Objective The main aim of this pilot study was to assess the feasibility of spinal neuronavigation for plate fixation of lumbar vertebrae in miniature breed dogs using a surgical navigation system in combination with a custom-made reference array. Study Design This was an experimental cadaveric study in five miniature breed dogs. Methods A 4-hole locking plate with four 2.0-mm locking screws was placed on two adjacent lumbar vertebrae using a neuronavigation system consisting of a mobile cone beam computed tomography linked to a navigation system. The procedure was performed by a novice surgeon. The plate and screw positions were assessed for surgical safety using predefined criteria. Surgical accuracy was determined by the deviation of entry and exit points between pre- and postoperative images. Results A total of five plates and 20 screws were placed. In 85% (17/20), screws were placed appropriately. The median entry point deviation was 1.8 mm (range: 0.3-3.7) and the median exit point deviation was 1.6 mm (range: 0.6-5). Conclusion Achievement of surgical accuracy in the placement of screws for fixation of lumbar vertebral plates in small breed dogs using neuronavigation with a custom-made reference array by a novice surgeon resulted in surgical safe plate placement in four of the five cadavers. Therefore, we judge the method as promising, however, further studies are necessary to allow the transfer of image-guided navigation for lumbar plate fixation into the clinic.

AbstractBackgroundChanges in the brain can affect the flow velocity of cerebrospinal fluid (CSF). In humans, the flow velocity of CSF is not only altered by disease but also by age and sex. Such influences are not known in dogs.HypothesisPeak flow velocity of CSF in dogs is associated with body weight, age, and sex.AnimalsPeak flow velocity of CSF was measured in 32 client‐owned dogs of different breeds, age, and sex.MethodsPeak flow velocity of CSF was determined by phase‐contrast magnetic resonance imaging (PC‐MRI) at the mesencephalic aqueduct, foramen magnum (FM), and second cervical vertebral body (C2). Dogs were grouped according to body weight, age, and sex. Flow velocity of CSF was compared between groups using linear regression models.ResultsDogs with body weight >20 kg had higher CSF peak velocity compared with dogs <10 kg within the ventral and dorsal subarachnoid space (SAS) at the FM (P = .02 and P = .01, respectively), as well as in the ventral and dorsal SAS at C2 (P = .005 and P = .005, respectively). Dogs ≤2 years of age had significantly higher CSF peak flow velocity at the ventral SAS of the FM (P = .05). Females had significantly lower CSF peak flow velocity within the ventral SAS of FM (P = .04).ConclusionBody weight, age, and sex influence CSF peak flow velocity in dogs. These factors need to be considered in dogs when CSF flow is quantitatively assessed.

(1) Background: Intervertebral disc extrusion may be accompanied by extensive epidural hemorrhage (EEH) and result in spinal cord compression. EEH is more commonly seen in French Bulldogs compared to other breeds. The majority of French Bulldogs have lumbar intervertebral disc extrusion, but it is unclear if there is an association between the site of thoracolumbar disc extrusion and EEH. This retrospective study’s aim was to investigate the association and prevalence between the site of thoracolumbar intervertebral disc extrusion and EEH in French Bulldogs. (2) Methods: Thoracolumbar MRI of French Bulldogs was examined for the site of intervertebral disc extrusion and the presence, distribution, and extent of EEH. (3) Results: In 148 French Bulldogs with thoracolumbar intervertebral disc extrusion, the most common location was L4/L5 (22%), followed by L3/L4 (20%) and T13/L1 (15%), and 70.3% had EEH. The highest incidence of EEH across all thoracolumbar sites was seen at L1/L2 (84.2%), followed by L5/L6 (81.3%) and L2/L3 (72.2%). The incidence of EEH was 70.5% across all lumbar sites and 66.9% for all thoracic sites. (4) Conclusion: In this population of French Bulldogs, the prevalence of lumbar disc extrusion was high, and 70.3% had EEH. There was no significant difference between the site of thoracolumbar intervertebral disc extrusion and EEH.

