Toomas Orro

Acute phase response in two consecutive experimentally induced E. coli intramammary infections in dairy cows.

BackgroundAcute phase proteins haptoglobin (Hp), serum amyloid A (SAA) and lipopolysaccharide binding protein (LBP) have suggested to be suitable inflammatory markers for bovine mastitis. The aim of the study was to investigate acute phase markers along with clinical parameters in two consecutive intramammary challenges with Escherichia coli and to evaluate the possible carry-over effect when same animals are used in an experimental model.MethodsMastitis was induced with a dose of 1500 cfu of E. coli in one quarter of six cows and inoculation repeated in another quarter after an interval of 14 days. Concentrations of acute phase proteins haptoglobin (Hp), serum amyloid A (SAA) and lipopolysaccharide binding protein (LBP) were determined in serum and milk.ResultsIn both challenges all cows became infected and developed clinical mastitis within 12 hours of inoculation. Clinical disease and acute phase response was generally milder in the second challenge. Concentrations of SAA in milk started to increase 12 hours after inoculation and peaked at 60 hours after the first challenge and at 44 hours after the second challenge. Concentrations of SAA in serum increased more slowly and peaked at the same times as in milk; concentrations in serum were about one third of those in milk. Hp started to increase in milk similarly and peaked at 36–44 hours. In serum, the concentration of Hp peaked at 60–68 hours and was twice as high as in milk. LBP concentrations in milk and serum started to increase after 12 hours and peaked at 36 hours, being higher in milk. The concentrations of acute phase proteins in serum and milk in the E. coli infection model were much higher than those recorded in experiments using Gram-positive pathogens, indicating the severe inflammation induced by E. coli.ConclusionAcute phase proteins would be useful parameters as mastitis indicators and to assess the severity of mastitis. If repeated experimental intramammary induction of the same animals with E. coli is used in cross-over studies, the interval between challenges should be longer than 2 weeks, due to the carry-over effect from the first infection.

Udder pathogens and their resistance to antimicrobial agents in dairy cows in Estonia

BackgroundThe goal of this study was to estimate the distribution of udder pathogens and their antibiotic resistance in Estonia during the years 2007-2009.MethodsThe bacteriological findings reported in this study originate from quarter milk samples collected from cows on Estonian dairy farms that had clinical or subclinical mastitis. The samples were submitted by local veterinarians to the Estonian Veterinary and Food Laboratory during 2007-2009. Milk samples were examined by conventional bacteriology. In vitro antimicrobial susceptibility testing was performed with the disc diffusion test. Logistic regression with a random herd effect to control for clustering was used for statistical analysis.ResultsDuring the study period, 3058 clinical mastitis samples from 190 farms and 5146 subclinical mastitis samples from 274 farms were investigated. Positive results were found in 57% of the samples (4680 out of 8204), and the proportion did not differ according to year (p > 0.05). The proportion of bacteriologically negative samples was 22.3% and that of mixed growth was 20.6%. Streptococcus uberis (Str. uberis) was the bacterium isolated most frequently (18.4%) from cases of clinical mastitis, followed by Escherichia coli (E. coli) (15.9%) and Streptococcus agalactiae (Str. agalactiae) (11.9%). The bacteria that caused subclinical mastitis were mainly Staphylococcus aureus (S. aureus) (20%) and coagulase-negative staphylococci (CNS) (15.4%). The probability of isolating S. aureus from milk samples was significantly higher on farms that had fewer than 30 cows, when compared with farms that had more than 100 cows (p < 0.005). A significantly higher risk of Str. agalactiae infection was found on farms with more than 600 cows (p = 0.034) compared with smaller farms. The proportion of S. aureus and CNS isolates that were resistant to penicillin was 61.4% and 38.5%, respectively. Among the E. coli isolates, ampicillin, streptomycin and tetracycline resistance were observed in 24.3%, 15.6% and 13.5%, respectively.ConclusionsThis study showed that the main pathogens associated with clinical mastitis were Str. uberis and E. coli. Subclinical mastitis was caused mainly by S. aureus and CNS. The number of S. aureus and Str. agalactiae isolates depended on herd size. Antimicrobial resistance was highly prevalent, especially penicillin resistance in S. aureus and CNS.

Association of bovine respiratory disease with clinical status and acute phase proteins in calves.

