Yorkshire terriers susceptible to respiratory symptoms
MedWire News: Yorkshire terriers have a significantly higher rate of respiratory symptoms (RS) than dogs of other breeds, observe researchers who conducted a study in Swedish and Danish dogs.
Specifically, the risk for RS among 5-year-old Yorkshire terriers in the study was 4.1-fold that for 5-year-old dogs of other breeds.
Age and gender were both significant risk factors for respiratory morbidity in the terriers, and the study results also revealed an increase in RS prevalence among female dogs as they aged, indicating a gender ratio reversal in RS prevalence, the team reports.
This finding in female dogs is "novel" remark Jakob Willesen (University of Copenhagen, Denmark) and colleagues in Veterinary Record.
They believe an estimation of respiratory disease in the Yorkshire terrier breed, together with identifying risk factors, is necessary to "support an evidence-based approach to clinical practice."
The team surveyed 295 owners of 354 Yorkshire terriers, and owners of 100 dogs from 48 other breeds for incidence of recurrent coughing and/or abnormal breathing in their animals while drinking, exercising, experiencing stress, and putting on a collar.
A respective 56.3% and 26.0% of terriers had RS and frequent RS, which was just over four times the rate reported in other breeds of dog, at 23.0% and 5.0%, respectively.
Overall, age was significantly associated with RS incidence, with higher RS incidence in older dogs, report Willesen et al. Similarly, gender showed a significant association with RS, with male dogs 1.7 times more likely to have RS than females.
However, while RS incidence was reasonably stable over time among male dogs, with a nonsignificant odds ratio (OR) of 1.1 per year increase in age, the probability of reporting RS increased significantly in female dogs as they aged. Indeed, for each 5-year age increase, the risk for RS increased 3.1-fold, note the researchers.
Willesen and co-authors suggest that cough sensitivity could be influenced by sex hormones, explaining the increase in RS in the female terrier population. This is mirrored in human medicine with over-representation of middle-aged women at specialist cough clinics, they note.
Another possible explanation is that the study data do not distinguish between incidence of RS and survival; a similar lifetime prevalence of chronic respiratory diseases could be masked by later onset of symptoms in female terriers or increased survival among females, concludes the team.
By Sarah Guy