Canine and human brain tumours exhibit similar incidence rates and prognoses. Recent studies have demonstrated that extracellular vesicles derived from human patients (PDEVs) can be loaded with contrast agents and exhibit tumour tropism in murine models. We showed in a previous study that gadolinium-labelled EVs derived from canine gliomas (cPDEVs) can selectively targets murine glioblastoma cells in animal models. As a further step, we investigated the potential heterologous and cross-species tumour tropism of cPDEVs with brain tumours. With the perspective of imminent clinical application as both markers and drug delivery tools, we have successfully established the isolation protocol for cPDEVs and confirmed the aseptic conditions of the procedure and therefore the sterility of the isolated EVs. To assess the functionality of cPDEVs as drug delivery tool, they were loaded with indocyanine green (ICG) and injected into murine models of cancer for in vivo fluorescence biodistribution studies. Biodistribution analysis in mice revealed that ICG-loaded cPDEVs injected into murine models of subcutaneous tumours accumulated exclusively in the neoplastic tissue, even when evaluated 24 h post-injection, thus showing the cross-species and heterologous selective tumour tropism of the nanoparticles. With these tests, we have established a safe protocol for isolating and loading autologous cPDEVs with various markers, thereby paving the way for the clinical testing phase. These significant findings suggest the potential use of cPDEVs as a theranostic tool in the management of canine brain tumours, with promising implications for translational medicine applications in the future.

Anesthesia for magnetic resonance imaging (MRI) and computed tomography (CT) requires special considerations. The environment with the magnet and the ionizing radiation poses challenges for the medical staff and the handling of the patient. Artifacts that can compromise image quality, mimic pathologic findings, and lead to prolongation of anesthesia times due to repeat examinations must be avoided. Depending on the patient's condition (state of consciousness, anesthesia risk) and the available technical MRI or CT equipment, the type of modality and the duration of the examination play a decisive role in the method of immobilization, anesthesia, maintenance, as well as accessibility to the patient and ensuring the safety of medical personnel and patients. Ferromagnetic materials may severely compromise the homogeneity of the magnetic field and not only lead to so-called susceptibility artifacts, but also pose a high safety risk to staff and patients. Reducing respiratory movements as a result of optimized positioning or controlled apnea phases can minimize respiratory-related artifacts. While positive pressure ventilation can reduce anesthesia-induced atelectasis and optimize diagnostic assessment of the lungs, increased inspiratory oxygen concentration results in a significant signal increase in the cerebrospinal fluid of the CSF suppression sequence. These factors, as well as the location of the examination room and, depending on the modality and available equipment, limited accessibility to the patient and noise exposure, must be considered into the overall anesthesia planning process. Regarding contrast agent administration, it is imperative to review predisposing factors and adverse side effects in the perioperative evaluation for anesthesia in MRI and CT. An emergency plan should be known by the entire MRI team. Several mechanical and clinical methods are available to the anesthesiologist and can help optimize clinical monitoring, which can be severely limited, and ensure the safety of staff and patients.

Intravascular lymphoma (IVL) is characterized by the proliferation of large malignant lymphocytes within the lumen of blood vessels. This retrospective, multi-center, case series study aimed to describe the MRI features of confirmed central nervous system IVL in dogs and compare them with histopathological findings. Medical record databases from seven veterinary centers were searched for cases of histologically confirmed IVL. Dogs were included if an MRI was performed. The MRI studies and histopathology samples were reviewed to compare the MRI changes with the histopathological findings. Twelve dogs met the inclusion criteria (12 brains and three spinal cords). Imaging of the brains revealed multifocal T2-weighted/FLAIR hyperintense and T1-weighted iso-hypointense lesions, with variable contrast enhancement; areas of abnormal diffusion both in arterial and venous territories in diffusion-weighted imaging; and meningeal enhancement. On gradient echo images (GRE), the changes comprised tubular susceptibility artifacts, consistent with the "susceptibility vessel sign", and additional variably sized/shaped intraparenchymal susceptibility artifacts. Spinal cord lesions presented as fusiform T2-weighted hyperintensities with scattered susceptibility artifacts on GRE and variable parenchymal and meningeal contrast enhancement. On histopathology, subarachnoid hemorrhages and neuroparenchymal areas of edema and necrosis, with or without hemorrhage, indicating ischemic and hemorrhagic infarctions, were found. These lesions were concurrent with severely dilated meningeal and parenchymal arteries and veins plugged by neoplastic lymphocytes and fibrin. Due to the unique angiocentric distribution of IVL, ischemic and hemorrhagic infarcts of variable chronicity affecting both the arterial and venous territories associated with thrombi formation can be detected on MRI.