Abstract Eighty-four calves with respiratory disease from 18 herds in different parts of Finland were chosen for a study evaluating the capacity of different respiratory pathogens to cause changes in different acute phase protein concentrations, white blood cell (WBC) count and clinical signs. The selected acute phase proteins were fibrinogen, haptoglobin, serum amyloid-A, lipopolysaccharide binding protein and α1-acid glycoprotein. From each calf, a paired blood sample was obtained for serological studies of bovine parainfluenza virus-3, bovine respiratory syncytial virus, bovine coronavirus, bovine adenovirus-3 and bovine adenovirus-7. Tracheobronchial lavage was performed to detect bacteria and mycoplasma. Isolation of Pasteurella multocida was associated with increased concentrations of all tested acute phase proteins. For other pathogens, no significant relationships were observed. No association was present between viral or bacterial findings and WBC count.

Lameness and fertility of sows and gilts in randomly selected loose-housed herds in Finland.

The prevalence of lameness among 646 sows and gilts in 21 selected herds was determined; 8·8 per cent of the animals were lame and the most common clinical diagnoses were osteochondrosis, infected skin lesions and claw lesions. The lame animals had higher serum concentrations of haptoglobin and C-reactive protein than the sound animals. Animals housed on slatted floors had twice the odds of being lame and 3·7 times the odds of being severely lame than animals housed on solid floors. Yorkshire pigs had 2·7 times the odds of being lame than Landrace or crossbred animals. Higher parity and the use of roughage decreased the odds of the sows not becoming pregnant; however, lameness was not a risk factor for non-pregnancy.

Acute phase protein changes in calves during an outbreak of respiratory disease caused by bovine respiratory syncytial virus.

Abstract Bovine acute phase proteins (APPs), lipopolysaccharide binding protein (LBP), serum amyloid A (SAA), haptoglobin (Hp) and alpha1-acid glycoprotein (AGP) were evaluated as inflammatory markers during an outbreak of bovine respiratory disease (BRD) caused by bovine respiratory syncytial virus (BRSV). Calves (n =10) presented mild to moderate signs of respiratory disease. Secondary bacterial infections, Pasteurella multocida and Mycoplasma dispar as major species, were detected in tracheobronchial lavage samples. Concentrations of SAA and LBP increased at week 1 had the highest values at week 3 and decreased at week 4 of outbreak. Some calves had high Hp concentrations at week 3, but AGP concentrations did not rise during respiratory disease. Higher SAA, LBP and Hp concentrations at a later stage of BRD (week 3) were associated with the low BRSV-specific IgG1 production, suggesting that these calves had enhanced inflammatory response to the secondary bacterial infection. In conclusion, APPs (especially SAA and LBP) are sensitive markers of respiratory infection, and they may be useful to explore host response to the respiratory infections in clinical research.

Host response in bovine mastitis experimentally induced with Staphylococcus chromogenes.

An experimental infection model was developed to study host response to intramammary infection in cows caused by Staphylococcus chromogenes. CNS intramammary infections have become very common in modern dairy herds, and they can remain persistent in the mammary gland. More information would be needed about the pathophysiology of CNS mastitis, and an experimental mastitis model is a means for this research. Six primiparous Holstein-Friesian cows were challenged with S. chromogenes 4 weeks after calving. One udder quarter of each cow was inoculated with 2.1 x 10(6)cfu of S. chromogenes. All cows became infected and clinical signs were mild. Milk production of the challenged quarter decreased on average by 16.3% during 7 days post-challenge. Cows eliminated bacteria in a few days, except for one cow which developed persistent mastitis. Milk indicators of inflammation, SCC and N-acetyl-beta-D-glucosaminidase (NAGase) returned to normal within a week. Milk NAGase activity increased moderately, which reflects minor tissue damage in the udder. Concentrations of serum amyloid A (SAA) and milk amyloid A (MAA) were both elevated at 12h PC. MAA was affected by the milking times, and was at its highest before the morning milking. In our experimental model, systemic acute phase protein response with SAA occurred as an on-off type reaction. In conclusion, this experimental model could be used to study host response in CNS mastitis caused by the main CNS species and also for comparison of the host response in a mild intramammary infection and in more severe mastitis models.

Tail biting induces a strong acute phase response and tail-end inflammation in finishing pigs.

The extent of inflammation associated with tail biting in finishing pigs was evaluated. Tail histopathology, carcass condemnation and the concentration of three acute phase proteins (APPs), C-reactive protein (CRP), serum amyloid-A (SAA) and haptoglobin (Hp), were examined in 12 tail-bitten and 13 control pigs. The median concentrations of APPs were higher (P<0.01) in bitten (CRP 617.5mg/L, range 80.5-969.9; SAA 128.0mg/L, 6.2-774.4; Hp 2.8g/L, 1.6-3.5) than in control pigs (CRP 65.7mg/L, 28.4-180.4; SAA 6.2mg/L, 6.2-21.4; Hp 1.2g/L, 0.9-1.5). There was a tendency for APP concentrations to rise with the histopathological score but the differences were only statistically significant between some of the scores. Five (42%) bitten cases and one (8%) control pig had partial carcass condemnations owing to abscesses (P=0.07). The results show that tail biting induces an inflammatory response in the tail end leading to an acute phase response and formation of carcass abscesses.

