Feral cat populations are a major concern in many regions throughout the world. Management of these populations can help to protect the health of the environment (eg. limiting damage to wild bird populations), domestic cat populations (eg. prevention of disease spread and injuries), humans (limiting spread of zoonotic disease) and the cats themselves (prevention of distress associated with overpopulation). Trap-Neuter-Return (TNR) programs are among the most successful methods for controlling these populations, however they necessitate the capture, restraint, transport, and sedation of cats who have very little contact with humans, which can be a very stressful experience for cats.
The existence of an anti-anxiety medication which is safe and efficacious after a single oral dose would be of great advantage to minimize fear and stress responses in TNR cats. Existing drugs either have unreliable oral bioavailability, dangerous side effects, or paradoxical responses. Gabapentin is an analgesic and anti-epileptic drug with good oral bioavailability and a good safety profile. It has been used with good anecdotal success to reduce fear in cats in exam situations. The purpose of this study was to determine if a single oral dose of gabapentin (50mg or 100mg per cat) decreases stress responses in TNR cats.
This study was designed as a double blind, placebo controlled trail investigating the effects of gabapentin on fear responses in trap-neuter-return feral cats. Stress response was quantified based on 4 factors: a published feline stress scale; respiratory rate; lack of appreciable sedation; and fewer injuries when confined. Cats were recruited from an existing TNR program using their standard protocol (ie cages covered in blankets, slow movements and low voices, etc). Cats included in the study were estimated at over 4 months of age, presented in a trap, and scored as ASA 1-2.
After presentation in the trap cats were administered 1.0mL of suspension containing either 50mg gabapentin, 100mg gabapentin, or vehicle alone. This was administered orally using a 3mL syringe attached to a tomcat catheter. Observations were made a baseline and 1, 2, 3, and 12h post treatment.
59 cats were screened for enrollment of which 53 met inclusion criteria. 19 were enrolled in the placebo group and 17 each in the 50mg and 100mg treatment groups. All data was statistically analyzed with the exception of facial injury score, due to the very high frequency of pre- and post- gabapentin injuries.
At both the 2 and 3h post administration time points cats showed significantly lower stress scores than at baseline. These scores returned to baseline at the 12h time point. The greated reduction was seen at the 2h time point. No difference in sedation score was seen at any time point. Respiratory rates decreased steadily over the 1h, 2h, and 3h measurements, however this was not statistically significant. While many cats had injuries likely attributable to their lifestyle or early trapping / transport phases, no new injuries were seen over the course of the study. No difference was seen between the 50 and 100mg groups.
The authors concluded that gabapentin administered orally attenuates fear responses for the first 3 h after administration in feral cats. No adverse effects were seen in any group other than mild transient hypersalivation.
There were several drawbacks to this study. Oral administration of drug in the method described may result in partial loss of drug. Administrating after transport and extensive handling may result in cats with a higher baseline stress level. Lack or prior assessment of cat’s stress levels around humans may have further biased results. Further work using larger sample sizes, earlier dosing (ie hidden in food placed as bait), at more time points, or in different cat populations may help to give more information.
Overall, this paper serves to establish what many veterinarians have suspected- that gabapentin at a 50-100mg/cat dose is safe and effective in reducing stress responses in TNR (and presumably other high-stress populations) cats.
