Which dog breed get lissencephaly?

Acta Veterinaria Scandinavica 2020

Diego Noé Rodríguez‑Sánchez1* , Giovana Bof Araujo Pinto1 , Edval Fernando Thomé1 , Vânia Maria de Vasconcelos Machado2 and Rogério Martins Amorim1

Background
Lissencephaly is a rare brain malformation in dogs characterized by smooth, thickened cortical surfaces and an absence or reduction of gyri (agyria) or abnormally broad gyri (pachygyria). It is associated with defects in neuronal migration during development. This study presents the first reported cases of lissencephaly in Shih Tzu dogs, detailing clinical presentations, diagnostic findings, and treatment outcomes.

Methods
Four Shih Tzu dogs with lissencephaly were evaluated between 2011 and 2018 at a veterinary neurology service in Brazil. Diagnostic workups included clinical and neurological evaluations, magnetic resonance imaging (MRI), and tests to exclude infectious and metabolic disorders. MRI findings and treatment responses were documented.

Results
Clinical Findings: All dogs exhibited early-onset neurological signs, including cluster seizures, tonic-clonic seizures, behavioral abnormalities, central blindness, and ventromedial strabismus.


MRI Features:
-All cases showed smooth cortical surfaces with either complete agyria or mixed pachygyria and agyria.
-Associated malformations included internal hydrocephalus, supracollicular fluid accumulation (SFA), and corpus callosum hypoplasia.
-Grade 2a lissencephaly was noted in three dogs and grade 3a in one.


Treatment Outcomes: Antiepileptic drugs (phenobarbital, potassium bromide, and levetiracetam) effectively controlled seizures, reducing frequency by >50% and eliminating cluster seizures. Behavioral abnormalities and blindness persisted despite treatment.


Limitations
The lack of histopathological confirmation limited the characterization of cortical abnormalities. MRI was performed using low-field scanners, potentially affecting resolution. The study’s retrospective nature precluded prospective control or standardized treatment protocols.

Conclusions
Lissencephaly should be considered in Shih Tzu dogs with early-onset seizures and forebrain abnormalities. MRI is the diagnostic tool of choice, allowing for the identification of associated cerebral malformations. Although antiepileptic drugs provide effective seizure control, other neurological signs, such as blindness and behavioral issues, often persist. Further studies are needed to explore genetic causes and improve therapeutic strategies.

Brain magnetic resonance imaging (MRI) in Shih Tzu dogs with lissencephaly. Transverse T1-weighted (a, e), T2-weighted (b, f), fluid-attenuated inversion recovery (FLAIR) (c), dorsal hybrid contrast enhancement (3D HYCE) (g) and mid-sagittal T1-weighted (d, h) imaging of the first and second cases. MRI of the first dog showed broad folds with simplified patterns and shallow grooves (pachygyria) in the frontal and parietal lobe region (arrow). Absence of the marginal gyri, middle ectomarginal gyri and caudal suprasylvian gyri was observed in these regions (arrowhead) (a, b). Ventriculomegaly and enlargement of the sole quadrigeminal cistern (type SFA-QC) was apparent (c, d). MRI of the second dog showed diffuse agyria (arrows) at the level of the interthalamic adhesion (e, f). Rudimentary lateral rhinal sulci were present (arrowhead), and cingulate gyri were not apparent. The internal capsule was abnormally small (e, f). Smooth cortical appearance was observed with a lack of the marginal gyri, middle ectomarginal gyri and middle suprasylvian gyri. Dorsocaudal outpocketing of the third ventricle (type SFA-III) and internal hydrocephalus were visualized (g, h)

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