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A l O-wcck-o ld pig from a herd in whi ch mortality had been 5 % after weaning was pr e sented for diagn o sis. It had ex te ns ive ne crotic cec itis a nd coliti s . Esche richia coli was c ult ure d fr om th e lun g . No bact e ria we re cult ured from liver, s p lee n an d kidn e y . No rma l bact eri al flora was o b tai ned fro m th e int estin e. Nemat od e par a sites were not fo und in th e s ma ll int e st ine. T he maj or a bnorma lity was su pe rficia l a n d de ep ne crosis o f th e mu co sa in th e cecum and colon . In areas whe re necrosis e xte n de d to the mu scularis muco sae , th e s ub m ucosa was thicken ed b y pr oli feration o f fibrobl asts a nd infiltr ati on with macr ophagc s , gra n ulo cy tes, lympho cyt es a nd plas ma ce lls . T he lun g ti ssu e was co ngested a nd moderat el y e de ma to us . A few pul mo na ry lobules a lso had so me ce llu la r ex ud a te (m ac rophage s a nd leucocyt e s) in b ronchiol es a nd a d jace nt alveoli al on g wit h partial co lla pse of th e a lveoli . Round or ovoid structur es a bo u t th e size of erythrocytes were cl ust ered in a lveoli a n d a lo ng a lveolar wa lls . Each had a lightly-stain e d pi nk ca ps u le . The ce ntra l a rea was clear or ha d o ne or more ligh tly stai ne d bl ue , ro u nd int ernal bodie s . They were mo st numerou s in lobule s with out ce llu la r ex uda te. Wh en sta ine d with th e ch ro m ic a cid-Sc hiff r eagent 19] with thre e rin se s o f so d ium bisulfit e so lu t io n ( 20 mol /I ) a fte r th e Sc h iff re agent ( Ba ue r's sta in), th e capsule a n d int ernal bodies stai ne d irregul arl y w ith fuc hs in . Fewer str uc t ures were visib le in th e Bau er-st ain ed t ha n H E-st a in ed sectio ns. So me of th e structu res lo ok ed lik e bl ac k di sk s or ovoids (f ig . I ) whe n sta ine d wit h Grocott's modificat ion of Gorn o ri's methen amine- sil ver nitrat e [7] . Mo st , how ev er, lo ok ed holl o w wit h grey o r bla ck borders. The di agn o sis wa s necroti c cecit is a nd co litis ; th e cause was undet e rmined . There was mod e rat e b ronch o pn eumon ia . Fu rt he r st udy of th e intraal ve ol ar bod ies was indica ted because th e site, morpho logic a ppeara nce a nd stai n ing rea cti on s we re co nsiste nt wit h th o se of Pneum ocystis carin ii . A lt ho ug h th ere are few reports o f thi s o rga n ism in swine, on e re po rt d escribe s it in 4-m onth-old pigs 15]. Fo r ma lin- fixe d lun g was minced int o sma ll blo cks ( I mrn") a nd washe d overn ight in 0 . 1 mol /l cacody late bu ffer , p H 7 .2 , be fore fur the r fixa tio n fo r I h in 1% OSO.1 in t he sa me bu ffe r. T he blo ck s were d eh ydrated , infiltrat ed a nd e m be d de d in a mi xture o f D o w |
