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ACCORDING to serological surveys the incidence of Leptospira canicoh infection in dogs in different European countries has been computed t o vary between 3.6 per cent. in Rome and 44 per cent. in Belgium (Raven, 1941). A considerable proportion of dogs in this country is probably infected though most of the evidence is based on the somewhat selected dog population of veterinary clinics. Nevertheless, Stuart (1946), in Glasgow, found that 40 per cent. of 100 unselected domestic dogs gave serological proof of previous L. canicola infection, and Broom and MacIntyre (1948) found 26 per cent. positive among dogs from different parts of England. The lesions caused by L. canicola in dogs are predominantly nephritic and it is the purpose of this paper t o give an account of these renal lesions and to discuss their significance in relation to general as well as to veterinary pathology.The earlier literature of this subject is somewhat obscured by terminology, but it is generally accepted that the terms '' dog typhus " and '' Stuttgart disease " are synonymous. " Stuttgart disease " was the title applied originally by Klett (1899, cited by Jenny and Kanter, 1946) of Stuttgaxt to the triad apathy, stomatitis and gastro-enteritis in dogs, a syndrome now attributed to the uraemic and toxsemic effects of L. cankola infection. At the beginning of this century, veterinarians in Europe were familiar with the pathology of the renal lesions of this condition which they regarded as acute interstitial nephritis of lymphocytic and plasma-cell type (Hyhlik, 1924). Lukeli and Derbek (1923, cited by Hyhlik) made a major contribution to the pathology of canine leptospirosis by the demonstration of spirochsetes in the renal tubules of 9 dogs which died during the 1922-23 epidemic of Stuttgart diseaae in Vienna. Kriv&Fek (1924), Wirth (1924) and Klarenbeek (1925) published confirmatory papers, and LukG (1925) reported spirochsetes in the kidneys of 97 of 105 fatal cases. He described also the cellular exudative process as a mononuclear infiltration resembling the acute interstitial nephritis of scarlatina.Henschen ( 1924) regarded interstitial lymphocytic nephritis 88 the most frequent and important inilammatory pondition of the canine kidney. He recognised subacute and chronic stages and described them in some detail, and though he did not know the organismal came, he postulated that this condition wm probably the precursor of the ' I Schrumpfnieren " so commonly seen in older dogs. Luke& Jelinek and Schramek (1925) also discussed the J. PATH. BAUl'.-VOL. LXm

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In IOO consecutive deaths from a coronary care unit, the coronary arteries were examined microscopically in longitudinal sections (serial and semi-serial) so that the entire extramural part of each artery was scrutinized. Occluded coronary arteries were found in 88 cases, the occlusions being due to thrombi in 17, to the contents of soft atheromatous plaques in 22, and to a mixture of soft plaque content and thrombus in 49; thus in 7I cases the coronary occlusions are due basically to the rupture of soft plaques. After deep-freezing, the entire myocardium of each heart was examined naked eye in serial slices (using Nitro-B T) and selected areas microscopically. The findings allowed tentative groupings into single episode, double episode, and progressive lesions according to age structure. Correlation of the coronary and myocardial findings has been attempted.The establishment of a coronary care unit in the Royal Infirmary of Edinburgh provided an opportunity to make a detailed study of the hearts of fatal cases with especial reference to the condition of the coronary arteries in relation to the myocardial lesions. The policy of the unit is to admit '(i) any patient under 70 years of age who is suspected of having sustained a myocardial infarction within the preceding 48 hours ("routine admission"); and (2) any patient of any age who has a dangerous arrhythmia' (Lawrie et al., I967). gists, and hearts from all the coronary care unit cases were set aside for examination by one or other of the authors. After weighing the organ, the coronary arteries were dissected from the heart, the right, left anterior, and left circumflex vessels being traced from their orifices as far as possible on the external cardiac surface. The unopened arteries were fixed separately in neutral I0 per cent formal saline for I8 to 24 hours before trimming by removal of adherent fat. With a sharp scalpel, each vessel was cut into pieces about 2 cm. long, beginning peripherally and as far as possible placing the cuts so as to avoid an occlusion. Calcified segments were also left uncut until decalcified. Materials and methodsThe arterial segments were embedded in paraffin so that longitudinal sections would expose the whole length of the lumen. Complete serial sections at 5 [± were made from selected blocks where occlusion was seen or believed to have occurred; these amounted to half the cases. In other cases not cut serially, semi-serial sections were taken off at different levels until the whole lumen of the vessel was available for examination. Routine stains were employed and all the sections were scrutinized by the authors separately.After removal of the coronary arteries, the hearts were placed in a deep-freeze cabinet at -20°C. suspended from glass rods to preserve the shape of the heart. When convenient, the hearts were thawed to a suitable consistency at room temperature, and sliced on a Berkel automatic slicer. Transverse sections from apex to base of the ventricles were taken at approximately 5 mm. thickness, the valves and atria be...

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