Lifespan and Causes of Death in the Irish Wolfhound - Vetsuisse ...

3.6.1.1 Possible Pathophysiologies
Primary Ciliary Dyskinesia (PCD) is a disorder of the cilia found in the epithelium of
the respiratory and male reproductive tract (internal wall of the vasa deferentia and
sperm flagella), as well as the auditory tubes, the cerebral ventricles and the
oviducts. These cilia play an important role in mucociliary clearance and in the
transport of germ cells through the reproductive tract. If their normal beating is
impaired, this can lead to chronic infectious bronchopneumonia, secretory otitis
media, hydrocephalus, and infertility (Edwards and Johnson 2004).
An alternative explanation would be that the syndrome is caused by a defect in the
immune system, the nature of which is yet to be determined. This would lead to an
increased susceptibility to infection, resulting in the clinical signs seen in affected
Irish Wolfhounds. In one study, a decreased response of lymphocyte response to
blastogenic factors was reported in three affected Wolfhounds (Leisewitz, Spencer et
al. 1997). The validity of these findings has recently been questioned through the
argument that very sick or dying dogs usually have a certain degree of abnormal
immune system responses as compared to healthy dogs (Casal 2004).
Given the available evidence for a hereditary base, the hypothesis of a viral infection
(Wilkinson 1969) should be considered outdated nowadays.
3.6.1.2 Symptoms
The condition occurs in young Irish Wolfhound puppies and is often apparent at birth.
A watery nasal discharge is present, which later turns purulent as secondary infection
occurs. As the infection progresses, bronchopneumonia develops, which, although
responsive to antibiotics, is often recurrent and a common cause of death. Turbinate
atrophy can also occur (Clercx, Reichler et al. 2003), and a persistent catarrhal
vaginal or preputial discharge has been recorded as a symptom in one study
(Wilkinson 1969).
In some cases, hydrocephalus (Clercx, Reichler et al. 2003; Casal 2004) and otitis
media (Clercx, Reichler et al. 2003) have also been reported, which would fit the
expected picture of PCD. While no significant number of electron microscopic ciliary
abnormities were found by Clercx, Reichler et al. (2003), unpublished data seem to
suggest that there are abnormal ciliary beating patterns and electron microscopic
ciliary abnormities in affected Wolfhounds (Casal 2004).
3.6.1.3 Diagnosis
The typical clinical history of recurrent non-contagious nasal discharge and
bronchopneumonia that have been present since birth or shortly afterwards is fairly
indicative of the syndrome. Thoracic radiography usually reveals features of chronic
bronchopneumonia and sometimes bronchiectasis. Thickened, sclerotic tympanic
bullae (otitis media) and rhinoliths can also be present. Trans-tracheal lavage
typically yields mucous to mucopurulent material that can be cytologically identified
as a purulent exudate. For the diagnosis of PCD, tracheal mucous clearance can be
measured using 99 Tc scintigraphy.
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