未経産牛乳房炎に関する研究 (第13報) : 病理所見

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　1. 1975年8月から11月にかけて, 宮崎県都城市･霧島地域酪農開発公社西岳牧場において発生したホルスタイン種乳用子牛の末経産乳房炎症例,急性期3頭,亜急性期2頭,亜慢性期3頭の計8頭について罹患乳房の病理検索を実施した.　2. 供試牛は8.3ヵ月齢から19ヵ月齢のもので,罹患乳房は1分房だけのもの5例,2分房にわたるもの3例であった.　3･供試牛は,現地の放牧場で症候(熱感･疼痛･腫脹･硬結)を発見して,なるべく早く宮崎大学へ運ばれ,臨床検査の後, 5頭は直ちに感電致死させて剖検した.しかし症候を発見した日に剖検した例でも,すでに病理組織学的に亜急性期の病変を呈しているものがあり,放牧中における本症の早期発見は比較的困難であることを示した.　4. 供試牛中の3頭については,うち2頭に治療を加え, 1頭はほとんど治療せずに放置して,それぞれ約1ヵ月間観察の後,感電致死させて亜慢性期の病理像を検索した.　発病初期における2週間の連続治療は,病勢をおさえるのに有効であったが,将来,妊娠･分娩の後における泌乳時に,その機能を完全に発揮させるには障害を残すであろうことが示唆された.　5. 未経産牛乳房炎罹患乳房の病理所見は次のとおりである.　　(1) 急性期では,乳房およびその周辺皮下の浮腫,乳管洞･乳管･乳小管内の膿汁滲出,乳管上皮細胞の膨化･変性.　　(2) 亜急性期では浮腫は消失するが,乳管部の小膿瘍の形成と,その周囲の間質に線維芽細胞の増殖,乳腺上皮細胞の剥脱と乳小管の萎縮.　　(3) 亜慢性期では,膿瘍を中心にした周囲の間質における反応性肉芽腫様病変が特徴的な所見で,導管を中心とする乳腺実質組織の崩壊･消失.　すなわち,未経産牛乳房炎の病理所見は,乳管の化膿性崩壊に続発する線維性被包化の強い膿瘍形成である.　6･治療せずに放置した症例は,乳房の皮膚に瘻管を形成するほどの大膿瘍化し,乳房内に膿瘍性空洞を形成していた.　7･乳房以外の臓器の病変としては,ピロプラズマの寄生による脾腫が8例中4例,肝臓の膿瘍形成が1例に所見されただけで,他には著変が認められなかった.　8. 罹患乳房内の細菌学的検索では, 全例からCorynebacterium pyogenesが検出されたが,Fusobacterium necroPhorum, Peptococcaceae,Bacteroidesも混じていた.1. A series of pathological researches on affected udders was carried with 8 cases of heiffer mastitis, 3 in acute-, 2 in subacute- and 3 in subchronic stadia, occurred on Holstein-Friesian heifers being raised in N Pasturage in Miyazaki Prefecture. 2. Onset was found within the range from 8.3 to 19 months of age on 5 cases with single- and 3 cases with double mammary areas. 3. The test heifers were transported to Miyazaki University for clinical examinations immediately after sppearance of symptoms (feverishness, pain, swelling, induration). Five heifers were autopsied upon electrocution, out of which 2 heifers already indicated subacute pathological changes, suggesting that it is very hard to discover the disease at an early stage in pasture while grazing. 4. Referring to the balance of 3 test heifers, two were under the therapeutical care while another was left with little therapy. After about one month's observation every one of them was electrocuted for studies of subchronic pathological features. The treatment given for 2 weeks in sequence at the initial stage was found effective to control the conditions of the disease, however, it was suggested that certain disorders would remain in future in a period of lactation after pregnancy and first parturition, which might disturb a perfect display of lactation. 5. The following pathological findings of mastitic udder were obtained: (1) In the acute stadium; edema in subcutis of udder, exudation of pus in mammary cistern, mammary ducts and intralobar mammary ducts as well as swelling and degeneration of epithelial cells of mammary ducts were observed. (2) In the subacute stadium; edema disappeared, however, small abscesses formed on mammary ducts, fibroblasts proliferated on interstitial tissue thereabout, exfoliated epithelial cells of mammary duct and atrophy of capillary mammary duct were observed. (3) In the subchronic stadium; a finding very characteristic was the reactional granulomatus change on interstitial tissue around the abscess, which was apparent in circumference of mammary gland and mammary ducts of mammary cistern. 6. The case, to which no treatment was given, showed an abscess as large as forming a syrinx on the skin of udder with an abscess cavern. 7. As pathological changes of organs other than mammae, nothing else with marked changes was observed but only 4 cases of splenic enlargement out of 8 cases as well as one case of abscess formation in liver. 8. Upon the bacteriological research on mastitic udders, Corynebacterium pyogenes was isolated from all of the cases. Besides, Fusobacterium necrophorum, Peptococcaceae and Bacteroides were also found being admixed therein.

著者

野坂大
宮崎大学農学部家畜病理学教室

未経産牛乳房炎に関する研究 (第13報) : 病理所見

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