Islandshästar med hosta och/eller prestationsnedsättning
skiljer de sig åt jämfört med andra raser?
The purpose of the study was to investigate whether or not Icelandic horses are
less severely affected in clinical symptoms of cough or decreased performance
than other breeds of horses. A breed variation in chronic respiratory disease
severity was suspected based on clinical experience at the Institution for surgery &
medicine, large animal, SLU Uppsala. A retrospective journal study of 17
Icelandic horses and 17 Swedish Standardbred horses with chronic problems with
cough and/or decreased performance compared several measurements of disease
severity.
The clinical signs, physical examination and laboratory testing results compared
were respiratory rate, abdominal breathing, lung auscultation, endoscopy results,
broncho-alveolar lavage (BAL) results and the blood gases pO2 and pCO2. All
parameters were available for all 34 individuals except for the blood gases, which
were analysed, in only four Icelandic horses and four Swedish Standardbred
horses.
The only parameters that appeared different between the two groups were
respiratory rate and pO2. The four Icelandic horses, which had blood gases
analysed, had more severe hypoxemia. But all had a greater inflammatory process
in the lower airways as shown by the increased neutrophils in the BAL results
compared to the 4 Standardbred horses. There was no difference between the 2
breeds of horse in the number of neutrophils in the BAL tests when all 17 horses in
each group were compared, therefore it is likely that if one compared Icelandic
horses with Standardbred horses having similarly severe inflammation there may
not have been a difference. We did not have the opportunity to compare blood
gases among individuals with equally severe inflammation as good controls. The
difference in hypoxemia in only 4 horses with especially severe disease was thus
not considered good proof of a difference between the 2 breeds.
The mean respiratory rate was different between the two groups. Mean respiratory
rate among the 17 Icelandic horses were 31,0 ± 9,7 compared with 16,8 ± 4,3
among the 17 Swedish Standardbred horses. In order to further consider this
difference, the respiratory rate was measured in 23 clinical healthy Icelandic
horses housed outside. The mean result was 16,4 ± 3,6. This is above than range
accepted as the normal respiratory rate for horses of 8-16 per minute. This suggests
Icelandic horses appear to have a higher respiratory rate normally and this may be
exaggerated when they are examined inside where it is warmer. The higher
respiratory rate among the 17 Icelandic horses in this study may only be mainly a
breed variation and not necessarily indicate that they are more severely affected
during chronic respiratory problems.
Our conclusion was that there was insufficient proof found in a more controlled
study to indicate that Icelandic horses are less severely affected by chronic
respiratory disease that appeared as the clinical problems of cough or decreased
performance. Further studies on respiratory rate and blood gas analysis may be
useful in understanding the two differences noted in our study.