Parasites of the Domestic Rabbit 563 is called mucoid. Extreme fluidity of loops. Sloughing ofí*of the mucosa and the bowel contents or a profuse watery submucosa of the small intestine and diarrhea are characteristic symptoms necrosis of the epithelium of the colon of diarrheal enteritis. When free blood is noted. Pathological changes are is found in the lumen of the intestine limited to the gastrointestinal tract. and cecum, the enteritis is called Antibiotic feed supplements (Auro- hemorrhagic. It is the most acute. fac-A, Penbac, and Terramycin-5) There may be no noticeable symp- and vitamin B12 incorporated in pel- toms. leted rations have been effective in Diarrheal enteritis occurred in 80 reducing mortality from enteritis. In percent of all cases; mucoid enteritis one series of tests, enteritis mortality in about 15 percent; and hemorrhagic was reduced by 75 percent by the enteritis in about 5 percent. The addition of 5 pounds of Aureomycin average age at death was lowest with supplement per ton of feed. hemorrhagic and highest with diar- The administration by mouth of 25 rheal. The course of the disease in milligrams per pound body of weight animals with diarrheal symptoms of Aureomycin or Terramycin to sick ranged from 24 to 72 hours. In the animals also has reduced enteritis mucoid stage it was 4 to 10 days. mortality. The stomach at autopsy is filled with fluid, and ulcérations in the pylorie KARL W. HAGEN, JR., isa member of region are often noted. Fluid, gaseous, the Animal Disease and Parasite Research or mucoid intestinal contents are Branchy stationed at the United States found throughout the entire alimen- Rabbit Experiment Station in Fontana^ tary tract. Formed droppings are not Calif. He is a graduate of the University of found in the large intestine. Adhesions California in Los Angeles and has studied are not uncommon in the intestinal rabbit diseases since ig^o.

