Swine dysentery

Treponema hjoepsenteriae a causative agent of swine dysentery, is sensitive to polyether antibiotics at low concentrations in vitro. In pigs, lasalocid was effective in controlling dysentery at levels of 0.005—0.05% in feeds (167). Several species of Mycoplasma are inhibited in vitro at a MIC range of 2.0—25 p./mL of polyethers including narasin, cartiomycin, and K41 (164). 

Pluske J.R., Siba P.M., Pethick D.W., Durmic Z., Multan B.P. and Hampson DJ. (1996). The incidence of swine dysentery in pigs can be reduced by feeding diets that limit the amount of fermentable substrate entering the large intestine . J Nutr, 126, 2920-2933. 

Siba, P. M., D. W. Pethick, and D. J. Hampson. Pigs experimentally infected with Serpulina hyodysenteriae can be protected from developing swine dysentery by feeding them a highly digestible diet. Epidemiol Infect 1966 116(2) 207-216. 

Sedecamycin is a macrolide primarily used for treating swine dysentery. As with most macrolides, sedecamycin is extensively metabolized in swine 20 metabolites have been detected, the major ones being lankacidin C, lankacidinol, and lankacidinol A (106). 

Ipronidazole and ronidazole are very similar in structure to dimetridazole and, thus, have several properties in common. They are added to the feed at dosages of 50-200 mg/kg for treatment and prevention of histomoniasis in turkeys, treatment of trichomoniasis in cattle, and treatment of swine dysentery. They have been also used as weight-gain and feed-efficiency improvers. A 4 day withdrawal period is recommended for both of these compounds. 

Metronidazole is used for treatment of bovine trichomoniasis by topical application or intravenous injection of 75 mg/kg bw. It is also used for treatment of swine dysentery at a dosage of 25 mg/kg bw/day for 4 days, whereas, for eradication of the disease in herds, treatment for 7 days followed, after 3-4 weeks, by a second treatment for 5 days in indicated. Metronidazole is a genotoxic carcinogen in animals. 

Treatment cf these disease states may be based on vaccination or drugs. In some cases, e.g. swine dysentery, no vaccines are available, so antibiotic treatment is essential. Antibiotic administration may be prophylactic or therapeutic with pigs, in particular, agents to control dysentery are routinely added to feedstuff or drinking water. The route of administration may also be highly important. For instance, in ruminants the preferred mode is injection, e.g. parenterally. The oral route, which introduces antibiotics directly into the rumen, may upset the delicate balance of rumen bacteria which are necessary to ferment carbohydrates to fatty acids — an essential component of the energy supply of ruminants. 

The macrolides include one compound of unique utility, tylosin (23). Tylosin has no application in human therapy, but is a drug of choice to treat swine dysentery. It is very... 

Nitroheterocycles, particularly nitrofurans and nitroimidazoles, are still widely used in veterinary medicine. The three imidazoles dimetridazole (32), metronidazole (33), and ronidazole (34) have broad spectrum activity and are used to treat swine dysentery and also enteric disease due to E. coli and Salmonella. Metronidazole (33) is also effective against ulcerative gingivitis in cattle. 

Other heterocycles used as veterinary antibacterials are trimethoprim (43) (see below) and the quinoxaline iV,iV -dioxide, carbadox (39). Carbadox (39) is used as a feed additive, in which role it is effective against T. hyodysenteriae in the control of swine dysentery (annual sales for 1981 US 45 million). An in vitro comparison of the effectiveness of carbadox (39) with other antibiotics for the control of T. hyodysenteriae has been carried out (79MI10805). 

Figure 12.9 Major organoarsenic animal feed additives. Arsanilic acid and Roxarsone are used to control swine dysentery and increase the rate of gain relative to the amount of feed in swine and chickens. Carbarsone and nitarsone (4-nitrophenylarsanilic acid) act as antihistomonads in chickens.

Promoting of swine growth [258, 259], against swine dysentery [184, 260], infection in turkeys [190, 261]... 

One of the newer semi-synthetic macrolides for veterinary use is 3-0-acetyl-4"-6)-isovaleryltylosin (AlV-tylosin) (15) Figure 5.6). Its in vitro spectrum is similar to tylosin, but includes activity against some tylosin-resistant organisms in vivo, it attains higher serum concentrations than tylosin [61, 77], It has been reported to prophylactically control Mycoplasma gallisepticum-inAmceA air sac lesions and Treponema hyodysenteriae-swine dysentery after oral administration [293, 294]. 

Arsanilic acid Control of swine dysentery. Growth promoter for chicken and swine. Improve pigmentation of chickens. Roxarsone Control of coccidiosis in chickens. 

Several arsenic compounds have been used in veterinary medicine. Arsenilic acid (C HgAsNOj) was used to treat swine dysentery, and arsenamide (CnHijAsNOjSj) for heartworm infection in dogs. Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) is still extensively used in the feed of broiler poultry to control coccidial intestinal parasites, improve feed efficiency, and promote rapid growth, and there is no indication that it will be soon replaced by another drug. 

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