Histopathological and histochemical study of mastitis in sheep
Iraqi Journal of Veterinary Sciences,
2022, Volume 36, Issue 3, Pages 719-723
AbstractOvine mastitis is considered one of the problems that cause economic losses through its impact on milk production, which is unfit for human consumption. The current study aimed to shed light on mastitis in sheep in different areas of Mosul city. The results of the recent study showed the presence of mammary macroscopic and microscopic changes. Macroscopic changes were represented by the large size of the udder and changes in the color and texture, as well as clarity of sloughing and desquamation of the skin with clear exudation, especially in advanced cases. On the other hand, other samples showed the presence of hard nodules on the udders. In contrast, the histological changes represented by degenerative and necrotic changes 3.5%, and 21.4% of the sample appeared to suffer from liquefactive necrosis and abscesses infiltrated with inflammatory cells, 25% of the samples infected with granulomatous mastitis (nodular mastitis), other models showed that the udder infected with atrophy and metaplasia in the rate of 21%, thickening of the blood vessel wall with clot represented 14.2% and the deposition of calcium salt was 14.2%. The current study concludes that mastitis in sheep is widespread in sheep raised in different areas of Mosul city.
Histopathological and histochemical study of mastitis in sheep
A.M. Rahawi, H.B. Al-Sabaawy and H.Kh. Ismail
Department of Pathology and Poultry Diseases, Faculty of Veterinary, Mosul University Mosul, Iraq
Ovine mastitis is considered one of the problems that cause economic losses through its impact on milk production, which is unfit for human consumption. The current study aimed to shed light on mastitis in sheep in different areas of Mosul city. The results of the recent study showed the presence of mammary macroscopic and microscopic changes. Macroscopic changes were represented by the large size of the udder and changes in the color and texture, as well as clarity of sloughing and desquamation of the skin with clear exudation, especially in advanced cases. On the other hand, other samples showed the presence of hard nodules on the udders. In contrast, the histological changes represented by degenerative and necrotic changes 3.5%, and 21.4% of the sample appeared to suffer from liquefactive necrosis and abscesses infiltrated with inflammatory cells, 25% of the samples infected with granulomatous mastitis (nodular mastitis), other models showed that the udder infected with atrophy and metaplasia in the rate of 21%, thickening of the blood vessel wall with clot represented 14.2% and the deposition of calcium salt was 14.2%. The current study concludes that mastitis in sheep is widespread in sheep raised in different areas of Mosul city.
Keywords: Sheep, Mastitis, Udders, Mosul
دراسة التغیرات المرضیة والکیمیائیة النسجیة لالتهاب الضرع فی الأغنام
أصیل محمد رحاوی، هدیل باسم ذنون و هناء خلیل إسماعیل
فرع الأمراض وأمراض الدواجن، کلیة الطب البیطری، جامعة الموصل، الموصل، العراق
یعتبر التهاب الضرع فی الأغنام من المشاکل التی تسبب خسائر اقتصادیة من خلال تأثیره على إنتاج الحلیب فضلا على تأثیره على نوعیة الحلیب المنتج الذی یکون غیر صالح للاستهلاک البشری. هدفت الدراسة الحالیة إلى تسلیط الضوء على التهاب الضرع فی الأغنام المربأة فی مناطق مختلفة لمدینة الموصل. أظهرت نتائج الدراسة الحالیة وجود تغیرات عیانیة ونسجیة عدیدة تمثلت التغیرات العیانیة بکبر حجم الضرع وتضخمة مع وجود تغیرات فی اللون والملمس فضلا عن وضوح تؤسف وانسلاخ الجلد مع وضوح النضح فیه، وبخاصة فی الحالات المتقدمة بالإصابة، فیما أظهرت عینات أخرى وجود عقیدات صلبة على الضرع. اظهر الفحص النسجی وجود تغیرات نسجیة مختلفة تمثلت بالتغیرات التنکسیة والنخریة والتی مثلت 3.5% من العینات فیما کانت نسبة العینات التی تعانی من النخر الاماعی والخراجات المرتشحة بالخلایا الالتهابیة هی 21.4% وکانت نسبة الالتهاب العقیدی بالضرع 25% فیما أظهرت عینات أخرى إصابة الضرع بالضمور والحؤول وبنسبة 21% کما أظهرت العینات وجود خثرة دمویة مع تثخن جدار الأوعیة الدمویة وبنسبة 14.2% فیما کانت نسبة ترسب أملاح الکالسیوم14.2%. نستنتج من الدراسة الحالیة بان التهاب الضرع فی الأغنام شائع وواسع الانتشار فی الحیوانات وفی مناطق مختلفة من مدینة الموصل.
