Bold personality makes domestic dogs entering a shelter less vulnerable to diseases

Abstract

It is widely recognised that for vertebrate species, personalities vary along an axis with extremes represented by 'proactive' and 'reactive' individuals. The aim of this study was to verify whether there is a relationship between personality and disease vulnerability in domestic dogs (Canis familiaris) exposed to an intensely stressful situation such as entering a shelter. Twenty-eight shelter dogs participated in the study. The ethogram consisted of approximately 100 behavioural patterns. Behavioural observations of dogs in their new environment, a Novel Object and a T-maze test were used to evaluate the personality of the dogs captured as strays and entering the shelter. A blood sample from each dog was obtained at admission into the shelter and after a month to evaluate their immunological state. Based on PCA analyses of observational combined with experimental data, the dogs were ordered along the boldness-shyness axis, with the first being the boldest. Excluding one (the 6th), the first 10 dogs showed an improved health status: absence of disease symptoms during the 30 days of monitoring and improved immunological parameters; the opposite was found for shy dogs. The results of this research seem to confirm findings in other vertebrate species, i.e., bold and shy dog vulnerability to diseases might be different, especially when they must cope with a stressful and highly infectious environment such as a dog shelter.

Fig 1. The inflatable killer whale tied to a string under a canopy within the enclosure where the novel object test was performed.

The dog was released and was alone in the enclosure. Printed with permission from Simona Borruso original copyright [original copyright 2013].

Fig 2. The facility utilised to carry out the T-maze test: A pre-structured enclosure with a "V" shape.

Each arm of the structure measures 40 m, and the arms are separated by a distance of 39 m. At the end of each arm there is a reward area where some food can be placed. The dog was released at point A and was alone in the maze.

Fig 3. The time latency of approach to the novel object of dogs who showed fear towards the unknown object.

Dogs are ordered from left to right from boldest to shyest.

Fig 4. The time latency of approach to the novel object of dogs who did not show fear towards the unknown object.

Dogs are ordered from left to right from boldest to shyest.

Fig 5. The average time latency (minutes) that the 28 dogs spent searching food in the T-maze test in the 10 trials.

In the 6^th trial, the location of the food was changed from the right to the left arm. Bars indicate the standard error.

Fig 6. The direction chosen by the 28 dogs in the 10 trials during the T-maze test.

Fig 7. Scatterplot of observed and expected probability against the personality index.

Health improvement = 1, worsening = 0.

Fig 8. Mixed model ANOVA—A between-subjects variable.

The results of the mixed model ANOVA—a between-subjects variable (bold vs. intermediate vs. shy personality class) and a within-subjects variable (haptoglobin values of the 1^st blood vs. the 2^nd blood sample).

Fig 9. Mixed model ANOVA—A within-subjects variable.

The results of the mixed model ANOVA—a between-subjects variable (bold vs. intermediate vs. shy personality class) and a within-subjects variable (dRoms values of the 1^st blood vs. the 2^nd blood sample).