Airbag (horse)

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The equine air sac ( Diverticulum tubae auditivae ) is a large, bubble-shaped extension of the Eustachian tube ( Tuba auditiva ) in equine species and some other odd-toed ungulates ( tapirs , rhinos ) and rock slippers . There are several theories about its functional importance. It seems most likely to function as a kind of brain cooler because the internal cranial artery ( internal carotid artery ) runs through it. Since the air sac is in open connection with the nasopharynx via the ear trumpet , infectious agents can penetrate the air sac. Therefore air sac diseases are not uncommon and can even be fatal.

Location and anatomical relationships

Between the base of the skull and the head of the pharynx, directly below the parotid gland, there is an air sac with a capacity of about 300 ml on each side. It borders the middle ear , head joint, and jaw joint . It is divided into a lateral and medial bay by the large branch of the hyoid bone . Some important nerves and vessels of the head are located directly on the air sac wall, which can be damaged by suppuration:

Major illnesses

  • Air sac mycosis : It is the most feared disease caused by mold ( Aspergillus fumigatus ). Air sac mycoses can hardly be treated and are ticking time bombs, as there is a risk that the molds also attack the internal carotid artery and then burst, which can lead to bleeding to death. In the meantime, however, there are some more modern therapy methods that significantly improve the prognosis. For example, the affected vessels can be ligated using transendoscopic clip application. Paralysis of individual cerebral nerves also occurs in mycoses. In terms of prognosis, these cases are clearly less favorable.
  • Air sac empyema : The accumulation of pus is mostly caused by bacteria . Frequently she joined the Druse on, a streptococcus - infection of the upper airways.
  • Air sac sympany: Air can accumulate if the tube valve is not functioning properly and can lead to severe expansion of the air sac.


  • FV. Salomon, H. Geyer, U. Gille (ed.): Anatomy for veterinary medicine. 2nd ext. Edition. Enke-Verlag, Stuttgart 2008, ISBN 978-3-8304-1075-1 .
  • Heinz Gerber: Horse diseases. Volume 1: Internal medicine including dermatology. 2nd Edition. UTB, Stuttgart 2013, ISBN 978-3-8252-8075-8 .