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Denagard Performance - Ileitis/Efficacy

by 5m Editor
17 January 2012, at 12:00am

Studies show Denagard® is highly effective against ileitis in pigs, according to Novartis Animal Health.


Dr Ulrich Klein
International Technical Services Manager

Key Points

Porcine proliferative enteropathy (ileitis) is a serious disease of swine around the world, causing huge economic losses for pork producers.

Denagard (tiamulin), a pleuromutilin antibiotic, has been shown to be highly effective for the treatment and prevention of ileitis.

Denagard (tiamulin) also minimizes production losses due to ileitis.

Introduction

Ileitis, also known as porcine proliferative enteropathy, remains a widespread, serious and costly disease for pork producers around the world. One report estimates that the prevalence on swine farms is 100 per cent in Taiwan, 96 per cent in the United States and Czech Republic and 95 per cent in Great Britain and Canada1. Economic losses annually due to ileitis may be as high as US$250 million in Western Europe alone2.

The cause of ileitis, Lawsonia intracellularis, is an intracellular bacterium. It can affect pigs in various types of production schemes, including all-in/all-out systems and high-health herds.

Finishing pigs tend to be affected by an acute ileitis, which can cause severe, bloody diarrhoea and, sometimes, sudden death. Chronic ileitis usually affects pigs from 6 to 20 weeks old. The chronic form may or may not cause diarrhoea, but eats away at profits by impairing feed efficiency and daily gain.

Controlled trials show that the clinical signs of ileitis as well as production losses resulting from the disease can be controlled with administration of Denagard® (tiamulin) either in feed or in water.

High Susceptibility to tiamulin

McOrist and Gebhart assessed the sensitivity of L. intracellularis isolates by determining minimum inhibitory concentration (MICs) for several antibiotics. They also determined the minimum bactericidal concentration (MBC) for selected antibiotics3. The MIC was defined as the lowest concentration that prevented multiplication of 99 per cent of L. intracellularis isolates. The MBC was the lowest concentration where use of a ‘pulse’ antibiotic treatment stopped the growth of L. intracellularis.

Up to three isolates of L. intracellularis were used to test each antibiotic and both intracellular and extracellular testing was conducted. Tiamulin, the active ingredient in Denagard had a low MIC of 4µg per ml. Tiamulin also had a MBC of <2µg per ml, compared to 4µg per ml for tylosin.

McOrist and colleagues subsequently reported on additional in vitro testing of tiamulin, which confirmed the drug’s MIC was again a low 4µg per ml when tested against L. intracellularis4.

In one report, McOrist and colleagues explain that pleuromutilins such as tiamulin are a type of antibiotic that act by selectively blocking ribosome protein synthesis. The drugs are thought to localize in the cytosolic compartment of exposed cells, where L. intracellularis is found5.

Further evidence that Denagard penetrates the necessary cells to control infection is apparent from yet another report issued in 20026. In the study, tiamulin uptake was evaluated and compared to that of norfloxacin, which is known to penetrate human polymorphonuclear leukocytes (PMN) and to produce intracellular concentrations several times higher than extracellular concentrations. Nielsen concluded that once accumulated, "tiamulin remains intracellularly active and participates in the protection of bacterial infection."

British Field Trials

Denagard has been shown to be effective in the field as well as in the lab. McOrist and colleagues reported on an ileitis control program conducted on British farms7. Faecal samples were monitored monthly for six consecutive months with an L. intracellularis-specific polymerase chain reaction (PCR). "On one farm with 150 sows, an outbreak of acute proliferative enteropathy in boars and gilts was controlled clinically by the use of tiamulin and chlortetracycline," the investigators say.

The field trial corroborated experimental work published by McOrist and colleagues, who showed that in weaner pigs artificially infected with L. intracellularis, treatment with Denagard in feed was effective for both treatment and prevention of ileitis8.

"It was found that continuous oral medication with 50ppm tiamulin in the feed could prevent pigs challenged with pathogenic L. intracellularis from developing ileitis. A therapeutic effect was also evident when 150ppm tiamulin was given orally to pigs seven days after the challenge, indicating that tiamulin could treat the disease," the investigators write.

They also say that the markedly higher growth rate of pigs receiving 50ppm tiamulin for two days before challenge could indicate a useful economic benefit from the use of this antibiotic.

US In-Feed Trial

The effectiveness of in-feed Denagard was evaluated by Walter and colleagues in a US study of 48 healthy pigs that were five weeks of age and weighed approximately 22kg9. All pigs were challenged with L. intracellularis, then once the symptoms of ileitis became evident, they received either Denagard at the rate of 38.5 ppm for four weeks or they served as controls and received no treatment. All pigs were monitored for 28 days and were examined upon necropsy at 37 days after infection.

