Extended antibiotic treatment of persistent bovine mastitis during lactation Efficacy, economics and

180 Pages·2014·1.29 MB·English

Extended antibiotic treatment of persistent bovine
mastitis during lactation
Efficacy, economics and social influences
Jantijn Swinkels
Utrecht, 2014
© Copyright J.M. Swinkels, 2014
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronically, mechanically, by photocopying, recording, or
otherwise, without the prior written permission of the author.
Cover illustration: Vaclav Komarek
Lay-out and printing: Ridderprint BV, Ridderkerk, the Netherlands
Extended antibiotic treatment of persistent bovine
mastitis during lactation
Efficacy, economics and social influences
Verlengde antibioticum behandeling van persistente mastitis
van melkvee tijdens de lactatie
Werkzaamheid, economie en sociale invloeden
(met een samenvatting in het Nederlands)
Proefschrift
ter verkrijging van de graad van doctor
aan de Universiteit Utrecht
op gezag van de rector magnificus, prof. dr. G.J. van der Zwaan,
ingevolge het besluit van het college voor promoties
in het openbaar te verdedigen op
dinsdag 9 december 2014 des middags te 12.45 uur
door
Johannes Martinus Swinkels
geboren op 21 juli 1961 te Helmond
Promotor: Prof. Dr. T.J.G.M. Lam
Contents
Chapter 1 General introduction 7
Chapter 2 Use of partial budgeting to determine the economic benefits of 19
antibiotic treatment of chronic subclinical mastitis caused by
Streptococcus uberis or Streptococcus dysgalactiae
Chapter 3 A partial budget model to estimate economic benefits of lactational 37
treatment of subclinical Staphylococcus aureus mastitis
Chapter 4 Efficacy of extended cefquinome treatment of clinical 63
Staphylococcus aureus mastitis
Chapter 5 Effect of extended cefquinome treatment on clinical persistence or 81
recurrence of environmental clinical mastitis
Chapter 6 Efficacy of standard vs. extended intramammary cefquinome treatment 99
of clinical mastitis in cows with persistent high somatic cell counts
Chapter 7 Social influences on the duration of antibiotic treatment of clinical 117
mastitis in dairy cows
Chapter 8 General Discussion 137
Summary 153
Samenvatting 159
Dankwoord - Acknowledgements 167
Curriculum vitae - Biography 171
List of publications 177

