Spay The Strays

Save the Strays! (GIPHY, n.d)

Imagine you gave your child permission to play outside, to later find out that an innocent, harmless act such as playing outside is no longer safe for your child anymore. Precious Reynolds of Willow Creek, California, is a typical 8-year-old who’s spunky and loves sports. In May 2011, she was flown to UC Davis Children’s Hospital. Precious developed brain inflammation, or encephalitis, and tests revealed she had rabies, which she obtained from a stray cat near her school that scratched her on the arm during recess. Anyone who is infected generally receives rabies shots, but Precious did not because no one knows exactly when she contracted the disease. Experts say the shots are only effective if given very soon after exposure (Carollo, 2011). Precious was extremely lucky to survive. This a very rare case, people who are usually affected with rabies and are not vaccinated typically do not live. Symptoms of rabies in humans can get as severe as hallucinations, partial paralysis, excessive salivation and more (Mayo Clinic, n.d). Sadly, Precious’s story, though tragic, is not uncommon. In addition to rabies, cats–and in particular feral cats–are known carriers of a wide range of zoonotic diseases.

It is estimated that there are around 50-87 million free-roaming cats in the United States alone (Mott, 2004, para. 4; Weiss, 2010, para. 3). On average, a cat has 1-8 kittens per litter and 2-3 litters per year. During a female’s productive lifetime, one cat could potentially birth 100 kittens. With each kitten reaching puberty at around 7 months, a single pair of cats and their kittens can produce as many as 420,000 kittens in only 7 years (Foster & Smith, 2004, para. 6, Fayette Humane Society, 2017, para. 5). With feral cat populations on the rise, the effect they create could get substantially worse. The spread of infectious diseases is a rampant problem when it comes to free roaming cats. What many fail to realize is that these animals carry multitudes of zoonotics diseases. Zoonotic diseases are any virus, bacteria, parasite, or fungi that can be spread between animals and humans (Center for Disease Control and Prevention [CDC], 2016).

Zoonotic Diseases

Between  1993 to 2010, cats accounted for majority of human rabies exposure incidents (32%) and post-exposure prophylaxis (PEP) treatments (31%) in New York (Gerhold & Jessup, 2013, p.190). The Center for Disease Control and Prevention states that rabies post-exposure prophylaxis consists of a dose of human rabies immunoglobulin and a rabies vaccine is given on the day of the exposure, and then a dose of vaccine is given again on days 3, 7, and 14. Wound cleansing is especially important in rabies prevention since, in animal studies, thorough wound cleansing alone without other post-exposure prophylaxis has been shown to markedly reduce the likelihood of rabies (CDC, 2016).  A separate investigation of rabies exposure in domestic animals in upstate South Carolina disclosed that free-roaming cats were disproportionately associated with potential human rabies exposure and were most frequently named rabid among domestic exposure animals (Gerhold & Jessup, 2013, p. 190).

Rabies must be treated quickly in humans through a series of shots in order to prevent serious symptoms (Schill, n.d.). There are approximately 300 rabid cats reported in the United States each year and involving every human rabies case, about 16% of them are due to cats (CDC, n.d., para. 3). Rabies is transmitted when a rabid cat bites a human and their saliva gets in the bloodstream. Though the percentages of cats having each of these diseases are somewhat low,  even if only 5% of feral cats have rabies, there could be up to 4 million feral cats carrying the disease in the United States. PEP treatments are typical for exposure to rabies and preventing it from getting worse. Since about 30% of rabies PEP treatments are caused by cats and there are typically 40,000 to 50,000 PEP treatments every year in the United States, this means that about 13.5 PEP treatments are due to cats every year . Each treatment costs a minimum of about $3,000, which leads to a total cost of $135 million in human PEP treatment every year in the United States alone (CDC, 2015, para. 2). As other zoonotic disease are studied, the overall cost of harboring these large populations of cats only increases.

Feral cats carry a dangerous intracellular parasite known as toxoplasmosis gondii (toxoplasmosis).  Toxoplasmosis is hereditary in cats and their kittens, but they may also be infected by eating other contaminated rodents or birds (CDC, n.d., p. 1). A study conducted on Prince Edward Island in Canada concluded that 29.8% of feral cats harbored toxoplasmosis (Stojanovic & Foley, 2011, p. 980). Toxoplasmosis spreads to humans who touch anything that had contact with contaminated feces.  This can easily be tracked into households on the bottom of shoes and can contaminate outdoor playgrounds. When toxoplasmosis spreads to humans, it can induce fever, enlarged lymph nodes, headache, stiff neck, loss of appetite, and several other symptoms (Hill & Dubey, 2002, p. 634).  This parasite is especially worrisome for pregnant women, newborn babies, and others who are immunologically compromised (CDC, 2013). If an infant is born with this disease, it may not be apparent right away but future complications can range from slight brain damage to seizures and intellectual disability (Medline Plus, 2015). Treatment of toxoplasmosis involves a six-week, twice daily medication called Daraprim . In 2015, the cost of this pill went from $13.50 to $750 each almost overnight resulting in the total cost of full treatment at about $63,000 per person (Hiltzik, 2015, para 2). Every year about 2,000 people need to take Daraprim, which means that $126 million is spent on this medication annually (Almendrala, 2015, para. 6). The prevalence of toxoplasmosis gondii in cats worldwide is estimated to be roughly 30-40% (Elmore et al., 2010, p. 192). If 30% of humans contract this zoonotic disease, about $40.8 million is spent on Daraprim annually due to feral cats.  

