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Updated: Jul 3, 2026
Bovine Mammary Gland Biopsy Techniques
Published on: December 23, 2018
Effects of experimental challenge of ewes with Mannheimia haemolytica on subsequent milk composition
Ilectra A Fragkou1, Nikos Solomakos, Mark P Dagleish
1Veterinary Faculty, University of Thessaly, Karditsa, Greece.
Abstract:
The objective was to describe the physicochemical changes during the early phase of subclinical mastitis and to associate them with pathological findings. A Mannheimia haemolytica strain was deposited into one teat duct of 25 ewes and the clinical, bacteriological, cytological, physicochemical (pH, milk composition), gross-pathological and histological findings were subsequently recorded. The organism was consistently isolated from samples of teat duct material (140/150) but not from mammary secretion (50/150). California Mastitis Test (CMT) scores increased (>1) and remained high (143/150 samples) after challenge; polymorphonuclear neutrophils (PMN) predominated in milk films, but the proportion of lymphocytes and macrophages progressively increased. Increased pH values (>7.0) were recorded in the mammary secretion from the challenged side. Furthermore, content of fat, total proteins and lactose therein decreased markedly. Histological changes (leucocytic infiltration, destruction of epithelial cells) were observed in the mammary parenchyma of the ewes. The present results confirm that the reduction of milk constituents is the effect of cellular damage and can occur soon after infection.
Insights
Early subclinical mastitis in ewes causes significant physicochemical changes in milk, including increased pH and reduced fat, protein, and lactose. These changes correlate with cellular damage and inflammation in the mammary gland.
Area of Science:
- Veterinary Medicine
- Animal Science
- Pathology
Background:
- Subclinical mastitis is a prevalent issue in dairy animals, impacting milk quality and production.
- Understanding early pathological and physicochemical changes is crucial for timely intervention.
Purpose of the Study:
- To characterize early physicochemical alterations in subclinical mastitis.
- To correlate these changes with pathological findings in ewes.
Main Methods:
- Experimental induction of subclinical mastitis using Mannheimia haemolytica in ewes.
- Monitoring of clinical, bacteriological, cytological, physicochemical (pH, milk composition), gross-pathological, and histological parameters.
Main Results:
- Mannheimia haemolytica was isolated from teat ducts but not mammary secretions.
- California Mastitis Test (CMT) scores increased, with polymorphonuclear neutrophils (PMN) and lymphocytes dominating milk cytology.
- Mammary secretions showed increased pH and decreased fat, protein, and lactose content.
- Histological examination revealed leucocytic infiltration and epithelial cell damage.
Conclusions:
- Early subclinical mastitis induces significant physicochemical changes in milk.
- Reduced milk constituents are a direct result of cellular damage following infection.
- These findings highlight the rapid onset of pathological changes in early mastitis.
