A multimodal approach to diagnosis of neuromuscular neosporosis in dogs.

BACKGROUND: Early diagnosis of neosporosis in dogs is challenging. OBJECTIVES: To evaluate the feasibility of a compound multimodal testing approach for diagnosing in dogs neuromuscular and combined forms of neosporosis. ANIMALS: A total of 16 dogs diagnosed with solely neuromuscular neosporosis or with a combination of neuromuscular and central nervous system neosporosis. METHODS: Retrospective review of clinical signs, laboratory findings, treatment, and outcome with focus on the diagnostic utility of different tests. Development of a chromogenic in situ hybridization (ISH) assay for the identification of Neospora caninum in paraffin-embedded muscle samples. RESULTS: 13/16 dogs had only neuromuscular signs of neosporosis, 3/16 had disease signs with concomitant central nervous system (CNS) involvement. Serology was performed in 15/16, with 10/15 showing titers >1 : 160 at admission. PCR on muscle samples detected N. caninum DNA in 11/16. Immunohistochemistry (IHC) detected N. caninum in 9/16 and ISH in 9/16. Histopathology revealed inflammatory myopathy in 10/16, necrotizing myopathy in 5/16, borderline changes in 1/16 and tachyzoites in 9/16. In 4 cases, N. caninum infection was confirmed with all 5 diagnostic methods, 3 cases with 4, 2 with 3, 6 with 2, and 1 animal with 1. CONCLUSIONS AND CLINICAL IMPORTANCE: Diagnosis of N. caninum infection should rely on a multimodal diagnostic approach and negativity of 1 single test should not allow for exclusion. Serology in combination with direct parasite identification via histopathology, DNA via PCR, or both modalities, appears a reliable diagnostic approach.

Effect of gadolinium contrast medium administration on susceptibility-weighted imaging of the canine brain.

Susceptibility-weighted imaging (SWI) is a gradient echo (GE) MRI sequence. Intravenous administration of gadolinium (Gd) may affect GE images, but its effect on SWI has not been investigated in veterinary medicine. This cross-sectional prospective study evaluated the effects of Gd on SWI. Seventy-one dogs that underwent brain MRI were included and distributed in two groups. Susceptibility-weighted imaging was performed pre- and postcontrast, obtained immediately after Gd administration (Group A: n = 35) or delayed (Group B: n = 36; median delay 19.9 min). Pre- and post-Gd SWI were analyzed for signal intensity changes in the lentiform nuclei of gray matter (GM), in the centrum semiovale of white matter (WM), and in brain lesions. No difference in GM signal intensity was identified in either group between pre- and postcontrast images (Group A, P = .395; Group B, P = .895). In group A, WM signal intensity was lower in pre- than post-Gd sequences (P = .019). Brain lesions were identified in 30/71 (41%) cases; the signal intensity of intracranial lesions was significantly lower in pre- than post-Gd images in both groups (P < .001); the number of lesions influenced the difference in signal intensity in group B (P = .043). Susceptibility artifacts did not change in appearance between pre- and postcontrast images in either the normal brain or in parenchymal lesions. In conclusion, Gd may modify the signal intensity of WM and brain lesions but does not affect the susceptibility artifacts and does not interfere with SWI interpretation.

First case of presumed trigemino-oculomotor synkinesis in a dog.

An 11-year old, intact male Border Collie was referred with a history of subacute and progressive left eye exophthalmos and mydriasis associated with reduced pupillary light reflex, ventrolateral strabismus, and absence of physiologic nystagmus in the left eye. Neuroanatomical localization was consistent with a left oculomotor neuropathy, involving the general somatic and visceral parasympathetic efferent components. Computed tomography and magnetic resonance imaging of the head were performed. Imaging findings were consistent with an infectious-inflammatory process involving the left retrobulbar space and regional muscles, extending intracranially through the left orbital fissure. Cerebrospinal fluid (CSF) was collected from the cerebellomedullary cistern, and the analysis revealed albuminocytologic dissociation. The dog was treated with amoxicillin and clavulanic acid and prednisolone at anti-inflammatory dose; a significant improvement of neurologic status was observed afterward. However, 4 weeks after the initial presentation, the dog showed an abnormal, bilateral adduction of both eyes and third eyelid protrusion of the left eye while chewing the leash; the dog's mental status was normal, and the patient did not appear to be in discomfort during these episodes. A presumptive diagnosis of acquired trigemino-oculomotor synkinesis, induced by the intracranial inflammation was made. To the authors' best knowledge, this is the first case of presumed trigemino-oculomotor synkinesis reported in veterinary medicine.

