THREE-DIMENSIONAL ULTRASONOGRAPHIC IN VITRO IMAGING OF LESIONS OF THE MENISCUS AND FEMORAL TROCHLEA IN THE EQUINE STIFLE

The purpose of this in vitro study was to evaluate the value of three-dimensional (3D) ultrasonography for the diagnosis of equine meniscal and trochlear ridge lesions under in vitro conditions. Lesions were created in the isolated meniscus and femoral trochlea of 25 cadaver stifle joints. Cylindric, conic, and cuboid lesions were created on the trochlear ridge. Five different meniscal tear configurations were created. A total of 107 lesions of the trochlear ridge and 103 lesions of the meniscus were created. 3D ultrasonography was performed in a waterbath, using a 7.5 MHz 3D scanner. Trochlear ridge lesions were seen as either hypoechoic or anechoic breaks in continuity or as irregular notches. One-hundred and one out of the 107 trochlear lesions were visible using 2D ultrasonography whereas 104 out of the 107 lesions could be seen using the 3D Cine mode. Three lesions could not be detected by either technique. Eighty-five out of the 103 meniscal lesions were seen with 2D ultrasonography and 90 with 3D Cine mode. Radial tears and horizontal tears were the least commonly visualized 3D. The 3D Cine mode led to a small improvement in lesion detection. 3D ultrasound could be considered as an extension and refinement of the ultrasound techniques already in use and can increase the diagnostic capabilities. However, technical improvements have to be achieved before 3D ultrasound can be used in the daily practice for diagnosis of equine stifle joint disorders.     

A REVIEW OF THE SONOGRAPHIC ASSESSMENT OF TUMOR METASTASES IN LIVER AND SUPERFICIAL LYMPH NODES

Diagnostic imaging techniques are an important part of the diagnostic workup and staging of cancer patients. Ultrasound is of particular interest in this respect. In so far as tumor metastases are concerned, ultrasonography of regional lymph nodes and of the liver can provide valuable information. In humans many criteria, some of them objective, have been evaluated as indicators of malignancy. The most diagnostically helpful of these include the short/long axis ratio of the lymph node, the pattern of distribution of the blood vessels within the lymph node, and to some extent the calculated values for resistive and pulsatility indices. Putative objective criteria to improve the specificity of ultrasound for metastases detection in the liver have also been evaluated. These include perfusion indices, primarily using analysis of Doppler frequencies (Doppler perfusion index) and hepatic venography using an ultrasound contrast agent. Contrast-enhanced ultrasonography is a new and promising area to help the initial diagnosis and characterization of malignancy, particularly for focal lesions in the liver. This review discusses the use of ultrasound for detection of metastases and presents material from four veterinary cases.     

Clinical Update on Diagnosis and Management of Disorders of the Digestive System of Reptiles

The diagnosis and treatment of digestive system disorders in reptile species continues to provide challenges owing to the differences in anatomy and physiology in this diverse group of animals. Continued research efforts into diagnostic techniques, in particular imaging (e.g., contrast radiography and ultrasonography), of gastrointestinal tract have resulted in clinical advancements for practicing veterinarians. The aim of this article is to provide veterinarians up-to-date and clinically relevant summaries on the diagnosis and therapy of digestive system disorders of reptiles commonly maintained as companion animals.     