Among pigs treated with Denagard evidence of gross lesions were found in only four per cent, evidence of microscopic lesions were found in only nine per cent and none had L. intracellularis shedding. In contrast, 33 per cent of the untreated controls had gross lesions, 33 per cent had microscopic lesions and 17 per cent had shedding of L. intracellularis.

In addition, average daily gain and feed consumption were significantly improved in the Denagard treatment group, as shown in Table 1.

Table 1. Body weight and feed consumption was better in the Denagard-treated groups compared to untreated controls.
Control Denagard p-value
Daily gain (g) 409 528 (+29%) 0.007
Feed intake (kg) 0.760 0.840 0.029
Gain/Feed 0.540 0.631 (+17%) 0.010

The investigators concluded that Denagard administered in feed effectively controls the clinical, pathological and negative productivity effects of ileitis in weaned pigs at a dose level of 38.5ppm.

US In-Water Trial

In a similar study conducted by Walter and colleagues to test the effectiveness of Denagard administered in water for controlling ileitis, 48 healthy pigs aged six weeks and all weighing about 22kg were challenged with L. intracellularis10. After the symptoms of ileitis became apparent, the pigs received either Denagard at the rate of 60ppm for five consecutive days or they received no medication and served as controls. All pigs were monitored for 15 days and were examined upon necropsy at 23 days after infection.

In the treated pigs, only 12 per cent had evidence of gross lesions, 21 per cent had evidence of microscopic lesions and 12 per cent had evidence of L. intracellularis shedding. Among the control group, 58 per cent had evidence of gross lesions, 92 per cent had microscopic lesions and 71 per cent had shedding of the organism.

As shown in Table 2, average individual body weight and average feed consumption was better in the pigs that were treated with Denagard compared to controls.

The investigators concluded that Denagard administered in water effectively controls the clinical, pathological and negative productivity effects of ileitis in growers at a dose level of 60.0ppm.

Table 2. Pigs treated with Denagard had better average daily gain and better feed consumption than untreated pigs.
Control Denagard p-value
Daily gain (g) 510 641 (+26%) 0.007
Gain/Feed 0.528 0.633 (+19.9%) 0.010

Conclusion

Detailed experimental studies as well as field trials demonstrate that Denagard is highly effective for the control of ileitis, a serious and costly problem in swine around the world.

Denagard not only controls the clinical signs of ileitis, it minimizes the adverse effects on productivity due to ileitis.

References

1 McOrist S. et al. 2003. Global Patterns of Porcine Proliferative Enteropathy. The Pig Journal. 51: 26-33.

2 McOrist S. 2003. Preclinical documentation. Expert Report and Comment.

3 McOrist S. and Gebhart, C. 1995. In vitro testing of antimicrobial agents for proliferative enteropathy (ileitis). Swine Health and Production, July-August 1995, 146-149.

4 McOrist S. et al. 1998. In vitro and in-life studies of efficacy of valnemulin for proliferative enteropathy (ileitis). 15th International Pig Veterinary Society Congress, Birmingham, England.

5 McOrist S. et al. 1995. Antimicrobial susceptibility of ileal symbiont intracellularis isolated from pigs with proliferative enteropathy. Journal of Clinical Microbiology. 33 (5): 1314-1317.

6 Nielsen B. 2002. Uptake and intracellular activity of tiamulin in polymorphonuclear leukocytes compared with norfloxacin. LEO Pharma, Biochemical Department. Data on file at Novartis Animal Health.

7 McOrist S. et al. 1999. Monitored control programme for proliferative enteropathy on British pig farms. Vet. Rec. 144 (8):202- 204.

8 McOrist S. et al. 1996. Treatment and prevention of porcine proliferative enteropathy with oral tiamulin. Vet Rec. 139 (25):615-618.

9 Walter D., et al. 2000. Effectiveness of tiamulin in feed for the control and treatment of porcine proliferative enteropathy (ileitis) due to Lawsonia intracellularis infection. 16th International Pig Veterinary Society Congress, Melbourne, Australia, p75.

10 Walter D., et al. 2000. Effectiveness of tiamulin in drinking water for the control and treatment of porcine proliferative enteropathy (ileitis) due to Lawsonia intracellularis infection. 16th International Pig Veterinary Society Congress, Melbourne, Australia. p31.

Further Reading

- Find out more information on ileitis by clicking here.


January 2012