Type I vs Type II Ketosis in Dairy Cows: Recognizing the Metabolic Differences

A cow with elevated BHB does not necessarily have the same metabolic problem as another cow with a similar result. When should ketosis be viewed primarily as an energy deficit, and when does hepatic fat accumulation become the bigger concern? 

The timing of ketosis after calving and the accompanying metabolic profile can help distinguish Type I from Type II ketosis—two forms that share hyperketonemia but arise through different metabolic routes. 

Type I: The Classic Energy-Deficit Pattern 

Type I, or nutritional, ketosis typically develops 2–6 weeks postpartum, when milk production peaks and energy demand rises sharply. During early lactation, increasing milk synthesis can outpace dietary energy intake, producing negative energy balance (NEB)^[1]. 

To compensate, the cow mobilizes adipose reserves. Hormone-sensitive lipase and adipose triglyceride lipase release non-esterified fatty acids (NEFAs), which are transported to the liver. When NEFA influx exceeds hepatic oxidative capacity, incomplete fatty acid oxidation contributes to ketone body production^[2],[3]. 

The metabolic pattern is characterized by: 

• Markedly elevated BHB and NEFA 
• Hypoglycemia 
• Insufficient hepatic gluconeogenesis^[1] 

For a cow presenting several weeks into lactation, particularly when the clinical picture includes reduced feed intake, weight loss or declining milk yield, this timing and metabolic profile support the Type I pattern. 

Type II: An Early Postpartum Liver-Associated Pattern 

Type II ketosis follows a different trajectory. It generally occurs within the first 1–2 weeks postpartum and is associated with excessive hepatic fat accumulation and impaired liver function. 

The distinction becomes particularly important when interpreting glucose status. Type II cows can have elevated BHB and NEFA, but severe hypoglycemia is not typical. Instead, they may exhibit hyperinsulinemia, impaired insulin signaling, and even hyperglycemia, reflecting systemic insulin resistance. 

Why does the liver become so important here? Excessive NEFA delivery to the liver can overwhelm its ability to oxidize fatty acids and export triglycerides as very-low-density lipoproteins (VLDL). The resulting lipid accumulation contributes to fatty liver and hepatic dysfunction^[3]. 

The Clinical Contrast^[3] 

The simplest way to frame the distinction is: 

Type I: 

Later postpartum → marked energy deficit → inadequate hepatic gluconeogenesis → hypoglycemia. 

Type II: 

Very early postpartum → excessive hepatic fat accumulation → impaired liver function → altered insulin and glucose regulation. 

Both can produce elevated BHB and NEFA, so these markers alone do not establish the type of ketosis. The postpartum timeline and accompanying glucose-metabolic pattern provide important context. 

What Should the Veterinarian Look For?^[3] 

When evaluating a ketotic cow, consider the metabolic pattern rather than treating the BHB result in isolation. 

First, check the timing. A case developing 2–6 weeks after calving fits the typical Type I window, whereas ketosis during the first 1–2 weeks raises consideration of Type II. 

Next, consider glucose status. Hypoglycemia is characteristic of Type I, while Type II may occur alongside insulin resistance or hyperglycemia. 

Finally, consider the metabolic setting. Type I is primarily driven by NEB during early lactation, whereas Type II is more closely linked to hepatic fat accumulation and impaired liver function. 

Clinical Bottom Line 

Type I and Type II ketosis should not be viewed as interchangeable forms of the same metabolic disturbance. Type I is primarily associated with the energy deficit of peak lactation, while Type II is associated with early postpartum hepatic fat accumulation and altered glucose-insulin regulation. Interpreting BHB and NEFA alongside postpartum timing and glucose status can provide a more clinically meaningful picture of the underlying metabolic problem.

References:

1. Shen L, Zhu Y, Xiao J, Qian B, You L, Zhang Y, Yu S, Zong X, Cao S. Serum adipokines play different roles in type I and II ketosis. Asian-Australasian Journal of Animal Sciences. 2019 Dec 24;33(12):1930. https://pmc.ncbi.nlm.nih.gov/articles/PMC7649395/pdf/ajas-19-0728.pdf
2. Wu ZL, Chen SY, Hu S, Jia X, Wang J, Lai SJ. Metabolomic and proteomic profiles associated with ketosis in dairy cows. Frontiers in Genetics. 2020 Dec 16;11:551587. https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2020.551587/pdf
3. Zhang Y, Wang C, Khan MZ, Ju Z, Huang J. Current Understanding of Bovine Ketosis: From Molecular Basis to Farm-Level Management. Animals. 2025 Dec 18;15(24):3644. https://www.mdpi.com/2076-2615/15/24/3644