Case report links porencephaly to subdural empyema in a dog

A newly published case report in Frontiers in Veterinary Science details an unusual and likely first-described presentation of subdural empyema and pachymeningitis developing within pre-existing porencephaly in a dog. The patient, a 2-year-old Golden Retriever, presented with progressive intracranial signs, and advanced imaging plus postmortem pathology ultimately showed infection and inflammation localized mainly to the right cerebral hemisphere. The authors describe the case as a novel combination of imaging and necropsy findings in a dog with unilateral subdural empyema superimposed on pre-existing encephaloclastic brain pathology. (frontiersin.org)

That background matters because porencephaly itself is rare in small animal practice and can be either developmental or secondary to prior destructive brain injury. Veterinary literature has described porencephaly in dogs and cats in association with seizures, structural brain abnormalities, and suspected prenatal or perinatal insults, while more recent work has also raised the possibility that some lesions may reflect postnatal trauma. Separately, intracranial empyema is an uncommon but recognized condition in dogs, with published case reports and small case series describing variable causes, imaging findings, treatment approaches, and outcomes. (frontiersin.org)

In the new report, MRI identified encephaloclastic porencephaly lesions, more severe on the right, along with abnormal changes inside the fluid compartments. The reported features included incomplete FLAIR suppression, ring-like T1-weighted contrast enhancement, increased post-contrast FLAIR hyperintensity, susceptibility signal through septations on SWAN imaging, and marked pachy- and leptomeningeal thickening and enhancement. The authors interpreted those findings as consistent with infection of the porencephalic fluid compartment, alongside hydrocephalus ex vacuo; moderate syringohydromyelia was also noted. Compartment-specific fluid sampling added another clue: CSF from the left side was normal, while fluid from the right showed neutrophilic inflammation consistent with empyema. (frontiersin.org)

Even with aggressive treatment, the dog’s neurologic condition worsened, and euthanasia was elected. Necropsy then confirmed subdural empyema with pachymeningitis, largely restricted to the right hemisphere, aligning with the imaging and sampling findings. That clinicopathologic correlation is one of the report’s main strengths, especially in a disease space where diagnosis can be difficult and published veterinary experience remains limited. (frontiersin.org)

Direct outside commentary on this specific paper was limited at the time of review, but the broader literature helps frame its significance. A retrospective series of nine dogs with intracranial empyema documented that these infections can present with a range of neurologic signs and MRI abnormalities, underscoring how easily they could be mistaken for other intracranial disease processes. Earlier case reports have also shown that some dogs with presumptive subdural empyema can survive with medical management, while more recent feline literature has described successful surgical treatment in selected cases. Taken together, that suggests early recognition and careful case selection may materially affect outcomes, even though this particular case had a poor prognosis. (onlinelibrary.wiley.com)

Why it matters: For veterinary neurologists, radiologists, emergency clinicians, and referral teams, the report is a reminder not to attribute all findings in a dog with known structural brain disease to the pre-existing lesion itself. If a patient with porencephaly shows progression, asymmetry, inflammatory CSF changes, or new contrast-enhancing septated fluid compartments, superimposed infection should stay on the list. The paper also reinforces the value of advanced MRI characterization and targeted sampling when anatomy allows, because standard assumptions about chronic cavitary lesions may miss a treatable infectious process. (frontiersin.org)

The case may also influence how clinicians counsel pet parents. Porencephaly is often discussed as a static or chronic structural abnormality, but this report suggests that, at least in rare circumstances, altered intracranial compartments may become sites of secondary inflammatory or infectious disease. That doesn’t establish a common pathway, and this is still a single case report, but it does broaden the conversation around monitoring, re-imaging, and escalation when clinical signs change. This is an inference from the case and the surrounding literature, rather than a conclusion the authors explicitly prove. (frontiersin.org)

What to watch: The next question is whether additional case reports or retrospective studies identify similar infections in dogs with porencephaly or other chronic cavitary brain lesions, and whether clearer MRI or CSF criteria emerge to guide earlier intervention and treatment planning. (frontiersin.org)