The spine

Computed tomography (CT) and magnetic resonance imaging (MRI) are becoming increasingly accessible in veterinary medicine. Because of their ability to image the bony spine and spinal cord noninvasively and with exceptional detail, these techniques have revolutionized the way spinal disorders are diagnosed in both people and animals. Although the veterinary literature on this topic is limited, interpretation of CT and MR images of the spine are facilitated by the similarity of human and animal disease processes. This article provides an overview of imaging strategies, normal anatomy, and the CT and MRI features of degenerative, infectious, neoplastic, and vascular diseases of the spine.     

INVITED REVIEW—IMAGE REGISTRATION IN VETERINARY RADIATION ONCOLOGY: INDICATIONS,IMPLICATIONS, AND FUTURE ADVANCES

The field of veterinary radiation therapy (RT) has gained substantial momentum in recent decades with significant advances in conformal treatment planning, image‐guided radiation therapy (IGRT), and intensity‐modulated (IMRT) techniques. At the root of these advancements lie improvements in tumor imaging, image alignment (registration), target volume delineation, and identification of critical structures. Image registration has been widely used to combine information from multimodality images such as computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) to improve the accuracy of radiation delivery and reliably identify tumor‐bearing areas. Many different techniques have been applied in image registration. This review provides an overview of medical image registration in RT and its applications in veterinary oncology. A summary of the most commonly used approaches in human and veterinary medicine is presented along with their current use in IGRT and adaptive radiation therapy (ART). It is important to realize that registration does not guarantee that target volumes, such as the gross tumor volume (GTV), are correctly identified on the image being registered, as limitations unique to registration algorithms exist. Research involving novel registration frameworks for automatic segmentation of tumor volumes is ongoing and comparative oncology programs offer a unique opportunity to test the efficacy of proposed algorithms.     

Zoo and wildlife medical education: a European perspective

Europe has a long and distinguished history in veterinary science and education, and it was here that the first professional investigations of pathological conditions in zoo animals took place. However, despite an increasing number of veterinarians working with wildlife, education in zoological and wildlife medicine has only recently become part of formal veterinary training at the undergraduate level. Consequently, current educational opportunities in zoological and wildlife medicine vary widely throughout Europe, both in availability and in composition. The need to establish agreed standards in education across Europe and to foster the mobility of students and teaching staff are reflected by international agreements such as the Bologna Treaty and the ERASMUS-SOCRATES program. Europe is also home to a number of voluntary professional organizations, such as the European Wildlife Disease Association and the European Association of Zoo and Wildlife Veterinarians, that actively promote the inclusion of zoological and wildlife medicine in veterinary education. Zoo and wildlife medicine is currently a veterinary specialization in Europe, but educational opportunities are likely to increase in availability in the future.     

Photodynamic therapy for companion animals with cancer.

Photodynamic therapy is an emerging form of cancer therapy in veterinary medicine, which capitalizes on a photochemical reaction to kill malignant cells. Photodynamic therapy has been used to successfully treat a variety of veterinary cancers, with documented efficacy similar to radiation therapy. However, equipment expense and availability of photosensitizer have limited the widespread use of photodynamic therapy by veterinarians.     

Trends in veterinary cancer imaging

With the recent advances in diagnostic imaging technology, cancer imaging in veterinary medicine has become more specific for disease diagnosis, more accurate for determining tumour margins and more sensitive for detecting metastatic disease. Ultrasound provides highly detailed images of parenchymal masses and infiltrative lesions while providing a means for aspiration or biopsy using real‐time image guidance. Computed tomography and magnetic resonance‐imaging techniques provide exquisite anatomical resolution that improves diagnostic accuracy, provides an accurate means of radiation or surgical treatment planning and a quantitative means for monitoring response to therapy. In addition to traditional anatomic imaging, new techniques are being developed for estimating functional parameters such as tumour perfusion, cell metabolism and gene expression. While conventional planar scintigraphy has been available for some time, newer nuclear imaging modalities such as positron emission tomography promise to further improve the accuracy of initial tumour diagnosis and staging and determination of response to therapy. Although many of these functional techniques are not yet clinically available, it is highly likely that some will be integrated into routine clinical practice in the near future.     

