SUMMARY Published figures from veterinary schools indicate that tumours may account for about 1 to 3 per cent of surgical cases. In this paper an account is given of clinical and pathological aspects of the tumours that are most likely to be encountered in practice, either as visibly or palpably detectable masses of tissue, or as internal tumours responsible for clinical signs. Amongst the common and important tumours dealt with, the most prominent are “equine sarcoid”, squamous‐cell carcinoma (of eye region and of glans penis), granulosa‐cell tumours and melanomas. Well over a hundred references provide entry to the relevant literature. The need for further pathological and clinical studies of equine tumours is stressed. RÉSUMÉ Les chiffres publiés par les Universités Vétérinaires indiquent que les tumeurs constituent de 1 à 3 % des cas chirurgicaux. Dans cet article, on mentionne les signes cliniques et pathologiques des tumeurs les plus fréquemment rencontrées dans la pratique, soit qu'il s'agisse de tumeurs visibles ou palpables, soit de tumeurs internes responsables de signes cliniques. Parmi les tumeurs les plus communes et les plus importantes, on note le “sarcoïde équin”, les carcinomes à cellules squameuses (de la région oculaire ou du gland pénien), les tumeurs à cellules granuleuses et les mélanomes. Plus de cent références sont fournies. La nécéssité de recherches plus poussées, tant cliniques que pathologiques est soulignée. ZUSAMMENFASSUNG Die von tierärztlichen Fakultäten publizierten Zahlen lassen erkennen, dass Tumorfälle ungefähr 1 bis 3% aller chirurgischen Patienten ausmachen. Dieser Artikel beschreibt die klinischen und pathologischen Gesichtspunkte bei Tumoren, die in der Praxis am ehesten angetroffen werden, entweder als sicht‐ und tastbare Gewebsmasse oder als innerliche Geschwülste, die für klinische Symptome verantwortlich sind. Unter den häufigsten und wichtigsten erwähnten Tumoren finden sich das “equine Sarcoid”, Plattenzellcarcinome (besonders in Augennähe und an der Glans penis), Granulosazelltumoren und Melanome. Ueber 100 Angaben erleichtern den Zugang zur einschlägigen Literatur. Das Bedürfnis für weitere pathologische und klinische Studien über Tumoren des Pferdes wird hervorgehoben.

Ahtrcrct. Sixty-four metastasized canine malignant mammary tiiniors were studied. The most important types of canine mammary cancer are discussed. Mammary squamous cell carcinomas of different types are found more frequently in the dog than in man. Mucinous carcinoma, a very rare type in the dog, s e e m to be more malignant than its counterpart in nian. Anaplastic carcinoma in the dog is a very malignant diffusely infiltrating and extensively metastasizing cancer. The malignant mixed tumors, although showing many resemblances to complex carcinomas, are discussed here as a separate gro~ip. Both categories of tumors seem to be extremely rare in nian. Simple carcinomas arc highly infiltrating tumors metastasizing frequently to the regional nodes and lungs; survival time is short. Complex carcinomas are generally less invasive than simple carcinomas, and lymphatic permeation is also less frequent, resulting in a lower percentage of affected nodes; the median survival time is relatively long. The sarcomas, growing mostly in an expansive way, tend to spread mainly to the lungs; survival time is short.Canine maminary adenocarcinonias, solid carcinomas, and spindle cell carcinomas have been discussed in a previous paper [9]. The present paper describes three special types of maminary carcinoma (squanious cell, mucinous, and anaplastic types) that had proved their malignant nature by metastasizing; a group of malignant mixed tumors that had metastasized is also discussed. The macroscopic and microscopic appearances of all tumor