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Electron microscopy was used to diagnose primary ciliary dyskinesia in a litter of English pointer dogs and in a golden retriever dog. A technique of membrane solubilization, fixation, and negative staining with glutaraldehyde tannic acid identified abnormally constructed central and B microtubules in respiratory cilia from dogs with primary ciliary dyskinesia. Shortened outer dynein arms commonly associated with primary ciliary dyskinesia actually represents the absence of a specific subset of the three most peripheral components of the whole outer dynein arm structure.

Using a procedure of membrane solubilization followed by tannic acid fixation-staining, we found abnormally constructed central and B microtubules in cilia from dogs with primary ciliary dyskinesia. We also found that a ciliary abnormality commonly associated with primary ciliary dyskinesia, "shortened outer dynein arms," actually represents the absence of a specific set of the 3 peripheral subunits that make up the outer dynein arms. We believe that this is the first time that these have been reported. Because the proximal subunits of the outer dynein arm are present and attached to the A microtubule, we argue that in these patients there is no structural abnormality of the A microtubule or the A-tubule attachment sites for outer and inner arms and radial spokes. Also, because a majority of cilia in these patients were motile, we believe that the data from this study support the concept that the outer dynein arms are not required for some motion but probably required for normal motility; however, the central microtubules, central microtubular complex, and probably the B tubules are essential for motility.

An 11-year-old Dalmatian was examined and treated for bilateral nasal discharge and cough of 6 months' duration. Response to medical treatment and surgical intervention was unsatisfactory. Histologic examination of lung tissue revealed chronic severe catarrhal bronchitis and bronchiolitis with bronchiectasis. Histologic findings and barium sulfate bronchography indicated abnormal mucociliary clearance in the respiratory tract. Electron microscopy revealed abnormalities or deletions of outer and/or inner dynein arms in 26% of the ciliary profiles from the affected dog. Similar abnormalities were not found in 500 ciliary profiles from age- and gender-matched control dogs.

Compared with neutrophils from healthy dogs, neutrophils from 2 dogs with primary ciliary dyskinesia had increased distance of random migration, but fewer of the neutrophils migrated. The affected dogs had an increase in the numbers of Staphylococcus aureus phagocytized. Lymphocyte blastogenesis in the affected dogs in response to standard mitogens was considered to be normal.