PATHOLOGY OF BACILLUS CEREUS MASTITIS

IN DAIRY COWS

B. Schiefer, K. R. Macdonald, G. G. Klavano and A. A. van Dreumel*

Canada, after intramammary treatment with antibiotic preparations, one of them contaminated with B. cereus. A total of over 80 cows and eight dairy herds were affected.

INTRODUCTION Bacillus cereus has been reported as the cause of acute, gangrenous mastitis in a number of cases (Table I). Infections resulted in spon-

death or the need for immediate slaughter of the affected cows. In cases where appropriate treatment was instituted, the life of the cows could be saved, but the affected necrotic quarter(s) became fibrosed, and loss of milk production as well as weight loss rendered the animals uneconomic. The purpose of this publication is to describe the pathology of bovine B. cereus mastitis, which occurred in 1974 in various provinces of

taneous

MATERIALS

AND

METHODS

One whole carcass from a cow which died of acute mastitis was submitted to the Veterinary Services Laboratory at Guelph, Ontario, and one to the Veterinary Services Division, Alberta Agriculture, Edmonton, Alberta. Portions of mammary tissue, supramammary lymph nodes, liver, spleen, and kidney of four cows were submitted as unfixed specimens and fixed in 10% formalin to the Department of Veterinary Pathology, W.C.V.M., Saskatoon, and a similar selection of tissues from five cows was submitted to the Veterinary Laboratory, B.C. Department of Agriculture, Abbotsford, B.C. Trimmed specimens were embedded in paraffin, and 6,u sections were stained with hematoxylin and eosin, the Gram-stain and with the Grocott technique.

*Department of Veterinary Pathology, W.C.V.M., University of Saskatchewan, Saskatoon, Sask. S7N OWO (Schiefer), Veterinary Laboratory, B.C. Department of Agriculture, P.O. Box 100, Abbotsford, B.C. (Macdonald), Alberta Agriculture, Veterinary Services Division, P.O. Box 8070, Edmonton, Alta. T6H 4P2 (Klavano) and Veterinary Services Laboratory, Ministry of Agriculture and Food. Box 3612, Guelph, Ont. NlH 6R8 (van Dreumel).

TABLE I B. cereus MASTITIS (LITERATURE REVIEW)

Number of animals with mastitis

Number of animals dead or slaughtered

Number of animals surviving after treatment*

Unknown

Unknown 0 0

Unknown 2 1 0 0 1 3 0

2 1 1 1 5

8 5

1 1 4 5 5

11

9

2

30

13

17

1

1

0

Possible mode of infection Unknown Teat injury Antibiotic treatment

Teat dilation Teat surgery

(one case) Teat surgery and intramammary

Author(s) 1 3 12 10 11 14 2 5 9

treatment

*Weight loss and loss of milk production has been reported 239

CAN. VET. JOUR., vol. 17, no. 9, September, 1976

Treatment with antibiotic product contaminated with B. cereus Intramammary treatment in most surviving animals.

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4, 8

CANADIAN VETERINARY JOURNAL

Some of the clinical findings and the bacteriological methods, which identified the causative agent as B. cereus are described elsewhere (13). Briefly, some of the affected cows developed acute mastitis within 24 hours after intramammary infusion with a commercial antibiotic product, commonly used for dry cow therapy. Most cows developed acute mastitis shortly after calving and some of those animals had been treated with the same antibiotic at the time of drying up. Gross Findings

The two carcasses were in good flesh, but the blood was watery and had failed to clot. There was marked subcutaneous edema over the udder. On cut surface the affected quarters were diffusely congested and fibrinous material was presented in the ductules. Numerous dark red, well demarcated areas which measured approximately 1.0-10.0 cm in diameter were scattered at random throughout the affected quarters. Within the discolored areas, the interstitial connective tissue septa appeared to be edematous, and lumina of vessels were quite easily recognized. The altered tissue portions had a firm consistency, quite similar to the findings in acute pneumonia with hepatization. The supramammary lymph nodes were markedly enlarged, edematous and gray foci 1.0-5.0 mm in diameter were evident in the cortex. The lungs were moderately edematous and emphysematous. The spleens were approximately twice normal size, dark red and turgid. The kidneys had a brownish discoloration of the cortex. The urinary bladders contained port wine colored urine. Gross lesions in the fixed and fresh tissue submitted to the laboratories were similar to those described for the entire carcasses.