Case report: Atypical and chronic masticatory muscle myositis in a 5-month old Cavalier King Charles Spaniel. Clinical and diagnostic findings, treatment and successful outcome.

Masticatory muscle myositis (MMM) is the second most common inflammatory myopathy diagnosed in dogs, but it is rarely described in puppies. The disease is characterized by the production of autoantibodies against 2M myofibers contained in masticatory muscle, although the cause of this production is still unclear. The aim of the present case report was to describe the clinical presentation, diagnostic findings, treatment, and follow-up of an atypical case of chronic masticatory muscle myositis in a very young dog. A 5-month old Cavalier king Charles Spaniel (CKCS) was presented to the AniCura Istituto Veterinario Novara with a two weeks, progressive history of lethargy and difficulty in food prehension. Neurological examination revealed bilateral masticatory muscle atrophy, mandibular ptosis with the jaw kept open, inability to close the mouth without manual assistance, jaw pain, and bilateral reduction of palpebral reflex and menace reaction; vision was maintained. A myopathy was suspected. Computed tomography (CT), magnetic resonance imaging (MRI), enzyme-linked immunosorbent assay test for 2M antibodies, and histopathological examination of masticatory muscle biopsy confirmed the diagnosis of MMM. Glucocorticoids treatment was started and clinical signs promptly improved. To the authors' knowledge, this is the first case describing mandibular ptosis in a dog affected by chronic MMM, successfully managed with medical treatment and the first report describing the CT and MRI findings in a young CKCS affected by MMM.

Endolymphatic sac tumor in an 8-month-old cat.

Background: The endolymphatic sac is an organ devoid of sensory receptors. It is connected with the endolymphatic compartment and contains endolymph. Endolymphatic sac tumor (ELST) is a rare neoplasm involving the middle and inner ear described in humans and dogs that does not show cellular characteristics of malignancy, but can be locally invasive and involve destruction of the temporal bone and adjacent structures. Case Description: An 8-month-old female cat was referred because of sudden onset of vestibular signs starting 3 days prior to referral. On clinical examination, the patient showed depression, right head tilt, left-sided facial paralysis, and horizontal nystagmus with fast phase to the left. The magnetic resonance images showed a voluminous extra-axial lesion, with irregular morphology and well-defined margins, with intracranial extension in the region of the pons, rostral medulla oblongata, cerebellar vermis, floccule, and left cerebellar hemisphere. Due to progressive clinical deterioration, the cat was euthanized 2 weeks later. A necropsy was then performed and histological samples were taken. The necropsy revealed the presence of a voluminous dark red irregular mass extending from the tympanic bulla to the posterior cranial fossa following the left glossopharyngeal nerve. The histopathological exam of the extra-axial lesion featured a nonencapsulated, moderately cellular, rather loose, proliferation of cuboidal to columnar epithelium breaching through chunks of an otherwise normal appearing dura mater and invading some cranial nerves. Sections of the cerebellum and brainstem revealed moderate, focal, impingement of the parenchyma with a very mild extension of the proliferating cells into the ventral left side of the medulla oblongata. Based on these histological characteristics, the lesion was defined as ELST, a rare neoplasm described in human beings and with two reports in dogs. Conclusion: To our knowledge, this is the first report describing an ELST in a cat.

Ventriculomegaly in Cavalier King Charles Spaniels with Chiari-like malformation: relationship with clinical and imaging findings.

