Goat Diseases
Pregnancy Toxemia and Ketosis in Goats
Also known as Twin kid disease, Ketosis, Ketonemia and Hypoglycemia
Pregnancy toxemia is a metabolic disorder of pregnant ruminants (pre-parturition) caused by abnormal metabolism of carbohydrates and fats, which occurs in the final stages of pregnancy. Ketosis (or ketonemia) is also a metabolic disorder associated with fat and carbohydrate metabolism but occurs after kidding during the early lactation stages. Both conditions are closely link and associated with negative energy balance.
Although many animals are able to cope and recover from a negative energy balance by metabolizing body fat albeit with a negative impact on productivity at the sub-clinical stage, some metabolize too much fat, become overwhelmed with the associated by-products (ketone bodies), and develop pregnancy toxemias (before kidding) and ketosis (after kidding).
What is Negative Energy Balance (NEB)?
The final stages of pregnancy and the onset of milk production (lactation) requires a lot of energy, this high demand is usually met by feed intake and topped up by body reserves. If the (metabolizable) energy from feed intake and the body reserves is less than required for the foetus to grow or to produce milk – the body is in a Negative Energy Balance (NEB).
NEB is considered the normal in high yielding animals during early lactation, however stress can cause further reduction in feed intake and lead to the onset of sub-clinical or clinical ketosis. NEB a detrimental consequence of human selection for high yielding animals, hence the emerging trends in diary cattle and reduction in milk yield and gain in animal welfare.
Fat mobilization
Due to low glucose levels in the blood, fatty acids and glycerol from ‘stores’ are oxidized to form Acetyl-CoA. However, the liver cannot cope with high levels of acetyl-CoA so it is converted into ketone bodies (including Beta-hydroxylbuterate, BHBA). These ketone bodies can be used by other tissues and muscles in the body, but if they cannot keep up, the ketones are excreted in milk and urine.
BHBA and other ketone bodies are found in blood, urine and milk of ruminants experiencing a period of negative energy balance (Herdt, 2000). In dairy goats blood BHBA concentration generally increases during late stages of pregnancy (Herdt, 2000).
Early detection of pregnancy toxemia or ketosis by measurement of BHBA is useful as clinical pregnancy toxemia usually has a poor rate of survival (Doré et al., 2013).
Risk factors for pregnancy toxemia in goats
Risk factors for pregnancy toxemia include carriage of multiple fetuses, age, and extreme body condition score (BCS), fat or thin (Rook, 2000). Obese animals carrying multiple fetuses are at highest risk to develop disease (Ermilio and Smith, 2011).
Clinical signs of pregnancy toxemia are usually non-specific at the onset of disease and may include anorexia, isolation from herd mates, swollen lower limbs, tremors, recumbency, blindness, ataxia, coma and death (Brozos et al., 2011; Doré et al., 2015; Rook, 2000).
In dairy goats the final month of pregnancy is a critical period for the management of energy balance because approximately 60 – 80% of fetal growth occurs during this period, and because dry matter intake declines simultaneously (Rook, 2000).
Pregnancy toxemia can be fatal in does and ewes if not diagnosed in a timely manner, therefore, early identification of goats at risk of developing pregnancy toxemia increases the chances of recovery (Brozos et al., 2011; Rook, 2000).
Risk factors for ketosis in goats
As the energy requirements of does considerably increases with the onset of lactation, most does will develop mild or lactational ketosis (Pichler et al., 2014). Goats in early lactation loses excessive body weight if the feed intake quantity and quality is not adequate to meet the energy requirements of producing milk, hence animals are in negative energy balance (Matthews, 2009).
In dairy goats, clinical ketosis manifests predominantly in early lactation (Stelletta et al., 2008). Does carrying multiple fetuses, undernourished or overweight animals are likely to develop clinical ketosis (Brozos et al., 2011; Rook, 2000).
Clinical signs include anorexia, recumbency, lethargy, muscle spasm of the head and neck (opisthotonos), dropped head, convulsion, sweet smelling breath, apparent blindness, bloat, teeth grinding, and frothy salivation (Vasava et al., 2016).
Diagnosis for pregnancy toxemia or ketosis
Characteristic biochemical patterns associated with pregnancy toxemia in goats showed that there is a decreased level of glucose and calcium in the blood, and increased levels of ketone bodies (Vasava et al., 2016).
Increased concentration BHBA and/ or low blood glucose during the late stage of pregnancy and early lactation are associated with pregnancy toxemia and ketosis. In dairy cows, dipsticks can be used to detect BHBA in urine or milk, however in goats, these semi-quantitative tests are not as accurate as blood tests.
Control and Prevention of Pregnancy Toxemia and Ketosis
Prevention of pregnancy toxemia and ketosis in goats is via nutritional management and identification of those animals at most risk. Feed intake should be monitored and adapted to meet the need of the doe. The feed ration will invariably be different for pregnant and lactating animals and therefore body condition scoring (see below) is a useful way to monitor and identify animals at risk (Harwood, 2016).
One of the guiding principles of sustainable livestock production is to feed high levels of roughage in the diet so as to promote good rumen digestion. However, as the doe progresses in the late stage of pregnancy, the energy density of the ration should increase to accommodate the inevitable reduction in dry matter intake. Anecdotally, there is evidence that in intensively reared small ruminants access to external paddocks and grazing during the late stage of pregnancy will contribute to reduce the onset of pregnancy toxemia.
Over fatness should be avoided in pregnancy wherever possible. Over-feeding from mid-pregnancy onwards leads to excessive fat being laid down internally.
Body Condition Score for Goats
Treatment for Pregnancy Toxemia
Variability in the recovery rate from one study to another with the same treatments, but slightly different protocols and definitions of pregnancy toxemia make it difficult to know what the ideal treatment should be, especially in severe cases. In general, once recumbency occurs the prognosis for recovery is poor. For this reason the focus should be on preventing the disease, and
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