Summary The incidence and significance of the appearance of various associated congenital malformations in a single individual have received poor attention in veterinary medicine. In this article, the malformations exhibited by four animals pertaining to three different animal species are described, and the possible reasons for the association of these anomalies are discussed from the viewpoint of the comparative medicine. All four animals showed two or three malformations constituting unrecognized teratological syndromes, so‐called one‐of‐a‐kind syndromes, which have not previously been described, at least in these particular animal species. A pig was affected by a series of craniofacial anomalies consisting in a first arch syndrome together with an occipito‐parietal meningocele. Another member of the porcine species showed holoprosencephaly with cyclopia, various defects in the left forelimb and an extensive omphalocele. A dicephalic cat with cervical rachischisis and myeloschisis and a dog exhibiting spina bifida, curled tail and atresia ani are also described.

Summary A newborn diprosopic female calf had a partially duplicated head with two faces each exhibiting a mouth, a snout, an anomalous incomplete mandible, two eyes and a lateral ear. A single ear with two small auditory canals was present on the midline between the two medial eyes. A type 1 persistent truncus arteriosus and hypoplasia of the thoracic portion of thymus were the most outstanding extracranial defects. In the heart, a persistent foramen secundum and a large patent foramen ovale allowed communication between the right and left atria. In the right ventricle, the small conus arteriosus was separated in part from the inflow tract by an anomalous 'septomarginal muscular septum'. An interventricular septal defect was also present. A large undivided truncus arteriosus, exhibiting a tricuspid truncal valve at its origin, arose for the most part from the conus arteriosus of the right ventricle. The truncus gave rise to the brachiocephalic trunk, the aortic arch, a small pulmonary trunk, from which the left and right pulmonary arteries emerged, and two coronary arteries. The etiology and pathogenetic mechanisms implicated in the appearance of persistent truncus arteriosus are reviewed. It is suggested that a deficit or insufficiency in the cranial neural crest may play a role in the pathogenetic mechanisms leading to the production of persistent truncus arteriosus and related defects in cephalic duplications.

A detailed anatomical study of a dicephalic iniodymic monosomic cat in conjunction with the morphogenetical implications of the observed anomalies is presented. The animal exhibited two heads joined at the level of an anomalous medial exoccipital bone. Two brains and two foramina magna were present. The vertebral column was single but the cranial cervical vertebrae (C2 to C5) had doubled bodies. Cervical rachischisis with myeloschisis were associated defects. Two nasopharyngeal and oropharyngeal cavities converged caudally into a single laryngopharynx. The esophagus, larynx and trachea were single. Duplication of the tongue and hyoid apparatus was present. Palatoschisis affected both oral cavities. Hypoplasia of the anatomical structures in the medial aspects of both heads was observed. Microphthalmia was also observed in both medial eyes. Comparative aspects of the morphology, causative agents, and mechanisms and anomalous morphogenesis of anterior duplications are reviewed and discussed.

In patients with coronary artery disease, noninvasive measurements of regional myocardial perfusion by Tc-99m sestamibi correlate well with invasive measurements of coronary endothelial function. These findings may have implications for monitoring the effects of interventions designed to improve endothelial function and microvascular function in patients with coronary artery disease.

The arterial and venous systems of the neck and heads of a dicephalic iniodymic monosomic cat are described. In the arterial system, an anomalous lingual branch of the right external carotid formed a large subhyoid arch, extending to the midline between both heads, giving off branches supplying the medial aspect of both heads and terminating in two medial internal carotid arteries each for the right or left head. This vessel was considered as an anomalous supernumerary common carotid artery. In the venous system, each lingual branch of linguofacial veins united and formed an anomalous venous arch. It received rostrally a long midline vein running between both heads and connecting with the medial internal jugular system. This vein received tributaries from the left and right heads and was considered as a supernumerary jugular vein. From these observations, and those of others in the literature, it can tentatively be suggested that, in congenital cephalic duplications in domestic mammals, the arterial blood supply for the medial aspect of both heads tends to come from the lingual branch of the external carotid artery, with an unexplained prevailing contribution of the right external carotid system. Two different venous patterns have been observed. In animal especies exhibiting a hyoid venous arch, such as carnivores, a midline supernumerary external jugular vein draining at the anomalous junction between lingual veins of both heads is formed, whilst in animals lacking a constant hyoid venous arch, such as ruminants, an asymmetrical supernumerary external jugular vein draining into the right "normal" external jugular vein has been repeatedly described.