Objectives The aim of this study was to evaluate the association between meningeal enhancement (MgE) and cerebrospinal fluid (CSF) analysis results, their individual association with bacteriology results from affected ear samples and whether these test results influenced clinicians' therapeutic choice in cats with otitis media and interna (OMI). Methods This was a multicentre retrospective study carried out over an 8-year period. Cats diagnosed with OMI, with or without a nasopharyngeal polyp, leading to peripheral vestibular signs were included. Only cats for which MRI with postcontrast T1-weighted sequences and CSF analyses available were included. Cats with intra-axial MRI lesions or empyema were excluded. Results Fifty-eight cats met the inclusion criteria. MgE was reported in 26/58 cases, of which nine had an abnormal CSF result (increased total nucleated cell count [TNCC] or total protein); 32/58 cases had no MgE, of which 10 showed abnormal CSF results. There was no association between bacteriology results (external ear canal or bulla) and MgE or abnormal CSF results. CSF abnormalities were statistically significantly more common in acute cases (n = 16/37) than in chronic cases (n = 3/21; Fischer's test P = 0.04). Prednisolone was prescribed in 10/16 cases with increased TNCC. Among the 42 cases with normal TNCC, 15 received prednisolone and 13 received non-steroidal anti-inflammatory drugs. Various antimicrobial drugs were prescribed in 53/58 cats. Duration of antimicrobial treatment was similar, regardless of positive bacterial culture (5.58 vs 4.22 weeks), abnormal CSF (5.83 vs 4.76 weeks) or MgE (5.33 vs 4.90 weeks). Conclusions and relevance No association was found between the CSF and MgE results. Furthermore, no association was found between MgE, CSF or bacteriology findings. In addition, abnormal CSF results might lead the clinician to treat with corticosteroids, but they did not have any impact on duration of antimicrobial treatment. CSF abnormalities were seen significantly less frequently in chronic cases. The outcome tended to be poorer when MgE was detected on MRI.

Background: Hyperthyroidism is the most frequent endocrinopathy in older cats.To date, there is no consensus on how to best calculate the dose of radioiodine to administer to hyperthyroid cats.Aim: The goals of this study were to compare thyroid function, renal function, and survival time between hyperthyroid cats receiving a fixed dose of radioiodine and those receiving an individualized dose calculated using a clinical scoring system.Methods: Medical records of 110 cats treated with radioiodine therapy at the University of Bern between 2010 and 2020 were reviewed.Thyroid function, renal function, and survival of cats treated with a fixed dose of radioiodine (2010-2015; n = 50) were compared to those of cats treated with an individualized dose (2015-2020; n = 60) at different time points after therapy.Results: Treatment with a fixed dose of radioiodine (mean = 168 ± 26 MBq) was associated with 69% of euthyroidism, 19% persistent hyperthyroidism, and 12% hypothyroidism, whereas treatment with an individualized dose (mean = 120 ± 30 MBq) led to 54% euthyroidism, 23% hyperthyroidism, and 23% hypothyroidism (p = 0.73).More than 12 months after treatment, the incidence of azotemia was comparable between cats treated with a fixed dose (37%) and those treated with an individualized dose (31%) (p = 0.77).No factors were found to be predictive of treatment failure (hypothyroidism or hyperthyroidism) after therapy.Median survival time after radioiodine therapy was 44 months.In a multivariate analysis, persistent hyperthyroidism was the only variable independently associated with a shorter survival time (HR = 6.24, p = 0.002). Conclusion:The method of calculating the dose of radioiodine (fixed vs. individualized) to treat feline hyperthyroidism does not appear to be decisive for posttreatment thyroid function, renal function, or survival.

Disproportionate dwarfism phenotypes represent a heterogeneous subset of skeletal dysplasias and have been described in many species including humans and dogs. In this study, we investigated Vizsla dogs that were affected by disproportionate dwarfism that we propose to designate as skeletal dysplasia 3 (SD3). The most striking skeletal changes comprised a marked shortening and deformation of the humerus and femur. An extended pedigree with six affected dogs suggested autosomal recessive inheritance. Combined linkage and homozygosity mapping localized a potential genetic defect to a ~4 Mb interval on chromosome 33. We sequenced the genome of an affected dog, and comparison with 926 control genomes revealed a single, private protein-changing variant in the critical interval, PCYT1A:XM_038583131.1:c.673T>C, predicted to cause an exchange of a highly conserved amino acid, XP_038439059.1:p.(Y225H). We observed perfect co-segregation of the genotypes with the phenotype in the studied family. When genotyping additional Vizslas, we encountered a single dog with disproportionate dwarfism that did not carry the mutant PCYT1A allele, which we hypothesize was due to heterogeneity. In the remaining 130 dogs, we observed perfect genotype–phenotype association, and none of the unaffected dogs were homozygous for the mutant PCYT1A allele. PCYT1A loss-of-function variants cause spondylometaphyseal dysplasia with cone–rod dystrophy (SMD-CRD) in humans. The skeletal changes in Vizslas were comparable to human patients. So far, no ocular phenotype has been recognized in dwarf Vizslas. We propose the PCYT1A missense variant as a candidate causative variant for SD3. Our data facilitate genetic testing of Vizslas to prevent the unintentional breeding of further affected puppies.

