OVINE COCCIDIOSIS
 

• Ovine coccidiosis is one of the most economically important diseases of sheep. It is becoming increasingly important in sheep production, particularly in intensive production systems.

• Coccidiosis is common in lambs aged 1-6 mo and most common in young lambs aged 2 - 8 weeks particularly after weaning. Ewes can act as a reservoir of infection and shed low numbers of oocysts, particularly around the periparturient period.

• Ovine coccidiosis is caused by pathogenic species of Eimeria; E. ovinoidalis (E. ninakohlyakimovae previously), E.crandallis, E. ahsata, E. aloringi A (ovina), and E. weybridenis (E.aloringi B). All other Eimeria of sheep are essentially nonpathogenic, even when large numbers of oocysts are present in feces.

• Eimeria crandallis and Eimeria ovinoidalis are the most pathogenic species. E. crandalis and E. ovinoidalis, are found in the ileum, but E. ovinoidalis is also occurs in the caecum and colon.

• Heavy oocyst challenge in young susceptible lambs which usually leads to outbreaks of clinical disease.

• Clinical coccidiosis occurs when damage to the gut is sufficiently severe to cause dysfunction at the beginning of the parasite's sexual multiplication stage, when parasite numbers reach their peak. The source of the initial outbreak of clinical coccidiosis is likely to be either residual contamination in the environment or low levels of oocyst shedding by the ewes. The level of the environmental infection with pathogenic species is probably the most important factor, but other factors, such as ration change, crowding stress, severe weather, or shipping may be participate in clinical coccidiosis occurrence. Lambs 1-6 mo old in lambing pens, intensive grazing areas, and feedlots are at greatest risk.

• Virtually all sheep flocks are infected with coccidia, but only some lambs develop Clinical coccidiosis. The lambs may suffer from dullness, inappetance, diarrhea (sometimes-containing blood or mucus), tenesmus, rectal prolapse, dehydration, weight loss, anemia, wool breaking, and sometimes death with a course of 1-3 weeks.

• Treatment: Coccidiosis should be treated as a flock problem rather than on an individual basis. Treatment of affected sheep with anticoccidial drugs once coccidiosis has been diagnosed is not effective, but severity can be reduced if treatment is begun early. Drugs that can be used for therapy of clinically affected animals include;
  • Sulfadimidine (sulfamerazine) 140 mg/kg BW /day for 3 days orally.
  • Monensin (Rumensin®) 2 mg/ kg BW for 20 days.
  • Sulfaquinoxaline at 0.015% concentration in drinking water for 3-5 days.
  • Concurrent Nematoridus infection can exacerbate the severity of coccidiosis and lambs may need to be dosed with an anthelmintic as well as an anti-coccidial drug.
  • Drugs can be very useful in helping to prevent coccidiosis during periods when coccidiosis is likely to be a hazard (28 consecutive days beginning a few days after lambs are introduced into the environment) and some of these are;
  .Sulfadimidine (sulfamerazine) 25mg/kg BW/day for 7 days.
  .Amprolium 5 mg/kg BW/day for 21 days in feed.
  .Monensin (Rumensin®) 20 mg/ kg feed continuously.
  .Lasalocid (Bovatec®) 25-100 mg/ kg feed from weaning until market or (15-70 mg/head/day, depending on body wt). Also, in ewe's diet from 2 weeks before and until60 days after lambing.
  .Sulfonamides and chlortetracycline combination has given protection in calves and lambs.

• Prevention of infection is dependent on good hygiene and husbandry. The first priority in controlling coccidiosis is to avoid circumstances that allow infection to build up to dangerously high levels.

• Keep the living area clean and dry and Feeders should be at a height. Housed lambs should be provided with adequate clean litter and bedding. Avoid overcrowding, the low stocking density and outdoor lambing management systems often applied. Infected animal areas must be thoroughly cleaned before the oocysts can multiply.

• With sequential lambing avoid grazing young and older lambs on the same pasture and in particular on the fields which carried ewes and lambs within the previous 2-3 weeks. Creep feeders should be moved regularly to prevent the build-up of infection.

• Infected lambs should be isolated and treated quickly to avoid exposure to other lambs.

• Minimize stress as much as possible. An adequate intake of colostrum will assist the lamb in coping with coccidial infection. In most confinement situations, prevention with coccidiostats is a wise strategy.