Metritis is a common uterine infection affecting cattle, characterized by acute inflammation of the uterus. It typically develops shortly after a cow gives birth, making the postpartum period highly vulnerable. The disease reduces milk yield and impairs reproductive performance. Because metritis occurs during the transition phase into lactation, early detection and management are paramount to mitigating long-term economic consequences.
Understanding Metritis: Definition and Types
Metritis is an inflammation affecting all layers of the uterine wall: the inner lining (endometrium), the muscular layer (myometrium), and the outer surface (serosa). This distinguishes it from endometritis, where inflammation is limited only to the uterine lining. The severity and timing of the infection categorize metritis into two primary types.
Puerperal Metritis, also known as acute metritis, is the most severe form and manifests within the first ten days following calving. This type involves a deep bacterial infection that often leads to systemic illness, causing the cow to become physically sick. Clinical Metritis occurs up to 21 days postpartum and is primarily characterized by uterine discharge without severe systemic signs of illness. This classification guides the appropriate level of intervention required.
Recognizing the Clinical Signs
The most recognizable sign of metritis is an abnormal uterine discharge that may appear watery and reddish-brown. This discharge often has a foul or fetid odor. In cases of Puerperal Metritis, these localized signs are accompanied by clear indicators of systemic disease.
A cow with severe metritis exhibits a fever, with a body temperature exceeding 39.5°C (103.1°F). Systemic illness also manifests as depression, lethargy, and a noticeable reduction in appetite and milk production. Conversely, a cow with Clinical Metritis primarily shows the characteristic uterine discharge, but without severe systemic indicators like high fever or depression. Recognizing this distinction is important because the presence or absence of systemic signs dictates the urgency and nature of the required medical treatment.
Primary Causes and Risk Factors
Metritis is fundamentally a bacterial disease resulting from uterine contamination following the birthing process. While bacterial contamination occurs in nearly all cows postpartum, metritis development depends on the cow’s immune response and the proliferation of specific bacteria. The uterine microbiome of affected cows shifts, favoring a high abundance of bacteria like Fusobacterium and Bacteroidetes.
The single greatest risk factor is a Retained Placenta, where the fetal membranes fail to be expelled within 12 to 24 hours after calving. Dystocia, or difficult/assisted calving, also significantly increases risk due to potential physical trauma and the introduction of environmental pathogens.
Predisposing factors relate to the cow’s metabolic health during the transition period. Cows experiencing a negative energy balance or low dry matter intake (DMI) before calving are more susceptible because their immune function is compromised. Subclinical hypocalcemia is also a risk factor because calcium is necessary for effective uterine muscle contractions that help clear the uterus of fluid and bacteria. Furthermore, an unsanitary calving environment, such as a dirty or wet maternity pen, directly increases the bacterial load to which the cow is exposed.
Treatment Protocols and Management
The goal of metritis treatment is to clear the infection and resolve the inflammation. For severe cases of Puerperal Metritis involving systemic illness, immediate intervention with systemic antibiotics is the standard approach. Broad-spectrum antibiotics, such as ceftiofur, are often administered by injection to reach therapeutic concentrations.
In addition to antibiotics, supportive care is necessary. This often includes the administration of non-steroidal anti-inflammatory drugs (NSAIDs), such as flunixin meglumine, to reduce fever and alleviate pain and inflammation. Cows that are dehydrated or unable to eat may also require fluid therapy and nutritional support to maintain metabolic stability.
For less severe cases of Clinical Metritis, the treatment focus shifts to promoting uterine clearance. Veterinarians may use hormonal therapy, such as an injection of Prostaglandin F2\(\alpha\) (PGF2\(\alpha\)), after the initial inflammatory period subsides. This hormone stimulates strong uterine contractions, aiding in the expulsion of infectious fluid and tissue from the reproductive tract. Modern veterinary practice generally discourages the direct infusion of antibiotics into the uterus due to concerns about introducing new bacteria, causing tissue irritation, and limited effectiveness compared to systemic treatment.
Prevention Strategies for Herd Health
Proactive management practices focused on the transition period are the most effective way to reduce metritis incidence. Maintaining a clean, dry, and well-bedded calving area minimizes the cow’s exposure to environmental bacteria during birth. Minimizing difficult births through careful sire selection and appropriate calving assistance protocols also lowers the risk associated with reproductive tract trauma and contamination.
Nutritional management plays a role in immune function. Ensuring cows maintain adequate dry matter intake and receive proper mineral supplementation, particularly calcium, helps prevent metabolic disorders like hypocalcemia. Implementing a daily monitoring program for all fresh cows for the first two weeks postpartum allows for the earliest possible detection of fever and abnormal discharge, enabling prompt veterinary intervention.