Serum Biochemical Changes in Pregnancy Toxemia of Goats: Practical Biomarkers for Diagnosis and Monitoring

Pregnancy toxemia is characterized by profound metabolic disturbances that develop when energy demands during late gestation exceed dietary energy intake. While clinical examination remains essential, serum biochemical and hormonal profiling can provide valuable information regarding disease severity, progression, and recovery. Changes in glucose metabolism, lipid mobilization, electrolyte balance, and endocrine responses collectively reflect the metabolic adaptations occurring during negative energy balance¹. 

Experimental observations from induced pregnancy toxemia demonstrate how these biomarkers evolve from acute disease to chronic illness and subsequently respond following restoration of adequate nutrition, offering useful insights for veterinarians involved in diagnosis and monitoring. 

Glucose and BHBA: Core Indicators of Energy Balance 

Glucose is the primary energy source for maternal tissues and the developing fetus. During the last weeks of gestation, a substantial proportion of circulating glucose is directed toward the fetoplacental unit to meet fetal energy requirements^1,2. 

Under experimentally induced pregnancy toxemia, blood glucose concentrations declined significantly as the disease progressed. Healthy pregnant does maintained an average glucose concentration of 3.21 mmol/L, whereas concentrations decreased to 2.60 mmol/L during acute pregnancy toxemia and 2.49 mmol/L during chronic disease. Following reintroduction of a balanced-energy diet, glucose concentrations improved to 2.98 mmol/L, returning to the normal physiological range for goats. 

In contrast, beta-hydroxybutyrate (BHBA), the principal circulating ketone body, increased progressively with disease severity. Average BHBA concentrations rose from 0.44 mmol/L in healthy animals to 1.39 mmol/L during acute disease and 2.02 mmol/L during chronic pregnancy toxemia before declining during recovery. These findings indicate that declining glucose and increasing BHBA occur simultaneously as negative energy balance worsens¹. 

Free Fatty Acids Reflect Lipid Mobilization¹ 

As glucose availability declines, body fat reserves become an alternative energy source. This metabolic adaptation was reflected by significant increases in circulating free fatty acids (FFA). 

Experimental findings showed FFA concentrations increased from 0.74 mmol/L in healthy does to 1.21 mmol/L during acute disease and 1.51 mmol/L during chronic pregnancy toxemia. Once adequate dietary energy was restored, FFA concentrations declined, indicating reduced reliance on fat mobilization. 

The coordinated changes in glucose, BHBA, and FFA illustrate the progression from negative energy balance to active ketone production and provide complementary information when evaluating suspected pregnancy toxemia. 

Electrolyte Alterations During Disease Progression 

Alongside energy metabolism, several serum electrolytes also changed during pregnancy toxemia. 

Calcium concentrations declined significantly in affected does compared with healthy pregnant animals. Potassium concentrations also decreased during both acute and chronic disease, while sodium showed modest reductions. Chloride concentrations did not differ significantly among the groups. 

These alterations were discussed in relation to the metabolic stress associated with pregnancy toxemia and may contribute to the clinical abnormalities observed during disease progression^1,3. 

Hormonal Responses Mirror Metabolic Stress¹ 

Hormonal profiling further demonstrated the metabolic adaptations accompanying pregnancy toxemia. 

Cortisol concentrations increased markedly in affected animals, rising from 21.44 nmol/L in healthy does to 76.14 nmol/L during acute disease and 102.25 nmol/L during chronic pregnancy toxemia. Following nutritional recovery, cortisol concentrations declined substantially, although they remained above healthy baseline values. 

Conversely, insulin concentrations decreased during disease progression. Healthy does maintained an average insulin concentration of 25.16 μU/mL, while concentrations declined to 18.21 μU/mL during acute pregnancy toxemia and 15.22 μU/mL during chronic disease. Recovery following restoration of adequate nutrition was accompanied by an increase in circulating insulin to 23.19 μU/mL. 

The observed hormonal changes demonstrated a positive association between cortisol, BHBA, and FFA, while glucose and insulin showed an inverse relationship during disease progression. 

Practical Clinical Insights 

For veterinarians managing late-gestation does, serum biochemical profiling can provide valuable support alongside clinical examination. 

Monitoring the following parameters may assist in evaluating disease progression and response to nutritional intervention: 

• Blood glucose 

• Beta-hydroxybutyrate (BHBA) 

• Free fatty acids (FFA) 

• Calcium 

• Potassium 

• Sodium 

• Cortisol 

• Insulin 

Rather than relying on a single biomarker, interpreting these variables collectively offers a more comprehensive picture of the metabolic status of affected animals. Experimental observations also demonstrated that many of these abnormalities improved following restoration of an adequate energy-balanced diet, highlighting their usefulness for monitoring recovery.

References  

1. Affan AA, Salleh A, Zamri-Saad M, Jayanegara A, Hassim HA. Clinical signs and blood variables of pregnancy toxemia goats during late gestation and postpartum. Tropical Animal Science Journal. 2022 Mar 1;45(1):84. https://scholar.archive.org/work/uhh346o6obawzj44aoslhslrpe/access/wayback/https://journal.ipb.ac.id/index.php/tasj/article/download/33113/22964 

2. Moallem U, Rosov A, Honig H, Ofir I, Livshits L, Gootwine E. Molasses-based supplement improved the metabolic status of late-pregnant ewes bearing multiple fetuses. Animal Feed Science and Technology. 2016 Sep 1;219:83-93. https://doi.org/10.1016/j.anifeedsci.2016.06.002 

3. Forslund KB, Ljungvall ÖA, Jones BV. Low cortisol levels in blood from dairy cows with ketosis: a field study. Acta Veterinaria Scandinavica. 2010 May 20;52(1):31. https://link.springer.com/content/pdf/10.1186/1751-0147-52-31.pdf