In humans, the link between negative life events and susceptibility to the common cold is well documented. Further, interventions that enhance emotional wellbeing can stimulate local immunity and reduce incidence of respiratory infections. It is also clear that, in cats, a stressful event such as entering an animal shelter can increase susceptibility to upper respiratory disease (URD) and cause recrudescent disease in cats with subclinical infections (e.g. feline herpesvirus type 1). This study examined whether behavioural interventions could enhance emotional wellbeing, stimulate secretory immunoglobulin A (S-IgA) and reduce incidence of URD in shelter cats.
A three-dimensional model was constructed using behaviours observed in 34 cats for 5min/per h (days 1, 3 and 5), S-IgA and cortisol concentration quantified from faeces produced within 24 hours of each observation day. The model showed a significant contrast between two groups of behaviour indicative of high and low arousal of the emotional defence system and were labelled Anxiety and Contentment respectively. Anxiety behaviours such as hiding, flat postures, freeze, crawl, startle, and retreat from humans were significantly contrasted to Contentment behaviours: sitting quietly at the front of the cage while observing activities, sleeping or resting while lying on their side, eating, grooming, walking and friendly response to humans. The third dimension indicative of low arousal of the appetitive / reward system included persistent meowing, scanning, pacing, pushing and destroying items in the cage, redirected aggression and various escape behaviours (e.g., pawing at walls/ hanging on cage bars, pushing on door latch). Loge S-IgA was higher for Content cats (mean 7.1 ±0.5 loge µg/g) compared to Anxious (5.6 ±0.6 loge µg/g) and Frustrated cats (5.6 ±0.7 loge µg/g) (P <0.001) cats. Although several Frustration (pace and escape behaviours) and Contentment (walk, friendly response) behaviours correlated positively to cortisol, overall the Mean values were not significantly different for Frustrated (4.2 ±2.0 loge µg/g), Content (3.7 ±1.6 loge µg/g), and Anxious cats (3.0 ±1.0 loge µg/g) (Estimate 0.13, SD 0.31, Wald 1.67E-01, P =0.68). The multidimensional model labelled University of Queensland Indices of Cat Wellbeing (UQ-ICW) was subsequently used to rate emotional states in 250 cats upon admission to the shelter. Cats were assigned to one of 3 treatment type. Gentling, cognitive enrichment or positive human interaction was provided for 10 mins 4 times daily over a 10 day period to Anxious, Frustrated or Content cats respectively. Emotional and immune responses were measured for 10 days using UQ-ICW and quantification of S-IgA respectively. Ocular and nasal samples were obtained at intake and subsequently on days 4 and 10 to test for shedding of URD pathogens common in cats. In the Anxious group (n=139), gentled cats were more likely to be rated as Content (IRR: 1.52, CI: 1.27-1.81, P < 0.001) and had higher S-IgA (6.8 Loge µg/g) than Control cats (5.9µg/g) (P <0.0001). Those responding positively to Gentling had higher Loge S-IgA (7.0µg/g) than negative responders (6.1 µg/g) (P = 0.001). Control cats were more likely to develop URD overtime compared to gentled cats (HR: 2.37, CI: 1.35-4.15, P < 0.0001).
In the Frustrated group (n=15), cats provided with cognitive enrichment were more likely to be rated as Content (IRR: 1.93, CI: 1.01-3.68, P <0.0001) and had higher Loge S-IgA than Control cats (6.7 µg/g versus 6.1µg/g, P = 0.03). Those responding positively to treatment had higher S-IgA than negative responders (6.8 µg/g versus 6.0 µg/g, P = 0.003). Treated cats were less likely to develop URD overtime (HR: 2.37, CI: 1.35-4.15, P < 0.0001).
For cats classified as Content (n=96), the positive interaction treatment increased the likelihood of sustained contentment compared with the Control treatment (IRR: 1.93, CI: 1.01-3.68, P < 0.0001). Loge transformed S-IgA levels was significantly higher for treated than for Control cats (7.28 µg/g versus 6.74 µg/g, P <0.0001). Control cats were more likely to experience onset of negative affect (Anxiety or Frustration) than treated cats (IRR: 0.61, CI: 0.42-0.88, P = 0.007) and were more likely to develop URD overtime (HR: 2.9, CI: 1.30-6.67, P = 0.01).
Overall, 28% of cats were shedding one or more infectious agent related to URD upon admission. Twenty-two percent were shedding Mycoplasma felis (M.felis) and fewer than 3% were shedding calicivirus (FCV), feline herpesvirus-1 (FHV-1) or Bordetella bronchiseptica. Overall, viral and bacterial shedding increased by 9% and 11% respectively over the three sampling times (days 1, 4 and 10) and was not significantly affected by source, sex, sterilization status or age (P > 0.05). Over 40 days post admission, the cumulative probability of developing URD was 1.7 times greater for strays than owner-surrendered cats and 3.3 times greater for cats that were shedders compared to non-shedders at entry to the shelter (P < 0.001). FHV-1 shedders were at greater risk of developing clinical signs than non-shedding cats (P = 0.002). Median time to clinical URD for shedders of FHV-1 was 6 days, compared to 11 days for non-carriers. There were no differences in shedding rate upon admission between cats assigned to treatment and controls (P>0.05) and no difference overtime for Frustrated and Content subgroups (P> 0.05). However, there was a significant increase in shedding overtime in non-gentled cats (22%, 36%, 61% on days 1, 4 and 10, respectively) but not for gentled cats (35%, 26%, 32% on days 1, 4 and 10, respectively) (P = 0.006).
Our findings suggest that negative emotional states such as Anxiety and Frustration reduce local immunity and that behavioural interventions can induce Contentment enhance IgA-mediated immunity and reduce incidence of URD in shelter cats.