LIVESTOCK
THE WESTERN PRODUCER | WWW.PRODUCER.COM | MAY 10, 2012
83
PARASITIC DISEASE | TREATMENT, PREVENTION
Sanitation important in preventing coccidiosis ANIMAL HEALTH
JOHN CAMPBELL, DVM, DVSC
There is often a connection between coccidiosis and stressors like weaning, bad weather and shipping
I
frequently receive calls at this time of year from producers and veterinarians about dealing with outbreaks of coccidiosis. Coccidiosis is a parasitic disease that can infect all farm animal species. However, the parasites that cause coccidiosis are host specific, in that there are species of the parasite that infect only cattle and other species that infect only sheep. It is caused by a single celled microscopic parasite that develops inside the intestinal cells of the infected animal. The infective form of the parasite, known as the oocyst, is found in the feces of infected animals. Calves and lambs can become infected shortly after birth by ingesting feces from contaminated udders. Coccidia oocysts are present in soil, vegetation and water sources of virtually all sites inhabited by cattle and sheep. They are capable of surviving and remaining infective in the environment for weeks or months, depending on environmental conditions. Moderate temperatures and wet or moist conditions enhance the survival and viability of the oocysts. Clinical disease caused by coccidia is usually limited to animals younger than a year. Adult animals will have immunity that is not absolute but will usually prevent clinical episodes. This immunity may be in place by as early as six weeks of age, but may be delayed if animals are protected from infection by medication or by lack of exposure before this time. Clinical coccidiosis is most commonly seen in crowded conditions such as confinement housing or crowded pens. Adult animals will pass normal levels of oocysts but will steadily raise the oocyst contamination to a dangerous level. Young confined animals that become infected quickly raise the contamination levels even higher. There is often a correlation between stressors such as weaning, weather events, shipping and clinical coccidiosis. The clinical signs of coccidiosis are caused by damage to the cells of the intestine wall by oocyst development. The incubation period is 17 to 21 days, which means clinical signs are usually seen at least 17 days after initial infections. It also suggests that calves or lambs that are sick before 17 days of age are
probably suffering from illness other than coccidiosis. The first signs of coccidiosis are unthriftiness and poor growth rates. Animals may have a tuckedup belly and have fecal staining around the tail. The most characteristic sign of clinical coccidiosis is watery feces, with little or no blood, and the animal shows only slight discomfort for a few days. Severely affected calves or lambs develop thin, bloody diarrhea that may continue for a week, or thin feces with streaks or clots of blood, mucus and shreds of sloughed intestinal tissue. They may develop a fever, lose weight, go off feed and become depressed and dehydrated. Straining during defecation is common. Some animals die during the acute period, while others die later from secondary complications such as pneumonia. Calves that survive severe illness can lose significant weight that is not quickly regained, or they can remain permanently stunted. Calves and lambs with additional infections, such as viral infections and pneumonia, may be more severely affected than calves with only coccidia infections. Coccidiosis is a self-limiting disease, and spontaneous recovery without treatment is common. However, some severely clinically affected animals may benefit from individual treatment with sulfa boluses or amprolium. Supportive fluid therapy may also be necessary for severely dehydrated animals. Consult your veterinarian to develop a treatment plan. Prevention is the key to controlling coccidiosis. Reduce contamination Sanitation efforts to reduce intake of oocytes revolve around attempting to reduce fecal contamination. This involves many of the management practices that are used to reduce all types of calf diarrhea: • a separate turn-out area for cows that have calved • a separate wintering area for cows before turning them into a clean calving area for the calving season • avoiding crowding • avoiding feeding on the ground • spreading out cow-calf pairs to minimize confinement and reduce fecal contamination A variety of medications work as coccidiostats to help prevent infection. These can be fed in creep feed to calves and lambs, but many young animals may not eat enough creep feed to prevent infection at a young age. Coccidiostats are effective at controlling coccidiosis in calves postweaning. Coccidiostats such as monensin have also been used in the cow herd to lower the levels of oocysts that cows shed into the environment before calving. A veterinarian can help design a control program for this common disease. John Campbell is head of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.
Calving challenges
Tanner Froshaug of Minton, Sask., was helping his dad bring in a heifer that was having difficulty calving on their ranch in the Big Muddy hills in southern Saskatchewan. Suddenly the heifer decided it had gone far enough into the bog and charged Tanner’s horse. In the end, the Border Collie came in to help get the heifer away from the mud, enabling the cowboys to help with the birth. | Carla Froshaug photos