Occupational per-patient radiation dose from a conservative protocol for veterinary (18) F-fluorodeoxyglucose positron emission tomography

The occupational external radiation dose to human medical personnel from positron emission tomography (PET) radiopharmaceuticals has been documented, but to date no corresponding veterinary staff dose data are available. Electronic personal dosimeters (EPDs) were used in this study to measure the per-patient external radiation doses to veterinary staff using a PET/CT (PET combined with computed tomography) protocol in which the patient radiopharmaceutical dose was injected after anesthetic induction. Radiation doses were recorded for the nuclear medicine technologists, the on-duty anesthesiology technologist, and an occasional observer from 19 veterinary (18) F-fluorodeoxyglucose PET/CT studies. Patient mass range was 2.8 to 61.0 kg (22.3 kg mean) and injected activity averaged 6 MBq kg(-1) . The dose range received by nuclear medicine technologists per procedure was 0-30 μSv (9.1 μSv mean), by anesthetists 1-22 μSv (8.2 μSv mean), and by the observer 0-2 μSv (0.5 μSv mean). In both feline and canine studies, placement of the EPD on staff was a significant predictor of radiation dose. Additional significant predictors of staff radiation dose from canine studies included job position and injected activity. The per-patient occupational radiation doses to veterinary PET/CT technologists were slightly greater than those reported for human nuclear medicine PET/CT technologists, but were comparable to estimated radiation doses for nurses caring for nonambulatory human PET/CT patients. Efforts toward maintaining staff radiation doses as low as reasonably achievable (ALARA) will be important as veterinary PET/CT caseload increases.     

Photodynamic therapy for the treatment of intranasal tumors in 3 dogs and 1 cat

Three dogs and 1 cat with intranasal tumors were treated with pyropheophorbide-a-hexyl ether-based photodynamic therapy (PDT). PDT was well tolerated by all the animals, and no adverse effects from photosensitizer injection, such as cutaneous photosensitization, were observed. Facial swelling was observed in all animals after each PDT treatment but resolved spontaneously within 72 hours after treatment. All animals had a decrease in severity of epistaxis, frequency of sneezing, and amount of nasal discharge after PDT. Clinical signs were controlled for variable time, although long-term responses were comparable with radiation therapy in 2 animals. This small case series demonstrates another application for PDT in veterinary medicine. On the basis of these findings. further studies are warranted to define the role of PDT in the management of intranasal tumors in dogs and cats.     

Advanced imaging for veterinary cancer patients.

This article presents an update on the recent advances made in veterinary advanced imaging specifically with regard to cross-sectional modalities (CT and MRI) and nuclear medicine (positron emission tomography [PET] and PET/CT). A brief summary of technical improvements and a review of recent literature are included to provide an overview of the progress made in this important element of the practicing veterinary oncologist's repertoire. An in-depth summary of PET is also included to introduce the technical aspects and potential clinical and research applications of this novel imaging modality in veterinary medicine.     

Thrombolytic Therapy in Dogs and Cats

Objective: To review the thrombolytic agents most commonly used in humans, their mechanisms of action, potential uses, adverse effects, and reports of their use in dogs and cats.
Human data synthesis: Thrombolytic agents avaliable in human medicine include streptokinase, urokinase, tissueplasminogen activator (t-PA), single-chain urokinase plasma activator (scu-PA) and anisoylated plasminogen-strep-tokinase activator complex (APSAC). These agents were originally used for the management of proximal deep vein thrombosis and severe pulmonary embolism but more recently, use of these drugs has been extended to include the treatment of acute peripheral arterial disease, cerebrovascular disease (stroke) and acute coronary thrombosis. The most predictable side effect associated with the use of thrombolytic therapy is hemorrhage.
Veterinary data synthesis: Clinical experience with thrombolytic agents in small animals is limited to streptokinase and t-PA. It is possible, that as in humans, canine and feline patients with PTE and right ventricular dysfunction may benefit from thrombolytic therapy but there are no veterinary studies to support this theory to date. Successful use of streptokinase has been documented in a small number of canine patients with systemic thromboembolism. ⁶³ Thrombolytic therapy is relatively efficacious in cats with aortic thromboemboli but is associated with a high mortality rate. ^59,60,64 With regard to use of t-PA in veterinary medicine, the small number of animals treated with varying protocols makes it impossible to provide safe and effective dose recommendations at this time.
Conclusions: Future goals for thrombolytic therapy in veterinary medicine include determination of more specific clinical indications, as well as design of effective protocols that minimize mortality and morbidity.     

Equine external beam radiation therapy: Techniques and challenges

Radiation therapy is becoming increasingly more available and in demand for small animal veterinary cases. Although there is a demand for radiation therapy in large animal cases, there are certain limitations of external beam radiation therapy for horses that restrict treatment options. Currently, there are only five veterinary teaching hospitals in the United States where external beam radiation therapy can be performed on horses and other large animals. This is in contrast to the roughly 80 facilities, both academic and private, available for small animals. The goal of this commentary is to give a brief overview of external beam radiation therapy and highlight the steps involved, and the technical difficulties faced, while treating horses with external beam radiation therapy.     

Current status of food animal antidotes.

