Position Statements

Free-roaming owned, Abandoned, and Feral Cats

April 29, 2020

Position

The Canadian Veterinary Medical Association (CVMA) supports evidence-based, effective and humane initiatives to reduce the population size and the impacts of free-roaming owned, abandoned and feral cats in order to promote animal health and welfare, public health and ecological and environmental health.

Summary

  • The CVMA endorses a One Health approach to the free-roaming cat issue that includes the acknowledgement of the ecological and environmental impacts, and public health risks associated with free-roaming owned, abandoned and feral cats.
  • The CVMA recognizes that adopting a One Health approach involves interdisciplinary collaboration with non-veterinary experts in the fields of ecology, public health, and human medicine to ensure the adoption of scientifically rigorous management approaches.
  • The CVMA recommends that veterinarians discourage the unsupervised roaming of owned cats due to the health and welfare risks to individual cats, their potential contribution to the stray and feral populations, impacts on wildlife populations, and increased zoonotic public health risk.
  • The CVMA supports evidence-based feral cat population management strategies that can effectively achieve declines at a population-level, and over time frames appropriate for the specific population. Managed feral cat colonies should not be located near wildlife areas, nor in areas where they can pose a public health risk. The CVMA prefers and encourages non-lethal alternatives, however it also supports euthanasia by qualified personnel who are trained and have shown competence in the use of veterinary approved euthanasia methods where non-lethal options are ineffective at population attrition or are justifiably impracticable.
  •  The CVMA supports further research to broaden and strengthen our evidence base on the most effective means to decrease and potentially eliminate the feral cat population.

Background

  1. Free-roaming cats can be categorized along a continuum ranging from socialized cats that are owned or previously owned but abandoned, to unsocialized feral cats. In Canada, there are an estimated 5.4 – 9.6 million free-roaming cats, with 1.5 – 4.1 million of these being feral or unowned (1).
  2. The veterinary community is equally concerned about the welfare of both the free-roaming cats and wildlife. Cats are a domestic species that society has introduced into the ecosystem, and although their welfare is important to many people, veterinarians must jointly consider public health risks, the effect these cats have on the ecosystem, wildlife welfare and conservation and the extent that acceptable welfare standards can be maintained for the cats.
  3. In Canada, free-roaming cats are estimated to kill 100 – 350 million birds per year and 1.3 – 4.0 billion in the United States (US) (1-3). In comparison, building collisions kill an estimated 16 – 42 million birds in Canada (4), and 365 – 988 million birds in the US (5). The number of mammalian wildlife killed by cats in Canada has not been enumerated, but in the US, the estimate is 6.3 – 22.3 billion mammals (2). In North America, estimates of the mortality rates for reptiles and amphibians due to cats are unknown, but could be significant, based on Australian estimates of 270 million to 1 billion reptiles killed each year by feral cats (6).
  4. In addition to acting as a non-native predator, domestic cats have also been shown to deleteriously impact wildlife populations through competition, hybridization and disease transmission (7). The ultimate risks to biodiversity are habitat loss and climate change, but sources of additive mortality such as cat predation can have substantial cumulative impacts on wild populations. Unlike other anthropogenic sources of wildlife mortality, the impacts of free-roaming cats are within the realm of influence and responsibility of veterinarians.
  5. Free-roaming owned, abandoned and feral cats serve as reservoirs for zoonotic diseases such as Rabies, Yersinia pestis, Bartonellosis, Toxocariasis, and Toxoplasmosis (8,9). These zoonotic diseases incur significant health and economic burdens (10-12). Limiting unnecessary exposure and environmental contamination of zoonotic parasites should be a public health priority (9,10).
  6. Data from a recent survey revealed that almost 80% of veterinarians support an indoor lifestyle for cats for health reasons (13). Outdoor owned cats experience higher rates of mortality and morbidity due to trauma, infectious disease, parasite loads, higher shelter relinquishment, and reduced owner investment (14-17). Numerous solutions exist, such as Catios, outdoor enclosures and harness training, that allow owned cats to experience an outside lifestyle without experiencing an increased health risk. They also serve to decrease the cat’s effect on the environment. Feral cats experience even lower welfare standards (15), therefore effective programs that reduce the number of cats living in non-enclosed colonies are an important contribution to feline welfare.
  7. Feral cat populations are typically composed of multiple, loosely organized colonies. Cats can move opportunistically among colonies based on varying densities, and food provisioning (18). Therefore, removing individual cats often leads to a redistribution of cats among colonies (termed as density-dependent dispersal or colloquially as a ‘vacuum’ effect’), but removals still reduce the overall population size (19). Effective management plans should aim to reduce the total number of feral cats living outside, across all colonies, not only at one particular colony.
  8. Many members of our society have negative feelings towards simply removing these cats from the environment via trap and cull, and others view that releasing them constitutes abandonment and neglect. That has prompted the development of numerous programs to remove them from the environment through nonlethal methods.
  9. As typically applied, trap-neuter-release (TNR) alone is ineffective at reducing cat population sizes over reasonable time frames (e.g., less 10 years) (19-24), with removal strategies such as high-volume adoptions, relocations and euthanasia being more efficacious (21,23-25). Large-scale TNR projects, which have reported successful declines, have concurrently removed approximately half of the individuals (26,27). Effective TNR programs need to target small, isolated populations, maintain high sterilization rates (>75%) (21,24), implement appropriate population monitoring, and manage adaptively (28). Initiatives should aim to combine effective cat management approaches with habitat protection to improve conservation outcomes (29).
  10. Feral cat management programs are impeded by the influx from the owned cat population via abandonment, strays or unintended litters (21,27,30), making it imperative that multi-faceted programs are established that include effective population management, habitat protection programs, public education, anti-roaming legislation, and accessible spay and neuter services.