Mastitis is one of the most severe diseases that affect the industry of dairy animals. It is the primary cause for both low yield and poor quality of milk (1,2). It also has great importance for the dairy industry, particularly in developing countries, because it has high economic and social impacts. Moreover, it leads to premature animal culling and cost of treatment, also has diverse effects on the welfare of affected animals and causes decreased milk production (3), leading to reduced growth rates and increased mortality in lambs (4). Mastitis is a mammary gland parenchyma infection typically caused by bacteria, fungi, and viruses (5) that lead to physical, chemical, and bacteriological milk changes and lead to pathological changes in glandular tissue (6). Mastitis can be divided into two clinical and subclinical mastitis (7,8) clinical mastitis is two types: clinical mastitis characterized by obvious signs of animal disease, such as irregular secretion, hot swollen quarter or whole udder, and ewes may be suffered from rapid plus, loss of appetite, dehydration and depression in severe cases (9) while the subclinical mastitis, which has no visible sign (10,11) but causes an increase in milk somatic cell count and bacteria detection (12) microorganism play critical roles in the incidences of ewes mastitis especially Staphylococcus spp which consider the most causative agent (13).This study amid to determine the effects of mastitis on sheep in a different area of Mosul city.
Materials and method
The experimental work was approved by ethical committee for animal extermination of the veterinary faculty of university of Mosul based on department scientific meeting on December the 15th
Collection of samples
Clinical examination and manual palpation were performed for 100 ewes from Veterinary Teaching Hospital, Wana district, Cockgley district, and Mushairefa district, from March to September 2019. The sample is from ewes suffering from clinical mastitis, representing 28 cases with clear signs of udder abnormalities.
Specimens were taken from diverse parts of the affected udders, fixed in 10% neutral buffer formalin and regularly processed embedded in paraffin wax, sectioned in 5-6 µm thickness stained with Harris’ hematoxylin and eosin stain (14,15,16), Masson’s and Mallory’s trichrome stain methods were used for better clarification of the histopathological lesion.
Prevalence of sheep mastitis
The current work results showed that the prevalence of sheep mastitis was 7% (Table 1).
Table 1: Showed the type of Histopathological lesion, percentage, and the number of infected ewes with mastitis.
% Infected (no)
Liquefactive necrosis and abscess
Atrophy and metaplasia
Thickening of the blood vessels wall
Deposition of calcium salt
The gross examination of clinically affected udders showed changes in the size, shape, color, and texture, including enlargement in one half of the udder or both discolorations, sloughing of skin and exudation, especially in the advanced cases, in some cases, the texture of the udder is soft. It contains fluid, while other infected ewes showed hard nodules (Figure 1).
Microscopic lesions finding
The percentage of the microscopic examination of tissue sections taken from mammary gland infected with mastitis equivalent is 30 % of specimens, which showed distortion in the shape and size of mammary alveoli, vacuolar degeneration with coagulative necrosis, sloughing of epithelial cell lining the mammary alveoli. Also, there is an accumulation of serous, proteinous substances in the lumen of the mammary alveoli; about 15% of collected specimens showed histological changes characterized by a multifocal area of liquefactive necrosis (micro abscess) with infiltration of inflammatory cells. The granulomatous reaction was equivalent to 20% in the alveolar parenchyma, which showed atrophy of alveolar tissue with infiltration of mononuclear inflammatory cells such as macrophage, lymphocytes, plasma cell, fibroblast, and giant cell. Others showed replacement of fibrous tissue instead of alveoli, diffused fibrosis which is equivalent to 20% of the affected cases. Atrophy of the alveoli and metaplasia of the glandular structure of mammary alveoli are equal to 15 %. Additionally, another section showed deposition of calcium salt in the lumen of some mammary alveoli. At the same time, other sections showed thickening in the interstitial tissue due to deposition of collagen fibrous, in addition to thickening of blood vessels wall and thrombus (Figures 2-5).
