TABLE OF CONTENTS
Coccidiosis in Sheep and Goats: Etiology, Clinical Signs, Diagnosis & Treatment
Coccidiosis in sheep and goats is an economically important protozoan disease caused by several species of Eimeria. It primarily affects young lambs and kids, resulting in enteritis, diarrhea, dehydration, poor growth, and, in severe cases, death.
The disease is most common under intensive management systems, where overcrowding, poor sanitation, and environmental contamination with sporulated oocysts facilitate transmission. Early diagnosis, appropriate anticoccidial therapy, and effective management practices are essential for reducing production losses and controlling the disease.
Etiology
Coccidiosis in sheep and goats is caused by host-specific protozoan parasites of the genus Eimeria. More than 13 Eimeria species have been identified in sheep and goats, although only a few are considered highly pathogenic. In sheep, E. ahsata, E. ovina, and E. ninakohlyakimovae are among the most important pathogenic species, whereas E. arloingi is the principal pathogenic species affecting goats. The disease primarily affects young lambs and kids, while adult animals usually act as asymptomatic carriers and shed oocysts in their feces, serving as a source of infection for susceptible animals.
In sheep and goats, coccidiosis is primarily a disease of young lambs and kids, particularly those maintained under intensive production systems. In intensive systems, infected adult animals (carriers) continue to shed oocysts, resulting in the buildup of oocyst contamination within the housing environment, which can lead to clinical coccidiosis in young animals. In addition, overcrowding and poor sanitation favor oocyst sporulation, thereby increasing the incidence of coccidiosis in feedlot animals.
Common Eimeria Species Affecting Sheep and Goats
| Name of the Species | General Features | Pathological Changes |
|---|---|---|
| 1. E. ahsata | The most pathogenic species of sheep coccidia, found in the small intestine. Its oocyst has a dome-shaped polar cap. | The wall of the ileum is thickened, with inflammation of Peyer’s patches. |
| 2. E. arloingi | The most common coccidial species of goats, found in the small intestine. The oocyst bears a distinct polar cap and produces large schizonts. | Polyp formation of the villi, hyperplasia, and edema of the small intestine, with local hemorrhages and desquamation of the epithelium. |
| 3. E. christenseni | Affects goats. The oocyst has a dome-shaped polar cap. | — |
| 4. E. crandallis | This Eimeria species is found in sheep. | — |
| 5. E. gilruthi | This species is found in the abomasum and small intestine of sheep and goats. It produces large schizonts. | — |
| 6. E. intricata | It affects sheep. Its oocyst is very large and bears a distinct polar cap. Schizogony occurs in the lower small intestine, whereas gametogony occurs from the mid-small intestine to the rectum. The prepatent period is 20–27 days. | — |
| 7. E. ninakohlyakimovae | This is one of the most pathogenic species affecting sheep, found in the posterior part of the small intestine, cecum, and colon. | The intestinal mucosa is covered with petechial hemorrhages. |
| 8. E. ovina | This is also one of the most common Eimeria species of sheep, found in the small intestine. In this species, only one generation of schizonts occurs in the epithelial layer and endothelial cells lining the central lacteals of the villi. The prepatent period is 22–29 days. | The giant schizonts and gamonts cause enlargement of the villi, forming papillomatous growths (polyps) that are visible to the naked eye. In the acute form, the intestinal wall is thickened, edematous, and hemorrhagic. |
| 9. E. parva | This species is found in sheep and goats. Asexual reproduction occurs in the small intestine, whereas sexual reproduction occurs in the cecum, colon, and small intestine. The giant schizonts are visible as whitish bodies in the mucosa. The prepatent period is 16–17 days. | The mucosa of the cecum and colon is thickened, edematous, and hemorrhagic. Necrotic areas may occur, and the intestinal contents become fluid and dark brown to hemorrhagic. |
| 10. E. punctata | This species is found in sheep. The oocyst wall bears cone-shaped pits. | — |
Among these species, E. ahsata, E. ovina, E. ninakohlyakimovae, and E. arloingi are responsible for most cases of clinical coccidiosis in sheep and goats.
Life Cycle
The life cycle is similar to the general life cycle of Eimeria. Infection occurs following ingestion of sporulated oocysts. The endogenous developmental stages (schizogony, gametogony, and oocyst formation) occur in different regions of the intestinal tract depending on the Eimeria species involved. The development of these stages occurs at the following locations.
Clinical Signs
The pathogenesis may vary among species. However, animals affected with coccidiosis commonly exhibit brownish to yellowish-green diarrhea. The feces may be streaked with blood if the disease is caused by species that undergo gametogony in the large intestine. Diarrhea may persist for up to 2 weeks.
Lambs and kids may die due to dehydration, although most recover. Abdominal pain, anemia, inappetence, weakness, and weight loss are other clinical signs associated with coccidiosis. A flat mucosa syndrome associated with villous atrophy occurs in ovine coccidiosis, leading to malabsorption and poor growth.
Diagnosis
- History
- Postmortem examination
- Fecal examination
Treatment
- Sulphaguanidine: 2 g/day for 6 days.
- Amprolium: 100 mg/kg for goats for 4–5 days.
- Nitrofurazone: 7–10 mg/kg for 7 days.
- Lasalocid: 12.5–100 mg/kid/day.
- Monensin: 22 mg/kg in feed.
Control
- Maintain hygienic animal housing.
- Avoid contamination of feed with feces.
- Replace bedding materials regularly.
