Clinical and Subclinical Mastitis in Goats: Recognition, Etiology, and Clinical Significance

Goat farming plays an important role in rural livelihoods due to its economic resilience, low initial investment requirements, and adaptability to challenging environmental conditions. With goats contributing significantly to global milk production, maintaining udder health is essential for sustainable dairy goat production. Among the major health challenges affecting dairy goats, mastitis remains a critical concern because of its impact on milk yield, milk quality, animal welfare, and farm profitability^1,2. 

Mastitis is an inflammatory condition of the mammary gland, primarily associated with infectious agents, although noninfectious factors can also contribute to its development. The condition damages milk-secreting tissues, alters mammary gland function, and disrupts normal milk production^3,4,5,6. For veterinarians working with dairy goat herds, early recognition of mastitis type, understanding the underlying causes, and implementing appropriate herd-level management strategies are essential for reducing production losses. 

Understanding Clinical Mastitis in Goats 

Clinical mastitis (CM) is the visible form of mammary gland inflammation and is characterized by noticeable changes in the udder and milk. Affected goats may present with udder swelling, increased local temperature, discoloration, pain on palpation, and systemic signs such as fever⁷. Milk abnormalities, including clots, altered colour, unpleasant appearance, and reduced yield, are important indicators during clinical examination^6,8. 

In field conditions, veterinarians should also consider behavioural changes associated with udder discomfort. Goats affected with clinical mastitis may show lameness, altered gait, reluctance to allow milking, or refusal to allow kids to suckle. Severe cases may progress to gangrenous mastitis, septicemia, or death if not managed promptly⁹. 

Although clinical mastitis occurs sporadically, it can have serious consequences. Reported annual incidence rates remain below 5% in several regions, including Algeria (3.55%), Brazil (2.78%), and Indonesia (1.82%)^10,11,12. Despite its lower occurrence compared with subclinical mastitis, the severity of clinical cases makes early veterinary intervention important. 

Subclinical Mastitis: The Hidden Challenge 

Subclinical mastitis (SCM) represents a greater challenge because affected goats often show no obvious udder abnormalities or visible changes in milk. Detection depends on diagnostic evaluation rather than clinical observation alone. This form accounts for approximately 30–50% of mastitis cases in goats and can silently spread within herds, contributing to persistent intramammary infections¹. 

Somatic cell count (SCC) is commonly used as an indicator of mammary gland inflammation. A milk SCC exceeding 1 × 10⁶ cells/ml is often considered suggestive of intramammary inflammation; however, interpretation in goats requires caution because healthy goats may naturally have higher SCC values compared with cattle¹. 

From a clinical management perspective, SCM deserves attention because unnoticed infections can gradually reduce milk production, affect milk quality, and increase the risk of progression to clinical disease. Regular herd monitoring and appropriate diagnostic approaches are therefore important components of preventive udder health programs. 

Etiology and Pathogenesis of Goat Mastitis 

Mastitis develops through interactions between the pathogen, host, and environment¹. Infectious organisms must enter through the teat canal and overcome natural protective barriers, including keratin and glandular lining cells. Once pathogens attach to mammary gland cells, they can multiply and initiate an inflammatory response¹. 

The immune response involves increased permeability of the blood-milk barrier, allowing immune cells such as neutrophils and lymphocytes, along with antibodies and inflammatory mediators, to enter the milk. This process contributes to characteristic signs such as swelling, heat, redness, and pain¹³. 

However, some pathogens can evade immune responses through mechanisms such as biofilm formation. Biofilms create protective structures around bacterial cells, making them more resistant to antimicrobial action and immune clearance^14,15. This can contribute to persistent infections and recurrent mastitis cases. 

Practical Clinical Insights 

• Differentiate clinical and subclinical mastitis during herd evaluation, as both forms require different monitoring approaches. 

• Do not rely only on visible udder abnormalities; apparently healthy goats may harbour subclinical infections. 

• Consider pathogen involvement, herd conditions, and management practices together when assessing mastitis cases. 

• Persistent or recurrent infections require evaluation of possible bacterial resistance mechanisms, including biofilm-associated infections. 

Conclusion 

Clinical and subclinical mastitis represent important threats to dairy goat production. While clinical mastitis demands immediate attention due to visible inflammation and potential systemic complications, subclinical mastitis requires consistent monitoring because of its hidden impact on milk production and herd health. A practical understanding of disease presentation, pathogenesis, and contributing factors enables veterinarians to develop effective mastitis management strategies and support better animal welfare and farm productivity. 