CHAPTER 1

General introduction

Introduction
INTRODUCTION
Mastitis is an inflammation of the udder. The inflammation is either visible (clinical mastitis)
or invisible (subclinical mastitis), and is caused by the immune system responding to an
intramammary infection (IMI) of bacteria that have invaded the udder through the teat canal. Some
bacteria can cause a persistent IMI of long duration while others typically cause a short, transient
infection. Mastitis can be a painful disease, potentially affecting animal welfare and milk quality.
Mastitis has economic consequences too, because it directly affects milk production, the primary
source of income for dairy farmers. Additional costs are due to increased culling, treatment and
discarded milk (Halasa et al., 2007). These costs are often underestimated by farmers (Huijps
et al., 2008). In their perception, mastitis is primarily an annoying disease disturbing the daily
milking routine and is often associated with uncertainty whether the cow will ever return to full
production (Jansen and Lam, 2012).
As with every disease, prevention is preferred over cure and thus, the primary focus of mastitis
management should be on preventive measures. Because mastitis is a multifactorial disease, the
causes can be complex. Generally, mastitis control can be effective by taking the right preventive
measures, as indicated in numerous papers describing cause and effect relationships between
risk factors and disease occurrence (Neave et al., 1969, Munoz et al., 2007). Although improved
management can successfully control mastitis, eradication of the disease is impossible because
dairy cows live in an environment with large amounts of bacteria for which the udder is an ideal
environment to thrive. Eventually, some quarters will be infected, and as a result, clinical mastitis
may occur and this disease has to be treated. Thus, despite control efforts, treatment of mastitis
is unavoidable on most if not all dairy farms.
Persistent infections
Many different bacterial species are able to cause mastitis. The initial interaction of the invading
pathogen with the host immune-system, the innate immune response, is important for the
outcome of infection. Mediators of inflammation are known to play critical roles in the innate
immune response to IMI (Bannerman, 2009). Some bacterial species, such as Escherichia coli,
usually show a short transient pattern (de Haas et al., 2004, Schukken et al., 2011). However,
dependent on the individual host immune response (Burvenich et al., 2003), E. coli may also
cause an acute, life threatening, clinical inflammatory response. Staphylococcus aureus is
typically able to avoid an acute inflammatory response because it does not induce the release
of major pro-inflammatory cytokines (Bannerman, 2009). Invasion with Staph. aureus usually
results in persistent (sub)clinical IMI that stay in the udder for a long time through adherence to
epithelial cells, intracellular survival and the formation of micro-abscesses, protecting them from
elimination by the immune system and antibiotics (Kerro Dego et al., 2002). The innate immune
response of cows to Streptococcus uberis seems to be typically somewhere in between E. coli
and Staph. aureus in the sense that this pathogen often causes a delayed but acute inflammatory
response (Bannerman, 2009) and a subsequent persistent (sub)clinical infection (de Haas et al.,
2004).
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Chapter 1
Although clear differences between bacterial species exist in their ability to cause persistent
infections, this is not a black and white story. Within bacterial species, strains differ in their ability
to cause persistent infection (Haveri et al., 2007). For example, E. coli usually causes transient
infections, but some bacterial strains appear more cow adapted and cause persistent infections
(Döpfer et al., 1999, Bradley and Green, 2001, Dogan et al., 2006).
An acute clinical inflammatory response to invading mastitis pathogens such as E. coli, may
be a concern for dairy farmers as it can a be a life threatening condition for the cow. Persistent
(sub)clinical infections such as Staph. aureus and Strep. uberis can be a concern too, as during
the long time span they remain in the udder, they become more difficult to cure, temporarily
flare-up to clinical mastitis and become a potential source of infection for herd mates. For cases
of persistent mastitis, farmers eventually have the choice to either treat the infected quarter with
antibiotics, or to remove the cow from the herd.
When antibiotic treatment is considered, the bacteriological cure has been reported to
generally be much higher for E. coli (70-80%, Pyörälä and Pyörälä et al., 1998) and Strep. uberis
(50-100%, St. Rose et al., 2003, Oliver et al., 2004a) than for Staph. aureus (29-52%, Pyörälä
and Pyörälä et al., 1998, Sol et al., 2000). If treatment is delayed, allowing the duration of infection
to increase, treatment success seems to deteriorate (van den Borne et al., 2010). Therefore, the
probability of treatment success of mastitis seems to be dependent on many factors, such as the
cow, the bacterial species, the specific strain, the associated immune response, and the duration
of infection.
Mastitis treatment
Mastitis, generally is an inflammatory response to a bacterial infection, and thus is usually treated
with antibiotics. Traditionally, antibiotic containing tubes are infused intramammary because it is
easy to apply after milking and high antibiotic concentrations can be reached at the site of infection
with minimum use of antibiotics (Hillerton and Kliem, 2002). Additional parenteral treatment is
sometimes advocated to increase cure rates of IMI (Ziv, 1980, Ziv and Storper, 1985, Owens et
al., 1988, Shpigel et al., 1997) and to cure or prevent bacteremia (Wenz et al., 2001, Erskine et
al., 2002). Basically, the goal of treatment is to maximize bacteriological cure because removing
causative bacteria is the best guarantee to restore the physiology of the affected quarter. However,
other aspects of antibiotic treatment, such as its impact on transmission dynamics, economics
and prudent use have to be considered too. From an epidemiological perspective, effective
treatment is important for prevention of recurrence of disease and spreading of pathogens to
herd mates via the milking machine, the milker or the cow’s environment. Because dairy farming
is an economic undertaking, economic optimization of treatment protocols is an important issue.
Last but not least, mastitis treatment protocols should incorporate prudent use of antibiotics in
order to prevent the development of antibiotic resistance of pathogens.
Progress in strategies to enhance bacteriological cure by mastitis treatment has been limited
in the last decades. This may be due to the difficulty to unravel the complex interaction of all the
factors that determine cure; the cow (Sol et al., 1994, 1997, Dingwell et al., 2003, Østerås et al.,
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