A REVIEW OF NONCONVENTIONAL ULTRASOUND TECHNIQUES AND CONTRAST-ENHANCED ULTRASONOGRAPHY OF NONCARDIAC CANINE DISORDERS

Modern ultrasound contrast media are gas-containing stabilized microbubbles that remain intact in the circulating blood for several minutes after intravenous injection and increase the intensity of the backscattered ultrasound. When the microbubbles disappear from the blood, they can be detected in the parenchyma of the liver and the spleen for about 30 more minutes (late liver- and spleen-specific phase). The insonated microbubbles produce second harmonic ultrasound frequencies, whose detection requires nonconventional ultrasound modalities such as pulsed inversion imaging. Nonconventional ultrasound techniques can also be used without microbubbles because second harmonics can be generated by ultrasound in tissues as well. The physical principles and advantages of nonconventional ultrasound techniques are described. The circulating microbubbles can be used not only to enhance weak Doppler signals, but also to perform dynamic contrast studies. Contrast-enhanced dynamic ultrasound studies--similar to contrast-enhanced CT and MRI examinations--have been used in humans to characterize lesions noninvasively (i.e., without biopsies) found during conventional ultrasound examinations. To map the distribution of contrast medium in a nodule or in an organ, specific scanning techniques such as stimulated acoustic emission have been developed. Stimulated acoustic emission occurs when high acoustic pressure ultrasonic waves disrupt the stationary or slowly moving microbubbles. This results in the release of a large amount of harmonic ultrasound frequencies. When the stimulated acoustic emission technique is used for dynamic studies, scanning must be interrupted several times to allow the microvasculature of the lesion to refill with microbubbles (interval delay imaging). The contrast patterns of malignant and benign hepatic nodules in humans have been the most intensively studied. Another type of dynamic study in humans measures the transit time of the contrast medium; that is, how fast the peripherally injected microbubbles reach the hepatic veins. Hepatic cirrhosis can be differentiated from other diffuse parenchymal liver diseases by a shorter transit time. Introducing nonconventional ultrasound techniques and ultrasound contrast media in veterinary diagnostic imaging may have potential value; however, intensive research should be carried out before ultrasound contrast agents can routinely be used in clinical practice.     

Ultrasonography of the acute abdomen

For many years, ultrasonography has been considered to be one of the most valuable imaging techniques for evaluation of the abdominal cavity and its organs. In most cases, abdominal ultrasonography helps obtain information that leads to a definitive diagnosis. Ultrasonography is also valuable to narrow the list of differential diagnoses obtained with other diagnostic techniques. This article discusses the role of ultrasound for the diagnosis of the most common diseases that can produce clinical signs of acute abdominal pain. Abdominal organs that can be evaluated using ultrasound include the liver, biliary system, pancreas, stomach, small intestine, kidney, urinary bladder, uterus, and prostate. Pathologies of the abdominal cavity and retroperitoneal space can be also diagnosed with ultrasonography. Interventional ultrasound techniques are useful to either assist in getting the definitive diagnosis or to treat certain pathologic conditions.     

Contrast ultrasound: general principles and veterinary clinical applications

The concept of contrast enhancement has significantly extended the usefulness of ultrasound imaging in human medicine and medical research over the past decade. The persistence and efficacy of ultrasound contrast agents has been improved and specific imaging sequences have been developed. Contrast ultrasound provides Doppler and grey-scale enhancement. Doppler examinations are improved when studying deep or small vessels and vessels with low flow velocities. Specific contrast imaging sequences allow detection of tissue enhancement with grey-scale ultrasound which enables assessment of tissue perfusion. Major clinical applications of contrast ultrasound in the human medicine field are the heart, the parenchymal organs such as the liver, spleen and kidneys, and vascular applications. Many other interesting applications have been identified and beside their diagnostic value, intensive research is currently investigating the use of ultrasound contrast agents for therapeutic applications such as targeted delivery of drug- or gene-loaded microbubbles. In the last few years, contrast ultrasound has also been introduced in veterinary medicine. Its usefulness has been shown in diseases of the liver, spleen, kidney, pancreas, lymph nodes and superficial tumours. In the present article, an overview of the physical principles, imaging techniques and image analyses is presented. In addition, a literature review details the current use in veterinary medicine and areas of potential utilization are discussed.     

Diagnostic imaging of lameness in small animals.

The demand for advanced diagnostic imaging procedures such as nuclear scintigraphy, ultrasonography, computed tomography, and magnetic resonance imaging has increased dramatically over the past 10 years. Veterinarians, seeking to improve their diagnostic capabilities and clients willing to pursue "best medicine" have driven this demand, resulting in installation of advanced imaging facilities at most academic and private referral practices. Knowledge of potential benefits of various modalities will allow the veterinarian to optimize his or her use of diagnostic imaging in his or her own practice or in a referral practice.     

