NORMAL CROSS-SECTIONAL ANATOMY OF THE FELINE THORAX AND ABDOMEN: COMPARISON OF COMPUTED TOMOGRAPHY AND CADAVER ANATOMY

Computed tomographic images of two adult domestic short-haired cats were obtained with a whole body scanner. Images of the thorax and abdomen were compared with cross-sectional anatomy cadaver specimens from the same two cats. Anatomic structures were first identified on the cadaver specimens with the aid of numerous anatomy texts and references and were then identified and labeled on the computed tomographic images. Results from this project provide an atlas of normal cross-sectional gross and CT anatomy of the feline thorax and abdomen that can be used in the interpretation of any cross-sectional imaging modality.     

MAGNETIC RESONANCE IMAGING OF THE NORMAL FELINE ABDOMEN: AN ANATOMIC REFERENCE

Magnetic resonance images of two adult domestic short-haired cats were obtained with a whole body scanner. Images of the abdomen were compared with cross-sectional anatomy cadaver specimens from the same two cats. Anatomic structures were first identified on the cadaver specimens with the aid of anatomy texts and references and were then identified and labeled on the magnetic resonance images. Results from this project provide an atlas of normal cross-sectional MRI anatomy of the feline abdomen.     

NORMAL VARIATION IN SIZE OF THE LATERAL VENTRICLES OF THE LABRADOR RETRIEVER DOG AS ASSESSED BY MAGNETIC RESONANCE IMAGING

Detecting canine brain lesions on computed tomography (CT) or magnetic resonance (MR) scans can be difficult if the lesions do not enhance well following administration of intravenous contrast material. Changes in the shape and position of the ventricular system can be important in the diagnosis of such lesions. Normal variation within the canine ventricular system has not been documented. MR scans from 62 normal Labrador retriever type dogs were evaluated. Five dogs had symmetric enlargement of the ventricles, while nineteen dogs had mild to severe ventricular asymmetry. The incidence of asymmetry in normal dogs must be considered when using ventricular configuration as an indication of central nervous system abnormality.     

SKULL RADIOGRAPHS: SILVER IMPREGNATION AS AN INTERPRETATION AID

Individual skull bones of newly killed young cats were stained with an aqueous solution of 0.5% silver nitrate. These bones became blackened grossly and more radiodense than adjacent unstained skull bones. It was possible to correlate the gross and radiographic appearance of selected bones stained with silver nitrate. This was a useful teaching aid.     

Clinical application of multidetector computed tomography and magnetic resonance imaging for evaluation of cranial nerves in horses in comparison with high resolution imaging standards

Although horses are affected by cranial nerve disease, our understanding of these structures' imaging anatomy is limited, and the optimal modality for imaging of each of these nerves is unclear. The aim of this study was to describe the imaging appearance of the equine cranial nerves on high‐resolution 1.5T magnetic resonance imaging (MRI) and computed tomography (CT) scans of a cadaver head, and with these as standards, examine the utility of MRI and CT performed in clinical cases. High‐resolution MRI and CT images were prospectively acquired of the head of a normal Thoroughbred gelding following euthanasia. Ten clinical cases undergoing high‐field MRI under general anaesthesia and 10 clinical cases undergoing CT in the standing horse under sedation were retrospectively evaluated by three reviewers to assess cranial nerve visibility. On high‐resolution, thin‐slice, MRI scans of the normal cadaver head, each of the 12 cranial nerves and their topographic location could be appreciated. On high‐resolution cadaver CT, cranial nerves II, V and VII were clearly visible, but others were less easily identified; osseous structures were clearly visualised. Clinical MRI and CT allowed for variable visualisation of the cranial nerves, dependent on the sequence and the orientation of scan planes. High‐field MRI allowed excellent visualisation of equine cranial nerves, whereas CT allowed for more detailed visualisation of the osseous canals and foramina. In live horses, the ability to identify all 12 nerves is challenging with either MRI or CT; however, high‐field MRI enables better visualisation of the nerve bundles than CT.     

ANATOMIC REFERENCE FOR COMPUTED TOMOGRAPHY OF THE HEAD OF THE FOAL

The purpose of this study was to produce an anatomic reference for computed tomography (CT) of the head of the foal for use by radiologists, clinicians, and veterinary students. The head from each of 2 foals, euthanized for reasons unrelated to head pathology, was removed and prepared for CT scanning. Using a third-generation CT scanner, 5-mm contiguous transverse images were acquired. The heads were then frozen and sectioned using a band saw, with the cuts matched as closely as possible to the CT slices. The anatomic sections were photographed and radiographed. The radiographs and anatomic photographs were digitized and matched with the corresponding CT image. Each CT image was compared with its corresponding radiographic and anatomic section to assist in the accurate identification of specific structures. Clinically relevant structures were identified and labeled in corresponding images (CT, anatomic slice, and radiograph of slice). Only structures identified in the CT image were labeled in 1 of the other 2 images. Sagittal (reference) images of the horse's head were reconstructed from the transverse CT scans, and were used to indicate the level from which each of the transverse images was obtained. Corresponding labeled images were then formatted together with a legend for identification of specific anatomic structures.     