Figure 1: photograph of sheep udder (A) showed rigidity of udders and contained nodules. (B) pus and swelling of the udders. (C) congestion and hemorrhage inside the tissue.
Figure 2: Micrograph of sheep mammary gland (A) showed coagulative necrosis in acini (H&E, 10 X). (B) sloughing of epithelial cells lining the alveoli with serous fluid (arrow) (H&E, 10X). (C) vacuolar degeneration of epithelial cells (H&E, 10X). (D) accumulation of proteinaceous serous material in the alveoli (H&E, 10X). (E) microabscesses (H&E, 10X).
Figure 3: Micrograph of ewes mammary gland showed (A and B) chronic infiltration of an inflammatory cell (H&E, 10X). (C) infiltration of plasma cells, lymphocytes, and giant cells (H&E, 10X). (D) showed (A) atrophy (arrow)and metaplasia of alveoli epithelium (Blue-arrow) (H&E, 10X) (B) metaplasia (H&E, 10X).
Figure 4: Micrograph of ewes mammary gland showed (A) calcium salt deposition inside the alveoli (H&E, 10 X). (B) deposition of collagen fibrous (H&E, 10X). (C and D) thickening of interstitial tissue due to deposition of collagen fiber (Mallory’s trichrome, 100x)
Figure 5: Micrograph of ewe’s mammary gland showed (A) thickening of blood vessels wall (H&E, 40 X). (B) thrombus (H&E, 100X). (C) diffused fibrosis (H&E, 40). (D and E) Fibrosis (Masson’s trichrome, 100x).
Mastitis is the most economically significant disease of the mammary gland in ewes. These economic losses are associated with direct or indirect factors such as the cost of the treatment of the sick animals, increased mortality rates, reduced milk production, and led excessive culling of the herd (17,18). Management of the pack have been associated with multiple causes that consider as a predisposing factor for ewe’s mastitis like hygiene, the conformation of the udders, healthy animal statues, suckling and prolificacy of the lamb, genetic factor (19) practices of the milk, and food, inadequate nutrition and decreased of vitamins-the causative organism like Strep. Agalactia, S. aureus, E. coli, and staph spp (20) can enter the mammary tissue in an ascending way by papillary ducts or from systemic infection (21,22).
Microscopic examination of the current study revealed acute mastitis in which the affected section showed infiltration of polymorphic nuclear leukocytes, the pathogenic bacteria reach the parenchyma of the mammary gland and access small ducts and alveoli, which then occluded by fibrin, leukocytes, and bacteria (23).
The interaction between milk leukocytes and pathogenic bacteria resulting in the establishment of inflammation (24), then macrophage release chemoattractant that attracted other polymorphonuclear cells from vasculature to the site of infection and accumulated in large numbers around the alveoli, neutrophil emigration occurs through gaps in the lining epithelia, or due to sloughing apart of it this inflammation and emigration of neutrophil are associated with sloughing or damage of the alveoli and epithelial ducts cell (25) these result agreement with (26,27), vacuolar and coagulative necrosis can results from damage of the mammary vasculature after infection with pathogenic bacteria and these result agreement with (28,29). Chronic mastitis pathology showed severe infiltration of mono morphonuclear cells. Giant cells with collagen fiber deposition in mammary gland tissue, transforming growth factor-beta (TGF-B), play a critical role in inducing fibroblast to synthesize collagen (30). These results agree with (31) that these lesions are due to progression of infection with pathogenic bacteria, leading to an increase in the number of macrophages and stimulation of fibroblast activity that resulted in damage of alveolar epithelium decreasing in secretary activity of it. Further, multiplication of connective tissue to the large ductal lumen and glandular intestinal tissues (32), at the last stage of mastitis, there was thickening of the alveolar wall which become cornified and hypertrophied and this agreement with (33,34), who mention similar changes in the mammary gland.
