Clinical Presentation, MRI Characteristics, and Outcome of Conservative or Surgical Management of Spinal Epidural Empyema in 30 Dogs.

Spinal epidural empyema (SEE) represents a neurological emergency in veterinary medicine, but information on this condition is limited to date. This retrospective case series study describes the clinical and magnetic resonance imaging (MRI) features, and the outcome of conservative or surgical management of SEE in 30 dogs diagnosed with SEE from September 2015 to March 2020 at one referral neurology centre. The most frequent clinical sign was pain 28/30 (93%), and 22/30 (73%) showed neurological signs with ambulatory paraparesis/tetraparesis 15/30 (50%), monoparesis 1/30 (3.3%), non-ambulatory paraparesis 3/30 (10%), or paraplegia 3/30 (10%). MRI was valuable for the diagnosis and in the follow-up. In this group of dogs, 24/30 (80%) were conservatively treated and 6/30 (20%) were surgically treated. The outcome was considered favourable in all dogs: 20/30 (66.6%) achieved full recovery (3 surgically treated and 17 medically treated) and 10/30 (33.3%) dogs had an improvement in the neurological signs with residual ambulatory paresis (3 surgically treated and 7 medically treated). Surgical treatment showed better short-term (7 days) outcomes than medical treatment in non-ambulatory paraparetic or paraplegic dogs (33%). Nevertheless, this study suggests that a good recovery may be achieved with conservative treatment even for non-ambulatory or paraplegic dogs. Further prospective studies, with a standardised protocol of diagnostic tests and a homogeneous distribution of conservatively and surgically treated dogs, are needed to establish treatment guidelines.

Clinical and magnetic resonance imaging features, and pathological findings of spinal lymphoma in 27 cats.

This multicentric retrospective study describes the clinical and MRI features and pathological studies of spinal lymphoma in 27 cats. MRI characteristics and their possible correlations with histopathological findings were studied. The most frequent neurological signs were rapidly progressive paraparesis (62.9%) or paraplegia (22.2%). Bimodal age distribution was found with 40.7% of cats aged ≤2.5 years (63.6% of them FeLV positive), and 44.4% of cats aged ≥8 years (16.7% of them FeLV positive). Spinal lymphoma was generally presented on MRI as an ill-defined epidural focal lesion with moderate to severe spinal cord compression, expanding more than one vertebral body. MRI lesions were typically localized in the lumbar vertebral segment (p = 0.01), circumferential to the spinal cord (p = 0.04), hyperintense on T2-weighted sequences (p = 4.3e-06), and isointense on T1-weighted sequences (p = 8.9e-07). The degree and pattern of contrast enhancement were variable. Other morphological patterns included paravertebral masses with extension into the vertebral canal and lesions centered in the spinal nerve roots. Involvement of vertebrae and adjacent spinal soft tissues was present in 74% of cases when present vertebral involvement was characterized by cortical sparing. When follow-up MRI studies (n = 4) were performed after treatment new lesions of similar nature but different localizations and extension were observed. Confirmation of spinal lymphoma was performed by CSF analysis in 4/27 (14.8%) of cases, by FNA in 6/27 (22.2%) of cases, by surgical biopsy in 10/27 (37%) of cases, by FNA and surgical biopsy in 1/27 (3.7%) of cases, by CSF, FNA, surgical biopsy and postmorten examination in 1/27 (3.7%) of cases, and postmorten studies in 5/27 (18.5%) of cases. Antemortem diagnosis was achieved in 22/27 (81.5%) cats. The presence of necrosis in histopathological studies as an unfavorable prognostic indicator of survival was significantly more probable when lesions were not hyperintense on T2-weighted sequences (p = 0.017). Spinal lymphoma in cats is a complex entity with heterogeneous imaging and histopathological appearance. However, certain MRI features may support a tentative diagnosis, which in a group of cases can be confirmed when combined with the CSF findings. For the rest of the cases, tissue sampling assisted by imaging findings remains necessary for definitive diagnosis.

