Progressive Behavioral Changes in a Dog

ArticleLast Updated April 20133 min readWeb-Exclusive
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An 8-year-old spayed Dachshund presented with a 2-week history of progressive behavior changes and a recent onset of circling to the left.

History

An 8-year-old spayed Dachshund presented with a 2-week history of progressive behavior changes and a recent onset of circling to the left. The owners described a quieter demeanor, frequent confusion with the dog’s normally routine activities, and staring at the wall for long periods of time. The dog had previously been systemically healthy, was routinely vaccinated, and current on parasite prophylaxis.  To the owner’s knowledge, there was no traumatic event or access to toxins preceding clinical signs.

Related Article: Localize the Lesion: Acute Painful Tetraparesis in a Dog

Physical Examination

The rest of the examination was unremarkable.

Neurologic Examination

  • Posture: The dog’s head, neck, and body appeared curved to the left.

  • Gait: The dog was ambulatory but occasionally circled to the left. No ataxia was noted.

  • Postural reactions—The dog’s proprioceptive placing and hopping was reduced to absent on the right side.

  • Cranial nerves—There was a reduced-to-absent menace response when the dog’s right eye was threatened. Palpebral and pupillary light reflexes were considered normal. Nasal stimulation appeared to result in normal head withdrawal bilaterally. There was normal physiological nystagmus seen as the dog’s head was moved from side to side. No muscle atrophy was noted over the dog’s head, and the jaw tone seemed appropriate. Tongue movement and gag reflex appeared normal.

  • Spinal reflexes—Thoracic and pelvic limbs had normal tone and intact reflexes.

  • Spinal pain—On palpation of the neck, the dog exhibited pain; on palpation of the thoracolumbar spinal column, the dog appeared comfortable.

Based on this and the video, ask yourself…

  • Where is the lesion localized?

  • What are the differentials?

  • What diagnostic tests are appropriate

Lesion Localization

Lesion LocalizationNeurologic examination suggested a lesion affecting the forebrain, which was lateralized to the dog’s left.

Related Article: Canine Idiopathic Inflammatory CNS Disease

Differentials

The differential diagnoses for a lesion causing a chronic progressive lateralizing forebrain lesion include:

  • Inflammatory disease (infectious or sterile/immune dysfunction)

  • Neoplasia, either affecting the brain primarily (commonly meningioma or glioma),or secondarily as a metastasis or a tumor or the skull, nose or ear cavity

Diagnostics

Diagnostics, recommended based on lesion localization and potential differentials, included:

  • Hematology MDB, serum biochemistry profile, and urinalysis was normal 

  • Thoracic and abdominal radiographs (evaluating for neoplasia) were considered normal; survey radiographs of the skull are rarely warranted or helpful unless a traumatic incident has occurred.

  • Abdominal ultrasonography, of value when investigating for systemic focus of infection or neoplasia, was considered normal.

  • A CSF tap, performed at the atlanto-occipital cistern postanesthesia, revealed a marked inflammatory response characterized by elevated protein concentration and mixed cell pleocytosis.  

  • A cranial MRI revealed a multifocal forebrain disease, predominantly affecting the left cerebrum; lesions seen were notably contrast, enhancing suggestion of an inflammatory and or neovascular component.

Outcome

Infectious disease serum titers were performed for Toxoplasma gondii, Neospora caninum, distemper virus, Cryptococcus spp and Aspergillus spp.  All titers were negative; as such, the inflammatory disease was presumed to be sterile (eg, granulomatous meningoencephalitis [GME] or meningoencephalitis of unknown origin [MUO]). The dog was started on an immunosuppressive regimen of oral steroids (2 mg/kg/day prednisone) and had a positive clinical response; the dose was tapered over the follow 4 months to 0.5 mg/kg/day prednisone, as relapse was seen when further reductions were made in this case.

Localize the Lesion is intended as a forum for those with specialized expertise to share their case experiences. As such, the content reflects one expert’s approach and is not subject to peer review.