References

  1. Blancher P. Estimated Number of Birds Killed by House Cats (Felis catus) in Canada. Avian Conserv Ecol 2013;8. Available from: http://www.ace-eco.org/vol8/iss2/art3/ Last accessed February 26, 2019.
  2. Loss SR, Will T, Marra PP. The impact of free-ranging domestic cats on wildlife of the United States. Nat Commun 2013;4:1396. Available from: https://www.nature.com/articles/ncomms2380 Last accessed February 26, 2019.
  3. Loss SR, Will T, Longcore T, Marra PP. Responding to misinformation and criticisms regarding United States cat predation estimates. Bio Invasions 2018;20:3385-3396. Available from: https://link.springer.com/article/10.1007/s10530-018-1796-y Last accessed February 26, 2019.
  4. Machtans CS, Wedeles CHR, Bayne EM. A First Estimate for Canada of the Number of Birds Killed by Colliding with Building Windows. Avian Conserv Ecol 2013;8:art6. Available from: http://www.ace-eco.org/vol8/iss2/art6/ Last accessed February 26, 2019.
  5. Loss SR, Will T, Loss SS, Marra PP. Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability. Condor 2014;116:8-23 Available from: https://doi.org/10.1650/CONDOR-13-090.1 Last accessed February 26, 2019.
  6. Woinarski JCZ, Murphy BP, Palmer R, Legge SM, Dickman CR, Doherty TS, et al. How many reptiles are killed by cats in Australia? Wildl Res 2018;45:247-266. Available from: https://doi.org/10.1071/WR17160 Last accessed February 26, 2019.
  7. Medina FM, Bonnaud E, Vidal E, Nogales M. Underlying impacts of invasive cats on islands: not only a question of predation. Biodivers Conserv 2014;23:327-342. Available from: https://link.springer.com/article/10.1007/s10531-013-0603-4 Last accessed February 26, 2019.
  8. Dubey JP, Jones JL. Toxoplasma gondii infection in humans and animals in the United States. Int J Parasitol 2008;38:1257-1278. Available from: https://www.ncbi.nlm.nih.gov/pubmed/18508057 Last accessed February 26, 2019.
  9. Gerhold RW, Jessup DA. Zoonotic Diseases Associated with Free-Roaming Cats. Zoonoses Public Health 2013;60:189-195. Available from: https://www.ncbi.nlm.nih.gov/pubmed/22830565 Last accessed February 26, 2019.
  10. Dabritz HA, Conrad PA. Cats and Toxoplasma: Implications for Public Health. Zoonoses Public Health 2010;57:34-52. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1863-2378.2009.01273.x Last accessed February 26, 2019.
  11. Flegr J, Prandota J, Sovicková M, Israili ZH. Toxoplasmosis – A Global Threat. Correlation of Latent Toxoplasmosis with Specific Disease Burden in a Set of 88 Countries. PLoS One 2014;9. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090203 Last accessed February 26, 2019.
  12. Schurer JM, Rafferty E, Schwandt M, Zeng W, Farag M, Jenkins EJ. Toxoplasmosis and Toxocariasis: An Assessment of Human Immunodeficiency Virus Comorbidity and Health-Care Costs in Canada. Am J Trop Med Hyg 2016;95:168-74. Available from: http://www.ajtmh.org/content/journals/10.4269/ajtmh.15-0729 Last accessed February 26, 2019.
  13. Sherwood LJ, Wilson AG, Cluny SS, Roche SM, Luszcz TMJ (2019). Perceptions of veterinarians in British Columbia of cat management strategies to reduce cat overpopulation and impacts on wildlife populations. Anthrozoos 2019;32 (5):613-629. Available from: https://www.tandfonline.com/doi/abs/10.1080/08927936.2019.1579473 Last accessed October 30, 2019
  14. Patronek GJ, Glickman LT, Beck AM, McCabe GP, Ecker C. Risk factors for relinquishment of cats to an animal shelter. J Am Vet Med Assoc 1996;209:582-588. Available from: https://www.ncbi.nlm.nih.gov/pubmed/8755976 Last accessed February 26, 2019.
  15. Jessup DA. The welfare of feral cats and wildlife. J Am Vet Med Assoc 2004;225:1377-1383. Available from: https://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1377 Last accessed February 26, 2019.
