Milk Fever in Dairy Cows
Understanding Milk Fever (Hypocalcemia)
Milk fever, also known as hypocalcemia or parturient paresis, is a common metabolic disease affecting dairy cows. It occurs when there’s a sudden decrease in serum calcium levels, typically around calving. This condition affects 5-10% of dairy cows annually, making it a significant concern for farmers. Milk fever can lead to a cow being down around calving time. It is essential to distinguish it from other diseases through thorough examination.
What Causes Milk Fever?
Milk fever happens because of a huge increase in the demand for calcium for colostrum production around calving. Cows with milk fever can’t mobilize calcium from their bones or increase absorption from their gut quickly enough. This means the cow can’t perform normal functions involving calcium, like muscle contraction.
Risk Factors for Milk Fever
Several factors can increase a cow’s risk of developing milk fever:
- Age: Cows in their third lactation or more are more susceptible.
- Breed: Certain breeds, like Jerseys, are at higher risk.
- History: Cows with a previous history of milk fever are more likely to develop it again.
- Diet: A high calcium diet during the dry period can increase the risk.
- Other factors: Low magnesium in the diet, being overweight, and stress at calving can also contribute.
Clinical Signs of Milk Fever
The clinical signs of milk fever can be divided into three stages:
- Stage 1: Cows may refuse concentrates, show aggression or apprehension, and have ataxia (incoordination), tremors, and bloat.
- Stage 2: Cows are unable to stand but can maintain sternal recumbency (lying on their chest). They may also have a full udder, a rectum distended with feces, and a dry muzzle.
- Stage 3: Cows are in lateral recumbency (lying on their side), have bloat, reduced temperature, and decreased respiratory and heart rates.
It’s crucial to treat milk fever as an emergency. The prognosis is good if treated within 6 hours.
Subclinical Milk Fever
Subclinical milk fever is more common than clinical milk fever. Cows with subclinical milk fever don’t show obvious clinical symptoms. The only way to detect it is by analyzing blood for calcium concentration within the first one to two days after calving. Subclinical hypocalcemia can lead to reduced efficiency and increased susceptibility to other diseases. According to the University of Minnesota Extension, subclinical cases can affect as many as 73 percent of animals of third and greater lactation.
How to Treat Milk Fever
The primary treatment for milk fever is intravenous calcium administration1.
- Intravenous Calcium: Calcium is administered slowly into the jugular vein to avoid cardiac arrhythmias. If arrhythmias occur, stop administration and give calcium at a lower rate.
- Subcutaneous Calcium: In less severe cases, subcutaneous calcium can be given.
- Oral Calcium: Oral calcium supplements can be useful in mild cases.
Recovery is usually rapid. The heart rate falls, the cow tries to stand, and looks brighter1. If the cow doesn’t respond to treatment, look for another cause or secondary muscle ischemia.
Preventing Milk Fever
Preventing milk fever involves proper management and nutrition4.
- Dry Period Nutrition: Provide a low calcium diet during the dry period. Dietary Cation Anion Balance (DCAB) acidifies the diet.
- Calcium Boluses: Administer calcium boluses like Bovikalc at the first signs of calving and after calving.
- Maintain Body Condition: Keep dry cows at a body condition score of 2.5-3.
- Ensure Adequate Water Intake: Providing dry cows with enough clean water is very important if you want them to consume enough dry matter.
Risks and Costs of Milk Fever
Milk fever can lead to other health issues:
- Dystocia (difficult calving)
- Uterine prolapse
- Retained placenta
- Mastitis
- Displaced abomasum
Subclinical hypocalcemia can result in decreased milk production, decreased immune function, increased risk of ketosis, decreased reproductive performance, and increased risk of early removal from the herd. According to the University of Minnesota Extension, the cost of direct and indirect effects of hypocalcemia on animal health and production can be substantial in a 250-cow herd.
Milk Fever and Seizures
In a study of 43 cattle with seizure disorders, hypocalcemia was identified as a definitive cause of reactive seizures [cite relevant search result if available]. Reactive seizures occur due to metabolic or toxic disorders.
Differential Diagnoses
When diagnosing milk fever, it’s essential to consider other conditions that may present similar symptoms2:
- Toxic mastitis
- Toxic metritis
- Traumatic injury
- Calving paralysis syndrome
The Importance of Early Detection
Early detection and treatment of milk fever are crucial for a successful outcome. Regularly monitor cows for clinical signs and consider blood testing for subclinical cases. Implement preventive strategies to minimize the risk of milk fever in your herd.
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