Equine mastitis–a review of 28 cases.
Abstract: Mastitis was diagnosed in 28 mares. Cytological evaluation of milk samples showed large numbers of neutrophils in 72 per cent and bacteria in 33 per cent. Aerobic bacteria were cultured from 71 per cent of samples. Streptococcus zooepidemicus was the most common isolate (37 per cent). Gram-negative species accounted for 42 per cent. Determination of the probability for antimicrobial susceptibility of bacterial isolates from mares with mastitis indicated that a trimethoprim-sulphonamide combination would be active against more than 75 per cent of isolates while penicillin would be active against less than 60 per cent. Systemic antibiotics, frequent milking, hotpacks and/or hydrotherapy and, if possible, infusion of an intramammary antibiotic preparation is recommended for treatment of equine mastitis.
Publication Date: 1989-09-01 PubMed ID: 2776721DOI: 10.1111/j.2042-3306.1989.tb02687.xGoogle Scholar: Lookup
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Summary
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This study investigates the diagnosis and treatment of mastitis in horses. It found that cytological examination of milk samples was effective in identifying infection, with Streptococcus zooepidemicus being the most common bacteria isolated. The study also tested antimicrobial susceptibility and made recommendations for mastitis treatment.
Mastitis Diagnosis in Horses
- The research was conducted on 28 mares diagnosed with mastitis, which is the inflammation of mammary gland in the breast or udder, mostly due to bacterial infection.
- The primary diagnostic tool was cytological evaluation of milk samples. Neutrophils, a type of white blood cell, were found in large numbers in 72% of samples, indicating an infection or inflammation.
- Bacteria, the typical cause of mastitis, were found in 33% of the samples.
- 71% of the samples showed the presence of aerobic bacteria, meaning bacteria that grow in the presence of oxygen. These data suggest that aerobic bacteria could be a significant cause of mastitis in horses.
Bacterial Isolates in Mastitis
- Among the bacteria cultured from the samples, Streptococcus zooepidemicus was the most frequently occurring isolate, found in 37% of samples.
- Gram-negative species, a category of bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation, accounted for 42% of the bacteria found.
Antimicrobial Susceptibility
- The researchers tested the probability of bacterial isolates being susceptible to different antimicrobial agents.
- They determined that a trimethoprim-sulphonamide combination would be active against more than 75% of isolates.
- On the contrary, penicillin was found to be less effective, with less than 60% of isolates showing susceptibility.
Treatment Recommendations
- Based on their findings, the researchers recommended a treatment regimen for equine mastitis.
- Treatment suggestions included the use of systemic antibiotics, frequent milking to relieve pressure, application of hot packs and/or hydrotherapy to soothe the inflamed area, and infusion of an intramammary antibiotic preparation when possible.
Cite This Article
APA
McCue PM, Wilson WD.
(1989).
Equine mastitis–a review of 28 cases.
Equine Vet J, 21(5), 351-353.
https://doi.org/10.1111/j.2042-3306.1989.tb02687.x Publication
Researcher Affiliations
- Veterinary Medical Teaching Hospital, Davis, California.
MeSH Terms
- Animals
- Anti-Bacterial Agents / therapeutic use
- Female
- Horse Diseases / microbiology
- Horse Diseases / therapy
- Horses
- Hydrotherapy / veterinary
- Leukocyte Count
- Mastitis / microbiology
- Mastitis / therapy
- Mastitis / veterinary
- Milk / cytology
- Neutrophils
- Retrospective Studies
- Streptococcal Infections / microbiology
- Streptococcal Infections / therapy
- Streptococcal Infections / veterinary
- Streptococcus / isolation & purification
Citations
This article has been cited 13 times.- Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
- Tyrnenopoulou P, Fthenakis GC. Clinical Aspects of Bacterial Distribution and Antibiotic Resistance in the Reproductive System of Equids. Antibiotics (Basel) 2023 Mar 28;12(4).
- Domańska D, Trela M, Pawliński B, Podeszewski B, Domino M. The Indicators of Clinical and Subclinical Mastitis in Equine Milk. Animals (Basel) 2022 Feb 11;12(4).
- Podico G, Gray SM, Wang L, Canisso IF. A novel Streptococcus species causing clinical mastitis in a pregnant donkey. J Vet Diagn Invest 2021 Sep;33(5):979-983.
- Hughes K. Development and Pathology of the Equine Mammary Gland. J Mammary Gland Biol Neoplasia 2021 Jun;26(2):121-134.
- To T. Inappropriate lactation in a 15-year-old thoroughbred mare. Can Vet J 2019 Apr;60(4):430-433.
- Gilday R, Lewis D, Lohmann KL. Mastitis in a neonatal filly. Can Vet J 2015 Jan;56(1):63-5.
- Kinoshita Y, Niwa H, Katayama Y. Development of a loop-mediated isothermal amplification method for detecting Streptococcus equi subsp. zooepidemicus and analysis of its use with three simple methods of extracting DNA from equine respiratory tract specimens. J Vet Med Sci 2014 Sep;76(9):1271-5.
- Tlustá M, Krahulec J, Pepeliaev S, Franke L, Cerný Z, Jílková J. Production of hyaluronic acid by mutant strains of group C Streptococcus. Mol Biotechnol 2013 Jul;54(3):747-55.
- Barlow J. Mastitis therapy and antimicrobial susceptibility: a multispecies review with a focus on antibiotic treatment of mastitis in dairy cattle. J Mammary Gland Biol Neoplasia 2011 Dec;16(4):383-407.
- Krahulec J, Tlustá M, Stuchlík S, Turňa J. Structure of the has operon promoter and the effect of mutations on the has promoter strength in Streptococcus equi subsp. zooepidemicus. Mol Biotechnol 2011 Oct;49(2):166-75.
- Krahulec J, Szemes T, Krahulcová J. Bioinformatics characterization of potential new beta-glucuronidase from Streptococcus equi subsp. zooepidemicus. Mol Biotechnol 2010 Mar;44(3):232-41.
- Las Heras A, Vela AI, Fernández E, Legaz E, Domínguez L, Fernández-Garayzábal JF. Unusual outbreak of clinical mastitis in dairy sheep caused by Streptococcus equi subsp. zooepidemicus. J Clin Microbiol 2002 Mar;40(3):1106-8.
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