The efficacy of pinch-induced behavioral inhibition (clip restraint) in domestic cats (Felis catus) declines with age

Domestic cats often need to be restrained for clinical procedures. One method that is commonly used to restrain cats is manual scruffing or pinch-induced behavioral inhibition (PIBI; i.e., clip restraint). However, few studies have evaluated its efficacy in cats. This study aims to evaluate the efficacy of PIBI in cats and determine if it declines with age. A total of 142 cats (72 females and 70 males) were used for this study. For the purpose of this study, the age groups were defined as kittens (0-0.5 years of age; n = 14), junior (0.5-2 years; n = 27), adult (2-6 years; n = 43), mature (6-10 years; n = 32), and senior (10-14 years; n = 26) cats. Cats were taken individually into a familiar room, placed on table, and 3 clothes pegs were put on their scruff. The cats were then released and the PIBI response graded as (1) no response, (2) weak, (3) moderate, (4) strong, or (5) very strong. Grades 3-5 were considered as effective restraint, defined as restraint without the need additional handling. Of the 142 cats, 95 (66.9%) were effectively restrained by PIBI and only one cat exhibited an overt negative response (vocalized and aggressively tried to remove the clips). However, the percentage of cats for which PIBI restraint was effective declined with age (P < 0.001): 100.0% of kittens, 74.1% of junior cats, 69.8% of adult cats, 53.1% of mature cats, and 53.8% of senior cats. The decrease in the efficacy of clip restraint with age was more pronounced in male cats than female cats. Neuter status did not significantly affect the probability of PIBI being effective for both male and female cats. The mean PIBI response grade declined with age, with the mean response being stronger in kittens (4.64 ± 0.20) than in cats older than 1 year of age (3.05 ± 0.12; P < 0.001). There was no difference in the graded response among junior, adult, mature and senior cats. Neuter status (entire vs. neutered) did not affect the PIBI response grade in female cats (3.37 ± 0.18 and 3.06 ± 0.33, respectively; P = 0.41), but the response was stronger in entire toms (3.84 ± 0.34) than neutered males (2.82 ± 0.19; P = 0.01). This was likely related to age as 15 of the 19 entire toms were less than 2.0 years old. In summary, PIBI provided effective restraint for 66.9% of the cats, but the efficacy of PIBI and response grade declined with age, with the biggest decline seen between kittens and junior cats.