Corpus Callosal Abnormalities in Dogs

Abstract

BackgroundCorpus callosal abnormalities (CCA) in dogs have been only sporadically reported and are poorly characterized.Hypothesis/ObjectivesTo describe the clinical presentation and magnetic resonance imaging (MRI) characteristics of dogs with CCA.AnimalsFifteen client‐owned dogs.MethodsRetrospective study. Records of the contributing institutions were reviewed to identify dogs diagnosed with malformations affecting the corpus callosum (CC); cases in which the CCA was thought to be secondary were excluded.ResultsThe most represented breeds were Staffordshire Bull Terriers (5/15) and Miniature Schnauzers (3/15; n = 3, 20%) and the mean age at time of presentation of 19 months (range 3–81 months). The clinical signs most commonly reported were adipsia/hypodipsia with associated hypernatremia (12/15), tremors (6/15), and seizures (6/15). Review of the MR images revealed that 10 dogs had absence of the rostral CC and hypoplasia of the caudal portion, 4 dogs had a diffusely hypoplastic and dysplastic CC, and 1 dog had a diffusely hypoplastic CC. In 14 cases, there was abnormal cortical development with fusion of the ventral frontal lobes and part of the diencephalon, indicating lobar holoprosencephaly.Conclusions and Clinical ImportancePrevious literature has mainly associated CCA with adipsia and only 12 of 15 dogs in the current series demonstrated this abnormality. There are different degrees of the malformation but in 10 dogs the rostral portion of the CC is most severely affected. Fourteen dogs have simultaneous fusion of the midline structures rostral to the CC; this region has several structures involved in thirst regulation and might explain this derangement.

The use of diffusion tractography to characterize a corpus callosum malformation in a dog

“…In previous reports in dogs, this widening was not reported. Therefore, LCFs were presumed absent, and the latter pathophysiological explanation has been historically accepted . In our dog, this widening was not identified on the structural sequences, but tractography did detect rostro‐caudally orientated white matter tracts within the medial hemispheric wall, confirming the presence of LCFs (see Figures and ).…”

“…Corpus callosum (CC) abnormalities are a cause of adipsia and hypodipsia, leading to life‐threatening hypernatremia, and long‐term neurological problems in the dog . This condition is associated with eventual euthanasia in approximately one‐third of reported cases .…”

“…Corpus callosum (CC) abnormalities are a cause of adipsia and hypodipsia, leading to life‐threatening hypernatremia, and long‐term neurological problems in the dog . This condition is associated with eventual euthanasia in approximately one‐third of reported cases . The histopathological and structural magnetic resonance imaging (MRI) features of this condition have been described in the dog but because of the inherent limitations associated with use of these techniques to document white matter structure, the underlying pathophysiology and exact malformations present in these cases still are conjectural …”

“…Tractography has been used to document white matter projections in the normal canine brain and specifically to segment and delineate the CC, but this technique has not yet been applied in the evaluation of white matter malformations . To date in the dog, CCM has only been diagnosed using standard structural MRI sequences, limiting our ability to determine the exact malformations present . We used fiber tractography to document complex white matter malformations associated with a CCM in a dog.…”

A deletion inGDF7is associated with a heritable forebrain commissural malformation concurrent with ventriculomegaly and interhemispheric cysts in cats

“…Congenital brain malformations in humans are caused by genetic variants, in utero infection, or other environmental factors. Dogs and cats are also occasionally diagnosed with congenital brain malformations (Reviewed in [1]), which are noted as breed predispositions, familial aggregations, and sporadic cases [2][3][4][5][6]. Congenital hydrocephalus is common in toy and brachycephalic dog breeds, such as the Maltese, Yorkshire terrier, Chihuahua, toy poodle, and pug dogs [7].…”