Controling APP by Combining Management Procedures with tilmicosin (Pulmotil) Medication.

by 5m Editor
15 December 2000, at 12:00am

By Noel Kavanagh, Consultant. Partial depopulation programmes are now widely used as an aid to control of viral diseases such as PRRS, Aujeszky's disease and TGE. In the case of Aujeszky's disease vaccination is used to prevent shedding of the virus however in some circumstances, where virus shedding continues in spite of vaccination, depopulation of the "hot spot" eliminates the focus of virus circulation and facilitates eradication of the disease from the farm. Programmes based on similar principles have been used in France and Denmark for eradication of PRRS.

In the case of Actinobacillus pleuropneumonia (App) the success of a control programme based primarily on antibiotic medication may be compromised if there is a high background level of Actinobacillus pleuropneumonia activity present such that pigs become continuously re-infected in spite of the use of medication.
Photo of App Lung Lesion
Lesion on dissected lung caused by App.

It was this problem of continuous re-infection with APP in the Stage 2 weaner area of a unit in Ireland that created a requirement to seek a more long term solution to the problems being experienced. The plan involved the use of in-feed tilmicosin (Pulmotil) medication, changing from a continuous throughput system in the Stage 2 weaner area to all in/all out and the removal of approximately three weeks of pigs from the production system (partial depopulation).

The programme of partial depopulation commenced in February and was completed in May 1999. The programme was initiated by removing 450 pigs (3 weeks of production) from the stage two weaner area (W2) at which point housing modifications commenced. Housing modifications involved dividing the stage two weaner area into 5 rooms and modifying the ventilation system so that the ventilation of each room was individually controlled.

Prior to the introduction of the programme the pigs were fed a diet containing tilmicosin (Pulmotil) at 200g per tonne in the stage one weaner area (W1), which was operated on an all in/all out system, for 26 days post weaning. They received medicated water containing phenoxymethyl penicillin for the following 28 days at a dosage rate of 10mg per kg bodyweight 3 days per week. At the commencement of the programme phenoxymethyl penicillin was replaced by Pulmotil to supply 200g per tonne of tilmicosin in the feed of the stage two weaners. This medication regime was maintained from February until August 1999 when in-feed medication was withdrawn from the stage two weaners whilst the stage 1 weaners continued to receive medicated feed.

The Response to the Management and Medication Programme:

Weaner mortality was analysed for a 32 week period before and following the introduction of the control programme in February 1999. Total weaner mortality reduced from 3.9%to 1.1% (P<0.001) in association with the modifications to the production, ventilation and medication regime (Fig. 1). A major reduction in mortality was recorded in the stage two weaner area where mortality levels reduced from 2.9% to 0.4% (P<0.001) whilst the stage one weaner area experienced a reduction of approximately 0.4% in mortality, from 1.0 to 0.6%(P>0.05). The combined performance of pigs in stage one and two improved, with a 9.1% improvement in average daily gain (ADG), a 6% improvement in average daily feed intake (ADFI) and a 3% improvement in food conversion ratio (FCR) being recorded (Table 1). The improvements in production recorded were accompanied by a marked reduction in the prevalence of clinical APP cases.

Weaner mortality for 32 weeks before and following
the introduction of the APP control programme.

Weaner mortality for 32 weeks before and following the introduction of the APP control programme.

Table 1.
A comparison of the performance of weaners in studies conducted in 1998 and 1999.

1998 1999
Initial weight (kg) 7.8 8.0
Weight, day 55 (kg) 35.4 38.7
ADG (g/day) 504 550
ADFI (g/day) 828 878
FCR 1.64 1.59

The programme was completed in the summer of 1999 and now approximately one year later, no relapses have been experienced. Currently, only the starter creep diet is medicated with tilmicosin (Pulmotil). Pigs are fed on the starter creep diet until approximately four weeks post weaning, when they are approximately 17kg bodyweight and have consumed approximately 10kg of feed.

The medication costs per pig are running at approximately IR£0.40 (£0.3 or US$0.5). The theory behind this programme is that pig lungs are cleaned of APP after weaning by the medication and then, approximately 26 days later when they move into the Stage 2 weaner house, the exposure rate is low, based on the new all in/all out production system and improved environment. So, re-infection doesn't take place and the pigs are taken through from approximately 17kg bodyweight to slaughter without the requirement for antibiotics, other than occasional pigs that require individual treatment for miscellaneous conditions.

I believe that the importance of a multi-disciplined approach to disease control, involving a combination of housing and ventilation changes all in/all out production immunisation and strategic medication is underestimated. All too often the blame is laid on the vaccine or medication being used, without taking into account the fact that under intensive systems of production a persistent high challenge may overcome the protection afforded by the most modern and efficient vaccines or antibiotics.

Further Information

Further information on Actinobacillus pleuropneumonia (App) can be found in's Quick Disease Guide. Click Here and select the App article from the drop down menu. Note you will need to Register or Login to view the additional information in the Pig Health Database.

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Pulmotil ® is a trademark for Elanco's brand of tilmicosin. Usage instructions and withdrawal periods may vary by Country. Always follow label instructions.

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