Hemangiosarcoma is the most common metastatic tumor involving the brain in dogs but detailed published descriptions of the magnetic resonance imaging (MRI) features are lacking. The objective of this multi-center, retrospective case series study was to describe MRI characteristics of canine hemangiosarcoma affecting the central nervous system (CNS). Medical records of seven referral institutions were retrospectively reviewed. Dogs were included if they had a histopathologically confirmed diagnosis of hemangiosarcoma affecting the CNS and undergone an MRI of the brain and/or vertebral column. Lesions were independently evaluated by two observers. Twenty dogs met the inclusion criteria and one dog had both intracranial and intramedullary hemangiosarcoma. Consistent MRI features included heterogeneous (17/21) lesions in all sequences with mainly mixed signal intensity (12/21), presence of susceptibility artifact on T2*w (15/16), associated moderate to severe perilesional edema (21/21), and moderate to strong (20/21) heterogeneous (14/21) or ring-like (6/21) contrast enhancement. Intracranial hemangiosarcoma was frequently multiple and intra-axial, affecting consistently the telencephalon and no differences in MRI features were found between primary and metastatic hemangiosarcoma. This is the first MRI description of primary intracranial hemangiosarcoma and primary intracranial epithelioid hemangiosarcoma. Vertebral hemangiosarcomas were segmental poorly marginated polyostotic and highly aggressive lesions invading the thoracic vertebral canal and paraspinal tissues. Epidural hemangiosarcomas were single and well-marginated lesions in the thoracolumbar and/or lumbar region. Intramedullary hemangiosarcomas were cervical, metastatic in origin, and frequently (3/4) accompanied by intracranial lesions. These described MRI features will aid early identification of hemangiosarcoma guiding subsequent diagnostics and therapeutics.

Abstract Background Lymphoma is the most common spinal cord neoplasm and second most common intracranial tumor in cats, but description of specific magnetic resonance imaging (MRI) features is lacking. Objective Describe the clinical and MRI features of lymphoma affecting the central (CNS) or peripheral (PNS) nervous system or both in cats. Animals Thirty‐one cats with confirmed cytological or histopathological diagnosis or both of lymphoma involving the CNS or PNS or both, and MRI findings of the lesions. Methods Multicenter retrospective descriptive study. Signalment and medical information were recorded. Magnetic resonance imaging findings were reviewed by 3 observers following a list of predefined criteria and consensus was sought. Frequency distributions of the different categorical data were reported. Results Median duration of clinical signs at time of presentation was 14 days (range, 1‐90). Neurological examination was abnormal in 30/31 cats. On MRI, lesions affecting the CNS were diagnosed in 18/31 cats, lesions in both CNS and PNS in 12/31, and lesions in the PNS only in 1/31. Intracranial lesions were diagnosed in 22 cats (extra‐axial, 7/22; intra‐axial, 2/22; mixed, 13/22), and spinal lesions were diagnosed in 12 (6/12 involving the conus medullaris and lumbosacral plexuses). Infiltration of adjacent extra‐neural tissue was present in 11/31 cases. Contrast enhancement was seen in all lesions, being marked in 25/30. Meningeal enhancement was present in all but 2 cases. Several distinct MRI patterns were observed. Conclusions and Clinical Importance Nervous system lymphoma in cats has a wide range of MRI features, of which none is pathognomonic. However, together with clinical data and cerebrospinal fluid (CSF) analysis, MRI may provide a strong tentative antemortem diagnosis.

