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United Suffolk Sheep Association |
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Sarco and Slaughter Condemnations Clell V. Bagley, DVM A producer called recently and was concerned because five of forty cull ewes had been condemned at slaughter due to Sarco. This is also called sarcocystis or sarcocystosis. It is caused by a parasite which encysts in the muscles of the sheep and causes an inflammation and discoloration. The condition is also called “eosinophilic myositis. It had been considered that this parasite caused no great problem for sheep, other than condemnation. However in recent years it has been learned that Sarco can cause illness in ewes and lambs and also abortion. Sarco is passed to sheep via ingestion of feed contaminated with sporocysts which are shed in the feces of infected dogs, coyotes, fox, cats and perhaps raccoons. These animals are infected by eating muscle tissue (carcasses) of infected sheep. So, the cycle goes round and around, similar to that of some tapeworms. Related parasites also affect cattle, swine, horses and even humans. To reduce or prevent Sarco, the most important step is to keep feces of all carnivores out of feed supplies for sheep. Cats love to “roost” in grain bins and hay stacks, and they defecate there. Dogs and raccoons may do the same or defecate in the feed bunks. It is important to prevent these situations as they can result in very high exposure rates. An effective preventive is to keep animals from ingesting carcasses of infected sheep and that is important for cats and sheep dogs. But, with guard dogs and coyotes that is not possible. Guard dogs and coyotes are a threat on grazing lands but there is currently no treatment that is effective in removing Sarco from these animals, to stop their shedding of the organism. There may be reduced spread in these grazing environments because the sheep may not graze in the immediate area of recent defecation.
Preventing Hydatid Disease of Man Clell V Bagley, DVM, Extension Veterinarian Utah State University
Hydatid disease of man is called echinococcosis. The causative agent is the larval stage of a tapeworm of dogs (Echinococcus granulosus). The adult stage of this tapeworm is very small and difficult to see; the eggs are microscopic and are not visible. These tiny eggs are sometimes transferred from the dog (hair to hand) or environment (grass, dirt to hand) to a person's mouth (wiping lips, chewing fingernails). After the eggs pass into the digestive tract, they penetrate the gut wall, enter the bloodstream and are carried to the liver, lung, etc. Here they attach and form cysts which will gradually increase in size. Some must be removed surgically from humans. Man is considered a “dead end” host in this disease because the infection doesn't spread from an infected person to another person, or even to a dog. The intermediate host is sheep, where the cysts are formed in them just as in man. If dogs are allowed to eat the internal organs of infected sheep the dogs become infected and the larval tapeworms develop into adults. That dog begins to shed eggs from its intestinal tract within about 7 weeks and the cycle repeats. Dogs may also be affected by other tapeworms but these are much larger, easily visible and do not cause the cyst problem in man. Parasites, in general, survive by sheer masses of numbers and that is the case with hydatid disease. A heavily infected dog may shed thousands of eggs each day. Only ONE of these has to get from the tail hair to the dog muzzle, to a person's hand, to mouth and it can result in hydatid disease for that person. Sheep are not the only intermediate host as it may occur in rodents as well. Control is most effective when implemented on a community, area, or county-wide basis. It must include: 1. Deworming of all dogs that MAY have eaten uncooked sheep viscera (internal organs). This must be repeated later, after any exposure to viscera. 2. Disposal of dead sheep and sheep viscera to prevent dogs access to eating it. 3. Elimination of stray dogs. 4. Control of all dogs to keep them from defecating in and around children's play areas. 5. Washing hands after handling or playing with dogs. Not all deworming products are effective against tapeworms and not all that are available for the common tapeworms are effective against Echinococcus. At least three products are available which are highly effective against Echinococcus and they are very safe for use in dogs. One of these products should be used on any dog that has eaten raw sheep viscera. For dogs which may continue to have periodic exposure to sheep carcasses, consult with your veterinarian and plan a routine deworming program for as often as once every 4 to 6 weeks. Guard dogs should certainly be considered in this category of periodic exposture to sheep viscera. Some communities may require that an injectable deworming product be used, to help insure adequate administration (some dogs spit pills out). The three products which have been shown to be effective are: DRONCIT (from Bayer Corporation): A prescription product available as an injection or tablet. The active ingredient is praziquantel. The label indicates usage against Echinococcus as well as the common tapeworms. DRONTAL (also from Bayer): a prescription product available as a paste. The active ingredients are febantel and praziquantel. The label now indicates usage for roundworms, hookworms (febantel), common tapeworms (praziquantel) and Echinocuccus. Research has shown it to be highly effective against the Echinococcus tapeworm (Andersen, et al., AJVR 46:253-255 (1985)). CESTEX (from Pfizer): A prescription product available as a tablet. The active ingredient is epsiprantel, which is very closely related chemically to praziquantel. The label only indicates usage for the common tapeworms but research has shown it to be highly effective against the Echinococcus tapeworm as well (British Veterinary Journal (1989)145:384; Research in Veterinary Science (1990) 49:378-379; and RVS (1991) 51:332-334). In the past, repeated deworming has not been strongly encouraged by some because of the fear it would remove the emphasis from the other control measures and also give a false sense of security. However, the products now available are much more effective against Echinococcus than those of years ago. Greater emphasis should be given to their routine and continued use. The other aspects of a community control program should still be emphasized and implemented. But families who own dogs should know that they can implement a control program of their own to give them a reasonable degree of security against hydatid disease, even if others in the community are not complying with the total program.
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