Ancillary testing for the ruminant respiratory system.

With greater use of a wide variety of diagnostic tools, such as transtracheal washing, respiratory endoscopy, chest radiography, thoracic ultrasonography, blood gas analysis, and lung biopsy, veterinarians are gaining tremendous insight into pathogenic mechanisms of the ruminant respiratory system. We have available many diagnostic aids; some fairly simple and inexpensive, others highly sophisticated and presently at far greater cost than justifiable on most individual food animals. Some methods recently developed, such as same-day viral particle detection in BAL samples,6 have tremendous potential for rapid and accurate diagnosis in ruminant pulmonary medicine. Undoubtedly, future research in this area will provide an ever widening array of powerful and rapid diagnostic aids to deal with respiratory disease of ruminants.     

Vitamin D and Ultraviolet B Radiation Considerations for Exotic Pets

Vitamin D is an essential hormone that regulates many different functions in vertebrates and can have a protective effect against various disease conditions. Providing exotic pets appropriate access to vitamin D, through the diet, ultraviolet B (UVB) exposure, or a combination of both, is important for veterinarians and exotic pet owners to consider. Although it is commonly thought that most animals derive the vitamin D they need through their diet, there are a number of species that appear to benefit more from UVB exposure. In addition, there has been minimal study to investigate appropriate dietary levels of vitamin D for many of our exotic pets. Although the recommendation of providing UVB lighting has been primarily limited to captive reptiles, research with other species (e.g., birds and small mammals) suggests that these animals may also benefit from this type of lighting. However, the provision of UVB is not without its potential side effects. The purpose of this article is to review the important roles of vitamin D in animals, the different methods animals use to acquire this hormone, the potential clinical signs associated with hypovitaminosis or hypervitaminosis D, the role of artificial UVB lighting in the synthesis of vitamin D, and the potential side effects associated with UVB radiation.     

Advanced reproductive techniques in goats.

The use of ultrasonography for pregnancy diagnosis and reproductive tract evaluation in the goat has become more common in the past decade. Pregnancy-specific hormone assays are commercially available for pregnancy determination in goats. Hormonal methods of synchronization of estrus for artificial insemination have been refined, but a number of factors still make pregnancy results variable. Caprine embryo transfer is widely used commercially. More advanced reproductive techniques such as in-vitro production of embryos and cloning have been accomplished in goats; success rates with these techniques will likely rapidly improve.     

Pregnancy Monitoring in Dogs and Cats Using 3D and 4D Ultrasonography

Three-dimensional (3D)/four-dimensional (4D) volume ultrasound is an established method in human medicine that offers various options for analysing and presenting ultrasound volume data. However, the successful application of the different 3D/4D imaging modalities in pregnant dogs and cats has not yet been reported in the literature. The main reasons for this are: (1) the high costs of 3D/4D ultrasound systems, (2) operation difficulties due to high breathing frequency in non-sedated animals and (3) the missing specific knowledge in veterinary medicine concerning how to perform high-quality volume scans. Automatically acquired ultrasound volume data sets were generated with two different ultrasound systems: the portable Voluson i and the stationary Voluson Expert 730. Different 3D/4D imaging modalities were tested in regard of their practicability in pregnancy monitoring in dogs and cats. Nine different volume imaging modalities were applied using the saved files. For the presentation of the static 3D volume data sets, we used the multiplanar, niche, surface, transparency, glass body, inversion, volume calculation and tomographic ultrasound imaging modes. For the dynamic 4D data, the surface and glass body modes were applied. By changing the human standard settings to the requirements of small animal anatomy, it was found that 3D/4D ultrasound has great potential for the characterization of pregnancy in queens and bitches. The 3D/4D technology offered advanced information about pregnancy status and birth prediction and improved the diagnostic confidence. By using standardized examination protocols, 3D/4D ultrasound will allow a reduction in examination time by generating even more relevant information. These benefits, combined with possible future cost reduction of commercial ultrasound systems, might lead to frequent utilization in routine pregnancy diagnostic and birth management in small animal practice.     

