A B S T R A C TSixty-seven cases of chemodectoma in dogs (fifty-nine aortic body, two glomus pulmonale, and six carotid body) were studied. The epidemiology, biological behaviour, and association with other tumours of canine and human chemodectoma were compared. The large number ofsites oforigin of human chemodectomas was not observed in the dog. The canine chemodectomas occurred as multiple tumours in 16% of the cases and were biologically similar to the human tumours. As with human chemodectomas, an association with endocrine tumours (such as phaeochromocytomas and thyroid neoplasms) was observed.The aortic body tumours were the most common and occurred more frequently in males. A higher rate of metastasis (22%) and a higher fiequency of multiple endocrine tumours in association with chemodectomas, not observed in the dog before, were seen. I n contrast to the high frequency of interstitial cell tumours and a low frequency of Sertoli cell tumours noted in previous studies, a low frequency of interstitial cell tumours and a high frequency of Sertoli cell tumours were seen in this study. Similarly, a previously reported high frequency of haemangiosarcoma was not observed in this series. A significantly higher frequency of chemodectomas was seen in the brachiocephalic dogs (Boxers and Boston terriers). Chemodectomas in man have shown familial predispositions. However, in brachiocephalic dogs the high frequency of chemodectomas may be caused by their partially obstructed air passages, rather than by a genetic factor only.A higher incidence of chemoreceptor-cell hyperplasia and chemo-785

De pa rtment of Path ology, the A nima l Me dica l Center a nd H ospi tal for Jo int Di sea ses a nd Med ical Center, New York, N . Y.Abstract . Epide rmo id cyst was seen in the tenth th oracic vertebra l bod y of a 4-yea r-o ld fem ale Sarn oyed dog a nd in the term inal phalan x of the fifth digit of the left forepa w of a 5-year -old spayed mon grel d og. T he cysts co ntai ned caseo us, gray-white mat erial a nd were lined with layers of sq ua mo us, gran ular or basal cells filled with kera tin. Cho lesterol clefts were embedd ed in th e vertebra l a nd phalan geal bon es.E pide rmo id cysts o f bon e a re rar e in man. T hey commonl y occ ur in the skull a nd less freque ntly in th e termin al p hala nges [I , 8, 12]. O ver 150 cases of epide rmo id cys t in th e skull a nd ove r 50 ca ses in th e pha la nges had been rep orted to 1964 [8]. Epi der mo id cysts of bone have not previou sly been described in a nimals, although epid ermoid cysts of th e derm is co mmo nly occ ur in th e dog [7, II]. Thi s paper repo rts epide rmo id cysts in a vertebra l bod y of o ne dog a nd in a phalan x of a no ther. Case ReportsCase J. A 4-yea r-o ld fema le Sa moye d dog was weak a nd had limp ed on its rea r legs for I month . It had recentl y develop ed progr essive pare sis a nd cer vical pain. Hem at ologic a nd blood che mica l va lues were norm al. Radi ographs showe d an osteo lytic focu s in the tenth thoracic vertebra. Th e dog was killed a t the ow ner' s req uest. T he tenth th o racic vertebra l bod y cont a ined a cyst, 1.5 x 1.3 ern, filled with caseo us, slightly gre asy, gray mat er ial ( fig. I). Th e cyst had a 4-m m o pe ning int o the spina l ca nal thro ugh which extru ded mat eri a l co mpressed the spina l cord ( fig. 2).Case 2. A 5-yea r-o ld spay ed mon grel dog had a n overgrow n na il associated with swelling a nd bleedin g in the fifth digit of the left fo rep a w. T he distal pha lanx was a mp uta ted an d submitte d for exa mina tion. It had a 2 x 4-mm cyst con tai ning caseo us, cha lky-whi te ma terial. T he o pera tive site was free of recurrence a fter 7 mo nt hs.

Abstract. Pulmonary granulomas were incidental findings at necropsy in 18 dogs, mainly of the brachycephalic breeds. These lesions were multifocal along smaller bronchi and the subpleural tissue at the margins of lobes. The granulomatous reaction contained numerous periodic acid-Schiff (PAS)-positive bodies that histochemically had reactions suggestive of a calcium-lipid-mucopolysaccharide complex. Although the cause is not clear, the location and distribution are suggestive of an inhalation or aspiration pneumonia.The shortened muzzle of brachycephalic breeds, particularly when there is concurrent upper respiratory disease, may predispose them to these bodies.Pulmonary granulomas of unknown cause were seen at necropsy as incidental findings in 18 dogs with a mean age of 10 years. All but two dogs were from large metropolitan areas of New York City and Philadelphia. Tissue specimens were submitted to the Armed Forces Institute of Pathology for histologic examination. The gross and histologic features of these lesions are described. Materials and MethodsThe breed, sex, and age of each dog is shown in table I. Parts of the pulmonary lesions were fixed in 10% formalin and embedded in paraffin. Sections were cut at 6 pni and stained with haematoxylin and eosin (HE), periodic acid-Schiff (PAS) with and without diastase, Mowry's modification of the colloidal iron stain for acid mucopolysaccharides (AMP) [4], alizarin red S before and after microincineration, Danielli's stain for tyrosinecontaining proteins, alcian blue, oil red 0, and the Prussian blue reaction for iron. Other stains included Congo red for amyloid, Mayer's mucicarmine, and Gomori's methenaminesilver stain (GMS). X-ray diffraction was performed by the powder method and a DebyeScherrer camera [l].