ULTRASONIC ANATOMY OF THE TENDONS AND LIGAMENTS IN THE DISTAL METACARPAL-METATARSAL REGION OF THE EQUINE LIMB

In a two-phase study, ultrasound was used to delineate the normal sonographic anatomy of soft tissues of the equine distal limb. The study was limited to the soft tissues of the palmar surface of the limb just proximal to the fetlock joint. In the first phase, cadavers were evaluated with a B-mode ultrasound machine, † Then the limbs were radiographed and dissected to compare their gross, radiographic, and ultrasonographic appearances. In the second phase, nine normal adult horses were ultrasonographically scanned. The sonographic appearance of the normal animals was compared with that of the cadavers. Front and rear limbs of all horses had similar ultrasonographic appearances. Flexor tendons and the suspensory ligament were easily identified as having linear, uniformly intense ecogenicity. The borders of the digital sheath and of the proximal palmar pouch of the fetlock joint had a less organized and less intense ecogenic appearance than the flexor tendons and suspensory ligament, and they were poorly delineated unless distended with fluid. Ultrasonography was used in three lame horses and aided the diagnoses of synovial proliferation in the fetlock joint, tendosynovitis, and bowed tendon. Diagnostic ultrasonography was effective in identifying and characterizing soft-tissue structures of the distal equine limb. It is a valuable, noninvasive diagnostic aid.     

MAGNETIC RESONANCE IMAGING OF THE NORMAL FELINE BRAIN

The Purpose of this study was to produce an atlas of magnetic resonance images (MRI) of the feline brain and associated structures. The head of nine clinically normal cats was imaged in 2 or 3 anatomic planes and 3 sets of technical parameters resulting in T1, T2, and proton-weighted density images. Images were compared with anatomic texts, with preserved and sectioned feline cadaver heads, with preserved and sectioned feline brains, and with intact, sectioned, and disarticulated feline skulls for aid in identification of structures. Anatomic and neuroanatomic structures are identified on selected images in different planes as reference for MR morphology of the normal feline brain and related structures.     

Morphological characteristics of the forebrain in the donkey (Equus asinus): A compared atlas of magnetic resonance imaging and cross-sectional anatomy

The brain is the most essential part of the central nervous system which regulates and coordinates all body activities. Based on its phylogenetic development from the neural tube, the brain is divided into rhombencephalon (hindbrain), mesencephalon (midbrain) and prosencephalon (forebrain). The present study is achieved to describe the morphological characteristics of the normal forebrain in the donkey using the matched magnetic resonance imaging (MRI) and cross-sectional anatomy. Ten cadaveric heads of healthy adult donkeys of both sexes were used. Two heads were examined using a 1.5 Tesla MRI scanner, and the brains of the other heads were gently extracted; six brains were sectioned into transverse, dorsal and sagittal slices, and two brains were grossly inspected. MR images were selected in correlation to their closely corresponding gross sections. Both cross-sectional anatomy and MRI scans showed extensive gyration of the neocortex. The forebrain structures appeared with variable intensities on three sequences, Flair, T1-weighted and T2-weighted MRI, enabling comprehensive evaluation of the relevant neuroanatomical structures. The present study provided a precise neuroanatomical atlas of the forebrain in the donkey which could help in the quick and efficient interpretation of clinical diseases of the forebrain, localization of the forebrain functions and evolutionary neurobiology.     

SILVER IMPREGNATION IN SITU

In evaluating radiographs of the limb joints and head, students encounter difficulty where superimposition occurs. By replacing calcium with silver salts in the bone, enhanced radiopacity can be produced. In this study, silver impregnation was used to increase the radiopacity of individual carpal and tarsal bones, selected bones of the skull and the sinuses, and guttural pouch of the horse. This provides an interpretation aid for teaching radiographic anatomy of these regions.     

