An Attempt to Eradicate Actinobacillus pleuropneumoniae and

08.08.2011
An Attempt to Eradicate Actinobacillus pleuropneumoniae and

An Attempt to Eradicate Actinobacillus pleuropneumoniae and
M. hyopneumoniaefrom a Danish MS-Herd
Acutely Infected with APP
Uffe Nielsen ,
 

Introduction
For many years the eradication of M.hyopneumonia (M.hyo) and A. pleuropneumonia (App) from swine-herds producing at near maximum capacities was an utopian vision. Either the various antibiotics had too low an effect on the pathogens, they were excessively costly, or we did not have the required knowledge and insight. Therefore, for many years, we vaccinated millions of pigs against M.hyo and attempted to control or eradicate App infections through various strategies such as:…SPF/MF; Vaccination; Adequate Ventilation; All in/All out;…etc…etc…
In general, I believe that we have won the battle, however in about 15% of the swine-herds in my care…mostly small ones…the production system is not conductive to a simple reliance on general good health…I am referring here to infections of the type M. hyopneumuniae, A. pleuropneumoniae, toxigenic P. multocida, and L. intracellularis.
 

Materials and Methods
However, with the availability of new knowledge and the introduction into Denmark of two new antibiotics: Tilmicosinphosphate (Pulmotil from Elanco of the USA), and Marbofloxacine (Marbocyl from Vetoquinol of France) the situation has changed.
Pulmotil is well known amongst this Forum and was chosen as the antibiotic against M. hyopneumonia (2). Pulmotil also works well against infections with L.intracellularis.
Marbocyl-a fluoroquinolone-has proven to be effective against various bacteria
which cause respiratory disorders in swine. A breakthrough in the use of fluoroquinolones against App infections in swine was reported at the IPVS in Melbourne (1). It was documented that if fluoroquinolones were dosed once with a peak concentration of at least eight times the MIC value for App a maximum kill effect far in excess of that obtained through multiple small doses would be obtained: 4mg/kilo bodyweight gives a plasmaconcentration of at least 1,5 μg/ml. In the herd in question, fluoroquinolones had a MIC value to App of 0,03 μg/ml, corresponding to a multiple of the MIC of 40-50! I have since Melbourne used Marbocyl in some well-diagnosed acute outbreaks of App-infections as a single injection with a double dose (4 mg/kg) to very good effect.
 

The Herd
An 180 MS sow-herd with no PRRS, selling ¾ of the pigs at 30 kilo, was acutely infected with App type 2 at day minus 16 (D-16). The herd was thereafter infected with both M.hyo and A.pp.
 

The Program
From D-14 to D+1, at which time we began the elimination program, we concentrated on therapeutic injections of acute App diseased animals with Marbocyl 2% , 4 mg/kilo. We are proud to say that during this period we did not lose a single pig!
The period prior to the beginning of the eradication program was utilized in finding a barn for the slaughter pigs and in conducting a complete inspection of the production system with respect to: ventilation; water supply; general hygiene; enough space at feeders;
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etc…etc…The farmer belongs to a higher-income-segment and mixes his own dry-feed for all groups of pigs present. We were able to sell slaughter pigs down to approximately 20 kilo’s bodyweight.
On days D+1 and D+6 all the pigs were injected with marbofloxacine with a dose of 4 mg/kilo. From D+1 through to D+6 all feed was medicated with tilmicosin-phosphate 400 ppm. From day D+7 through to D+14 all feed was medicated with tilmicosin-phosphate 200 ppm. Throughout this period I closely observed and followed the progress of the herd. We did not use any immunomodulators or extra vitamins,…etc…etc…
 

Results
During the medication period we did not lose a single pig as a result of lung-infections.
Neither were any forms of side-effects or other harmful effects observed. On the contrary, we noticed a significant increase in the general health of the herd.
Coughing as a symptom disappeared completely after one week, and has not appeared since. At the moment of writing 5 months have passed since we stopped the medication and the herd is still negative with respect to clinical signs and serology.
 

Discussion
The results presented in this paper represent the first time that an eradication was attempted with success in Denmark with an acute App. infected MS-herd producing at almost full capacity. Concerning M.hyo, at the current time in Denmark the Swiss model is still recommended, in which pigs under 9-10 months of age are removed from the farm while the remaining are treated with a suitable drug. The weakness of this model is that when pork prices are rising, farmers have no interest in destroying their production. When prices are falling, they appear to be very cautious as to investing in projects in which the outcome is uncertain. Eradication of App infections are not recommended as such, due to a success rate of around 45%.
I want to stress the fact that in this protocol I have used two different antibiotics from two seperate medical companies. In my last attempt to eradicate similar infections from a chronic infected herd I utilized three different antibiotics and immunomodulators.
If we as Veterinarians can construct programs which attain success-rates approaching between 75%-80%, than I believe that considerable interest could be generated amongst farmers in implementing such programs.
 

References
1. Friis, Christian (2000) Role of Pharmacokinetics and Pharmacodynamics in the outcome of infections. Proceedings of the 16th I.P.V.S. Congress, p. 82-84
2. Marbofloxacin reference book ( 1999) Vetoquinol S.A. 70204 Lure Cedex, France.
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