Evaluation of CHD7 as a candidate gene for choanal atresia in alpacas (Vicugna pacos)

[Choanal atresia in an alpaca cria (Vicugna pacos)]

After birth, an alpaca cria was noticed to exhibit weakness and respiratory distress, particularly when attempting to suckle milk from the dam's udder. Clinical findings indicated the presence of bilateral choanal atresia and the animal was subsequently euthanised. A computed tomography scan and a pathological examination were performed to describe the malformation in detail. Choanal atresia is a common malformation in neonatal South American camelids, surgical treatment is not recommended. This case report provides an overview of the clinical findings as well as the results of imaging and pathologic examinations and may help to raise awareness of this malformation for early recognition.

Cytogenetic Mapping of 35 New Markers in the Alpaca (Vicugna pacos)

Alpaca is a camelid species of broad economic, biological and biomedical interest, and an essential part of the cultural and historical heritage of Peru. Recently, efforts have been made to improve knowledge of the alpaca genome, and its genetics and cytogenetics, to develop molecular tools for selection and breeding. Here, we report cytogenetic mapping of 35 new markers to 19 alpaca autosomes and the X chromosome. Twenty-eight markers represent alpaca SNPs, of which 17 are located inside or near protein-coding genes, two are in ncRNA genes and nine are intergenic. The remaining seven markers correspond to candidate genes for fiber characteristics (BMP4, COL1A2, GLI1, SFRP4), coat color (TYR) and development (CHD7, PAX7). The results take the tally of cytogenetically mapped markers in alpaca to 281, covering all 36 autosomes and the sex chromosomes. The new map assignments overall agree with human–camelid conserved synteny data, except for mapping BMP4 to VPA3, suggesting a hitherto unknown homology with HSA14. The findings validate, refine and correct the current alpaca assembly VicPac3.1 by anchoring unassigned sequence scaffolds, and ordering and orienting assigned scaffolds. The study contributes to the improvement in the alpaca reference genome and advances camelid molecular cytogenetics.

Use of a novel surgical approach for treatment of complete bilateral membranous choanal atresia in an alpaca cria

CASE DESCRIPTION A 4-hour-old 6.3-kg (13.9-lb) female alpaca cria was evaluated because of severe respiratory distress and difficulty nursing since birth. CLINICAL FINDINGS The cria had open-mouth breathing and cyanotic membranes, with no airflow evident from either nostril. Supplemental oxygen was delivered, and the patient was anesthetized and intubated orotracheally; a CT evaluation of the head confirmed bilateral membranous obstruction of the nasal cavities, consistent with complete bilateral choanal atresia. TREATMENT AND OUTCOME Choanal atresia was treated with an endoscopically assisted balloon-dilation technique, and temporary tracheostomy was performed. Stenosis recurred, requiring revision of the repair and intranasal stent placement 3 days after the first surgery. The tracheostomy tube was removed the next day. Complications during hospitalization included mucoid obstruction of the tracheostomy tube, granulation tissue development in the trachea near the tracheostomy site, mucoid stent obstruction, aspiration pneumonia, and presumed partial failure of passive transfer of immunity. The stents were removed 2 weeks after admission, and the cria was discharged 3 days later. The owner was advised that the animal should not be bred. At last follow-up 3 years later, the alpaca was doing well. CLINICAL RELEVANCE Surgical treatment with a balloon-dilation technique and placement of nasal stents with endoscopic guidance were curative in this neonatal alpaca with bilateral membranous choanal atresia. Computed tomography was useful to determine the nature of the atresia and aid surgical planning. Because a genetic component is likely, owners should be advised to prevent affected animals from breeding.