Regionalisation of the muscle fascicle architecture in the equine longissimus dorsi muscle

REASON FOR PERFORMING STUDY: The longissimus dorsi is the largest muscle in the equine back and plays an important role in locomotor ability and performance in the horse. In vivo studies suggest that the mechanical function varies between different muscle segments, in part determined by anatomy. It is possible therefore that variations in function reflect variations in the anatomy of the longissimus dorsi along its length. OBJECTIVES: To identify if there are regional variations in muscle architecture of the longissimus dorsi. METHODS: Computed tomography scans were obtained from 8 cadaver backs to identify the cross-sectional area and volume of the muscle. The 3D orientations of the muscle fascicles were quantified in situ by their direction cosines using a magnetic digitisation system. RESULTS: Mean +/- s.e. volume of the muscle was 2.34 +/- 0.18 l for each side and mean length of the vertebral column from T4 to L6 dorsal spinous processes was 56.57 +/- 2.0 cm. There were significant differences in the cross-sectional area and the moment arm lengths between muscle segments (P<0.05). In the lumbar region, the mediolateral moment arms were 2-3 times greater than the dorsoventral moment arms. There were significant variations in the direction cosines (n = 7129) between muscle segments and between different regions within each segment (P<0.05). POTENTIAL RELEVANCE: These observations indicate that the muscle fascicle architecture predisposes the longissimus dorsi to different functions both along its length and between different regions within each segment. Detailed 3D anatomical measures of the structure with in vivo measures of function (back motion and muscle activity) will be investigated in further studies.     

Cross-sectional anatomy of the rabbit neck and trunk: Comparison of computed tomography and cadaver anatomy

Computed tomographic images of the neck, thorax and abdomen in four healthy adult rabbits were obtained with a conventional CT using a slice-thickness of 5 mm. CT images were obtained with the animals positioned in sternal recumbency on a removable plastic support directly laying on the CT-table. At the end of the CT session, each rabbit was euthanized and, while carefully maintaining the same position on the plastic support, the animal was moved into a −20 °C freezer until completely frozen. Each cadaver was then sectioned at 10 mm slices, with the first section starting at the tip of the nose, respecting the imaging protocol. The frozen sections were cleaned and then photographed on each side. Anatomic structures were identified and labeled first on each side of the frozen section and then on the corresponding CT image with the aid of the available literature. Results from our study provide an atlas of normal cross-sectional gross and CT anatomy of the rabbit neck, thorax and abdomen, useful in the interpretation of any cross-sectional imaging modality in this species.     

ANATOMY OF THE PORTAL AND HEPATIC VEINS OF THE DOG: A BASIS FOR SYSTEMATIC EVALUATION OF THE LIVER BY ULTRASONOGRAPHY

The objective of this study was to define, in detail, the anatomy of the portal and hepatic veins in the dog in order to establish a procedure for the systematic evaluation of the liver by ultrasonography. Anatomical details were obtained from the formalin fixed livers of ten dogs. The hepatic and portal veins were removed intact from these livers so that a detailed pattern of distribution could be established and the numbers of branches could be counted. Silastic casts were also made of the hepatic and portal veins of two livers, one in situ and one in which it had been removed. The former was to enable the relationship of the portal to the hepatic veins to be established as closely as possible within the animal and the other to provide a model of the distribution of each venous system within the liver. Contrast medium was infused into two other livers and radiographs taken to establish the relationship of each branch to each lobe. It was found that there was a consistent pattern of venous branching to each lobe of the liver in the dog with little variation between individual specimens. All liver lobes contained definite venous branches so that the left lateral and medial, quadrate, right medial and lateral, caudate and papillary veins could be distinguished in each venous system. We believe that an appreciation of this venous distribution will aid in the systematic evaluation of the liver during ultrasonography by enabling identification of each liver lobe. It should be of value for differentiating portal from hepatic veins and veins from dilated bile ducts.     

An epidemiologic systems analysis model for African trypanosomiasis

Systems analysis and simulation modelling were applied to describe the quantitative epidemiology of trypanosomiasis. With the aid of a causal loop diagram, and based on mechanistic decomposition of the components of the trypanosomiasis-tsetse complex, a Forrester flow diagram was developed. Interactions between factors in the system and variables required in the model were estimated from existing data. Appropriate differential equations were set up to describe the dynamics of the model based on mass action theory.Simulation involved integrating birth and death rates, infection and population dynamics as they relate to the carrying capacity of the land, and fluctuations in temperature and rainfall. Both deterministic and stochastic aspects were considered. The model was computerized using a continuous systems modelling program and integration time intervals of one day. Simulations were run using various initial conditions as provided by data from southwestern Ethiopia.The performance of the model was satisfactory when compared with an independent set of data. The procedure enhanced our understanding of the dynamics of the trypanosomiasis-tsetse complex; it could thus be used as a guide to evaluating different programs to control trypanosomiasis in Ethiopia and in other African countries.     

