Coccidiosis in domestic Rabbits
The most important species of rabbit coccidium is Eimeria stieclae, which occurs in the liver. All the other species are found in the intestine. Of these, the most important are E. residua, E. magna, E. media and E. perforans. Kheisin (1957) has assembled information on the localization of the intestinal species.
Coccidiosis is primarily a disease of young rabbits; adults are carriers. Rabbits become infected by ingesting oocysts along with their feed or water. The severity of the disease depends upon the number of oocysts they ingest and also upon the species involved. Mixed infections are the rule, infections with a single species usually being seen only under laboratory conditions. Crowding and lack of sanitation greatly increase the disease hazard.
Some of the coccidia of the domestic rabbit (Oryctolagus cuniculus) also occur in cottontails (Sylvilagus spp.). Some have also been reported from jack rabbits and hares (Lepus spp.). However, after reviewing the cross-transmission studies carried out to date, Pellerdy (1956a) concluded that, except for E. stiedae, none of the coccidia of jack rabbits and hares occur in domestic rabbits and cottontails, and none of the coccidia of the latter two genera occur in Lepus. If this conclusion is confirmed, the listing above of Lepus as a host of E. magna, E. perforans, E. media and E. irresidua would be incorrect. Further cross-transmission experiments are needed to settle this matter.
Liver coccidiosis can be diagnosed by finding the characteristic lesions containing coccidia. Intestinal coccidiosis can be diagnosed by finding the coccidia on microscopic examination. However, the mere presence of these parasites in a case of enteritis does not mean that they caused it. Many rabbits carry a few coccidia without suffering any noticeable effects. In a 3-year study of mortality among hutch-raised domestic rabbits in California, Lund (1951) considered coccidiosis to be the cause of enteritis in only 80 out of 1541 affected animals.
Some of the sulfonamides have been found helpful in preventing coccidiosis if given continuously in the feed or drinking water. Succinylsulfathiazole, sulfamerazine or sulfamethazine mixed with the feed at the rate of 0.5% have been recommended (Horton-Smith, 1947; Gerundo, 1948), as have been 0.02 to 0.05% sodium sulfaquinoxaline or sodium sulfamerazine in the drinking water. Lund (1954) found that the administration of 0.03% sulfaquinoxaline in the feed controlled E. stiedae infections effectively if begun not more than 4 days after experimental infection. The drug was not completely effective at this level, but it did give practical control. Lund stated further that this drug had not been found to harm rabbits when fed continuously.
However, long-term, continuous feeding of such drugs is not particularly desirable, nor is it usually necessary. It has been the usual experience with poultry, and there is evidence that the same thing is true with rabbits (see Horton-Smith, 1947), that if the hosts are exposed to coccidiosis during the drug-feeding period (as they usually are), an aborted infection occurs which is sufficient to induce immunity. The drug can then be safely stopped.
Prevention: Coccidiosis can be prevented by proper management (see Lund, 1949). Feeders and waterers should be designed so that they do not become contaminated with droppings, and should be kept clean. Hutch floors should be selfcleaning or should be cleaned frequently and kept dry. Manure should be removed frequently. The animals should be handled as little as possible, and care should be taken not to contaminate either the animals themselves or their food, utensils or equipment. In addition, the rabbitry should be kept as free as possible of insects, rodents and other pests.