Corpus callosal abnormalities in dogs

Abstract

Background: Corpus callosal abnormalities (CCA) in dogs have been only sporadically reported and are poorly characterized.

Hypothesis/objectives: To describe the clinical presentation and magnetic resonance imaging (MRI) characteristics of dogs with CCA.

Animals: Fifteen client-owned dogs.

Methods: Retrospective 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.

Results: The 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 importance: Previous 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.

Keywords: Adipsia; Corpus callosum; Dog; Holoprosencephaly.

Figure 1

Midsagittal T2‐weighted MR image of a normal corpus callosum.

Figure 2

Midsagittal T2‐weighted MR images of (A) 3‐month Rottweiler with absence of the rostral CC and hypoplasia of the caudal portion, (B) 18‐month Pug with a diffusely hypoplastic and dysplastic CC, and (C) 3‐year 6‐month Border Collie with a diffusely hypoplastic CC.

Figure 3

Midsagittal (A) and transverse (B) T2‐weighted MR images of a 7‐month Schnauzer crossbreed dog demonstrating fusion of the cyngulate gyri, lateral ventricles, and ventral frontal lobes with associated loss of some normal midline structures. On transverse MR images, the lateral ventricles have upturned, pointed corners reminiscent of bat wings as is typically seen with complete or focal aplasia of the CC.

Figure 4

Midsagittal T2‐weighted MR images of a (A) 5‐month Staffordshire Bull Terrier and a (B) 3‐month Miniature Schnauzer with dilatation of the pineal recess and Chiari‐like malformation.