Acute phase proteins in milk in naturally acquired bovine mastitis caused by different pathogens

The concentrations of haptoglobin (Hp) and serum amyloid A (SAA) and the activity of N-acetyl-β-D-glucosaminidase (NAGase) in milk from 234 cows with spontaneous mastitis caused by different pathogens were measured to assess whether they corresponded with the clinical signs of mastitis and whether there were any differences between pathogens. Ninety-eight of the cows had clinical mastitis and 136 had subclinical mastitis. There were statistically significant positive correlations between the concentrations of SAA and Hp and the activity of NAGase. Significant differences in the concentrations of acute phase proteins and NAGase activity were found in milk from cows with mastitis caused by different pathogens. The highest concentrations of Hp and NAGase were found in cases of mastitis caused by Escherichia coli and Arcanobacterium pyogenes, and the lowest concentrations were from cases of mastitis caused by coagulase-negative staphylococci. Very low SAA concentrations were found in milk from the cases caused by A pyogenes, in contrast to cases caused by other major mastitis pathogens. The median concentration of SAA was over 10 times higher in cases of mastitis caused by E coli than in mastitis caused by other pathogens. There were significant differences in the mean Hp concentration and NAGase activity between clinical and subclinical mastitis. In approximately one-third of the samples, the Hp concentration was below the detection limit, potentially compromising the use of Hp as a mastitis marker.

Oral ketoprofen is effective in the treatment of non-infectious lameness in sows.

The efficacy of ketoprofen in the treatment of non-infectious lameness in sows was examined in a double-blinded study. Two dose rates of oral ketoprofen were compared to placebo treatment over five consecutive days. Lameness was assessed with a five-grade scoring system prior to and on the last day of the treatment. The rate of treatment success was 54.3% for the ketoprofen 4mg/kg group (n=46), 53.2% for the ketoprofen 2mg/kg group (n=47) and 20.8% for the pigs in the placebo group (n=48). The difference between both ketoprofen groups and the placebo group was significant (P=0.001), but there was no difference between the two ketoprofen groups (P=0.78). Oral ketoprofen was well tolerated and no adverse events were observed. As lameness is a very common problem in sows, oral ketoprofen appeared to be a practical way to alleviate pain and improve the welfare of sows.

Seroepidemiology of bovine herpesvirus 1 (BHV1) infection among Estonian dairy herds and risk factors for the spread within herds

The objectives of this study were to reassess the herd level and within-herd prevalence of bovine herpesvirus 1 (BHV1) infection in Estonian dairy cattle, estimate the sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA) for bulk tank milk (BTM) testing and determine the risk factors related to high prevalence of the infection in herds. To estimate the herd prevalence, BTM samples from each of the 1,205 herds that sell milk to dairy companies were analysed for BHV1 antibodies. One hundred and three herds with known BHV1 infection status were selected to estimate within-herd prevalence and to calculate the sensitivity and specificity of BTM ELISA. In these herds serum samples were collected from cows and youngstock, together with BTM samples. A commercial blocking ELISA test was used to analyse samples for antibodies against BHV1. A questionnaire was completed to collect herd data. The sensitivity and specificity of the BTM ELISA were 76.5% and 97.2%, respectively, and the true herd prevalence of BHV1 was calculated to be 22.0%. The herd prevalence increased significantly with herd size, being 3.4% in the smallest category (less than 20 cows) and 85.7% in herds of size over 400. The mean within-herd prevalence was 37.8% (range 1-100, median 31.5). The mean within-herd prevalence increased with herd size. Data from 59 infected herds was used to determine the risk factors associated with high within-herd prevalence (>50%) of BHV1, using logistic regression analysis. As, in some infected herds, the youngstock were uninfected, risk factors for the presence of BHV1 among youngstock from 6 months until calving were analysed. The results indicate the importance of iatrogenic spread of the virus, since the overall within-herd prevalence was higher in those herds in which a veterinarian was an employee of the farm and an inseminator worked only for the particular farm. The presence of bovine viral diarrhoea virus (BVDV) in a herd was associated with a higher prevalence of BHV1.