Coccidiosis is not caused by a bacteria, virus, or roundworm but by single cell protozoa. There are multiple coccidia species that are found in the environment. Some of these are non-infective, some moderately infective, and others are highly infective. Strains of coccidia are animal species specific with some very limited crossover between sheep and goats.
The following are some coccidia facts:
- Coccidia are always present in the herd or flock, and most adult animals carry coccidian but are immune to clinical disease.
- Immunity occurs more in sheep than in goats.
- Lambs and kids develop immunity about 4 weeks after exposure.
- The protozoa are present in the small intestine, and young animals are most susceptible (30-60 days of age).
- Stress can trigger severe infections that can result in death.
- Chronic infections result in “poor doing” lambs/kids and create long-term intestinal damage.
The life cycle of coccidia is quite complicated and has many stages of development. The cycle is 21 days in length and proliferates inside the epithelial cells of small intestine, which causes damage to the cells of the small intestine. Oocytes (eggs) from adult protozoa are released via feces into environment. These oocytes go through a process called sporulation (hatching), which is enhanced by warm, moist conditions. Early development during the first 16 days following ingestion initiates damage without clinical symptoms. Clinical symptoms, diarrhea with or without blood, occur after day 18. Other symptoms can include stomach pain, decreased appetite, dehydration, rectal straining (can lead to prolapse) and chronic poor doers as a result of small intestine damage. Animals are infective 14-17 days after ingestion. Animals begin to excrete eggs after day 22. The implications of this life cycle are that there is a gap between symptoms (diarrhea) and egg excretion so fecal egg counts are not always a good indicator of infection, as shedding of eggs only occurs at the end of the infection period after the damage has been done. It is recommended to collect post mortem samples as this is the best way to confirm coccidiosis.
Producers should not have to treat for coccidiosis if a prevention program is followed. Treating symptomatic animals is a poor approach and labor intensive because if you see clinical cases, there has already been subclinical losses and damage.
Cleanliness is the first course of action to take in the prevention of coccidiosis as oocytes are spread in feces. A clean barn is essential especially before lambing or kidding. Keep pens dry by using adequate bedding, prevent contamination of feed and water, and do not feed animals on the ground. Feeding a coccidiostat as a preventative before known times of susceptibility is also encouraged.
- Monensin (Rumensin) – approved for goats and effective day 7-10 of life cycle
- Lasalocid (Bovatec) – approved for sheep and effective day 7-10 of life cycle
- Decoquinate (Deccox) – approved for sheep and goats and effective day 0-16 of life cycle
For prevention in young lambs and kids, treat the dams with a coccidiostat for at least 21 days prior to birth and continue to provide in kid or lamb feed for 60-90 days for additional protection. For prevention in growing animals entering the feedlot, feed a coccidiostat for 30 days after the animals go into the feedlot. Michigan State University Extension recommends feeding according to label instructions and working with your veterinary as some of these drugs are not labeled for both sheep and goats and may require off label use.
In conclusion, coccidiosis is preventable in sheep and goat herds. Knowing the facts of how it is transmitted, and the lifecycle will help producers maintain their herds and flocks health.