John & Susan Merrell
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Scio, OR 97374
503-394-3790
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Choanal Atresia

Choanal atresia is a devastating congenital defect which is relatively common in alpacas and very uncommon in most other animals and people.

Choanal atresia is the lack of a connection between the nose and the mouth. Normally, the nasal passages lead back into the pharynx which connects to the opening of the trachea which then leads into the lungs. The area where the nasal passages meet the pharynx at the end of the hard palate is called the choanae. Atresia is the absence of a normal opening. Therefore, choanal atresia is the lack of a normal opening at the choanae. The normal opening is absent because the bone or membrane present during embryonic development fails to break down . A study conducted at Oregon State University concluded that this defect is heritable, but it has not been definitively proven yet, and there remains a great deal of debate within the alpaca community. Some advocate the most conservative strategy of removing both parents of a cria with choanal atresia and not just breeding to different animals. Continuing to breed alpacas who are suspected carriers of choanal atresia may only serve to increase the incidence of the choanal atresia genes (if it is heritable) in the population.

Choanal atresia creates a dead end at the back of the nasal passages. The blockage of the choanae may be partial or complete or on one or both sides. With complete blockage on both sides, no air can be breathed in through the nose to reach the lungs. Air can only reach the lungs by way of the mouth. alpacas are obligate nasal breathers and must be able to breath through their nose to survive. This is especially a problem for newborns. They must be able to breath and nurse at the same time. With blocked nasal passages, crias must than breath and drink milk through their mouth. This is not possible without choking and gasping and getting milk down into the lungs. Milk in the lungs quickly leads to a severe aspiration pneumonia which will kill the cria within hours to days.

Choanal atresia is also associated with nasal bone deformities. The nasal bones may be too short or too close together, making it more difficult to breath if the choanal atresia is not complete. Other congenital defects may be present in a cria with choanal atresia. There may be heart defects, limb defects or other defects in the head.

The signs of choanal atresia in the neonatal cria are:

  • Labored breathing
  • Prolonged and difficult expiration
  • Open-mouthed breathing
  • Choking and gagging while nursing
  • Pale or blue colored gums (from lack of oxygen)
  • Weakness
  • Lack of weight gain
  • Breathing through nose unless stressed (from partial atresia)
  • Swallowing of air

Choanal atresia is strongly suspected based on the clinical signs and is definitively confirmed with radiographs. Euthanasia is the recommended treatment for a cria with choanal atresia. It is possible to perform surgical correction to save the life of the cria, but the cria still has a guarded to poor prognosis. Surgery is not commonly performed because other defects present complicate treatment, the surgical openings created may not be enough for the alpaca to breath normally, there is still a high risk of aspiration pneumonia and a low chance of a satisfactory result. To surgically treat choanal atresia, a tracheostomy must be performed and remain in place for 3 to 4 weeks while the choanae openings heal. It is very difficult to maintain a tracheostomy site for this amount of time in a barnyard animal without multiple respiratory infections. The time and expense involved as well as the suffering of the animal are often not worth the effort.

 
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