Diagnostic correlation of CT-MRI and histopathology in 10 dogs with brain neoplasms

Ten dogs with primary (n = 8) and metastatic (n = 2) brain tumours were studied in an attempt to evaluate the diagnostic sensitivity of computed tomography (CT) or magnetic resonance imaging (MRI). Of the clinical signs noticed, seizures (seven of 10), behavioural abnormalities and cognition dysfunction (seven of 10), compulsive walking and circling (six of 10), sensorimotor (five of 10) and neuro-opthalmological (two of 10) dysfunction were the most common. In all 10 animals that finally died of the disease or were killed, the histopathological diagnosis that followed necropsy was taken as a golden standard in the CT or MRI prediction of the histological type of brain neoplasms. In every instance, tumour detection, morphology and histological differentiation were possible with the aid of either CT (seven of 10) or MRI (three of 10) imaging especially after contrast enhancement. Only one CT-evaluated dog, diagnosed as meningioma, was found to be astrocytoma on histopathology. Interestingly, a rare case of cerebellar medulloblastoma was correctly identified in MRI scans.     

Computed tomographical (CT) anatomy of the thoracoabdominal cavity of the male turkey (Meleagris gallopavo)

In the present work, our goal was to match high-resolution computed tomography (CT) scans with cross-sectional anatomical pictures of the turkey (Meleagris gallopavo). Two male BUT 6 (a commercial line) turkeys were used. CT scans with 1 mm slice thickness were performed. The images covered the trunk from the level of the 9th cervical vertebra to the end of the coccyx. The anatomical sections and the CT scans were matched, and the important structures were identified and labelled on the corresponding pictures. The aim of this study was to create a reference for evaluating CT scans of avian species.     

Magnetic resonance imaging features of feline intracranial neoplasia: retrospective analysis of 46 cats

The purpose of this retrospective study was to determine the magnetic resonance imaging (MRI) characteristics of feline brain tumors and to determine whether these characteristics can be used to accurately predict the histologic diagnosis. MRI scans of 46 cats with histologically confirmed brain tumors were reviewed, including 33 meningiomas, 6 lymphomas, 4 gliomas, 2 olfactory neuroblastomas, and 1 pituitary tumor. MRI features including axial origin, shape, location, signal intensity, contrast enhancement, peritumoral edema, and mass effect were reviewed and characterized for each tumor type. Tumor shape, axial origin, contrast enhancement, and degree of peritumoral edema aided in the identification of tumor type. Meningiomas were always extra-axial and were most often ovoid with marked contrast enhancement and mild peritumoral edema. Gliomas were always intra-axial with ring enhancement and generally caused more peritumoral edema than other tumors. The brain tumor was detected on MRI in 45 (98%) cats. Two blinded independent reviewers correctly identified 82% of all of the tumor types on the basis of MRI appearance alone. Thus, MRI is an excellent diagnostic tool for the detection of brain tumors in cats, and it provides important information to aid in the diagnosis of tumor type.     

Donkey dental anatomy. Part 2: Histological and scanning electron microscopic examinations

Ten normal cheek teeth (CT) were extracted at post mortem from donkeys that died or were euthanased for humane reasons. Decalcified histology was performed on three sections (sub-occlusal, mid-tooth and pre-apical) of each tooth, and undecalcified histology undertaken on sub-occlusal sections of the same teeth. The normal histological anatomy of primary, regular and irregular secondary dentine was found to be similar to that of the horse, with no tertiary dentine present. Undecalcified histology demonstrated the normal enamel histology, including the presence of enamel spindles. Scanning electron microscopy was performed on mid-tooth sections of five maxillary CT, five mandibular CT and two incisors. The ultrastructural anatomy of primary and secondary dentine, and equine enamel types-1, -2 and -3 (as described in horses) were identified in donkey teeth. Histological and ultrastructural donkey dental anatomy was found to be very similar to equine dental anatomy with only a few quantitative differences observed.     

Performance of a canine weight-loss program in clinical practice

Two canine studies evaluating the effectiveness of a specific computerized weight reduction program in two different clinical settings are summarized to give an overall assessment of an obesity management software program. The weight loss program utilizes a low calorie food formulation (dry, canned and treat) and software to suggest daily calorie intake for weight loss. The software utilizes current body weight and a desired weekly rate of weight loss to predict the dog's body weight in 30 days. The dietary product and software were used in a 3- and 6-month weight loss regime for 60 overweight adult dogs in two different clinical settings. On average, the dogs in this summary lost 0.75% per week regardless of more aggressive rates set by the nutritionist. Accuracy in predicting future weights by the software was dependent upon the desired rate of weight loss selected, the equation used to estimate maintenance energy requirement, and owner compliance. Over time, accuracy in predicting future canine weights improved. All healthy, overweight or obese dogs summarized in these two studies did lose weight and reached an optimal or at least lower body condition score with the aid of this software program and diet.