Application of ultrasound for genetic improvement.

Genetic improvement programs for livestock would be enhanced by the ability to accurately and easily measure body composition of live animals or to make measurements at anatomical reference points that can be used to accurately predict body composition. Advances in ultrasonic technology, such as real-time imagery and portable ultrasound units, have renewed interest among animal scientists working with genetic improvement programs and the livestock industry groups they serve. Ultrasound has been used for more than 30 yr and, for swine, has been demonstrated to improve significantly the accuracy of predicting body composition. However, many studies have shown less success in improving prediction of body composition from the use of ultrasonics to measure live beef cattle and sheep. The swine industry probably will be the first to benefit measurably from use of ultrasound technology in large-scale genetic improvement programs for carcass merit. Considerable research and development is needed before ultrasound technology can be effectively used in similar large-scale programs in the beef cattle and sheep industries.     

The use of ultrasound in monitoring reproductive physiology of beef cattle.

Real-time, B-mode ultrasonography provides the opportunity to improve the methods of evaluation of ovarian function and diagnoses of pregnancy in beef cattle. Determination of the sex of a fetus early in pregnancy (d 55 to 85) and verification of embryo viability by monitoring fetal heartbeat are unique methods involving ultrasound scanning. These techniques and a method for evaluating the technique of artificial insemination can be used to improve reproductive management of cattle. The way in which ultrasound technology may have its greatest impact is as a tool for improving on the method of palpation per rectum for monitoring ovarian function and pregnancy in beef cows and heifers. Determination of fetal sex and monitoring embryo mortality are less likely to be applied regularly in herd management, but these procedures will be valuable in conducting research in reproductive physiology of beef cattle.     

Fertilization studies and assisted fertilization in mammals: their development and future

Studies of mammalian fertilization progressed very slowly in the beginning because of difficulties in obtaining a large quantity of fully mature eggs at one time. With progression of techniques to collect and handle eggs and spermatozoa, research in mammalian fertilization advanced rapidly. Today, far more papers are published on mammalian gametes and fertilization than those of all other animals combined. The development of assisted fertilization and related technologies revolutionized basic research as well as human reproductive medicine and animal husbandry. Reproduction is fundamental to human and animal lives. The author lists a few subjects of his personal interest for further development of basic and applied research of gametes and fertilization. Each reader will probably have more exciting subjects of future investigation.     

ENDOSCOPIC ULTRASONOGRAPHY FOR THE DIAGNOSIS OF INTRATHORACIC LESIONS IN TWO DOGS

Endoscopic ultrasound was developed initially in humans to overcome limitations of conventional ultrasound in examining certain internal organs due to intervening bone or air-filled structures. Endoscopic ultrasound has been used most widely in investigation of the gastrointestinal tract in humans, but many intrathoracic applications as well as endoscopic ultrasound-guided techniques have recently been described. Mediastinal and pulmonary structures can be examined with endoscopic ultrasound since a high frequency ultrasound probe can be brought into close contact with the areas of interest via a transesophageal approach. The purpose of this report is to describe the application of endoscopic ultrasound as an aid in the diagnosis of intrathoracic disease in the dog. Two dogs, one with a history of prior esophageal foreign body extraction, the other with apathy, weakness and dyspnea were referred for further investigation. Both dogs had caudal intrathoracic soft tissue opacities diagnosed radiographically, but their origin and nature were difficult to determine. Conventional ultrasound was limiting in both dogs due to their location and superimposition of gas-filled structures. With endosonography lesions were characterized more completely. We have found endoscopic ultrasound to be an elegant diagnostic tool for the investigation of radiographically detected intrathoracic lesions in the dog whose origins are difficult to determine or do not lend themselves to investigation by conventional ultrasound. Endoscopic ultrasound provides valuable diagnostic information complementary to that provided radiographically which aids in therapeutic planning. Endoscopic ultrasound was also more sensitive for detecting mediastinal lymphadenomegaly than radiography in one of the dogs. An additional advantage of endoscopic ultrasound is the fact that US-guided tissue sampling can be performed during the examination.     