FIGURE 1. Interstitial edema, thrombosis of veins and lymph vessels in a case of acute B. cereus mastitis. H & E. X40.

numbers of polymorphonuclear leukocytes. Within the lactiferous ducts, nuclear detritus and fibrin were found. The necrobiotic process in the alveoli did not extend to the interstitium suggesting that the spead of the disease was mainly via the canaliculi. Gram-stained sections revealed presence of Gram-positive organisms in the necrotic alveoli Histological Findings Selected tissues from the entire carcass and only (Figure 3). The organisms were found in tissues submitted from other carcasses re- large numbers in most of the affected alveoli vealed similar lesions and they are described (Figure 4). High power microscopic examination clearly demonstrated the rod-shaped bactogether. In the mammary glands the interstitial septa teria (Figure 5), and no other bacteria were were found to be edematous and acute throm- seen on Gram-stained sections. The Grocottbosis of veins and lymph vessels was noted stain failed to demonstrate the organisms (Figure 1). In addition to the proteinaceous clearly, and no fungal elements were seen in exudate, numerous erythrocytes were found in such stained sections. Mammary tissue with acute necrosis and the interstitial tissue. The parenchyma showed a peculiar pattern of selectively necrotic al- the heavy growth of Gram-positive organisms, veoli (Figures 1 and 2), characterized by the as described above, did not show any signs of presence of eosinophilic material in the lumen, subacute or chronic mastitis of other etiology necrosis of alveolar cells, and presence of scant or type, whereas portions of grossly normal 240

PATHOLOGY

thrombi. Free hemoglobin was also present in the lumina of many pulmonary vessels. Focal areas of necrosis were evident in some sections of spleen with marked congestion of the red pulp. There was also marked erythrophagocytosis in the red pulp. Based on the histological findings, a diagnosis was made of acute necrotizing mastitis due to Gram-positive bacilli which were identified as B. cereus (13). In addition, death due to toxemia with disseminated intravascular coagulation (DIC) and hemolysis with secondary hemoglobinuria was diagnosed. DISCUSSION

It has been suggested that B. cereus is not a natural pathogen for the bovine udder and that special circumstances must prevail if mastitis is to result from exposure (7). However, there is little doubt that the agent is capable of causing a severe, toxic, moderately febrile, and hemorrhagic mastitis, usually proceeding to gangrene of infected quarters (5, 6, 7).

FIGURE 2. Focal alveolitis and necrosis. Edema of interstitial tissue. H & E. X63. appearing quarters of some animals revealed presence of lesions suggestive of chronic or subacute mastitis of undetermined etiology. There was an acute lymphadenitis in sections of supramammary lymph nodes with focal areas of necrosis in the cortex and large numbers of inflammatory cells, predominantly neutrophils and macrophages in the medullary sinusoids. The liver showed presence of centrolobular hypoxic necrosis. Around the bile ducts, moderate numbers of plasma cells and mastcells were seen. Sections of the renal tissue revealed presence of hemoglobinemic casts in the tubules (Figure 6) with extensive secondary hemoglobinuric nephrosis of proximal convuluted tubules. Hyaline thrombi were evident in capillaries of some glomerular tufts and capillaries at the corticomedullary junction. Sections of lung revealed thickened alveolar septa due to edema and mild mononuclear reaction. The alveolar capillaries were engorged with blood and many had hyaline 241

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FIGURE 3. Presence of clusters of Gram-positive bacteria (black) in necrotic alveoli of mammary gland. Gram-stain. x40.

CANADIAN VETERINARY JOURNAL

SUMMARY

Acute gangrenous mastitis was diagnosed in two dairy cows, which were necropsied, and in nine submissions of selected tissues from animals which died acutely with signs of toxemia. The most outstanding lesion was focal, hemorrhagic necrosis of the mammary glands. Numerous Gram-positive bacteria were identified in histological sections in the areas of necrosis. Further findings were acute lymphadenitis of supramammary lymph nodes, disseminated intravascular coagulation, and hemolysis with secondary hemoglobinuria. Bacillus cereus was isolated from the affected mammary glands. RtSUMi Les auteurs ont diagnostique une mammite gangreneuse aigue chez deux vaches soumises pour necropsie et dans certains tissus de neuf autres vaches mortes rapidement apres avoir manifeste des signes de toxemie. Des foyers

FIGURE 4. Numerous Gram-positive bacteria in the alveoli. Gram-stain. X400.

