Comparative Efficacy of Tiamutin and Lincospectin in Drinking Water for Treatment of Mixed Enteric - Respiratory Infections in Finishing Pigs
 
by
D.G.S. Burch^*, G. Webster^**, M. Morgan^**, M. McDonald^** and U. Klein^***

*Octagon Services Ltd, Old Windsor, Berkshire, UK
^**Meadows Veterinary Centre, Old Meldrum, Aberdeenshire, UK
^***Novartis Animal Health Inc., Basel, Switzerland
 
Presentation - International Pig Veterinary Society Congress (2006) Copenhagen, Denmark, 2, p 343.

Introduction
Antibiotic growth promoters (AGPs) were removed from pig feed from 1st January 2006 in the EU. Based on the Danish experience, it was expected that there would be an increase in diarrhoea and treatments in grower and finisher pigs (1) mainly due to ileitis but also mixed infections with Brachyspira spp. With the anticipated removal of the AGP salinomycin, which is incompatible with the pleuromutilin, tiamulin (Tiamutin® - Novartis), it gave the opportunity to test Tiamutin at therapeutic levels, to develop strategic control programmes against these mixed infections, as Tiamutin is active against Lawsonia intracellularis (LI), B. hyodysenteriae (BH) and B. pilosicoli (BP). A field trial was set up to test Tiamutin's clinical efficacy and effect on performance and economic parameters on a farm with a history of mixed enteric infections in the finishing sheds.

Materials and Methods
The farm comprised 12,500 sows, mainly kept outdoors. The piglets were weaned at 4 weeks into straw yards and kept in source batches. These batches were then moved at 10weeks of age (30kgs bwt) into the finishing sheds, where they were kept for a further 14-18weeks (115-120kg bwt) in their source batches of about 100pigs/pen in a shed of upto 24 pens. The shed could be divided into two, so the top and bottom half had its own feed and water system and was of a straw-based, solid floor, scrape-through design. The sheds had a history of BP and salmonella infections and more recently BH had been identified, hence salinomycin and lincomycin/spectinomycin (Linco-Spectin® - Pfizer) had been used for control. Other infections, such as PMWS, PDNS, PRRS, enzootic pneumonia (EP) and occasionally Actinobacillus pleuropneumoniae (APP) were also present and controlled with chlortetracycline (CTC) and trimethoprim/sulphadiazine (TMPS) in feed.

Photo 1 Solid floor pig shed holding over 2000 pigs

Photo 2 Strawed pig pens holding approximately 100pigs per pen

 

Photo 3 Swine dysentery - blood with diarrhoea

Photo 4 Diarrhoea - associated with viral challenge of PRRS and PCV2

 

Photo 5 Pig with PDNS in hospital pen

Photo 6 Pig with PDNS and scrotal necrosis

 

Approximately 2,300 pigs were brought into the shed and allocated to the 12 pens in each half of the building. There was an additional hospital straw barn for severely sick pigs (primarily PMWS/PDNS cases), which needed treatment and these were removed from the trial. The pig's weights were calculated at the start by differences in the lorry tare weights, as was the feed (no AGPs) and the weight of the pigs at the end of the study. The pigs were treated on arrival with CTC and TMPS in the feed for 2 weeks. They were monitored daily by the stockmen and weekly by the farm supervisor and investigator (veterinarian). The pigs were scored weekly for diarrhoea and respiratory infections (coughing) using a simple score system based on the number of pigs affected/pen. When 10% of the pigs in a pen were coughing or had diarrhoea, treatment was given via the drinking water either Tiamutin 12.5% solution at 8mg/kg bwt or Lincospectin 100 soluble powder at 10mg/kg bwt for 5 days to the top and bottom half of the shed respectively, via Dosatron® water medicators. Faeces samples were taken at the start, during and at the end of the study when diarrhoea was observed. Samples were cultured and submitted to PCR tests for BH, BP and LI at SAC Aberdeen and Edinburgh. The Brachyspira isolates were also submitted to MIC testing. Blood samples were taken in trial week 1, 8, and 14 of the study for additional diagnostic information and tested for PRRSV, SIV, Mycoplasma hyopneumoniae (MHP) and LI.

Results
The results are summarised in Table 1. There were three waves of disease. The first was associated with BP and PRRSV in the first few weeks and the treatments were given at week 3 and the pigs recovered promptly (see Graphs 1, 2 & 3). This also coincided with an increase in mortality and hospitalisations primarily associated with PMWS (see Graph 4). There was a second disease wave at week 7 when there was clinical dysentery and PCR positives for BH and LI. Treatment was given in week 8 and a rapid response was noted, especially in the tiamulin-treated pigs and samples were PCR negative. There was an increase in coughing and diarrhoea from week 11, BH and LI were demonstrated in faeces again and sero-conversion to LI and MHP were increasing. Significant EP and APP lesions were recorded at slaughter. Salmonella spp were not isolated and SIV was not found serologically.

Table 1. Performance, economic, MIC and lung lesion results

Discussion
The strategic applications of therapeutic medications were generally effective in controlling mixed enteric and respiratory infections commonly encountered in the field. Tiamutin showed a noticeably improved response with regard to dysentery and ileitis treatment in comparison with Linco-Spectin (week 8) and overall showed production improvements, which economically gave an additional €2.25 margin/pig and 37.4% ROI. A metaphylactic treatment approach to control, with tiamulin given in the drinking water on shed entry, has since been adopted.

Reference:
1. Larsen, P. (2002) WHO International Invitational Symposium, Foulum, Denmark, pp 51-55.

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