The objective of this study was to calculate lateral ventricles dimension in Cavalier King Charles Spaniel dogs with Chiari-like malformation and investigate the association between ventriculomegaly and signalment, clinical signs, ventricular asymmetry, grade of Chiari-like malformation, syringomyelia and index of medullary kinking. Retrospectively, 43 client-owned Cavalier King Charles Spaniels, older than 1 year of age, with magnetic resonance imaging diagnosis of Chiari-like malformation were enrolled. Initial and follow-up (up to 36 months) clinical status was graded. Images were reviewed to quantify the enlargement of lateral ventricles, evaluate ventricular symmetry, grade of Chiari-like malformation, grade of syringomyelia and medullary kinking index. Cases presenting epileptic seizures during the evaluation period were also recorded. The most common initial clinical signs were scratching and neck pain. Ventriculomegaly was identified in 70% of dogs, Chiari-like malformation grade 2 was observed in 77% of cases, ventricular asymmetry and syringomyelia were identified in 54% and 80% of dogs, respectively; the median medullary kinking index was 37.77%. Moreover, 28% of dogs presented epileptic seizures. No significant association was identified between dimension of lateral ventricles and signalment, clinical signs, and imaging findings; no significant association was identified between ventriculomegaly and epilepsy (P≥0.05). In conclusion, the prevalence of ventriculomegaly in Cavalier King Charles Spaniels is high but this finding does not seem related to the severity of clinical signs, presence of Chiari-like malformation, syringomyelia and craniocervical junction abnormalities such as medullary kinking.

Primary orthostatic tremor and orthostatic tremor-plus in dogs: 60 cases (2003-2020).

BACKGROUND: Orthostatic tremor (OT) is a rare movement disorder characterized by high-frequency (>12 Hz) involuntary, rhythmic, sinusoidal movements affecting predominantly the limbs while standing. OBJECTIVE: To describe the signalment, presenting complaints, phenotype, diagnostic findings, treatment, and outcome of a large sample of dogs with OT. ANIMALS: Sixty dogs diagnosed with OT based on conscious electromyography. METHODS: Multicenter retrospective case series study. Dogs were included if they had a conscious electromyography consistent with muscle discharge frequency >12 Hz while standing. RESULTS: Fifty-three cases were diagnosed with primary OT (POT). Giant breed dogs represented most cases (83%; 44/53). Most dogs (79%; 42/53) were younger than 2 years of age at onset of signs, except for Retrievers which were all older than 3.5 years of age. The most common presenting complaints were pelvic limb tremors while standing (85%; 45/53) and difficulty when rising or sitting down (45%; 24/53). Improvement of clinical signs occurred in most dogs (85%; 45/53) treated medically with phenobarbital, primidone, gabapentin, pregabalin or clonazepam, but it was mostly partial rather than complete. Orthostatic tremor-plus was seen in 7 dogs that had concurrent neurological diseases. CONCLUSIONS AND CLINICAL IMPORTANCE: Primary OT is a progressive disease of young, purebred, giant/large-breed dogs, which appears to begin later in life in Retrievers. Primary OT apparently responds partially to medications. Orthostatic tremor-plus exists in dogs and can be concomitant or associated with other neurological diseases.

Agreement of surgeon's perception of the effectiveness of spinal cord decompression with findings on postoperative magnetic resonance imaging for dogs surgically treated for intervertebral disk extrusion.

OBJECTIVE: To determine the accuracy of the surgeon's perception versus postoperative MRI findings in assessing the effectiveness of spinal cord decompression achieved in dogs surgically treated for intervertebral disk extrusion (IVDE) and whether postoperative MRI findings were more likely to be associated with various outcomes. ANIMALS: 68 dogs surgically treated for cervical or thoracolumbar IVDE. PROCEDURES: Data on clinical, neurologic, pre- and postoperative MRI, and intraoperative findings as well as outcomes and recovery times (6-month follow-up period) were prospectively collected and compared between various groups. RESULTS: 54 (79%) dogs had thoracolumbar IVDE, and 14 (21%) had cervical IVDE. Median degree of spinal cord compression as assessed on transverse T2-weighted MRI images was 45.6% before surgery and 8.8% after surgery. The correlation between surgeons' perception (n = 3) and postoperative MRI findings for the degree of spinal cord decompression achieved was only fair (κ = 0.40). Unsatisfactory spinal cord decompression as assessed via postoperative MRI was associated with severity of preoperative neurologic grade and preoperative compression, thoracolumbar (vs cervical) IVDE, and ventral (vs ventrolateral or dorsolateral) circumferential distribution of extruded material. Satisfactory (vs unsatisfactory) decompression as assessed via MRI was associated with a lower postoperative neurologic grade, greater likelihood of a successful outcome, and lower mean recovery time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that for dogs surgically treated for IVDE, the surgeon's perception of adequate spinal cord decompression may be less reliable than postoperative MRI findings. Postoperative MRI appeared particularly useful for dogs with a severe preoperative neurologic status, severe preoperative spinal cord compression, and thoracolumbar IVDE.

