This study investigated female dog preferences for eliminating on either fake grass or concrete in a veterinary hospital environment. Based on anecdotal observations in practice it was predicted that fake grass would be preferred for both urination and defecation. 57 bitches were recruited on an ad hoc basis (all hospitalised female dogs during a 3 week period). Dogs were allocated to one of two groups on the basis of predicted motivation to urinate: High (n = 14) versus Low (n = 43). Motivation estimation was based on clinical condition and intravenous fluid provision. Dogs were given on-leash toileting opportunities throughout the day in a concrete-floored outside exercise run. Half the run was covered with fake grass and half was left uncovered. The run side the fake grass was situated on was switched daily and the run disinfected between urination episodes. Whether the dog urinated or defecated, the latency to urination and the substrate eliminated on was recorded. 30 out of 57 dogs urinated at least once during hospitalisation and 7 dogs urinated on multiple occasions. 6 dogs defecated once during hospitalisation (One sample binomial test, P = 0.031) and all acts of defecation occurred on fake grass. High motivation dogs were more likely to urinate than low motivation dogs (High: 11 out of 14; Low: 19 out of 43; two sample binomial test, P < 0.025). However, when dogs urinated, the latency to do so was similar between groups (Mean (seconds): High: 45.2; Low: 48.3; U = 99.0, P = 0.832). Astroturf was the preferred substrate: 29/30 dogs selected Astroturf for their first urination episode (One sample binomial test, P < 0.001, 95% C.I. 0.8278–0.9992) and 7 out of 8 dogs exclusively selected fake grass for subsequent episodes of urination (up to six episodes per dog). There was no effect of motivation on substrate preference.

It is concluded that fake grass shows is potentially a suitable alternative to concrete for the purposes of elimination. However, the implications of this preference and the hygienic aspects of fake grass management must be quantified before its use is recommended in veterinary practice.