The aim of the present study was to evaluate the use of a novel intraoperative cone-beam computed tomography (CBCT)-based automated registration system for frameless stereotactic brain biopsy in companion animals. An experimental cadaveric study evaluated thalamic and piriform lobe target site needle placement error in three dogs and three cats without a history of intracranial disease. Diagnostic accuracy and diagnostic yield were prospectively evaluated in twenty-four client-owned dogs and four cats with intracranial disease. Twenty-one procedures were performed post mortem (eighteen dogs and three cats), and seven biopsy procedures were performed in alive patients (six dogs and one cat). Procedural duration was evaluated in ten post mortem and four living patients. Outcome was evaluated in six dogs and one cat. In dogs, the calculated median needle placement error was 1.8 mm (range 0.71-2.84 mm) and 1.53 mm (range 1.45-1.99 mm) for piriform lobe and thalamus target sites, respectively. In cats, the calculated median needle placement error was 0.79 mm (range 0.6-1.91 mm) for the piriform lobe target site and 1.29 mm (range 0.47-2.69 mm) for the thalamic target site. The diagnostic yield was 96.4% (95% CI 0.81-0.99), the diagnostic accuracy was 94.4% (95% CI 0.72-0.99). Median total procedural duration for post mortem biopsies was 57.5 min (range 41-69 min). Median total procedural duration for intra vitam biopsies was 122.5 min (range 103-136 min). Three dogs were discharged 1 day after biopsy and one dog after 6 days. Two dogs and one cat were euthanized 24 and 48 h after biopsy. Intraoperative CBCT-based automated image registration for frameless stereotactic biopsies in companion animals is capable of providing diagnostic brain biopsy specimens independent of skull size and morphology with diagnostic yield and accuracy comparable to published values for diverse frameless and frame-based stereotaxy systems used in veterinary medicine. Duration of the procedure is not negatively affected and within the published range with other systems. Mobile intraoperative CBCT-based registration combined with neuronavigation delivers diagnostic brain biopsies in companion animals.

Gliomas of the brain may appear as expansile ring-enhancing masses in MRI studies, mimicking the appearance of intra-axial abscesses. The aims of this study were to compare the MRI features of ring-enhancing gliomas and intra-axial brain abscesses in dogs and cats and to identify the characteristics that might help differentiate them. For this multicenter, retrospective, and observational study, the inclusion criteria were as follows: (a) a definitive diagnosis of glioma or abscess based on cytological or histopathological examination following CSF collection or surgical biopsy/necropsy, respectively; (b) MRI study performed with a high- or low-field MRI scanner, including a same plane T1W pre- and postcontrast, a T2W and a T2 FLAIR sequence in at least one plane. If available, delayed T1W postcontrast, T2*W GE, DWI/ADC, and SWI sequences were also evaluated. Sixteen patients were diagnosed with ring-enhancing gliomas, and 15 were diagnosed with intra-axial abscesses. A homogenous signal on T1W (P = 0.049) and T2W (P = 0.042) sequences, a T2W (P = 0.005) or T2*W GE (P = 0.046) peripheral hypointense halo, and an even enhancing capsule (P = 0.002) were significantly associated with brain abscesses. A progressive central enhancement on delayed T1W postcontrast sequences was correlated with ring-enhancing gliomas (P = 0.009). The combination of the following features was suggestive of brain abscess: homogeneous T1W or T2W signal intensity, a T2W or T2*W GE peripheral hypointense halo and an evenly enhancing capsule. Central progression of enhancement on delayed T1W postcontrast sequences was suggestive of glioma.

In-depth understanding of pathophysiological processes occurring in the vasculature of the equine distal limb is of great importance to improve both diagnostic and therapeutic approaches to diseases. To gain further insights, a model allowing high-resolution 3D-visualization of the vasculature is necessary. This pilot study evaluated the feasibility of restoring vascular perfusion in frozen-thawed distal equine cadaver limbs without prior preparation using computer tomographic imaging (CT). Five frozen-thawed, radiographically normal forelimbs were perfused with a lipophilic contrast agent through the median artery and radial vein in three phases (arterial, venous, and arterial-venous combined (AVC) dynamic). For comparison, one additional limb was perfused with a hydrosoluble contrast agent. The CT-studies (16-slice MDCT, 140 kV, 200 mA, 2 mm slice thickness, 1 mm increment, pitch 0.688) were evaluated at 11 specified regions for visualization of the vasculature and presence of artifacts or anatomic variations. The protocol used in this study proved to be feasible and provided good visualization (93.1%) of vasculature with low rates of artifacts. During the different phases, vascular visualization was similar, but while filling defects decreased in the later phases, extravasation worsened in the 2 limbs where it was observed. Subjectively, the best quality of angiographic images was achieved during the AVC dynamic phase. Perfusion with hydrosoluble contrast resulted in significantly lower vascular visualization (74.0%) and higher artifact rates. This study shows that reperfusion of frozen-thawed equine distal limbs with a lipophilic contrast agent allows for high-quality 3D-visualization of the vasculature and may serve as a model for in situ vascular evaluation in the future.

