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Risk factors for euthanasia at an animal shelter

Mozes R, Pearl DL, Niel L, Weese JS. Epidemiological investigation of euthanasia in an Ontario animal shelter. J Feline Med Surg. 2017 Jun 1;:1098612X17715152. PubMed PMID: 28627283.

Euthanasia is an unfortunate consequence of feline overpopulation and surrender of cats to animal shelters at rates above their capacity.  Between 6-8 million animals are surrendered to shelters in the United States each year, 10-25% of which are euthanatized. In some areas, over 50% of cats may be put to sleep. While a proportion of cats are euthanized for medical or quality of life reasons, many are still euthanized as a result of overcapacity, finances, or non-adoptability. Identification of the factors associated with risk of euthanasia may allow veterinarians, shelter staff, and even pet owners to help better manage shelter populations.

Previous studies have investigated several factors contributing to feline euthanasia. It has been suggested than younger cats, neutered males, purebreds, and white or grey coat color have been associated with lower risks of euthanasia. Other characteristics, however, have not been analyzed, and limited data exists on multivariate risk factors. The purpose of this study was to identify the relation between risk of euthanasia and age, sex, breed, source of cat, color, time in shelter, spay/neuter status, jurisdiction, time of year, and number of times in shelter.

This study was designed as a retrospective evaluation of records of cats presenting to an animal shelter Ontario, Canada over a one year period. The shelter was an open admission facility with foster programs in place to increase capacity. During the course of the study, no disease outbreaks occurred that may have biased results. After collection of data, data regression (linear and non-linear) and extensive statistical analysis (the details of which are beyond the scope of this summary) were preformed to determine univariate and multivariate correlations between the above factors and the risk of euthanasia. Risks were presented as odds ratios for risk of euthanasia.

5439 animals were admitted over a one year period, of which 3737 (69%) were cats. 3435 had sufficient information recorded to enroll in analysis. Approximately equal number of males and females were enrolled, most of which were non-purebred. 78% of cats were strays, 11% were surrendered, 8% were euthanasia requests and 3% were born in the shelter. Of these cats, 1989 (53%) were euthanized.

Most cats were only admitted once.

While univariate analysis was preformed, the multivariate analysis (correcting for the effects of confounding factors) provides the most information (for example, if male cats were more likely to be old, this may artificially increase the risk of males being euthanatized). This suggested several trends:

  • Male cats were more likely to be euthanized than females
  • Surrenders and euthanasia requests were more likely to be euthanized than strays (likely because surrenders and euthanasia requests are more likely to have health or behavior issues)
  • Black cats were more likely to be euthanized than cats of other colors (likely to difficulty photographing and showing, and less unique features)
  • Cats were most likely to be euthanized in the summer, followed by spring, and least likely in the fall and winter (likely due to higher kitten populations)
  • Cats spending 5-20 days in the shelter were more likely to be euthanized than those spending s<5 days (likely due to stray periods or high adoptability) or >20 days (likely due to being fostered or long term investments in care).
  • Re-admission had no effect on rate of euthanasia (potentially due to a cancelling effect from some cats being owned “repeat offenders” and others being difficult to rehome).
  • Intact animals and animals of unknown sex had consistently high euthanasia rates regardless of age, whereas neutered animals increased in risk of euthanasia with increasing age.

Several limitations exist to this study. All data was collected from a single shelter, and so regional variations in both human and feline populations may bias results. Data was also collected over a single year, and so many trends (such as seasonality) have very limited data points to compare.   Data was also retrospective in nature, and so further, prospective studies in more varied populations over longer time spans may provide deeper insight.

Overall, this paper provides valuable information on the risk factors of euthanasia in cats surrendered to animal shelters. This may help shelter staff, veterinarians, and pet owners to identify higher risk populations and take steps to minimize the risk of medically unnecessary euthanasia, plan education and marketing campaigns, and also to plan for seasonal and demographic trends. (MRK)

See also:
Fantuzzi JM, Miller KA and Weiss E. Factors relevant to adoption of cats in an animal shelter. J Appl Anim Welf Sci. 2010; 13: 174–179.