Parasites of the Domestic Rabbit

EVERETT E. LUND

DOMESTIC RABBITS raised com- celled parasites that invade the lining mercially in this country are usually of the intestine, multiply prolifically, maintained in individual hutches, and eventually leave the body of the each of which contains at most a doe rabbit in the droppings. At this stage and her litter of unweaned young. The they are in a resistant form and are degree of isolation secured by this called oöcysts. When conditions of practice, together with the employ- temperature and moisture are favor- ment of reasonable measures of sani- able, the minute oöcysts develop to an tation, has been effective in controlling infectious stage within a few days. parasitism in our domestic rabbits. They are then ready to attack another There are, however, a few parasitic rabbit, if taken in with feed or water or diseases that still become troublesome. as the animal washes itself. Coccidiosis is the most prevalent of At least four species of coccidia live all parasitic diseases of domestic rab- entirely in the lining of the intestine bits. It is caused by microscopic one- of domestic rabbits, save for their 564 Yearbook of Agriculture 1956 passage from one animal to another. times they may be useful in subduing Not all are equally harmful. Rabbits severe outbreaks. A pelleted ration tolerate moderate numbers of any of containing one-half pound of sulfa- these species without suffering meas- quinoxaline per ton of feed (0.025 urable damage. Excessive numbers of percent concentration) may be oflfered the larger species produce soft drop- in place of the regular ration for 2 or pings or diarrhea, indisposition to 3 weeks to reduce the incidence of feed, a consequent loss in rate of gain, intestinal coccidiosis to a point at and at times death. which control by suitable manage- There is no positive means of diag- ment practices is sufficient. The in- nosing intestinal coccidiosis without a testinal coccidia develop a tolerance microscopic examination of the drop- when the drug is used continuously. pings, the intestinal or cecal (blind One species of coccidium, Eimeria pouch) content, or the intestinal wall. stiedae, multiplies in the liver of Even then, experience is needed to domestic rabbits. Like the other judge whether the number of para- species, it enters the intestinal wall sites present is great enough to account but lodges in the liver before reproduc- for the symptoms, because other dis- ing. Infections more than 16 days old orders, particularly mucoid enteritis, are easily recognized by the creamy- may produce similar symptoms and white, circular nodules produced on be present at the same time. the liver. Because infections of any The control of intestinal coccidiosis degree disfigure the liver, making it in domestic rabbits rests largely on the unmarketable, and prejudice the mar- employment of management practices keting of the entire carcass, liver coccid- that minimize the danger of fecal con- iosis is always of economic significance. tamination of feed, water, hutch floors, Liver coccidiosis by itself does not and other equipment. Self-cleaning produce diarrhea or any other ex- floors that permit droppings to fall ternal symptoms, except in the most through, out of reach of the animals, extreme cases. Then the liver may be so reduce to about one-tenth the hazard greatly enlarged as to distort the body that is presented by soil or floors on of the animal. Some animals afl'ected to which manure accumulates. Feeders this extent die; usually ruptured livers, about 4 inches above floor level, pro- peritonitis (body cavity inflammation), vided with guards to keep animals or pneumonia are complications. A from perching in them, also are neces- technician with experience can diag- sary. If watering cannot be accom- nose some cases of liver coccidiosis by plished with automatic valves placed a microscopic examination of the 8 to 9 inches above floor level, the droppings, but the disfiguring lesions water containers must also be provided remain on the liver several weeks after with guards. the last evidence of oöcysts in the fecal Handling of animals must be re- pellets, so only internal symptoms can duced to a minimum. Equipment— be entirely trustworthy. brushes, scrapers, pails, and other Liver coccidiosis is acquired in the utensils—should never come in contact same way as intestinal coccidiosis. The with one hutch after another. The control measures also are the same. oöcysts are quite resistant to all usual Liver coccidiosis can be held to much disinfectants but are susceptible to lower incidences than can intestinal drying. If the hutch floors and other coccidiosis with the same control meas- equipment are kept clean and dry, ures. In well maintained commercial infections heavy enough to be of rabbitrics, 2 to i o percent of the ani- economic significance are unlikely. mals may have light cases of intestinal Even the best substances used for coccidiosis, while liver coccidiosis is treatment have only transitory effects cither absent or present in less than on the intestinal coccidia, but some- 0.5 percent of the herd. Parasites of the Domestic Rabbit 565 A ration containing 0.025 percent be accepted as almost certain evidence of sulfaquinoxaline is more than 90 of ear mange. percent effective against the liver Treatment consists of cleaning the coccidium. Its effectiveness continues, ear first with a bland oil, such as ordi- so the ration can be fed indefinitely. nary vegetable oil used in cooking, and But this is not necessary, and if the then swabbing the entire inner surface drug is used at all, it should be used of the ear with medicated oil. Enough only as an emergency measure, until oil should be applied so that it runs management control can be effected. into the auditory canal and wets all surfaces thoroughly. Cases of long EAR MANGE is probably the second standing have such heavy encrusta- most important parasitic disease of do- tions that it is necessary to extend the mestic rabbits. It is caused by a small cleaning over a period of 2 or 3 days, mite, usually Psoroptes communis cunic- so that the heavy cakes can soften uli, which is just visible to the naked before one attempts to extract all of eye. Studies conducted in California thexn. A mixture of i part of iodoform, in 1948 and 1949 revealed that 45 to 10 parts of ether, and 25 parts of 80 percent of the commercial rabbitries vegetable oil is effective. It may be visited had been troubled w^ith ear prepared by any druggist. A second mange. The incidence among mature application of this mixture should be animals was found to range as high as made 7 to i o days after the first, to kill 84 percent but averaged ïI percent. recently hatched mites, or ones having Ear mange is usually contracted by strayed from the area. A 0.25-percent close or prolonged contact with ani- solution of lindane in vegetable oil is mals already infected or by placing effective and inexpensive, but should animals in quarters recently occupied not be used unless the operator w^ears by affected ones. rubber gloves or can otherwise avoid The tiny mites that are able to find prolonged contact wdth the solution their way into the auditory canal at while it is being applied. The drug is the base of the ear pierce the skin with harmful when absorbed through the their sharp mouth parts, feed, and skin. permit the escape of the clear serum. All animals near the affected ones, The serum hardens into scales, be- recently in contact with them, or in neath which the mites continue their quarters recently occupied by such activity, feeding, mating, laying eggs, animals should be treated, except producing more layers of scales, and does within 10 days of kindling. These spreading. Finally thick crusts are should be treated after they have formed, and the area involved extends kindled, to avoid restraining them at a far up the inner surface of the ear and time when abortion may be induced, occasionally even to the head and should they struggle violently. It is neck near the ear. unnecessary to treat unweaned ani- Intense itching is provoked by all mals, but any being saved beyond the this activity. Affected rabbits shake age of 8 or 10 weeks should be treated. their heads, rub their ears with their Once a herd is free of mange it is not front feet, and scratch vigorously at difficult to keep it so. All new intro- the base of their ears with their hind ductions to the herd and animals feet. Parallel scratches one-fourth to being returned to it after contact with three-eighths inch apart at the base other rabbits should be treated as a of the skull or on the neck are self- routine practice in all rabbitries. inflicted by the nails of the hind feet Ear mange does not often cause and are indicative of ear mange. By mortality, but it makes its victims un- looking into the car, one can see yel- thrifty and seriously interferes with low crusts of dried scrum, sometimes production. It particularly influences tinged with blood. Their presence can lactation and the care of the young. 566 Yearbook oj Agriculture 1956 Occasionally mites penetrate the ear- PiNWORMS are fairly common in do- drum, so that infections arise in the mestic rabbits, especially in old does. middle ear. The organs of balance in The glistening white worms, one-half the inner ear may be affected; the inch long, often are seen on the surface animal turns its head to one side and of freshly passed droppings or shining may even roll over in an effort to through the wall of the cecum (blind orient itself to gravity. This condition gut) of mature animals that are is called wry neck and can result from slaughtered. any of several causes, but ear mange is Ordinarily pinworms do little or no a common one. Animals showing wry harm. They may become numerous, neck may live, but they arc useless and especially in animals 2 to 3 years old. should be destroyed or marketed, if Mature worms usually become suffi- no other infection is present. ciently inactive to be swept out of the cecum from time to time with its nor- BODY MANGE of domestic rabbits is mal movement of contents. also caused by tiny mites of other The worms manage to stay next to species. This disorder is not common, the intestinal wall in most instances but when it is present the areas first and in that way escape from the rabbit involved are usually the back and the on the outside of the droppings, rather neck, although it may occur anywhere. than become sealed up within the The affected areas lose the hair, and mucus-covered pellets. Worms voided the skin is red, with an abundance of in that way often crawl away from the white scales. Diagnosis depends on droppings (unless they are on con- finding the mites or their eggs on hair crete, sheet iron or some dry, unre- plucked at the margins of the bare sponsive surface) and dry up; the fe- areas. A microscope or a good lens may males then liberate the hundreds of be needed to make sure of that. microscopic eggs that fill almost their Treatment of body mange is tedious. entire bodies. The eggs become infec- If the areas involved are not numerous, tive after several days, and some are treatment may be practical for ani- consumed with feed and water or as mals of more than ordinary value. One the animals wash. should clip the hair from an area at Pinworms infrequently perforate the least one-half inch beyond that which cecum, permitting bacteria to infect is obviously affected and swab the skin the body cavity. Death from peritoni- thoroughly with vegetable oil or a tis may result. mixture of i part of flowers of sulfur in Pinworms rarely become a serious 3 parts of vegetable oil. The iodoform problem if management methods nec- preparation mentioned for the treat- essary for the control of coccidia and ment of ear mange is also satisfactory, other intestinal disorders are observed. but the lindane preparation should not Phenothiazine is effective in ridding be used if more than 5 to 6 square rabbits of pinworms if administered at inches of skin are to be swabbed, be- the rate of 0.2 gram per pound of body cause there would be danger of too weight on each of 2 days, with 3 or 4 great absorption of the toxic drug. days intervening. Rabbits are able to Body mange is spread by contact, detect the drug in the ration, but it through the use of infected hutches, can be given in gelatin capsules. This and by the shed hair as it blows or is is such a nuisance it can be recom- carried about, as on the clothing of mended only when the grower is par- the attendant. Hutches that are clean ticularly desirous of freeing an animal and dry and free from hair cannot of w^orms for some special reason. harbor mites capable of establishing infection more than a few days at TAPEWORM LARVAE—developmental summer temperatures and hardly stage—sometimes disfigure the livers more than 2 weeks in cold weather. of rabbits with irregular, creamy- Diseases and Parasites of Minks 567 white streaks. The streaks are the scars equipment, and everything the rabbit of the paths taken by the larvae as may touch entirely free of possible con- they migrate through the liver. The tamination with droppings of carni- larvae finally come to rest as little vores, particularly dogs. He should glistening beads of jcllylike material never permit a dog to sleep on feed on the membranes supporting the sacks and bales of hay or straw or to intestine. contaminate anything that will reach Each such little bead is an embryonic the rabbits. And, conversely, to keep tapeworm, which must now await con- the dog from becoming infected, he sumption by a carnivorous animal, should not allow it to feed on the such as a dog. In its intestine the em- viscera of infected rabbits. bryo will grow into a mature tape- worm; its eggs later escape in the EVERETT E. LUND is a parasitologist in dog's droppings and can infect another the United States Department of Agricul- rabbit. ture. He received his training at Iowa State Disfigured livers are objectionable College and the University oj California at and often prejudice the value of the Berkeley. After having taught several years entire carcass. To prevent this type of in universities here and abroad^ he joined infection in rabbits, the owner has to the Department of the Interior in ig^^ and keep all feed, water, nest-box straw, the Department of Agriculture in 1^46,

