Spinal cord protothecosis causing paraparesis in a dog.

Area of Science:

• Veterinary Neurology
• Infectious Diseases
• Diagnostic Pathology

Background:

• Protothecosis is a rare infectious disease caused by Prototheca algae.
• Central nervous system (CNS) protothecosis presents with neurologic signs following chronic diarrhea and weight loss.
• Antemortem diagnosis is challenging, often relying on postmortem findings.

Purpose of the Study:

• To report a case of canine CNS protothecosis.
• To demonstrate the efficacy of antemortem diagnostic methods for CNS protothecosis.
• To highlight the role of cerebrospinal fluid (CSF) analysis and PCR in diagnosis.

Main Methods:

• A paraparetic dog with suspected CNS protothecosis underwent comprehensive diagnostic evaluation.
• Methods included CSF cytology, PCR, DNA sequencing, computed tomography, and serology.
• Prototheca organisms were identified and speciated in CSF samples.

Main Results:

• The dog presented with progressive paraparesis, weight loss, and diarrhea.
• CSF analysis revealed eosinophilic pleocytosis and confirmed the presence of Prototheca organisms.
• PCR and DNA sequencing identified the causative agent as Prototheca zopfii.
• Despite treatment, the dog's condition worsened, leading to euthanasia.

Conclusions:

• Antemortem diagnosis of CNS protothecosis in dogs is achievable.
• Cerebrospinal fluid cytology combined with PCR and DNA sequencing are valuable diagnostic tools.
• Early and accurate diagnosis can guide treatment and management decisions for Prototheca infections.