The availability of antidotes in veterinary medicine has been an issue for more than a decade. Antidotes are available for food animals through extralabel use, regulatory discretion, and compounding. There is little economic incentive for pharmaceutical companies to pursue approval of antidotes and other drug products that have a small market. In addition, human food safety concerns must be addressed when approving antidotes for use in food animals. This article provides a brief history of antidote availability, current mechanisms for procuring food animal antidotes, and availability of specific antidotes for use in food animals.     

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 for the assessment of acquired abdominal vascular diseases in small animals: A pictorial review

Advances in interventional radiology and surgical techniques now allow complex abdominal diseases to be more successfully treated in small animals. Abdominal vascular alterations, acquired as individual process or as complication of other lesions such as neoplasia, can be life‐threatening or at least greatly limit curative interventions of underlying diseases. Computed tomography (CT) and high‐definition ultrasonography are now readily available in veterinary referral centers. Yet, there is little information currently available on the use of these modalities for the diagnosis and characterization of these vascular alterations. The purpose of this article is to review the CT and ultrasonographic findings of acquired vascular diseases in the abdomen of dogs and cats, using both the veterinary and human medicine literature as references, and highlighting essential concepts through figures.     

Ophthalmic imaging.

The availability of advanced imaging modalities in veterinary medicine has greatly widened the diagnostic imaging capabilities possible.Ultrasonography provides a rapid noninvasive modality that provides detailed examination and resolution of the intraocular structures and soft tissues surrounding the orbit of opaque eyes.Ultrasonography is cost-effective and widely available to practitioners,referral centers, and academic institutions. In many areas,mobile specialist ultrasonographers are available to supplement the equipment and skills of the practitioner. The added strengths of CT and MRI lie in their cross-sectional capability and better image quality. Unfortunately, the cost of CT and MRI currently limits their availability to referral centers and academic institutions.Primarily because of financial considerations, CT is currently more widely available for evaluation of equine disorders than MRI. A thorough evaluation of the multiple images and an understanding of normal anatomy and abnormal tissue patterns are indicated to maximize the use of each modality. Unlike ultrasonography, which can be performed in awake horses, the costs and contraindications of general anesthesia in some critical patients should also be considered when using CT and MRI. Finally, imaging artifacts are frequently encountered with each of these modalities. Thus, a thorough understanding of the various types of artifacts that occur is important so as to avoid interpretation pitfalls.     

Only one medicine: the future of comparative medicine and clinical research

This article reviews the roots of comparative medicine and argues that during the 20th century it failed to realise its full potential. New opportunities arise from the growing availability of precise, minimally invasive, clinically compatible techniques, which enable us to benefit from the availability of spontaneous analogues of human disease in animals. Particularly with multifactorial diseases, these offer a unique blend of authenticity and acceptability. To realise the full benefits to both animals and humans, we need much closer alignment of human and veterinary clinical medicine.     

New drugs in veterinary dermatology.

This article discusses several different new drugs currently being used in dermatology. Most of the drugs discussed showed some promise as being a useful therapy in veterinary medicine, but a few have questionable efficacy (nonsedating antihistamines). The majority of these drugs have not had any pharmacokinetic or clinical trials conducted on them in small animals. Hopefully, in the future, more studies are funded so that we can determine the clinical therapeutical efficacy and appropriate doses for these drugs.     

COMPUTED TOMOGRAPHIC ANATOMY OF THE DISTAL EXTREMITY OF THE HORSE

X-ray computed tomography (CT) is an imaging tool that is becoming increasingly available for use in veterinary medicine. Advantages, including depiction of detailed cross-sectional anatomy, improved contrast resolution, and computer reformatting, make it a potentially valuable diagnostic technique. Veterinary application of CT has been primarily limited to use in small animals. Current reports describe the technique for use in the horse, but there are no published studies correlating serial CT images with equine cross-sectional anatomy. A study of the distal extremity of the horse was undertaken to facilitate interpretation of images produced using CT. Transverse CT images of the distal forelimb of equine cadavers were evaluated relative to gross anatomic dissection. Resolution of bone architecture in transverse plane images was satisfactory, but soft-tissue' resolution, although satisfactory for visualization of major structures, was relatively poor, probably due to lack of interposed fat and insufficient differences in physical density and atomic number. Thus it appears in the equine distal limb that CT may be most useful for evaluation of complex bone abnormalities.     

Use of complementary veterinary medicine in the geriatric horse.

The use of complementary and alternative veterinary medicine continues to grow within the veterinary community. As more clients seek out complementary and alternative medicine for their own health care, they begin to seek out these forms of therapy for their animals. For the equine practitioner, this includes those clients with geriatric animals. It is hoped that this article provides some insight into what conditions may be helped with CVM (complementary veterinary medicine) and when an equine practitioner may want to consider CVM as a form of therapy for the geriatric horse.