Diseases and Parasites of Minks

JOHN R. GORHAM

THE BOTULISM bacterium, Clostrid- nated, frozen, stored food and the iuin botulinum^ produces a potent toxin uneaten ration in the pens. in contaminated meat. Such meat, fed Antitoxin that contains toxin-neu- to minks, can kill them in 18 to 96 tralizing antibodies against the three hours. Almost immediately the ani- common types of toxins, designated A, mals sufíí*cr muscular incoordination B, and G, should be administered to and stifi'ness. Paralysis of the front or every mink on the ranch as soon as hind legs follows. The muscles used in possible. breathing become paralyzed by the For prevention, a toxoid—preven- toxin, and the minks die. tive inoculation—offers fair promise of The carcasses of sick horses and being helpful. The first work on botu- spoiled feed that has had a chance to lism toxoids for minks was done in become warm for a time should never Sweden. Following the disastrous out- be used. breaks of botulism in this country The treatment of minks affected with when spoiled whale meat was fed, botulism often is to no avail. Prompt research workers in Utah and Wis- recognition by the rancher will give consin and at the Department of Agri- the veterinarian a better chance to culture Fur Animal Disease Station save the minks that have not eaten developed an experimental toxoid, enough of the poisoned food to show which is available commercially. It is symptoms. The owner should throw emphasized, however, that care in away immediately all the contami- management and selection of feed is