March 1, 2022

Audience: Executive Leadership, Shelter/Rescue Staff & Volunteers, Veterinary Team

Organization: Oregon State University
Investigator(s): Monique Udell
Grant Amount: $75,636.00
Project Type: Basic Research
Project Status: Research Complete

Project Summary

This Oregon State University study examined the impact of socialization and foster experiences on cat stress and behavior toward humans. Cats were placed in one of 4 groups: control; socialization with the shelter; socialization during a one-night foster, or socialization during a one-week foster. While fostering is common for dogs, it has often been assumed that fostering cats, especially short-term, could be stressful or problematic for this species. However, the study did not find evidence to support this. Instead, the most noteworthy change in behavior was a trend towards increased sociability for fostered cats.


The objective of the project was: to evaluate foster and socialization programs that could benefit cats in terms of adoption, behavior and welfare outcomes.


80 cats were pseudo-randomly assigned to one of four groups of 20 each, (1) control, (2) enhanced socialization within the shelter, (3) participation in a foster sleepover program, and (4) participation in a traditional foster program, with age and sex of cat considered for consistency between groups. Cats in groups 1 and 2 stayed in-shelter while cats in groups 3 and 4 left to stay in a foster home. Cats in the control group received no additional socialization while cats in the enhanced socialization group received three 15-minute socialization sessions with a set partner. Cats in the foster groups either left the shelter for 1-day (sleepover) or for 1-week (traditional foster). Cat social behavior was examined and stress levels were measured by urinary cortisol levels at several timepoints: (A) with baseline a day before the intervention, (B) a day during the intervention, (C) a day after the completed intervention, (D) and a week after the intervention.


  • Eight cats did not urinate in the box at baseline and were excluded from further analysis.
  • On average, short-term socialization and foster interventions did not lead to a statistically significant increase in social behavior or decrease in stress levels of cat participants, although analysis is ongoing.
  • The study did not find evidence of significant increases in stress, or in fearful or unwanted behavior in cats after participation in 1-day or 7-day fostering.
  • While fosters were adopted most quickly on average, differences in LOS between the experimental groups and control were not statistically significant.


These findings challenge the assumption that fostering in cats, especially short-term, could be stressful or problematic for cats. It is possible that greater behavioral and stress related benefits would have been seen with longer or more intensive socialization or fostering programs. It is also possible some individuals may benefit while others do not, and further analysis is pending. However, a meaningful outcome of this project can also be found in the absence of differences between the groups, with results indicating that cats were not at a behavioral disadvantage and did not have higher cortisol levels when sent to foster for a day or week. Such knowledge could serve to increase lifesaving efforts by allowing cats to more readily go to foster homes when shelter space is limited, to help meet medical needs, or even for socialization or training opportunities that could extend beyond those employed in this study.