Syringohydromyelia in Dogs: The Genomic Component Underlying a Complex Neurological Disease.

Syringohydromyelia (SHM) is a neurological disorder characterized by the appearance of fluid-containing cavities within the spinal cord. Although SHM is thought to be under multigenic control, the molecular basis of this disease remains poorly defined. A genome-wide association study (GWAS) was carried out comparing the whole genome sequences (WGS) from 12 dogs with SHM and 2 panels of 26 dogs (either older than 5 years and showing the absence of SHM or belonging to breeds not susceptible to SHM) to identify candidate genes associated with the development of SHM. Seven candidate genes were identified. Of these, five genes were determined to be involved in bone development (PLXNA2, HHAT, MBOAT2, ITGAV) and calcium homeostasis (HPCAL1). Although further validation is needed at the transcript level, it is worth highlighting the association of a possible pathogenic variant which generated a new intronic branch-site sequence in PLXNA2 (T/C, CFA7:7043294). Considering previous studies in dogs that show SHM related to craniocervical junction (CCJ) malformations, these genes can be considered good candidates for the development of this disease. This report dissects the genomic component of SHM in dogs, which paves the way for further research on this complex disease found both in canine and human species.

Presumptive Haematomyelia Secondary to Warfarin Toxicosis in a Dog.

A 3-year-old male entire Boxer was presented for a 6-day history of progressive symmetric nonambulatory tetraparesis with diffuse spinal hyperesthesia. Eight days prior to admission, the dog ingested warfarin accidentally, exhibiting systemic clinical signs of intoxication 2 days later. Upon referral, the dog was nonambulatory with paretic thoracic limbs and plegia with absent nociception on pelvic limbs, spinal reflexes were decreased to absent in all four limbs, and urinary and faecal incontinence were noticed. Magnetic resonance imaging (MRI) of the cervical, thoracic, and lumbar regions of the vertebral column revealed intramedullary lesions extending from the first cervical segments to the conus medullaris consistent with extensive intramedullary haemorrhages. Despite management with vitamin K1 and physiotherapy, 6 weeks later, improvement was limited to thoracic limb motor function, and euthanasia was elected. This case reports an extensive presumptive haematomyelia with severe neurological deficits suspected to be secondary to warfarin intoxication in a dog.

Can MRI differentiate between ring-enhancing gliomas and intra-axial abscesses?

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.

Benign juvenile idiopathic epilepsy in captive Iberian lynx (Lynx pardinus) in the ex situ conservation program (2005-2019).

BACKGROUND: Benign juvenile idiopathic epilepsy has been described in humans but rarely in animals. The objectives of the study were to describe the clinical signs, clinical data, imaging findings, genetic examinations, treatment, long-term outcome and prognosis in Iberian lynx with juvenile epilepsy. Medical records, video recordings and diagnostic data from 2005 to 2019 were reviewed. RESULTS: Twenty lynx cubs with early onset of epileptic seizures (ES) from the conservation program were included. The average age at seizure onset was 75 days. Isolated and cluster ES were recorded. Focal ES, focal ES evolving into generalized ES with a stereotypical pattern and generalized ES were observed. All the cubs were normal between episodes, had a normal neurological examination and unremarkable investigations. Phenobarbital was used as a first line antiepileptic drug (AED). ES halted 10 days (0-34) after starting treatment in eight out of twenty cubs (40%). Treatment was discontinued in this group after a mean of 578 days and no further ES were reported (mean follow-up longer than 5 years). Eleven animals (55%) continued on AED treatment for a mean of 1306 days (70-3466). An adult-onset was observed for one lynx (5%). Polytherapy was necessary in seven lynxes (35%). The inheritance pattern observed was compatible with an autosomal recessive condition. Based on this assumption, mating between two identified carriers has been avoided since 2012, which may have contributed to the subsequent decrease in prevalence, with no further cases detected in 2018 and 2019. CONCLUSIONS: Lynx pardinus may have an early onset self-limiting ES syndrome characteristic of benign juvenile idiopathic epilepsy. Information obtained from this study strongly suggests a genetic basis for the here presented epilepsy.