Comparison of intranasal versus intravenous midazolam for management of status epilepticus in dogs: A multi-center randomized parallel group clinical study.

BACKGROUND: The intranasal (IN) route for rapid drug administration in patients with brain disorders, including status epilepticus, has been investigated. Status epilepticus is an emergency, and the IN route offers a valuable alternative to other routes, especially when these fail. OBJECTIVES: To compare IN versus IV midazolam (MDZ) at the same dosage (0.2 mg/kg) for controlling status epilepticus in dogs. ANIMALS: Client-owned dogs (n = 44) with idiopathic epilepsy, structural epilepsy, or epilepsy of unknown origin manifesting as status epilepticus. METHODS: Randomized parallel group clinical trial. Patients were randomly allocated to the IN-MDZ (n = 21) or IV-MDZ (n = 23) group. Number of successfully treated cases (defined as seizure cessation within 5 minutes and lasting for ≥10 minutes), seizure cessation time, and adverse effects were recorded. Comparisons were performed using the Fisher's exact and Wilcoxon rank sum tests with statistical significance set at α < .05. RESULTS: IN-MDZ and IV-MDZ successfully stopped status epilepticus in 76% and 61% of cases, respectively (P = .34). The median seizure cessation time was 33 and 64 seconds for IN-MDZ and IV-MDZ, respectively (P = .63). When the time to place an IV catheter was taken into account, IN-MDZ (100 seconds) was superior (P = .04) to IV-MDZ (270 seconds). Sedation and ataxia were seen in 88% and 79% of the dogs treated with IN-MDZ and IV-MDZ, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Both routes are quick, safe, and effective for controlling status epilepticus. However, the IN route demonstrated superiority when the time needed to place an IV catheter was taken into account.

PDGFs and PDGFRs in canine osteosarcoma: new targets for innovative therapeutic strategies in comparative oncology.

Platelet derived growth factor receptor (PDGFR)α and PDGFRß are tyrosine kinase receptors that are overexpressed in 70-80% of human osteosarcomas (OSAs) and may be suitable therapeutic targets for specific kinase inhibitors (TKIs). Canine OSA shows histopathological and clinical features similar to human OSA, and is considered an excellent model in comparative oncology. This study investigated PDGF-A, PDGF-B, PDGFRα and PDGFRß expression in 33 canine OSA samples by immunohistochemistry and in seven primary canine OSA cell lines by Western blot and quantitative PCR analysis. Immunohistochemical data showed that PDGF-A and PDGF-B are expressed in 42% and 60% of the OSAs analysed, respectively, while PDGFRα and PDGFRß were expressed in 78% and 81% of cases, respectively. Quantitative PCR data showed that all canine OSA cell lines overexpressed PDGFRα, while 6/7 overexpressed PDGFRß and PDGF-A relative to a normal osteoblastic cell line. Moreover, in vitro treatment with a specific PDGFR inhibitor, AG1296, caused a dose- and time-dependent decrease in AKT phosphorylation. Collectively, these data show that PDGFRs/PDGFs are co-expressed in canine osteosarcomas, which suggests that an autocrine and/or paracrine loop is involved and that they play an important role in the aetiology of OSA. PDGFRs may be suitable targets for the treatment of canine OSA with a specific TKI.