Imaging and genetic investigations of neural tube defect in a calf: case report and review of the literature

Imaging of a subcutaneous abscessation in the back of a calf with hindlimb paralysis

Background

Ultrasonography is not chosen as the common imaging modality to diagnose spinal cord diseases. The present report indicates good diagnostic efficacy of ultrasonography for identifying spinal cord compressed by subcutaneous mass when scanning through the defected vertebral laminae and spinous process.

Case Description

A five-month-old female Holstein calf presented with progressive hindlimb paralysis following a surgical resection of a back mass conducted at 21 days of age. The mass was subsequently histopathologically diagnosed as a pulmonary choristoma. Alongside hindlimb paralysis, the calf developed a swollen back at the lumbar region where the mass was removed. This suggested regrowth of the resected mass, causing injury to the underlying spinal cord. Ultrasonography identified the subcutaneous involvement of the capsular mass, which had three anechoic cavities separated by the echogenic septal structures. The spinal cord could be ultrasonographically demonstrated as adjacent to the mass through the defected vertebral laminae and spinous process in the second and third lumbar vertebras. Ultrasound-guided centesis allowed the collection of purulent exudates in which Escherichia coli was isolated. Myelography and subsequent computed tomography (CT) revealed a partial blockage of the intradural flow of contrast media at the levels of the second and third lumbar vertebras, diagnosed as spina bifida on the CT images. When applying ultrasonography to the spinal cord within a saline pool soon after the subcutaneous abscess was successfully resected, the spinal cord was characterized by the interrupted and partly extended hyperechogenic line of the central canal within the echogenic parenchyma. The echotexture of the spinal cord showed damage due to compression from the subcutaneous abscess. The animal had a sub-optimal postoperative outcome, including limited improvement of the neurological signs.

Conclusion

In the present case, combining ultrasonography, radiography (myelography), and CT was very effective for diagnosing spina bifida, with the subcutaneous abscess inducing spinal cord compression. Additionally, using intraoperative ultrasonographic scanning to evaluate the degree of spinal cord damage can contribute to predicting the postoperative outcome.

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.

Split Cord Malformation in a Thoroughbred Horse

We report a 9-year-old Thoroughbred gelding that had sudden onset lameness of the right forelimb with episodes of lateral decubitus and generalized pain after completion of a normal training session. The clinical signs subsequently became less pronounced with only mild right forelimb lameness. However, after further orthopaedic examination, it developed severe, acute ataxia and paraplegia, the Schiff-Sherrington phenomenon and risus sardonicus. At necropsy, a partial duplication of the cervical spinal cord was identified, consistent with split spinal cord malformation type II or diplomyelia. However, the clinical significance of this finding is not clear.

Comparison of inherited neural tube defects in companion animals and livestock

Neural tube defects (NTDs) are congenital malformations resulting from the improper or incomplete closure of the neural tube during embryonic development. A number of similar malformations of the protective coverings surrounding the central nervous system are also often included under this umbrella term, which may not strictly fit this definition. A range of NTD phenotypes exist and have been reported in humans and a wide range of domestic and livestock species. In the veterinary literature, these include cases of anencephaly, encephalocele, dermoid sinus, spina bifida, and craniorachischisis. While environmental factors have a role, genetic predisposition may account for a significant part of the risk of NTDs in these animal cases. Studies of laboratory model species (fish, birds, amphibians, and rodents) have been instrumental in improving our understanding of the neurulation process. In mice, over 200 genes that may be involved in this process have been identified and variant phenotypes investigated. Like laboratory mouse models, domestic animals and livestock species display a wide range of NTD phenotypes. They remain, however, a largely underutilized population and could complement already established laboratory models. Here we review reports of NTDs in companion animals and livestock, and compare these to other animal species and human cases. We aim to highlight the potential of nonlaboratory animal models for mutation discovery as well as general insights into the mechanisms of neurulation and the development of NTDs.

Cerebrospinal fluid analysis in 58 ruminants showing neurological disorders

ABSTRACT: Ruminants may be affected by a wide variety of central nervous system (CNS) diseases. Cerebrospinal fluid (CSF) analysis forms the basis for ante mortem diagnostic evaluation of ruminants with clinical signs involving the CNS. Despite its importance as a tool to aid diagnosis, data regarding CSF examinations in spontaneous cases of CNS diseases in ruminants from Brazil are limited, and most reports involve experimental studies. Therefore, this study aimed to report the results of CSF analysis in 58 ruminants showing signs of neurological disorders. CSF samples for analysis were obtained from 32 cattle, 20 sheep, and 6 goats by cerebello-medullary cistern (n=54) or lumbosacral space (n=4) puncture. These ruminants showed neurological signs related to viral (n=13), mycotic (n=3), or bacterial (n=15) infections, and toxic (n=21), traumatic (n=4), or congenital disorders (n=2). CSF analysis from ruminants with viral infections presented lymphocytic pleocytosis, even though CSF showed no changes in several cases of rabies. Neutrophilic pleocytosis, cloudiness, presence of fibrin clots, and abnormal coloration were evident in the CSF of most cases of CNS bacterial infection, such as meningoencephalitis, meningitis, abscesses, myelitis, and a case of conidiobolomycosis. On the other hand, CSF was unchanged in most cases of toxic disorders, as botulism and hepatic encephalopathy. Elevated CSF density was observed in 60% of ruminants diagnosed with polioencephalomalacia. Our findings show that evaluation of CSF is a valuable diagnostic tool when used in association with epidemiological, clinical and pathological findings for diagnosis of CNS diseases in ruminants.