Peer-reviewed veterinary case report
Occipitoatlantoaxial malformation in two non-Arabian horses.
- Journal:
- Journal of the American Veterinary Medical Association
- Year:
- 1985
- Authors:
- Wilson, W D et al.
- Species:
- horse
Plain-English summary
Two horses, a 19-month-old Appaloosa mare and a 3-year-old Quarter Horse gelding, were found to have a condition called occipitoatlantoaxial malformation, which affects the joints at the base of the skull and the top of the neck. Both horses had been holding their heads and necks in unusual positions since they were born, but they only started showing signs of nerve problems when they were older. A veterinarian was able to diagnose the issue by feeling the neck and head area, and they noticed that the horses had limited movement at one joint and unusual movement at another. X-rays showed that the bones at the base of the skull were fused together, and this was confirmed when the horses were examined after they passed away. Unfortunately, the treatment options for this condition are limited, and the outcome is not favorable for these horses.
Abstract
Occipitoatlantoaxial malformation was diagnosed in a 19-month-old mare of Appaloosa breeding and in a 3-year-old Quarter Horse gelding. Both horses had abnormal head and neck carriage since birth, but neurologic deficits did not become evident clinically until the horses reached 2 and 3 years of age, respectively. Palpation and manipulation of the base of the skull and cervical area proved to be useful diagnostically. Movement could not be elicited at the atlantooccipital joint but, in comparison with clinically normal horses, the range of dorsoventral motion at the atlantoaxial joint was increased. Alternate subluxation and relocation of this joint generated audible clicking sounds. Radiography revealed symmetric atlantooccipital fusion, with modification of the atlas, atlantoaxial joint, and axis. These findings were confirmed at necropsy.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/4019299/