Artifacts During Short-Term Interictal Electroencephalographic Recording in Dogs.

The electroencephalogram (EEG) is an electrodiagnostic technique widely used in both scientific research and clinical medicine. It makes it possible to study the neurophysiology of brain activity by recording real-time changes in electrical potential produced by cortical activation. The importance of EEG in diagnosing canine epilepsy demonstrates its usefulness when the owner's description of crises is not clear or when the episodes cannot be differentiated from behavioral or cardiac disorders. However, EEG recordings also often record electrical activity from sources other than the brain, which may interfere with the clinical event-related signal. This activity is known as artifactual electrical activity, and the signal changes recorded in these cases corrupt the trace when they are superimposed on brain activity or even, in some cases, mimic pathologic abnormalities. The first step in analyzing and interpreting EEG traces is to recognize artifacts and other specific transient events. This retrospective study set out to ascertain whether artifacts comparable to those described in humans are observed in protocols used to perform short-term interictal EEG for canine epilepsy and how these can be classified.

Use of MRI for the early diagnosis of masticatory muscle myositis.

The medical records of two dogs that were diagnosed with masticatory muscle myositis (MMM) were reviewed. The reported clinical signs included intense pain when opening the mouth and restricted jaw movement. MRI detected widespread, symmetrical, and inhomogeneously hyperintense areas in the masticatory muscle. Electromyography (EMG) demonstrated severe and spontaneous pathologic activity in the temporal and masseter muscles. With early therapeutic treatment, remission of symptoms occurred within 2 mo, and no relapses were observed for the subsequent 2 yr. The gold standard for the diagnosis of MMM is the 2M antibody test, but the purpose of this study was to evaluate the use of MRI as an accurate and efficient diagnostic tool for the initiation of early therapy for the treatment of muscle myositis.

Epidural dirofilariosis in a paraparetic cat: case report of Dirofilaria immitis infection.

A 6-year-old neutered female cat was examined for chronic and progressive pelvic limb ataxia that progressed to non-ambulatory paraparesis over 1 month. Haematological and serum analyses were mainly within normal ranges. Thoracic and abdominal radiographs did not reveal any morphological abnormalities. Magnetic resonance imaging investigation of the thoraco-lumbar spine demonstrated a well-defined, extradural mass that extended into the epidural space from the L2 to L3 vertebral bodies and expanded in the L2 to L3 left intervertebral foramen. During surgery, a long, narrow, white parasite which was weakly adherent to the phlogistic epidural fat tissue was gently removed from the spinal canal. Histological examination of the pathological tissue supported a diagnosis of epidural steatitis surrounding a female adult Dirofilaria immitis. This is a novel case of natural D immitis infection with spinal localisation in a cat, well documented with magnetic resonance investigation, and cytological and histological examinations, introducing a novel differential diagnosis for extradural spinal masses in cats.

MR cisternography/myelography of post-traumatic spinal CSF fistulae and meningeal lesions in small animals.

BACKGROUND: The diagnosis of post-traumatic spinal cerebrospinal fluid (CSF) fistulae due to dural tears or lesions remains a challenge. Thus far, CT myelography is the standard test used to diagnose these complications. PURPOSE: To evaluate the diagnostic ability of gadolinium-enhanced MR cisternography/myelography (intrathecal gadopentate dimeglumine or Gd-DTPA) in small animals that had experienced accidental spinal trauma. MATERIAL AND METHODS: Four dogs and one cat suffered traumatic accidents resulting in neurological deficits underwent spinal MRI with intrathecal Gd-DTPA after routine plain films and MR images. RESULTS: T2-weighted SE images showed high water content in the epidural space or in the surroundings of the vertebrae in four animals. MR myelography revealed CSF leakage in all of them. In two animals CSF leaks were observed exuding from the spinal canal and tracking towards adjacent loose fat and interfascial planes. In two other animals Gd-DTPA extravasation was diffusely collected in paraspinal tissues around the vertebral arch. In the fifth animal a focal pseudomeningocele was observed adjacent to the traumatized region. CONCLUSION: Intrathecal administration of Gd-DTPA is an effective method to reveal and confirm post-traumatic spinal CSF fistulae or other dural lesions in animals with potential application in humans.

