Oral and Poster Abstracts

2 University of Nottingham, Department of Veterinary Medicine,
Nottingham, United Kingdom
3 Orchard Veterinary Group, Glastonbury, United Kingdom
4 Quality Milk Management Services Ltd., Wells, United Kingdom
Objectives: The primary objective of the study was to determine the
impact of the duration of treatment on the efficacy of penethamate
hydriodide (Mamyzin ® Injection) in the cure of persistent bovine intramammary
infection in U.K. dairy cows.
Materials and Methods: Cows with a history of a high somatic cell count
(SCC), four functional quarters, no significant teat lesions and in good
general health were enrolled into a treatment study (n=95). Two different
regimes were assessed using penethamate hydriodide, which was
administered either as a four-day (“on-label”) course or a seven-day
(“extended”) course. Intra-mammary infection status was monitored
using both bacteriology and quarter somatic cell counting from 1-week
pre-treatment until 4-weeks post-treatment. Multi-level statistical models
were specified and interpreted within a Bayesian framework to estimate
the probability of a difference between the two treatment groups
(expressed as an odds ratio), using a flat, normal prior distribution.
Results: Preliminary results have shown that both treatment groups
experienced a significant reduction in the prevalence of gram-positive
major pathogens from before until after treatment accompanied by a
fall in somatic cell counts at both the quarter and cow level. There was
a reduced odds of identifying a major pathogen after treatment in
quarters treated for 7 days compared to quarters treated for 4 days
(mean odds ratio = 0.57) and a posterior probability of 93% that
treatment for 7 days resulted in fewer quarters with major pathogens
than treatment for 4 days. There was an increased odds that quarters
would remain below 200,000 cells/ml for 28 days after treatment for 7
days compared to treatment for 4 days (odds ratio = 1.87) and a
posterior probability of 79% that treatment for 7days resulted in fewer
quarters > 200,000 cells/ml than treatment for 4 days.
Conclusion: This study demonstrates the efficacy of Mamyzin ®
Injection in the treatment of persistent IMI in dairy cows in the U.K.
and has identified an increased probability of a cure when using a 7day,
extended therapy regime, compared to 4-day, on-label treatment
regime. In addition, the results can be used to inform clinical decisionmaking
for the treatment of high SCC cows.
Key words: somatic cell count, penethamate hydriodide, extended
therapy, persistent infection, streptococcus uberis
172 Challenge with Streptococcus uberis to Evaluate the Efficacy
of Teat Sealers in Preventing Mastitis
N. Williamson, K. Petrovski, C. Fernandez
Massey University, Institute of Veterinary, Animal and Biomedical
Sciences, Palmerston North, New Zealand
External teat sealers based on tetrahydrofuran (DryFlex (DF)) and a
wound seal for humans 2-octylcyanoacrylate (Band-Aid (BA)) to prevent
dry period mastitis were investigated. Streptococcus uberis has the
highest incidence in the dry period and early lactation in New Zealand. It
is a ubiquitous environmental pathogen, is normally easy to cure using
antibiotics and thus was an appropriate challenge organism. Quarter milk
samples were taken for bacteriological culture from 175 cows, 4 and 1
days before dry-off and twice within 4 days after calving. After the last
milking, 88 cows received DF and 87 cows received BA. Pairs of contralateral
quarters were randomly assigned to the treated or the control group.
All quarters were dipped in a Strep. uberis broth 2 and 4 days after dry-off
and were assessed daily for clinical mastitis. Clinical mastitis iwas
greatest 6-11 days after dry-off in both groups. Strep. uberis was the most
prevalent bacterium isolated. In the DF group, 35 cases of clinical mastitis
occurred in 176 treated quarters, compared with 83 in the 176 control
quarters. In the BA group, 67 cases of clinical mastitis occurred in 174
treated quarters, compared with 64 in 174 control quarters. DryFlex reduced
mastitis after dry-off but not after calving. Octylcyanoacrylate did not
reduce clinical mastitis after dry-off. A DryFlex type teat sealer showed
potential in preventing mastitis in the early dry period, but has now been
withdrawn worldwide. The effect of experimentally induced clinical
mastitis in the early dry period on the subsequent lactation was examined.
Cows (127) developing clinical mastitis after challenge were treated with
antibiotic. Yields of milk, fat, protein and milk solids were analysed with
respect to treatment group. No significant effect of treatment group on
lactation yields of milk, fat, protein or milk solids occurred. No difference
in production occurred (milk yield, 5126 vs. 5010 litres; fat yield, 267 vs.
264 kg; protein yield, 182 vs. 179 kg) between cows that had mastitis and
52 XXV. Jubilee World Buiatrics Congress 2008
those that did not. Promptly treated clinical mastitis due to Strep. uberis
did not affect production in the subsequent lactation. The ability to
demonstrate differences in efficacy and absence of production effects in
the subsequent lactation mean this challenge model appears suitable for
evaluating teat sealers.
Key words: mastits, Streptococcus uberis, teat sealer
173 Use of Leukocyte Differential Patterns to Optimize Diagnosis
of Bovine Intramammary Infections: Evaluation of
Partitioned vs. Non-partitioned Testing
A. Rivas 1 , K. Anderson 1 , G. Leitner 2 , M. Chaffer 2 , O. Krifucks 2 ,
R. Rodriguez 1
1 North Carolina State University, College of Veterinary Medicine,
Raleigh, NC, United States
2 Kimron Veterinary Institute, Bacteriology,Beit-Dagan, Israel
Objectives: To explore the use of leukocyte patterns in diagnosing
infectious mastitis.
Materials and methods: Quarter milk samples were investigated in 3
cross-sectional studies conducted in the US (study I, n=120; and study
III, n=500) and Israel (study II, n=484). The somatic cell count (SCC),
milk microbiological cultures, and the percentages, total counts and
relative proportions of lymphocytes, macrophages and neutrophils
were established. Non-periparturient (studies I and III) and
periparturient (study II) cows were assessed. Samples were collected
without (studies I and III) and with previous determination of health
status (study II). Disease prevalence was >40% (study I) and