Illustration of a healthy sheep being examined by a veterinarian, representing mastitis prevention through vaccination.

Sheep Mastitis: Is a New Vaccine the Answer to a Common Problem?

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Discover how a commercially available vaccine could revolutionize the fight against mastitis in sheep, improving cure rates and potentially reducing the need for antibiotics."

Mastitis, a persistent challenge in the dairy industry, affects sheep and other livestock worldwide. This costly disease leads to significant economic losses and often involves chemical and physical abnormalities in milk. While advancements in prevention and treatment have been made, mastitis remains a major concern. This article dives into the latest research on a commercially available vaccine and how it can potentially revolutionize the fight against this common ailment.

Subclinical mastitis, often detected through somatic cell counts (SCC) and California Mastitis Tests, is a prevalent form of the disease. The gold standard for diagnosis includes isolating and identifying the causative agent through culture. Traditional approaches have limitations, and the need for more effective and sustainable solutions is paramount.

This study investigates the effects of a commercially available polyvalent mastitis vaccine on ewes affected by subclinical mastitis. The research explores how this vaccine impacts bacteriological cure rates and milk composition, offering a new perspective on managing and preventing this critical disease in sheep.

Can Vaccination Significantly Improve Cure Rates and Reduce Antibiotic Use in Sheep?

Illustration of a healthy sheep being examined by a veterinarian, representing mastitis prevention through vaccination.

The study, conducted on 164 lactating ewes, divided them into normal and subclinical mastitis groups. Each group was further split into vaccinated and non-vaccinated subgroups. The vaccine, administered according to manufacturer recommendations, targeted common mastitis-causing pathogens like Streptococcus agalactiae and Staphylococcus aureus.

The results showed that the bacteriological cure rate in the vaccinated group was 76%, compared to 69% in the non-vaccinated group. Vaccination of normal ewes resulted in a significant reduction in bacterial growth at days 28 and 42. The new intramammary infection rates in the vaccinated normal ewes were 19% and 20% respectively, while in the vaccinated group the rate was 33% and 30%.

The bacteriological cure rates were notably higher in vaccinated ewes.
Vaccination of normal ewes showed significant benefits, reducing bacterial growth and new infections.
No significant adverse effects were observed during the study.
The potential for a more sustainable approach to mastitis management is highlighted.

These findings suggest that the vaccine offers a protective effect, particularly in normal ewes. While there was no significant effect on milk composition parameters, the study indicates that the vaccine could play a crucial role in the prevention and treatment of mastitis in sheep, potentially reducing the need for antibiotics and improving overall flock health.

The Future of Sheep Mastitis Management

This preliminary study highlights the potential of vaccination in managing sheep mastitis. Further research, particularly case-controlled studies, is needed to fully understand the extent of immunity provided by the vaccine. This approach could lead to a more sustainable and effective strategy for controlling mastitis, reducing economic losses, and promoting the well-being of sheep.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.14202/vetworld.2018.125-129, Alternate LINK

Title: Bacteriological Cure Rate And Changes In Milk Composition In Mastitis Vaccinated Ewes Affected With Subclinical Mastitis

Subject: General Veterinary

Journal: Veterinary World

Publisher: Veterinary World

Authors: Myassar O. Alekish, Z. Bani Ismail, H. M. Hammouri, M. H. Daradka, S. Al Taha, I. Olymat

Published: 2018-02-01

Everything You Need To Know

What is mastitis and why is it a concern for sheep farmers?

Mastitis is a common and costly disease affecting sheep and other livestock, leading to economic losses and abnormalities in milk. Subclinical mastitis, often detected through Somatic Cell Counts (SCC) and California Mastitis Tests, is a prevalent form. Traditional treatments have limitations, making more effective and sustainable solutions necessary to reduce the impact on flock health and productivity. Identifying the causative agent through culture remains the gold standard for diagnosis.

How does the commercially available polyvalent mastitis vaccine impact cure rates in ewes with subclinical mastitis?

The commercially available polyvalent mastitis vaccine has shown promise in improving bacteriological cure rates in ewes affected by subclinical mastitis. A study showed a 76% cure rate in the vaccinated group compared to 69% in the non-vaccinated group. This suggests that the vaccine can aid in managing and preventing the disease, particularly when used preventatively in normal ewes. The vaccine targets common mastitis-causing pathogens like Streptococcus agalactiae and Staphylococcus aureus.

What are the benefits of vaccinating normal ewes against mastitis?

Vaccinating normal ewes can lead to significant benefits, including a reduction in bacterial growth and new intramammary infections. The study indicated that new intramammary infection rates in vaccinated normal ewes were 19% and 20% at days 28 and 42, respectively, compared to 33% and 30% in the non-vaccinated group. This protective effect suggests the vaccine is particularly useful as a preventative measure.

What are the implications of using a vaccine to manage sheep mastitis in terms of antibiotic use and sustainability?

Using a vaccine to manage sheep mastitis offers the potential to reduce the reliance on antibiotics, contributing to a more sustainable approach to disease management. By improving cure rates and preventing new infections, the vaccine can minimize the need for antibiotic treatments, addressing concerns about antimicrobial resistance. This strategy aligns with promoting overall flock health and well-being while reducing economic losses associated with mastitis.

What future research is needed to fully understand the effectiveness of the mastitis vaccine for sheep?

While the study showed promising results, further research, particularly case-controlled studies, is needed to fully understand the extent of immunity provided by the mastitis vaccine. These studies should focus on long-term effects, detailed analysis of milk composition parameters, and the vaccine's efficacy against various strains of mastitis-causing pathogens. Additional research could also explore optimal vaccination strategies and potential synergistic effects with other management practices.