Chronic mastitis can result in squamous metaplasia as a compensatory mechanism of alveolar epithelial loss. These pathological alterations agree with (35), who mentions that metaplasia leads to reducing the function of the cell through changes in the type of cell that give more protection to tissue. Calcium deposition in the mammary gland parenchyma results from Glycoprotein or cellular debris (36,37). Calcium-binding protein may become subsequently binding to such residue. Calcium-binding proteins would build up in this fashion, helping to maintain mineral deposition but not causing calcification. Mineralization is known to be triggered by bacterial infection and cellular debris (38,39,40).
We concluded from our results that ewe’s mastitis could be considered an acute sheep disease that affects the function of udders and mammary glands, leading to loss of animal life. Prevention is necessary as treatment, repetitive monitoring, and periodical exam are recommended for all dairy herds to detect mastitis.
The researcher would thank the College of Veterinary Medicine, the University of Mosul, for supporting this research.
Conflict of interest
The author advertises that there is no collision related to this research.
- The prevalence of sheep mastitis was 7%.
- Mastitis is one of the most severe diseases that affect the industry of dairy animals, causing high economic and social impacts.
- The current study showed the presence of many macroscopic and microscopic changes in the mammary gland.
- Sani RN, Moezifar M. Comparison of seasonal effects on some hematological and biochemical parameters between ewes with subclinical mastitis and healthy ewes. Iraqi J Vet Sci. 2016;30 (1):5-8. DOI: 10.33899.201/ijvs 6.116861
- Mavrogianni VS, Menzies PI, Fragkou IA, Fthenakis GC. Principles of Mastitis Treatment in Sheep and Goats. Vet. Clin .N Am: Food Animal Practice. 2011;27 (1):115–20. DOI: 10.1016/j.cvfa.2010.10.010
- Gonzalo C, Tardáguila JA, De La Fuente LF, San Primitivo F. Effects of selective and complete dry therapy on prevalence of intramammary infection and on milk yield in the subsequent lactation in dairy ewes. J Dairy Res. Cambridge University Press (CUP); 2004;71 (1):33–8.DOI:1017/s002202993006526
- Abdallah ES, Eissa M, Menaze A. The Prevalence and Etiology of Subclinical Mastitis in Sheep and Goats. ZVJ. 2018 ;46 (2):96–104. DOI: 10.21608/zvjz.2018.14381
- Singh A, Chhabra D, Sikrodia R, Shukla S, Sharda R, Audarya S. Isolation of E. coli from Bovine Mastitis and Their Antibiotic Sensitivity Pattern.Int.J.Curr.Microbiol.appl-Sci. 2018 10;7 (10):11–8.DOI: 10.20546/ijcmas.710.002
- Ezzo O, Ahmed Y, Mansour S. Some Udder Problems associated with productivity in Goats. EJVS. 2020;51 (1):1-9. DOI: 10.21608/ejvs.2019.13869.1087
- Makovicky P, Nagy M, Makovick y P. Comparison of external udder measurements of the sheep breeds Improved Valachian, Tsigai, Lacaune and their crosses. Chil. J. Agric. Res.2013;73 (4):366–71.DOI:10.4067/s0718-58392013000400006
- Al-Juboori AA, Kamat NK, Sindhu JI. Prevalence of some mastitis causes in dromedary camels in Abu Dhabi, United Arab Emirates. Iraqi J Vet Sci. 2013;27 (1):9-14. DOI: 10.33899/ijvs.2013.82861 9.Fragkou IA, Boscos CM, Fthenakis GC. Diagnosis of clinical or subclinical mastitis in ewes. Small Rumi. Res. 2014;118 (1-3):86-92. DOI: 10.1016/j.smallrumres.2013.12.015
