Evaluation of a treatment protocol in dogs with intraspinal spirocercosis

OBJECTIVE

To evaluate the efficiency and safety of a doramectin-based treatment protocol in dogs affected by intraspinal spirocercosis (Spirocerca lupi).

ANIMALS

Client-owned dogs that were admitted to a veterinary hospital during 2021 to 2022 with acute onset of neurological signs and diagnosed with intraspinal spirocercosis. All dogs underwent complete neurological evaluation, CSF analysis, PCR confirmation of CNS S lupi infection, and follow-up evaluation of at least 6 months.

PROCEDURES

Upon diagnosis, dogs were treated with doramectin at a dose of 400 μg/kg, SC, q 24 h for 3 consecutive days, followed by the same dose once a week for 6 weeks. Prednisone was administered at a dose of 1 mg/kg, PO, q 24 h and tapered every 3 days. Antimicrobial clindamycin was administered at a dose of 12.5 mg/kg, PO, q 12 h for 7 days to reduce the risk of secondary spinal cord infection. Short- and long-term outcomes (1 week to 56 months) were recorded.

RESULTS

8 dogs fulfilled the inclusion criteria, 7 of which presented with neurological deficits and 1 with cervical pain. Initiation of treatment was associated with stopping the deterioration in 7 of 8 dogs. Seven dogs improved and 6 recovered ambulation. One dog was euthanized due to lack of improvement. Six of the recovered dogs were still ataxic on the last follow-up examination at 6 to 56 months. No adverse effects of the drug were noted.

CLINICAL RELEVANCE

Frequent administration of doramectin was found to be safe and effective in preventing neurological deterioration in dogs with intraspinal spirocercosis.

First Case of Idiopathic Eosinophilic Meningoencephalitis in a Sheep

A 1.5-year-old ewe was presented with neurological signs that had been observed from about 2 days prior to death. There had been no clinical response to anti-inflammatory and antibiotic treatment. Histopathological examination of the brain revealed a severe and widespread eosinophilic meningoencephalomyelitis of unknown aetiology. Defining histological features included diffuse angiocentric eosinophilic infiltrates in the neuroparenchyma and meninges, neuronal necrosis, astrocytosis, neuropil vacuolation and occasional glial scars. Differential diagnostics for eosinophilic meningoencephalitis were taken into account and investigated by means of special stains, immunohistochemistry, bacteriology and polymerase chain reaction. No pathological changes or ancillary tests were supportive or revealed a specific aetiology for the condition and therefore it was considered idiopathic. Idiopathic meningoencephalitis is a rare disease, mainly described in man and rarely in dogs, with no apparent aetiological cause or potential breed predisposition. To our knowledge this is the first case of idiopathic eosinophilic meningoencephalitis in a sheep and provides a histopathological guideline for prospective comparative pathology studies.

Clinical presentation and magnetic resonance imaging findings in 11 dogs with eosinophilic meningoencephalitis of unknown aetiology

OBJECTIVES

To describe the clinical presentation, MRI findings and outcome in dogs with eosinophilic meningoencephalitis of unknown origin.

MATERIALS AND METHODS

Dogs were included in this retrospective study if they had complete medical records, complete neurological examination, MR imaging, cerebellomedullary cerebrospinal fluid sample consistent with eosinophilic pleocytosis and negative infectious disease testing.

RESULTS

Eleven dogs were included with a median age of 22·0 months (range 7·6 to 92·0 months). Nine breeds were represented. Neurological abnormalities included obtundation (n=10), menace response deficits (n=9), proprioceptive deficits (n=7), ataxia (n=7) and seizures (n=2). Neuroanatomical localisation was multi-focal (n=4), central vestibular system (n=4), diffuse forebrain (n=2) or left trigeminal/facial nerves (n=1). Seven dogs had peripheral eosinophilia. Ten dogs had bilateral symmetrical lesions affecting the cortical grey matter, which was hyperintense on T2-weighted and fluid-attenuating inversion recovery images and iso- to hypointense on T1-weighted images with associated meningeal contrast enhancement. MRI findings were consistent with diffuse meningitis and atrophy or necrosis of cortical grey matter. One dog had increased contrast uptake in the left trigeminal nerve. Ten dogs receiving corticosteroids survived to discharge, with seven also receiving cytarabine arabinoside. Median survival time was 762 days.

CLINICAL SIGNIFICANCE

Eosinophilic meningoencephalitis of unknown origin affects younger larger-breed dogs, with the majority having suspected diffuse cerebrocortical meningitis and cortical (polio)encephalitis, which can be identified on MRI. Response to immunosuppressive treatment is good in the medium to long term, although further studies are required in this area.

Clinical characteristics of Spirocerca lupi migration in the spinal cord

Spirocerca lupi is a nematode infecting dogs mostly in tropical and subtropical areas. Although its typical target is the esophageal wall, aberrant migration is not uncommon, including migration of unknown incidence into the spinal cord. While successful treatment of intraspinal S. lupi (ISSL) infection depends on early diagnosis, tools for definitive ante-mortem diagnosis are unavailable. We therefore aimed at characterizing clinical signs and clinical pathology findings of ISSL in dogs. For that, we analyzed medical records of dogs hospitalized in 2005-2016 presenting with neurological signs consistent with ISSL, which were diagnosed definitively post-mortem. Retrieved information included signalment, medical history, chief complaint, physical and neurological evaluation, neuroanatomical localization at presentation, clinical pathology, imaging findings, treatment, outcome and post-mortem findings. Ten midsize to large breed dogs were included, 7 of which had received prophylactic treatment. In all 10 dogs, onset was acute and neurological deterioration until presentation (2 h-6 d) was fast. Neurological examination localized the lesions within the spinal cord and paresis or paralysis was asymmetric in all dogs. Spinal pain was documented in 9/10 dogs. Cerebrospinal fluid (CSF) analysis was abnormal in all dogs and was characterized by pleocytosis in 8/10, whereas cytology revealed the presence of eosinophils in all dogs. Advanced imaging excluded spinal cord compression in all dogs tested. Post-mortem examination detected spinal cord migration tract in all cases. Nematodes were found in the spinal cord parenchyma (8/10) or adjacent to it (2/10) in all dogs. A larva was found in the subarachnoid space of one dog and an adult nematode in the thoracic intervertebral artery of another. Esophageal nodules were found in 5/10 dogs. These findings suggest that the combination of sudden onset of acute asymmetric paresis accompanied by pain, presence of eosinophils in the CSF and lack of compressive lesion may serve as sufficient evidence for tentative diagnosis of ISSL in endemic areas.