References 

1. Tibebu A, Teshome Y, Tamrat H, Bahiru A. Mastitis in goat: A review of etiology, epidemiology, economic impact, and public health concerns. One Health. 2025 Dec 1;21:101131. https://www.sciencedirect.com/science/article/pii/S2352771425001673 

2. Yuan YG, Peng QL, Gurunathan S. Effects of silver nanoparticles on multiple drug-resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa from mastitis-infected goats: an alternative approach for antimicrobial therapy. International journal of molecular sciences. 2017 Mar 6;18(3):569. https://www.mdpi.com/1422-0067/18/3/569 

3. Farkašová Z, Zigo F, Halás Š, Záhumenská J, Pecka-Kiełb E, Vargová M. Cultivation tests for rapid detection of mastitis pathogens in dairy cows. Acta Veterinaria Brno. 2025 Feb 6;93(11):37-45. https://actavet.vfu.cz/media/pdf/actavet_2024093110037.pdf 

4. Fthenakis GC. Correspondence of somatic cell counts in bulk-tank milk to prevalence of subclinical mastitis in sheep flocks. Animals. 2023 Nov 16;13(22):3541. https://www.mdpi.com/2076-2615/13/22/3541 

5. Michael CK, Lianou DT, Tsilipounidaki K, Florou Z, Vasileiou NG, Mavrogianni VS, Petinaki E, Fthenakis GC. Longitudinal study of antibiotic resistance of Staphylococci from cases of subclinical mastitis in sheep in Greece: Incidence and risk factors. Antibiotics. 2023 Dec 7;12(12):1703. https://www.mdpi.com/2079-6382/12/12/1703 

6. Yan Y, Zhu K, Liu H, Fan M, Zhao X, Pan M, Ma B, Wei Q. The relationship between mastitis and antimicrobial peptide S100A7 expression in dairy goats. Veterinary Sciences. 2023 Nov 14;10(11):653. https://www.mdpi.com/2306-7381/10/11/653 

7. Balemi A, Gumi B, Amenu K, Girma S, Gebru MU, Tekle M, Ríus AA, D’Souza DH, Agga GE, Kerro Dego O. Prevalence of mastitis and antibiotic resistance of bacterial isolates from CMT positive milk samples obtained from dairy cows, camels, and goats in two pastoral districts in Southern Ethiopia. Animals. 2021 May 24;11(6):1530. https://www.mdpi.com/2076-2615/11/6/1530 

8. Danmallam FA, Pimenov NV. Study on prevalence, clinical presentation, and associated bacterial pathogens of goat mastitis in Bauchi, Plateau, and Edo states, Nigeria. Veterinary World. 2019 May 7;12(5):638. https://pmc.ncbi.nlm.nih.gov/articles/PMC6584850/pdf/Vetworld-12-638.pdf 

9. Rainard P, Gitton C, Chaumeil T, Fassier T, Huau C, Riou M, Tosser-Klopp G, Krupova Z, Chaize A, Gilbert FB, Rupp R. Host factors determine the evolution of infection with Staphylococcus aureus to gangrenous mastitis in goats. Veterinary research. 2018 Jul 25;49(1):72. https://link.springer.com/content/pdf/10.1186/s13567-018-0564-4.pdf 

10. Gabli Z, Djerrou Z, Bensalem M. Prevalence of mastitis in dairy goat farms in Eastern Algeria. Veterinary world. 2019 Oct 15;12(10):1563. https://pmc.ncbi.nlm.nih.gov/articles/PMC6868258/pdf/Vetworld-12-1563.pdf 

11. Lima MC, Souza MC, Espeschit IF, Maciel PA, Sousa JE, Moraes GF, Ribeiro Filho JD, Moreira MA. Mastitis in dairy goats from the state of Minas Gerais, Brazil: profiles of farms, risk factors and characterization of bacteria. Pesquisa Veterinária Brasileira. 2018 Sep;38(09):1742-51. https://www.scielo.br/j/pvb/a/hPHrPjQkZFcyyLfqR9x36sk/?format=pdf&lang=en 

12. Suwito W, Nugroho WS, Adji RS, Andriani A, Kusumaningtyas E, Martini T. Phenotypic characteristic of Staphylococcus aureus from subclinical mastitis in Etawah-crossbreed goats in Yogyakarta, Indonesia. Veterinary world. 2022 Nov 15;15(11):2587. https://pmc.ncbi.nlm.nih.gov/articles/PMC9798069/pdf/Vetworld-15-2587.pdf 

13. Acosta AC, Oliveira PR, Albuquerque L, Silva IF, Medeiros ES, Costa MM, Pinheiro JW, Mota RA. Frequency of Staphylococcus aureus virulence genes in milk of cows and goats with mastitis. Pesquisa Veterinária Brasileira. 2018 Nov;38(11):2029-36. https://www.scielo.br/j/pvb/a/gLnj7HDfvx9LRdhrQtgKbBv/?format=pdf&lang=en 

14. Helgadóttir S, Pandit S, Mokkapati VR, Westerlund F, Apell P, Mijakovic I. Vitamin C pretreatment enhances the antibacterial effect of cold atmospheric plasma. Frontiers in cellular and infection microbiology. 2017 Feb 22;7:43. https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00043/pdf 

15. Li XH, Lee JH. Antibiofilm agents: A new perspective for antimicrobial strategy. Journal of Microbiology. 2017 Oct;55(10):753-66. https://jmicrobiol.or.kr/upload/pdf/jm-55-10-753.pdf