Common Nutritional and Metabolic Diseases of Small Ruminants

Pregnancy toxemia (PT) is one of many metabolic disorders that affect pregnant small ruminants. Its etiology has its foundation in the abnormal metabolism of carbohydrates and fats, which occurs at the final stage of pregnancy (Edmondson et al 2012). More specifically, this disease is due to a lack of glucose as an energy source, either from poor nutrition, excessive demand from multiple fetuses, or a combination of the two. Recent evidence suggests that the glucose homoeostatic system of ewes bearing twins is significantly more susceptible to hypoglycemic stress than that of ewes bearing single lambs. These findings also show that the primary cause of hypoglycemia in late gestation twin-pregnant ewes is an increased susceptibility to a stress related reduction in glucose production rate rather than due to increased uptake by the fetus(es) (Schlumbohm and Harmeyer 2007). Any condition causing increased energy demand or decreased energy intake which results in a negative energy balance can be a cause. There are four categories of disease according to Edmondson et al (2012) 1) primary PT caused by inadequate nutrition (poor quality feed, period of fasting) 2) fat ewe/doe PT seen in overconditioned ewes/does in early gestation (suffer a nutritional decline in late gestation, possibly from smaller rumen capacity) 3) starvation PT seen in severely under-conditioned ewes/does (lack of feed after drought, heavy snow or flood) and 4) secondary PT due to concurrent disease such as parasites, poor dentition, or lameness. Animals carrying twins or triplets require 180% or 240% more energy, respectively, than those with a single fetus (Ermilio and Smith 2011) .