The lesions found in the mammary glands, and the observed general reaction of the animals affected in the outbreaks described here, are certainly consistent with previously described cases of mastitis due to B. cereus and it is easy to understand why disease caused by this agent has been called pseudoanthrax. B. cereus is more likely to establish residence in normal quarters than in quarters where other infections or inflammatory responses are present (7), and most proved clinical cases appeared either at calving or during the first period of lactation. According to a recent report on experimental B. cereus mastitis (8) severe toxemia may occur within 18 hours postinfection. Despite treatment, which may save the life of the animal, gangrene of affected quarters with necrosis of the skin, followed by fibrous induration, and weight loss, are the sequela observed (3, 7, 8). Serum antibodies have been shown to increase rapidly in the first three weeks postinfection. A sharp decrease in milk serum antibodies six weeks postinfection was accompanied by a color change of the secreted milk from red to amber (8).

FIGURE 5. High-power view of Gram-positive rod-shaped bacteria in one alveolus. Gram-stain.

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PATHOLOGY

REFERENCES

1. BARNUM, D. A. Report of Ontario Veterinary College, p. 19. 1954. 2. BIANCARDI, G. Mastitis acuta bovina da Bacillus cereus. Segnalazione e studio di 8 casi. Arch. vet. ital. 14: 31-45. 1963. 3. BROwN, R. W. and R. K. SCHERER. A report on two cases of acute mastitis caused by Bacillus cereus. Cornell Vet. 47: 226-240. 1957. 4. BuRow, H., C. C. MERCK und U. KURTH. Bacillus cereus als Ursache einer Mastitis beim Rind. II. Mitt. Antibiogramm und Pathogenitiitspriifungen des isolierten Stammes. Zentbl. Vet Med. B 21: 93-99. 1974. 5. GLOOR, H. Die Cereus-Mastitis des Rindes. Schweizer Arch. Tierheilk. 110: 63-80, 1968. 6. HEIDRICH, H. J. and W. RENK. Diseases of the Mammary Glands of Domestic Animals. Philadelphia and London: W. B. Saunders. 1967. pp. 224-225. 7. JASPER, D. E., R. B. BUSHNELL, J. D. DELLINGER and A. M. STANG. Bovine mastitis due to Bacillus cereus. J. Am. vet. med Ass. 160: 750-756. 1972. 8. MERCK, C. C. und H. BUROW. Bacillus cereus als Ursache einer Mastitis beim Rind. I. Mitt. Bericht uber das Auftreten einer B. cereus Mastitis sowie uber Infektionsversuche bei einem Schaf und einer Kuh mit dem isoliertem Stamm. Zentbl. VetMed. B 20: 810-817.

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1973. FIGURE 6. Hemoglobinemic casts in renal

tubules; hyaline thrombi in glomerular capillaries. H & E. x100. de necrose hemorragique au sein des glandes mammaires constituaient la lesion principale. Les coupes histologiques de ces foyers necrotiques recelaient un grand nombre de microbes Gram positifs. Les autres lesions comprenaient: une lymphadenite aigue des ganglions retro-mammaires, de la coagulation intra-vasculaire disseminee et de l'hemolyse accompagnee d'hemoglobinurie secondaire. Les auteurs isolerent aussi Bacillus cereus des glandes mammaires atteintes de mammite.

9. NIELSEN, V. Q. Fund af Bacillus cereus ved perakut forl0bende mastitis. Nord. VetMed. 24: 508-515. 1972. 10. NILEHN, P. 0. Infectioner med anthraxliknade mikrober. Nord. VetMed. 10: 325330. 1958. 11. R6HR, W. und H. SCHWARZ. Ein kasuistischer Beitrag zur Cereus-Mastitis des Rindes. Berl. Munch. Tierarztl. Wschr. 74: 53-54. 1961. 12. TERPLAN, G. Saprophyten als Mastitiserreger. Arch. Lebensmittelhyg. 8: 37-38. 1957. 13. PERRIN, D. J., J. GREENFIELD and G. E. WARD. Acute Bacillus cereus mastitis associated with use of a contaminated antibiotic. Can. vet. J. 17: 244-247. 1976. 14. WEIDLICH, N. Uber Infektionen der Milchdriise des Rindes mit Bacillus cereus. Mh. VetMed. 16: 816-818. 1961.

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Pathology of Bacillus cereus mastitis in dairy cows.

PATHOLOGY OF BACILLUS CEREUS MASTITIS IN DAIRY COWS B. Schiefer, K. R. Macdonald, G. G. Klavano and A. A. van Dreumel* Canada, after intramammary t...
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