The volumes of equine teeth may change considerably over time for several reasons including domestication, routine dental floating, and the hypsodont and anelodont nature of the teeth. Cone beam computed tomography (CBCT) of the head is routinely performed in standing horses and, in this proof of concept study, the feasibility of measuring tooth volume from CBCT datasets was determined. The CBCT images of 5 equine cadaver cheek teeth were segmented with a software 3-dimensional (3D) Slicer using a predefined protocol, corrected manually, and re-assembled into a 3D model. Individual tooth volume (V-S) was calculated from the model. After extraction, the volumes were also measured using the "gold-standard" water displacement method (V-W) for comparison. The V-S of 77 teeth ranged from 7114 to 42,300 mm(3) which strongly correlated with V-W (r = 0.99)(,) and on average V-S was 6.1% less than V-W. There was no significant difference in V-S between the right and left arcades in individual animals. Maxillary cheek tooth volume was on average 40% larger than it was for mandibular counterparts. Semi-automatic image segmentation of equine cheek teeth from CBCT data is feasible and accurate but requires some manual intervention. This preliminary study provides initial data on the volume of equine cheek teeth and creates new possibilities for future in vivo studies.

Abstract Background Cerebrospinal fluid (CSF) flow in disease has been investigated with two‐dimensional (2D) phase‐contrast magnetic resonance imaging (PC‐MRI) in humans. Despite similar diseases occurring in dogs, PC‐MRI is not routinely performed and CSF flow and its association with diseases is poorly understood. Objectives To adapt 2D and four‐dimensional (4D) PC‐MRI to dogs and to apply them in a group of neurologically healthy dogs. Animals Six adult Beagle dogs of a research colony. Methods Prospective, experimental study. Sequences were first optimized on a phantom mimicking small CSF spaces and low velocity flow. Then, 4D PC‐MRI and 2D PC‐MRI at the level of the mesencephalic aqueduct, foramen magnum (FM), and cervical spine were performed. Results CSF displayed a bidirectional flow pattern on 2D PC‐MRI at each location. Mean peak velocity (and range) in cm/s was 0.92 (0.51‐2.08) within the mesencephalic aqueduct, 1.84 (0.89‐2.73) and 1.17 (0.75‐1.8) in the ventral and dorsal subarachnoid space (SAS) at the FM, and 2.03 (range 1.1‐3.0) and 1.27 (range 0.96‐1.82) within the ventral and dorsal SAS of the cervical spine. With 4D PC‐MRI, flow velocities of >3 cm/s were visualized in the phantom, but no flow data were obtained in dogs. Conclusion Peak flow velocities were measured with 2D PC‐MRI at all 3 locations and slower velocities were recorded in healthy Beagle dogs compared to humans. These values serve as baseline for future applications. The current technical settings did not allow measurement of CSF flow in Beagle dogs by 4D PC‐MRI.

Epilepsy is a common neurologic disease frequently encountered by small animal practitioners. The disease comprises a multiplicity of clinical presentations and etiologies and often necessitates a comprehensive as well as cost-intensive diagnostic workup. This is mandatory in order to be able to diagnose or exclude a metabolic cause of the seizures and to distinguish between idiopathic and structural epilepsy. The examination by means of magnetic resonance imaging (MRI) represents a central component of the diagnostic workup, which in turn has essential effects on treatment and prognosis. In order to achieve standardized examination and comparable results, it is of utmost importance to use defined MRI protocols. Accordingly, communication and interaction between clinical institutions may be facilitated and as of yet undetected structural changes might be recorded in future MRI techniques. This review article sets particularly emphasis on the definition and classification of epilepsy as well as its diagnostic imaging procedures and refers to statistics and specialists' recommendations for the diagnostic workup in dogs.

