for presence of basophils in BALf and consolidation of > 3 cm in depth (OR = 2.6; CI = 1.2-5.6; P = 0.01). Abnormal lung sounds were associated with detection of eosinophils in BALf (OR = 2.8; CI = 1.0-8.1; P = 0.05). Total nucleated cell count (TNCC) (P <  0.001) was positively and macrophage percentage (P = 0.02) negatively associated with volume of lavage fluid recovered. Macroscopic blood staining of BALf increased TNCC (P = 0.002) and lymphocyte percentage (P = 0.001). CONCLUSIONS: Only a limited number of clinical signs and ultrasonographic findings were associated with nBAL cytology. BALf cytology offers additional and distinct information in calves aiding in detection and prevention of respiratory conditions. In this population, selected from herds not reporting any recent respiratory illness, a high number of calves had ultrasonographic lung consolidation and high neutrophil percentage in BALf, suggesting that subclinical disease presentations frequently occur.

Rapid detection of tetracycline resistance in bovine Pasteurella multocida isolates by MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA).

Pasteurella multocida is notorious for its role as an opportunistic pathogen in infectious bronchopneumonia, the economically most important disease facing cattle industry and leading indication for antimicrobial therapy. To rationalize antimicrobial use, avoiding imprudent use of highly and critically important antimicrobials for human medicine, availability of a rapid antimicrobial susceptibility test is crucial. The objective of the present study was to design a MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA) procedure for tetracycline resistance detection in P. multocida. This procedure was validated on 100 clinical isolates with MIC-gradient strip test, and a comparison with disk diffusion was made. Sensitivity and specificity of the MBT-ASTRA procedure were 95.7% (95% confidence interval (CI) = 89.8-101.5) and 100% (95% CI = 100-100), respectively, classifying 98% of the isolates correctly after only three hours of incubation. Sensitivity and specificity of disk diffusion were 93.5% (95% CI = 86.3-100.6) and 96.3% (95% CI = 91.3-101.3) respectively, classifying 95% of the isolates correctly. In conclusion, this MBT-ASTRA procedure has all the potential to fulfil the need for a rapid and highly accurate tetracycline susceptibility testing in P. multocida to rationalize antimicrobial use in outbreaks of bronchopneumonia in cattle or other clinical presentations across species.

Use of a breeding bull and absence of a calving pen as risk factors for the presence of Mycoplasma bovis in dairy herds.

Mycoplasma bovis is an important cause of pneumonia and mastitis in cattle throughout the world, often reported as emerging. In absence of an effective vaccine for M. bovis, current prevention and control strategies rely on the identification of risk factors for within- and between-herd spread. The objective of this study was to determine the prevalence of M. bovis in Belgian dairy herds and to identify risk factors associated with a positive PCR or antibody ELISA bulk tank milk (BTM) test. A cross-sectional study was performed in 2016 on 100 dairy farms, analyzing BTM using PCR and antibody ELISA. Information on herd-level risk factors focusing on biosecurity and management were collected through a questionnaire and sourced from the national herd identification system (SANITRACE, Animal Health Service Flanders). Multivariable logistic regression was used to identify herd-level risk factors for the presence of M. bovis DNA and antibodies in BTM. The apparent prevalence on BTM was 7 and 17% for PCR and antibody ELISA, respectively. The true prevalence was 7.1% [95% confidence interval (CI) = 2.1-11.5%] and 24.8% (95% CI = 16.4-33.2%). There was no overlap between ELISA- and PCR-positive farms, resulting in a combined true prevalence of 31.8% of the Belgian farms being in recent contact with M. bovis. Risk factor analysis showed that herds with a breeding bull [M. bovis-positive results for 45.5 and 13.6% of herds with and without a bull, respectively, odds ratio = 4.7 (95% CI = 1.1-19.8)] and without a calving pen [M. bovis-positive result in 52.4 and 20.6% of the herds without and with a calving pen, respectively, odds ratio = 3.7 (95% CI = 1.06-12.5)] had higher odds to harbor M. bovis antigen or antibodies in BTM. In conclusion, the present study points to a several fold increase in the prevalence of M. bovis in Belgian dairy herds. The importance of the breeding bull and calving pen in the between- and within-herd spread of M. bovis might have been underestimated in the past. Focusing on these factors might contribute to more effective control programs in the future.

Veal Calves Produce Less Antibodies against C. Perfringens Alpha Toxin Compared to Beef Calves.

Enterotoxaemia is a disease with a high associated mortality rate, affecting beef and veal calves worldwide, caused by C. perfringens alpha toxin and perfringolysin. A longitudinal study was conducted to determine the dynamics of antibodies against these toxins in 528 calves on 4 beef and 15 veal farms. The second study aimed to determine the effect of solid feed intake on the production of antibodies against alpha toxin and perfringolysin. The control group only received milk replacer, whereas in the test group solid feed was provided. Maternal antibodies for alpha toxin were present in 45% of the veal calves and 66% of the beef calves. In beef calves a fluent transition from maternal to active immunity was observed for alpha toxin, whereas almost no veal calves developed active immunity. Perfringolysin antibodies significantly declined both in veal and beef calves. In the second study all calves were seropositive for alpha toxin throughout the experiment and solid feed intake did not alter the dynamics of alpha and perfringolysin antibodies. In conclusion, the present study showed that veal calves on a traditional milk replacer diet had significantly lower alpha toxin antibodies compared to beef calves in the risk period for enterotoxaemia, whereas no differences were noticed for perfringolysin.