  16. Nutter FB, Levine JF, Stoskopf MK. Reproductive capacity of free-roaming domestic cats and kitten survival rate. J Am Vet Med Assoc 2004;225:1399-1402. Available from: https://avmajournals.avma.org/doi/abs/10.2460/javma.2004.225.1399 Last accessed February 26, 2019.
  17. Hoopes J, Hill JE, Polley L, Fernando C, Wagner B, Schurer J, et al. Enteric parasites of free-roaming, owned, and rural cats in prairie regions of Canada. Can Vet J 2015;56:495-501. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25969584 Last accessed February 26, 2019.
  18. Spotte S. Free-ranging Cats?: Behavior, Ecology, Management. Wiley Blackwell 2014. 320 pages. Available from: https://www.wiley.com/en-us/Free+ranging+Cats%3A+Behavior%2C+Ecology%2C+Management-p-9781118884010 Last accessed February 26, 2019.
  19. Longcore T, Rich C, Sullivan LM. Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return. Conserv Biol 2009;23:887-894. Available from: https://doi.org/10.1111/j.1523-1739.2009.01174.x Last accessed February 26, 2019.
  20. Lohr CA, Cox LJA, Lepczyk CA. Costs and Benefits of Trap-Neuter-Release and Euthanasia for Removal of Urban Cats in Oahu, Hawaii. Conserv Biol 2013;27:64-73. Available from: https://doi.org/10.1111/j.1523-1739.2012.01935.x Last accessed February 26, 2019.
  21. Miller PS, Boone JD, Briggs JR, Lawler DF, Levy JK, Nutter FB, et al. Simulating Free-Roaming Cat Population Management Options in Open Demographic Environments. PLoS One 2014;9. Available from: https://doi.org/10.1371/journal.pone.0113553 Last accessed February 26, 2019.
  22. Bissonnette V, Lussier B, Doizé B, Arsenault J. Impact of a trap-neuter-return event on the size of free-roaming cat colonies around barns and stables in Quebec: A randomized controlled trial. Can J Vet Res 2018;82:192-197. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30026643 Last accessed February 26, 2019.
  23. Andersen MC, Martin BJ, Roemer GW. Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats. J Am Vet Med Assoc 2004;225:1871-1876. Available from: https://doi.org/10.2460/javma.2004.225.1871 Last accessed February 26, 2019.
  24. Loyd KAT, DeVore JL. An evaluation of feral cat management options using a decision analysis network. Ecol Soc 2010;15:art10 Available from: http://www.ecologyandsociety.org/vol15/iss4/art10/ Last accessed February 26, 2019.
  25. Boone JD, Miller PS, Briggs JR, Benka VAW, Lawler DF, Slater M, Levy JK, et al. A Long-Term Lens: Cumulative Impacts of Free-Roaming Cat Management Strategy and Intensity on Preventable Cat Mortalities. Front Vet Sci 2019;6. Available from: https://doi.org/10.3389/fvets.2019.00238 Last accessed August 21, 2019.
  26. Levy JK, Gale DW, Gale LA. Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. J Am Vet Med Assoc 2003;222:42-46. Available from: https://avmajournals.avma.org/doi/10.2460/javma.2003.222.42 Last accessed February 26, 2019.
  27. Levy JK, Isaza NM, Scott KC. Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter. Vet J 2014;201:269-274. Available from: https://www.ncbi.nlm.nih.gov/pubmed/24980808 Last accessed February 26, 2019.
  28. Boone JD. Better trap–neuter–return for free-roaming cats. J Feline Med Surg 2015;17:800-807. Available from: https://journals.sagepub.com/doi/abs/10.1177/1098612X15594995 Last accessed February 26, 2019.
  29. Doherty TS, Dickman CR, Nimmo DG, Ritchie EG. Multiple threats, or multiplying the threats? Interactions between invasive predators and other ecological disturbances. Biol Cons 2015;190:60-68. Available from: https://doi.org/10.1016/j.biocon.2015.05.013 Last accessed June 6, 2019.
  30. Flockhart DTT, Coe JB. Multistate matrix population model to assess the contributions and impacts on population abundance of domestic cats in urban areas including owned cats, unowned cats, and cats in shelters. PLoS One. 2018;13:e0192139. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29489854 Last accessed February 26, 2019.