Abstract Background The diagnosis of idiopathic epilepsy (IE) in dogs is based on exclusion of other potential causes of seizures. Recently, a novel magnetic resonance imaging (MRI) sequence that utilizes a variant of the rotary saturation approach has been suggested to detect weak transient magnetic field oscillations generated by neuronal currents in humans with epilepsy. Hypothesis/Objectives Effects on the magnetic field evoked by intrinsic epileptic activity can be detected by MRI in the canine brain. As proof‐of‐concept, the novel MRI sequence to detect neuronal currents was applied in dogs. Animals Twelve dogs with IE and 5 control dogs without a history of epileptic seizures were examined. Methods Prospective case‐control study as proof‐of‐concept. All dogs underwent a clinical neurological examination, scalp electroencephalography, cerebrospinal fluid analysis, and MRI. The MRI examination included a spin‐locking (SL) experiment applying a low‐power on‐resonance radiofrequency pulse in a predefined frequency domain in the range of oscillations generated by the epileptogenic tissue. Results In 11 of 12 dogs with IE, rotary saturation effects were detected by the MRI sequence. Four of 5 control dogs did not show rotary saturation effects. One control dog with a diagnosis of neuronal ceroid lipofuscinosis had SL‐related effects, but did not have epileptic seizures clinically. Conclusions and Clinical Importance The proposed MRI method detected neuronal currents in dogs with epileptic seizures and represents a potential new line of research to investigate neuronal currents possibly related to IE in dogs.

ZusammenfassungEpilepsie ist eine neurologische Erkrankung, die dem Kleintierpraktiker im klinischen Alltag häufig begegnet. Die Erkrankung umfasst eine Vielzahl klinischer Ausprägungen und Ätiologien und die klinische Aufarbeitung bedarf in vielen Fällen einer kostenaufwendigen und umfangreichen Diagnostik. Diese ist notwendig, um eine metabolische Ursache für die Krampfanfälle festzustellen oder auszuschließen bzw. zwischen idiopathischer und struktureller Epilepsie unterscheiden zu können. Für die Klassifikation der Epilepsie ist die Untersuchung mittels Magnetresonanztomografie (MRT) ein zentraler Bestandteil der Diagnosefindung, die sich entscheidend auf Therapie und Prognose auswirkt. Die Standardisierung von MRT-Protokollen hat große Bedeutung, um eine einheitliche Untersuchung und vergleichbare Ergebnisse zu erzielen. Dies kann die Kommunikation und Interaktion zwischen klinischen Einrichtungen erleichtern und die Möglichkeit bieten, noch unerkannte strukturelle Veränderungen im MRT zu erfassen. Dieser Übersichtsartikel beschäftigt sich im Zentralen mit der Definition und Klassifikation der Epilepsie sowie der bildgebenden Diagnostik der Epilepsie beim Hund und nimmt Bezug auf Statistiken und Empfehlungen von Spezialisten zur klinischen Fallaufarbeitung.

OBJECTIVE To report on the feasibility, indications, and diagnostic yield of cone beam computed tomography (CBCT) of horses' extremities performed under standing sedation. STUDY DESIGN Retrospective clinical case series. SAMPLE POPULATION Fifty-nine CBCT examinations in 58 horses. METHODS Examinations were categorized for indications for CBCT dependent on a suspicion, presence, or absence of a diagnosis prior to CBCT. The number of acquisitions per examination, total time for the examination, diagnostic score of each acquisition (diagnostic, diagnostic-compromised, nondiagnostic), and additional diagnostic information regarding preexisting diagnostic information were recorded. RESULTS Three (median) acquisitions were performed per examination in a median study time of 14 minutes. In 24 of 33 cases with a suspected diagnosis, this diagnosis was confirmed or definitively refuted; in seven of 33 cases, the suspected diagnosis was refuted without a new diagnosis; and, in two of 33 cases, the suspected diagnosis could not be confirmed nor could a new diagnosis be made. In five of nine cases without a preexisting diagnosis, a diagnosis was established. In 16 cases with a diagnosis prior to CBCT, additional information was recorded, or a surgical plan was prepared. In 14 of 18 cases in which additional contrast techniques were used, additional information was gained. CONCLUSION Standing CBCT of the horses' extremities is feasible and can produce diagnostic information in a timely fashion. CLINICAL SIGNIFICANCE The results provide evidence of the practicality and diagnostic potential of standing CBCT of horses' extremities.