- Kiossis E, Brozos CN, Petridou E, Boscos C. Program for the control of subclinical mastitis in dairy Chios breed ewes during lactation. Small Rumin Res. 2007;73 (1-3):194–9.DOI:10.1016/j.smallrumres.2007.01.021
10. Sahoo P, Sahoo N, Biswal S. Etiology and Antibiogram of Subclinical Mastitis in Cow of Puri District, India. IJCMAS. 202010;9 (7):374–9.DOI:10.20546/ijcmas.2020.907.040
11. Ryan MK, Whitney C, Stewart J, Bret T, Carl J,Yeoman BB, Chad M, Rowley CM, Lindsey C, Megan L, Van E, Thomas W Murphy. Subclinical mastitis in sheep: etiology and association with milk somatic cell count and ewe productivity in three research flocks in the Western United States. Transl Anim Sci. 2019;3:1739-1743. DOI: 10.1093/tas/txz078
12. Mr MSR, Mr QTA-O, Mr MAH, Mr MAA. Mastitis in mare: case report. Iraqi J Vet Sci .2018;32 (1):109-111. DOI: 10.33899/ijvs.2018.153831
13. Spencer LT, Bancroft JD. Microtomy: Paraffin and frozen. In:Survaran SK, Kayton C, Bancroft ID editors. Bancroft's theory and practice of histological techniques.7th ed. China: Churchill Livingstone.2013;125-127. DOI: 10.1016/b978-0-7020-4226-3.00007-x
14. Vasileiou NGC, Chatzopoulos DC, Sarrou S, Fragkou IA, Katsafadou AI, 2Mavrogianni VS. Role of staphylococci in mastitis in sheep. J Dairy. 2019;86 (3):254-266. DOI: 10.1017/s0022029919000591
15. Suárez-Trujillo A, Capote J, Argüello A, Castro N, Morales-DelaNuez A, Torres A. Effects of breed and milking frequency on udder histological structures in dairy goats. J. Appl Anim. Res. 2013S;41 (2):166–72.DOI:10.1080/09712119.2012.739096
16. Gussmann M, Steeneveld W, Kirkeby C, Hogeveen H, Nielen M, Farre M. Economic and epidemiological impact of different intervention strategies for clinical contagious mastitis. J Dairy Sci. ADSA. 2019;1483-1493. DOI: 10.3168/jds.2018-14939
17. Audarya SD, Chhabra D, Sharda R, Gangil R, Sikrodia R, Jogi J. Epidemiology of Bovine Mastitis and Its Diagnosis, Prevention and Control. Mastitis in Dairy Cattle, Sheep and Goats. 2022.DOI. 10.5772/intechopen.100582
18. Gelasakis AI, Mavrogianni VS, Petridis IG, Vasileiou NGC, Fthenakis GC. Mastitis in sheep - The last 10 years and the future of research. Vet Micro. 2015;181:136-46. DOI: 10.1016/j.vetmic.2015.07.009
19. Abdul-Rahman SY, Sultan K. Effect of vitamin A and grazing in some physiological characters and milk production of Meriz does. Iraqi J Vet Sci. 2019;359-365. DOI: 10.33899/ijvs.2019.163080 21.El-Shymaa A, Abdallah1, Mohamed I, Eissa2 & Afaf M, Menaze2. The Prevalence and Etiology of Subclinical Mastitis in Sheep and Goats .2018; 46 ( 2): 96-104. DOI: 10.21608/zvjz.2018.14381
20. Santos V, Simplício K, Sanchez D, Coutinho L, Teixeira P, Barros F. B-Mode and Doppler Sonography of the Mammary Glands in Dairy Goats for Mastitis Diagnosis. Reproduction in Domestic Animals. 2015 ; 50 (2):251–5.DOI: 10.1111/rda.12479
21. Kotb EZ, Abd El-Fattah EM, Azab FO, Leil AA. Ultrasonography, Histopathological Udder Alterations And Bacteriological Investigations For Diagnosis Of Mastitic Goats. JAVS.2020;5 (2):77-86. DOI: 10.21608/javs.2020.85593
