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

Anencephaly, a severe neural tube defect characterized by the absence of major parts of the brain and skull, is a rare congenital disorder that has been observed in various species, including cats. Considering the uncommon appearance of anencephaly, this paper aims to present anencephaly in a stillborn male kitten from an accidental inbreeding using various paraclinical methods. Histological examination of tissue samples from the cranial region, where parts of the skull were absent, revealed the presence of atypical nerve tissue with neurons and glial cells organized in clusters, surrounded by an extracellular matrix and with an abundance of blood vessels, which are large, dilated, and filled with blood, not characteristic of nerve tissue structure. In CT scans, the caudal part of the frontal bone, the fronto-temporal limits, and the parietal bone were observed to be missing. CT also revealed that the dorsal tubercle of the atlas, the dorsal neural arch, and the spinal process of the C2-C7 bones were missing. In conclusion, the kitten was affected by multiple congenital malformations, a combination of exencephaly-anencephaly, maxillary brachygnathism, closed cranial spina bifida at the level of cervical vertebrae, kyphoscoliosis, palatoschisis, and partial intestinal atresia. The importance of employing imaging techniques cannot be overstated when it comes to the accurate diagnosis of neural tube defects.

Risk factors for, and genetic association with, intestinal atresia in dairy calves

Intestinal atresia is an under-diagnosed congenital defect in cattle. It results in complete occlusion of the intestinal lumen and, unless surgically corrected, results in death or euthanasia of the affected calf. There is limited information on the incidence of this condition or on risk factors, including predisposing alleles, associated with the defect. In this study, active surveillance of 39 dairy farms over 8 years identified 197 cases of intestinal atresia among 56 454 calves born, an incidence of 0.35%. The majority of cases (83%) had occlusion of the jejunum, although cases with blockage of the colon (14%) or anus (4%) were also identified. The defect was twice as common in male as in female calves (p < 0.0001), and was more common in progeny of older cows than in progeny of first or second lactation cows (p < 0.001). Year and farm of birth were also significantly associated with incidence (p < 0.05). The incidence of intestinal atresia was highest among the progeny of three related Jersey sires, suggesting that a gene for intestinal atresia was segregating within this family. Linkage analysis utilising 28 affected progeny of two half-sib putative carrier sires identified two putative quantitative trait loci associated with the defect, on chromosomes 14 and 26, although no clear candidate genes were identified. There was no evidence of a sire-effect among the progeny of Holstein-Friesian sires. However, a case-control genome-wide association study involving 91 cases and 375 healthy controls, identified 31 SNP in 18 loci as associated with the defect in this breed. These data suggest that intestinal atresia in dairy calves is not a simple Mendelian trait as previously reported but a complex multigenic disorder.

Congenital segmental intestinal anomalies in calves

This focus article has been prepared by Alwyn Jones, veterinary investigation officer with SRUC Veterinary Services.

An unusual colon atresia in a calf: at the junction of the distal loop and transverse colon. A brief overview

Congenital defects are those abnormalities present at birth. During embryogenesis, many anomalies can occur. The primitive gut tube lengthens quickly and rotates, allowing the gastrointestinal tract acquire its final position and orientation. Because the colon of large animals is complex, most changes occur in this segment. Thus, in ruminants, colon atresia is the most frequent malformation, affecting mainly ascending colon, at the level of the spiral loop. There are no previous references about a very atypical colon atresia at the junction of distal loop and transverse colon, such we have described in a 5-day-old calf, after a history of abdominal distention and absence of feces at birth, even with a patent anal opening. Atresia coli was detected at distal position of the typical colon atresia, at the junction of distal loop and transverse colon. In addition, the distal blind end was bent into a U-shape supported by the mesocolon. Besides the anatomical findings of this worthwhile atresia coli we discuss its possible etiology, in which local factors, such as a compromised blood supply during embryogenesis, are more consistent than genetic factors. Finding out the causes of atresia coli would help to reduce its incidence, lessen animal suffering and economic loss.