Clinical, pathologic, and magnetic resonance imaging characteristics of canine disc extrusion accompanied by epidural hemorrhage or inflammation.

Our aim was to characterize the magnetic resonance (MR) imaging features of canine disc extrusion accompanied by epidural hemorrhage or inflammation. We correlated the imaging characteristics of this type of disc extrusion in 46 dogs and compared these features with clinical signs and pathologic findings. Data from 50 control dogs with MR imaging features of a disc extrusion with no associated hemorrhage or inflammation, characterized by a T2-hypointense extradural mass, were used for comparison of the relative location of the two types of lesions and prognosis. Disc extrusion causing epidural hemorrhage or inflammation is more common in the caudal aspect of the lumbar spine than disc extrusions that do not cause signs of hemorrhage or inflammation (P < 0.05) in MR images. In dogs with disc extrusion and associated epidural hemorrhage or inflammation, there was no association between MR imaging features and signalment, the presence or absence of hemorrhage, or pathologic findings. The appearance of the lesion created by disc extrusion with epidural hemorrhage and inflammation encompasses a wide variety of imaging features, likely related to the duration of the hemorrhage and associated inflammatory changes. In 10 of 46 dogs these secondary changes masked identification of the disc extrusion itself in the MR images. An awareness of the variety of MR imaging features of disc extrusion accompanied by extradural hemorrhage or inflammation is important to avoid making an incorrect diagnosis and to facilitate a proper surgical approach. The prognosis of dogs with disc extrusion accompanied by hemorrhage or inflammation does not appear to be different than for dogs with disc extrusion and without imaging signs of epidural hemorrhage or inflammation.

Imaging diagnosis: traumatic dural tear diagnosed using intrathecal gadopentate dimeglumine.

A dog with traumatic monoplegia had a spinal cord lesion, identified using conventional magnetic resonance imaging. In addition, the intrathecal use of gadopentate dimeglumine allowed identification of two sites of cerebrospinal fluid leakage from the vertebral canal, supporting a diagnosis of brachial plexus avulsion. Veterinary

Magnetic resonance imaging of the intratemporal facial nerve in idiopathic facial paralysis in the dog.

The most common cause of peripheral facial nerve paralysis in dogs, in the absence of otitis media, is thought to be idiopathic. Gadolinium-enhanced (Gd) magnetic resonance (MR) imaging has been used to study peripheral facial weakness in humans with a wide variety of disorders, including Bell's palsy, the clinical equivalent of idiopathic facial nerve paralysis in dogs. Gd-MR imaging may be useful to demonstrate abnormal enhancement of the intratemporal facial nerve. The aim of this study was to define the role of the Gd-MR imaging in dogs with idiopathic facial nerve paralysis, with regard to pattern of enhancement, and to search for prognostic information. Six dogs with peripheral facial nerve paralysis, followed between 2003 and 2005, were studied. Physical and neurologic examinations, as well as clinical tests, were performed, including routine hematology, serum biochemistry, thyroid screening, cerebrospinal fluid analysis, and MR imaging. The time interval between the onset of the clinical signs, the progress of the disease, and the final recovery was noted in each dog. The following four intratemporal segments of the facial nerve were analyzed: internal acoustic meatus, labyrinthine segment/geniculate ganglion, tympanic segment, and mastoid segment. Along its length, contrast enhancement was found in four dogs. In this group, contrast enhancement of the facial nerve was found in all segments of two dogs, in three segments of one dog, and in one segment of the other dog. In the four dogs with enhancement, one recovered completely in 8 weeks and three have not recovered completely. The two dogs without evidence of enhancement recovered completely in an average time of 4 weeks.