Relationship of age, sex, body weight, and hematologic and respiratory variables with airway reactivity in adult cats.
OBJECTIVE
To evaluate the association between airway reactivity and age, sex, body weight, and radiographic findings in cats.


METHODS
32 mature cats that constituted 2 age groups (17 young cats that were 1 to 2 years old and 15 old cats that were 12 to 13 years old).


METHODS
Cats were placed in the chamber of a barometric whole-body plethysmograph (volume, 38 L), and box pressure was measured at baseline and after aerosol administration of increasing concentrations of carbachol. Airway reactivity was assessed by monitoring increases in enhanced pause (PENH), a unitless variable that measures bronchoconstriction as derived from dose-response curves. The endpoint chosen was the provocative concentration of carbachol that increased PENH to 300% of the baseline value (PCPENH300).


RESULTS
We did not find a correlation between PCPENH300 and sex, body weight, number of eosinophils, PENH before bronchoconstriction, respiratory frequency, tidal volume, or minute ventilation. Airway reactivity was significantly less in the old cats (mean +/- SD PCPENH300, 0.578 +/- 0.051%), compared with the value for the young cats (0.053 +/- 0.006%). Radiographic patterns differed significantly between groups of cats; a greater proportion of old cats (12/15) had bronchointerstitial patterns, compared with the proportion of young cats (4/17).


CONCLUSIONS
These data support the notion that age exerts a strong influence on airway reactivity in adult cats, and radiographic differences suggest that structural changes in older cats may contribute to this effect. These findings have important implications for interpretation of results of airway reactivity tests in cats.
Hirt
Reinhard A
RA
First Medical Clinic for Small Animals and Horses, Veterinary University of Vienna, A-1210 Vienna, Austria.
Dederichs
Diana
D
Boehler
Alexandra
A
Hoffman
Andrew M
AM
D000367:Age Factors; D000403:Airway Resistance / Q000502:physiology*; D000818:Animals; D016084:Bronchoconstriction / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002415:Cats / Q000502:physiology*; D018679:Cholinergic Agonists / Q000494:pharmacology; D005260:Female; D008297:Male; D010993:Plethysmography, Whole Body / Q000662:veterinary; D012129:Respiratory Function Tests / Q000662:veterinary
D018679:Cholinergic Agonists; D002217:Carbachol