Response of adult domestic cats in Sri Lanka to Acalypha indica root embedded toys and the influence of single nucleotide polymorphisms in olfactory receptor genes on the elicited behavior

Abstract

Exclusively indoor cats exhibit many behavioral complications due to their reduced activity levels and limited behavioral diversity. Environment enrichment is a tool to stimulate adult indoor cats and make them more active. In this research, we evaluated the feasibility of using a toy embedded with roots of the herbal plant, Acalypha indica, as an environmental enrichment tool in adult domestic short-haired cats and how the single nucleotide polymorphisms (SNPs) in the feline olfactory receptor genes influence the animals’ behavioral response toward the toys. A single-blinded crossover study was conducted to evaluate the behavioral changes of adult cats (n = 38) presented with a stuffed plush toy embedded with Acalypha indica roots (treatment) and an empty toy without Acalypha indica roots (control) for 15 min. Activities were recorded, and an ethogram was constructed. Interaction time percentage, presence or absence of interactive behavior types, and total interactive behavior type counts were calculated. Statistical analyses were performed using RStudio software. Differences between treatment and control groups were evaluated using Mann-Whitney U test. Significant differences in interaction time percentage (P = 0.002) and behavior count (P = 0.001) were shown between treatment and control toy types. McNemar’s Chi-squared test results indicated that the proportion of licking (P = 0.004), chewing (P = 0.008), and face rubbing (P = 0.02) behavior types were significantly higher when cats were given the Acalypha indica toy. Based on these three significant behavior types, responders (n = 10) and non-responders (n = 10) for treatment toys were identified and assessed for variations in OR10K1, OR10V1, and OR2B11 olfactory receptor genes. Seven, five, and two SNPs were identified in the coding regions of OR10K1, OR10V1, and OR2B11 genes, respectively. Allele frequencies of SNPs at 354 bp and 688 bp positions of OR10K1 were considerably different between responders and non-responders, and SNP at 354 bp substituted arginine by a stop codon at site 107 in the amino acid chain. The present study showed that a toy embedded with roots of Acalypha indica holds potential as an environmental enrichment tool in adult domestic cats. However, the variations in olfactory genes, such as OR10K1, could change their behavioral responses toward these olfactory enrichment toys.