Norbert Czubaj

Prevalence of dorsal notch and variations in the foramen magnum shape in dogs of different breeds and morphotypes

Abstract The study evaluated shape of the foramen magnum (FM) in dog with regard to its constitutional type (small, medium and large breeds) and morphotype (brachycephalic, mesaticephalic and dolichocephalic dogs). We used multi-slice CT scanner to examine occipital area of 138 purebreds dogs. Two studied groups could be distinguished – living animals undergoing standard diagnostic CT procedure (n = 47) and macerated skulls of euthanized dogs (n = 91). Morphometric analysis was focused on presence of dorsal notch within foramen magnum. This anatomical feature was present in 33.3% of examined dogs. It was more often observed in small size dogs (70%) and those of brachycephalic morphotype (94.1%). For the first time dorsal notch was noted in breeds such as French Bulldog, Fox Terrier, Keeshond, Standard Schnauzer, English Bulldog, Cocker Spaniel, Boxer and Rottweiler. We distinguished four different shape of FM: oval, pentagonal, rhomboid and circular. Most common FM shape was oval (41 dogs; 45%) whereas circular type was least observed (5 dogs; 5.5%). The pentagonal shape was noticed in 27 specimens (29.7%) and the rhomboid shape in 18 dogs (19.8%). Authors conclude that dorsal notch is not pathology and should be considered a morphological variation within the normal anatomy. Results presented in this study should be taken into account during interpretation of the CT images of the craniocervical junction.

Morphology of the transverse ligament of the atlas and the alar ligaments in the silver fox ( Vulpes vulpes var )

BackgroundRecent new anatomical and histological features of craniocervical junction in dogs and cats were described providing evidence of differences between the carnivore species. No information on these structures in foxes exists.ResultsTwo parts of the alar ligaments were found. A longer one aroused from dens of axis to the internal (medial) surface of the occipital condyles and was called apical part. A shorter part originated from the entire length of the lateral edge of the dens of axis and terminated on the internal wall of the vertebral foramen of atlas and thus was called the lateral part. The transverse ligament of the atlas was widened in the mid region, above the dens of axis, and thickened at enthesis. Periosteal fibrocartilage was detected in the transverse ligament of the atlas at the enthesis, and sesamoid fibrocartilage was present on periphery in the middle of the ligament.ConclusionsThe craniocervical junction in foxes differs in part from other carnivores such as dogs and cats but resembles that of mesaticephalic dogs. The sesamoid and periosteal fibrocartilage supports the transverse ligament of the atlas whereas the alar ligaments have no cartilage.

Lymphatic drainage of cerebrospinal fluid in mammals – are arachnoid granulations the main route of cerebrospinal fluid outflow?

The outflow of the cerebrospinal fluid (CSF) in animals was over the years the subject of detailed analysis. For a long time it was stated that arachnoid granulations of the venous sinuses play a key role in CSF circulation. However, recent studies on this subject have shown that a considerable part of the CSF is drained to the lymphatic vessels. Moreover, disorders in the CSF passage may result in severe central nervous system diseases such as e.g. hydrocephalus. In this paper, we summarize the current knowledge concerning the lymphatic drainage of the CSF in mammals. We present in detail comparative anatomy of different species taking into account cranial and spinal compartment. In addition, we clarified role of the lymphatic vessels in the CSF outflow and the relationship between impairment in this transport and central nervous system diseases. In the author’s opinion knowledge on CSF circulation is still poorly examined and therefore required comment.

Rostral cranial fossa as a site for cerebrospinal fluid drainage – volumetric studies in dog breeds of different size and morphotype

BackgroundHydrocephalus is a multifactorial condition, whose aetiology is not fully understood. Congenital hydrocephalus frequently occurs in small and brachycephalic dog breeds. Although it is widely accepted that the cribriform plate located in the rostral cranial fossa (RCF) is a site of cerebrospinal fluid (CSF) drainage, the RCF has not been studied extensively. Literature reports indicate that a decreased caudal cranial fossa (CCF) volume in the course of the Chiari-like malformation may obstruct CSF circulation. We hypothesised that morphological diversity among different breeds in the volume of the RCF may affect CSF circulation. The aim of the study was to carry out a volumetric analysis of the RCF and the cranial cavity and to determine the ratio between them in dog breeds of different size and morphotype. We performed computed tomography (CT) morphometric analysis of the RCF compartment by obtaining volume measurements from the transverse and reformatted sagittal and dorsal planes.ResultsThe rostral cranial fossa percentage – volume of the rostral cranial fossa/volume of cranial cavity × 100 (volRCF/volCC × 100) was lower in small and brachycephalic dog breeds than in the other dogs.ConclusionsA reduced RCF volume was detected in small and brachycephalic dog breeds, some of which are predisposed to congenital hydrocephalus. This may lead to overcrowding of brain parenchyma in the RCF and may impede CSF circulation. Our observations may be useful for future studies focusing on the causes and new therapies to treat conditions such as hydrocephalus and syringomyelia.