Anencephaly, bifid tongue, and cleft palate in a Pomeranian dog: GFAP and NeuN immunoreactivities

Abstract

Anencephaly is a congenital disease manifesting with the absence of the brain due to the failure of the cranial part of the neural tube to close during the embryonic stage. The disease may be accompanied by other anomalies and usually results in premature death. A stillborn puppy of a 2-year-old female Pomeranian dog is examined in this case. The lack of brain tissue and accompanying abnormal skull formation was noted macroscopically. The eyes were protruding out of their normal position (exophthalmos), and a bifid tongue together with a secondary cleft palate was present. On serial sections stained with Haematoxylin-Eosin, only the medulla spinalis among the central nervous system structures could be inspected microscopically. Immunohistochemistry staining revealed GFAP immunoreactivity in the astrocytic glial cells. NeuN immunoreactivity was detected in the neurons in the medulla spinalis and spinal ganglions. Incomplete retinal layers were observed on the eye sections stained with Haematoxylin-Eosin and NeuN. The case was concluded to be coherent with skull and nervous system congenital malformations rarely observed in dogs. To the best of our knowledge, this represents the first description of a dog with anencephaly, bifid tongue and cleft palate.

Exencephaly–Anencephaly Sequence Associated with Maxillary Brachygnathia, Spinal Defects, and Palatoschisis in a Male Domestic Cat

“…Similar dog cases are reported in the literature; thus, a case of anencephaly in the Pomeranian breed presented the lack of cerebral hemispheres in cavum cranii, incomplete skull formation, and exophthalmos, associated with tongue split and palatoschisis [19]. Another case with anencephaly associated with cranioschisis was reported in Pincher breed [18].…”

“…Regarding the gender predisposition to NTDs, in veterinary medicine it is not known, probably due to low number of reported cases (most of the articles cited in this paper were females) [13,18,19], but a female predisposition has been reported in human medicine, possibly because of a sex-related genetic effect or an epigenetic effect [4] but not due to the different rate of embryonic growth and development between females and males [12].…”

“…The ocular protrusion, so called "frog eye" sign, is a consequence of the absence of the fetal calvarium. Normal vision in such cases is affected due to retinal ganglion cells reduction and optic nerves abiotrophy as a sequel of secondary retrograde degeneration [14,19]. Histological results conducted on brain tissue described atypical nerve tissue with an abundance of large, dilated, and filled blood vessels, named area cerebrovasculosa, seen also in the literature in both human and animal cases with anencephaly in which the lack of encephalon was not total [4,7,14,35].…”

“…Another case with anencephaly associated with cranioschisis was reported in Pincher breed [18]. In all cases, the puppies were stillborn [14,19], died soon after parturition [18] or were sacrificed soon after birth due to the severe malformations [15], being unable to suckle and to coordinate. Cases of anencephaly have also been reported in wildlife, captive or free-ranging (bears, dolphins).…”

“…Anencephaly is reported rarely on OMIA ("Online Mendelian Inheritance in Animals", a database intended to list all hereditary diseases with simple determinism) in calves (OMIA:000044-9913) [8][9][10], sheep (OMIA:000044-9940) [11], greater Indian rhinoceros (Rhinoceros unicornis) (OMIA:000044-9809), and Indo-pacific bottlenose dolphins (Tursiops aduncus) (OMIA000044-79784) [12], but also in bears [13] and dogs [14][15][16][17][18]. In dogs, in almost all cases, puppies affected by anencephaly also presented with other malformations such as brachygnathia [14], atresia ani, hydrocephalus [16], gastroschisis, amelia of the right anterior limb [17], cleft palate [15], or cleft palate and cleft tongue [19]. Some rare cases with severe NTDs were reported in captive wild animals, such as a horned rhinoceros (Rhinoceros unicornis) [20], and a brown bear (Ursus arctos arctos) [13], where the etiology is more complicated to identify because these animals are kept under strict health control, so the influence of environmental factors is minimal, although possible nutritional deficiencies, especially in folic acid, are proposed.…”