Healthy sheep grazing in pasture

Sheep Mastitis Vaccine: Does It Really Work?

Rhea Morgan in Health & Wellness December 2025 • 3 min read.

"Uncover the facts about using mastitis vaccines in ewes, including effectiveness, benefits, and what it means for your flock's health and milk quality."

Mastitis is a costly disease for livestock owners, impacting milk quality and overall productivity. While there have been technological advances in mastitis treatment and prevention, it remains a persistent problem causing significant economic losses. The disease leads to physical and chemical milk abnormalities, classified as clinical or subclinical mastitis.

The gold standard for diagnosing both clinical and subclinical mastitis involves isolating and identifying the causative agent through culture. Additional methods, such as the California mastitis test and somatic cell count (SCC), help in detecting subclinical mastitis, providing more comprehensive ways to ensure livestock health.

Decreasing udder exposure to pathogens, while boosting the immune responses of animals, remain key in mastitis control. With the effectiveness of mastitis vaccines using a variety of agents, this study is examining a commercially available vaccine in Awassi sheep. This examines how bacteriological cure rates affect Awassi sheep.

Decoding the Awassi Sheep Mastitis Vaccine Study: What Were the Goals?

The primary goal of the study was to assess the efficacy of a commercially available polyvalent mastitis vaccine on the bacteriological cure rate of existing subclinical mastitis in Awassi sheep. To conduct the study, 164 lactating ewes were divided into two groups based on udder health and milk somatic cell count (SCC):

The researchers then divided each group randomly into treatment groups:

Group 1: Normal (N; n=80)
Group 2: Subclinical mastitis (SC; n=84)
N vaccinated (Nvax; n=38)
N non-vaccinated (Nnvax; n=42)
SC vaccinated (SCvax; n=42)
SC non-vaccinated (SCnvax; n=42)

The vaccine was administered according to the manufacturer’s guidelines, and milk samples were collected aseptically from all ewes before vaccine administration (T0) and again on days 28 (T2) and 42 (T3) of the experiment.

Main Outcomes of the Study

This study provides preliminary evidence of the protective effects of vaccination against mastitis in sheep. Further research, including case-controlled studies, is needed to fully understand the level of immunity the vaccine provides. In conclusion, while this is a preliminary study, it suggests that vaccination could play a role in managing mastitis in sheep. Keep in mind that further research is needed to confirm these findings and determine the vaccine's long-term effectiveness.

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Everything You Need To Know

What is mastitis and why is it a concern for livestock owners?

Mastitis is a costly disease affecting livestock, specifically impacting milk quality and overall productivity. This disease causes significant economic losses due to physical and chemical milk abnormalities, classified as clinical or subclinical. The implications of mastitis include reduced milk yield, treatment costs, and potential animal welfare concerns, making it a critical issue for livestock owners.

How is subclinical mastitis detected in sheep, and what methods are used?

Subclinical mastitis, unlike clinical mastitis, doesn't show obvious signs. It is often detected through methods like the California mastitis test and somatic cell count (SCC). The gold standard for diagnosing both clinical and subclinical mastitis involves isolating and identifying the causative agent through culture. These methods provide a more comprehensive way to ensure livestock health and identify issues before they become severe.

What was the primary goal of the Awassi sheep mastitis vaccine study?

The primary goal of the study was to assess the efficacy of a commercially available polyvalent mastitis vaccine on the bacteriological cure rate of existing subclinical mastitis in Awassi sheep. This involved evaluating how well the vaccine could improve the udder health of ewes experiencing subclinical mastitis. The research aimed to determine if the vaccine could reduce the presence of mastitis-causing bacteria.

Describe the experimental design of the Awassi sheep mastitis vaccine study, including the different groups and procedures.

The study involved 164 lactating ewes divided into two groups based on udder health and milk somatic cell count (SCC). Group 1 consisted of Normal (N; n=80) ewes, while Group 2 included ewes with Subclinical mastitis (SC; n=84). Each group was further divided into vaccinated and non-vaccinated subgroups: N vaccinated (Nvax; n=38), N non-vaccinated (Nnvax; n=42), SC vaccinated (SCvax; n=42), and SC non-vaccinated (SCnvax; n=42). The vaccine was administered according to the manufacturer’s guidelines, and milk samples were collected before vaccination (T0) and on days 28 (T2) and 42 (T3) to assess the vaccine's impact.

What are the main takeaways from the Awassi sheep mastitis vaccine study, and what further research is needed?

The study provides preliminary evidence of the protective effects of vaccination against mastitis in sheep. While the initial findings are promising, further research, including case-controlled studies, is needed to fully understand the level of immunity the vaccine provides and confirm its long-term effectiveness. This preliminary study suggests that vaccination could play a role in managing mastitis in sheep, but more comprehensive studies are crucial.