22. Larsgard AG, Vaabenoe A. Genetic and environmental causes of variation in mastitis in sheep.Small.Rumin.Res. Res . 1993;12 (3):339–47. DOI:10.1016/0921-4488 (93)90069-t
23. Sheet OH, Jwher DMt, Al-Sanjary RA, Alajami AD. Direct detection of Staphylococcus aureus in camel milk in the Nineveh governorate by using the PCR technique. Iraqi J Vet Sci.2021; 35 (4): 669-672. DOI: 10.33899/ijvs.2020.127725.1524
24. Almashhadany DA. Diagnosis of brucellosis in sheep and goats raw milk by fast and reliable techniques. Iraqi J Vet Sci. 2021;35 (4): 663-668. DOI: 10.33899/ijvs.2021.127697.1523
25. Jubb K, Kennedy A. Palmer’s pathology of domestic animals. UK: Elsevier; 2007. 179-84 p. DOI: 10.1016/b978-070202823-6.50022-1
26. Santillo MA, Caprese R, Ciliberti AS. Immune competence of the mammary gland as affected by somatic cell and pathogenic bacteria in ewes with subclinical mastitis. J Dairy Sci. 2012; 95, (7):3877-3887. DOI: 10.3168/jds.2012-5357
27. Kerro Dego O, editor. Mastitis in Dairy Cattle, Sheep and Goats. Intech Open; 2022 DOI. 10.5772/intechopen.92965
28. Todhunter DA, Smith KL, Hogan JS. Environmental Streptococcal Intramammary Infections of the Bovine Mammary Gland. J D S. American Dairy Science Association; 1995;78 (11):2366–74.DOI:10.3168/jds.s0022-0302 (95)76864-3
29. Zachary JF. Pathologic Basis of Veterinary Disease. 6th ed lllinois: Elsevier; 2017. 1318 p
30. Stockton JL, Torres AG. Multinucleated Giant Cell Formation as a Portal to Chronic Bacterial Infections. Microorganisms. MDPI AG. 2020;8 (11):1637- 1638. DOI: 10.3390/microorganisms8111637
31. Zeisberg M, Kalluri R. Cellular Mechanisms of tissue fibrosis comman and organ-specific mechanism associated with tissue fibrosis. Am J Physiol Cell Physiol. 2013;304 (3):c216-c225. DOI: 10.1152-ajpcell.00328.2012
32. Roberson JR. Establishing treatment protocols for clinical mastitis. Vet Clin. N.Am.-Food Anim Pract . 2003;19 (1):223–34 .DOI:10.1016/s0749-0720 (02)00071-3
33. Michael A, Stephen C. Nickerson Mastitis and its Impact on Structure and Function in the Ruminant Mammary GlandR., J Mammary Gland Biol Neoplasia. 2011;16 (4):275-89. DOI: 10.1007/s10911-011-9231-3
34. Alawa J, Ngele M, Ogwu D. Chronic caprine mastitis in Nigerian goat breeds. microbiological flora and histopathological findings. Small Rumin Res. 2000;35 (3):203–7. DOI:10.1016/s0921-4488 (99)00099-1
35. GE K. Study on Prevalence of Bovine Subclinical Mastitis and Associated Risk Factors in Smallholder Dairy Farms of Mecha District. Int J Epidomiol. 2020;4 (5).DOI:10.23880/eij-16000161
36. Murawski M, Schwarz T, Jamieson M, Ahmad B, Bartlewski PM. Echotextural characteristics of the mammary gland during early lactation in two breeds of sheep varying in milk yields. Animal Reproduction . 2019;16 (4):853–8. DOI:10.21451/1984-3143-ar2019-0025
37. Mavrogianni VS, Cripps PJ, Papaioannou N, Taitzoglou I, Fthenakis GC. Teat disorders predispose ewes to clinical mastitis after challenge with Mannheimia haemolytica. Vet Res. 2006;37 (1):89–105.DOI:10.1051/vetres:2005042
38. Seegers H, Fourichon C, Beaudeau F. Production effects related to mastitis and mastitis economics in dairy cattle herds. Vet Res . 2003;34 (5):475–91.DOI:10.1051/vetres:2003027
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