Dr. Guillermo Zavala - Runting Stunting Syndrome in Broiler Chickens

Runting Stunting Syndrome (RSS) is an enteropathy of young chickens, primarily broilers, and is characterized by slow growth, poor uniformity, severe watery diarrhea, and relatively low mortality. The primary changes and lesions consist of thinning of the intestinal wall due to villus shortening, and crypt hyperplasia followed by the development of cryptal cysts, known as ectasia. The most severe lesions of the gut involve the duodenum and jejunum, hence the impact of RSS on growth. The liver of affected chickens appears darkened and devoid of fat deposits. The gall bladder is typically enlarged, and the intestinal lumen is filled with watery to foamy contents. RSS increases overall feed conversion and decreases growth. A large proportion of stunted chicks are often culled. The survivors reaching the processing plant display low uniformity and soiled feathers, which can translate in increased risk for carcass contamination with foodborne bacteria. RSS is considered a multifactorial disease in which incubation conditions, husbandry, and a variety of enteric viruses result in a neonatal enteropathy with significant economic consequences.