Quantification of methane emitted by ruminants: a review of methods

The contribution of greenhouse gas (GHG) emissions from ruminant production systems varies between countries and between regions within individual countries. The appropriate quantification of GHG emissions, specifically methane (CH₄), has raised questions about the correct reporting of GHG inventories and, perhaps more importantly, how best to mitigate CH₄ emissions. This review documents existing methods and methodologies to measure and estimate CH₄ emissions from ruminant animals and the manure produced therein over various scales and conditions. Measurements of CH₄ have frequently been conducted in research settings using classical methodologies developed for bioenergetic purposes, such as gas exchange techniques (respiration chambers, headboxes). While very precise, these techniques are limited to research settings as they are expensive, labor-intensive, and applicable only to a few animals. Head-stalls, such as the GreenFeed system, have been used to measure expired CH₄ for individual animals housed alone or in groups in confinement or grazing. This technique requires frequent animal visitation over the diurnal measurement period and an adequate number of collection days. The tracer gas technique can be used to measure CH₄ from individual animals housed outdoors, as there is a need to ensure low background concentrations. Micrometeorological techniques (e.g., open-path lasers) can measure CH₄ emissions over larger areas and many animals, but limitations exist, including the need to measure over more extended periods. Measurement of CH₄ emissions from manure depends on the type of storage, animal housing, CH₄ concentration inside and outside the boundaries of the area of interest, and ventilation rate, which is likely the variable that contributes the greatest to measurement uncertainty. For large-scale areas, aircraft, drones, and satellites have been used in association with the tracer flux method, inverse modeling, imagery, and LiDAR (Light Detection and Ranging), but research is lagging in validating these methods. Bottom-up approaches to estimating CH₄ emissions rely on empirical or mechanistic modeling to quantify the contribution of individual sources (enteric and manure). In contrast, top-down approaches estimate the amount of CH₄ in the atmosphere using spatial and temporal models to account for transportation from an emitter to an observation point. While these two estimation approaches rarely agree, they help identify knowledge gaps and research requirements in practice.     

Considerations for analysis of time-to-event outcomes subject to competing risks in veterinary clinical studies

In veterinary medicine, prospective clinical trials are increasingly utilized to address questions regarding effectiveness of therapies and patient prognosis. A large number of these trials involve time-to-event (TTE) endpoints, which require special methods of analysis to handle data in which not all subjects are observed to have the event of interest. Analyses and interpretation of the results can be further complicated when an endpoint of interest is not observed in some patients because they incur a competing risk, such as death from an unrelated cause. Competing risks have been the source of confusion in many epidemiologic analyses leading to the potential for misinterpretation. In this article, we review key considerations for the TTE analysis in the setting of competing risks. We briefly review standard TTE tools, namely Kaplan–Meier survival curves and Cox regression. In the setting of outcomes with competing risks, we provide guidance on the appropriate analysis techniques, such as cumulative incidence curves, to estimate the risk of an event of interest. We also describe a common pitfall of treating competing risks as censoring in Kaplan–Meier survival curve analysis, which can overestimate the event rate of interest. We describe two common regression methods that examine associated risk factors in the presence of competing risks and highlight the different research questions these methods address. This article provides an introductory overview and illustrates concepts with examples from veterinary trials and with example data sets.     

Troponin--a new marker in the diagnostics of muscle diseases in animals

The dysfunction of muscles, especially that of the cardiac muscle, is one of the most dangerous for the life pathological states. The determination of biochemical indexes such as AST, ALT, CK, LDH, mioglobin, etc., which has been used so far in animals is not a sufficient diagnostic method. Therefore, new markers, levels of which could reflect the state of a patient more precisely, have been sought. Troponin, a protein found in skeletal and cardiac muscles only, has been considered a reliable index of myocardial ischemia in animals, especially in dogs. Its diagnostic properties have appeared to be a valuable complementation of the other diagnostic methods and thus could have gained a lot of veterinary practitioners interest.