Unlike toxoplasmosis, dermatophytosis (ringworm) is transmitted from animal to human just through contact. A study of about 5600 cats was performed in an animal shelter in the U.S. over a 24 month period and a little over 10% of them contained skin lesions from ringworm (Moriello, 2014, Prevalence). Ringworm is extremely contagious, 1 in 10 humans that adopt a cat from that shelter are likely to contract ringworm if not informed of the condition beforehand. Cats can get ringworm from digging in the soil or from contacting another infected animal (Schill, n.d.). The symptoms of a cat with ringworm are similar to those in humans. Ringworm is characterized by missing spots of fur, mostly on the head, ear or chest, and visible spots of red, ring-like shapes in humans.  While ringworm is not fatal for humans or cats, it causes itchy or cracked skin, a ring-shaped rash, and hair loss wherever it is present (Bennington-Castro, 2016). Treatment of ringworm includes applying a nonprescription antifungal cream, lotion, or powder on the affected areas of the skin (CDC, 2015). It is estimated that approximately 3 million cases of ringworm occur on humans in the United States every year (Ghannoum, 2009, p. 258). Since these lotions cost about $10 each, it means that around $30 million is spent on ringworm cream annually. If 10% of these cases are due to feral cats, $3 million is spent on treatments each year.

Cost of Treatments

The costs of the rabies, ringworm and toxoplasmosis treatments are alarmingly high due to the amount large numbers of feral cat populations. Overall, the total combined costs of the treatments of all these diseases annually are about $178.8 million and a majority of that money is due to the spread of disease from cat to human. Not only are these diseases from feral cats directly, but they can be transferred to household pets, increasing the overall risk of being infected. More than 60 million people have toxoplasmosis, 3 million people have ringworm, and it is unknown how many people get PEP treatment every year (CDC, 2013, para. 1). In order to prevent the outbreak of zoonotic diseases from feral cats to humans and other animals,  U.S Fish & Wildlife Service should introduce Trap-Neuter-Release programs where feral cat populations are most significant.


Trap-Neuter-Return is a humane approach to addressing community cat populations to minimize the effect they have on those around them. In a TNR program, community cats are humanely trapped with box traps, brought to a participating veterinarian to be sterilized, vaccinated, ear tipped for future identification, and then returned to where they were found (Alley Cat Allies, 2017). The most efficient method of trapping involves establishing a feeding routine for outdoor cats in a specific location and time. Once that is established, the food is withheld for some time, making the cat more likely to go into narrow spaces, such as a box trap, to retrieve it (Neighborhood Cats, 2017). TNR improves the lives of cats, addresses community concerns on the effect of outdoor cats, reduces complaints about these cats, and stops the breeding cycle. With the decline in breeding populations as a result of these programs, there are less cats to spread the diseases described above.

A TNR program in Florida, named Operation Catnip, was assessed over 2 years for its impact on shelter intake. The study was conducted in an area of high shelter cat intake and resulted in a 66% decrease in shelter impoundment over the time period (Levy, Isaza, & Scott, 2014). Over two years, a total of 2,366 cats, approximately 54% of the projected community population, were effectively, sterilized, assessed and vaccinated (Levy, Isaza, & Scott, 2014, p. 269). A decrease in the amount of cats entering shelters correlates with a lower population of stray cats, shedding light on the success of these programs. Not only do TNR programs sterilize cats to prevent further reproduction, but these programs also fund vaccinations, such as rabies prior to being released to their original habitat. This is not only critical for the health of these animals, but it can also play a role in decreasing the spread of disease between cats and other species.  

Trap-Neuter-Return programs have also seen success in cities across the world. A 3-year study done in Albuquerque, New Mexico following a large scale, targeted TNR program saw similar results as Operation Catnip. Success of this program was evaluated based on shelter intake and deaths, with intake decreasing by 38% and shelter deaths by 82% respectively. (Johnson & Cicirelli, 2014, p. 3). In 2011 alone, 3,500 cats were euthanized due to overpopulation as opposed to 632 deaths in 2014. Not only did this TNR program reduce euthanasia rates, but intake of kittens under 8 weeks of age dropped by 33% (Johnson & Cicirelli, 2014, p. 6). This reduction strongly indicates that the breeding population of community cats was reduced. Subsequently, Baltimore Animal Rescue and Care Shelter, known for its high intake rates, received 39% fewer kittens under 4 months of age, again showing a probable decline in the breeding population caused by targeted a TNR program (Mendes-de-Almeida, et al. 2011, p. 272). Similar stories are seen with these intensive programs in Texas, Arizona, Massachusetts, and even Italy (Nutter, 2005). With the reductions in breeding populations and intake of outdoor cats by animal shelters, targeted TNR programs are a feasible option.

Regarding the funding of these programs, there are several projects filled with willing staff and volunteers to tackle overpopulation. The Community Cats Projects are partnered with well-known organizations, such as PetSmart Charities and Best Friends Organization. PetSmart Charities alone donated more than $3.6 million to fund these efforts (Best Friends, 2017). Best Friends is an organization located across the country, from New York to Los Angeles, and provides these high-volume, 3-year programs in neighborhoods with the source of highest shelter intake. Alley Cat Allies is another non-profit organization with more than 600,000 supporters around the world. Their team of cat experts, organizers, attorneys, and researchers aim to provide low-cost spay and neuter policies while educating the public on the importance for stray cat health (Alley Cat Allies, 2017). These non-profit organizations aim to reduce the costs of TNR programs. Working with organizations such as PetSmart, the U.S. Fish and Wildlife Service should cover the costs in order to alleviate the public health issues that feral cats pose to humans and other animals. Once a TNR program is established within a community, any household can volunteer to humanely trap outdoor cats and bring them to participating veterinarians once they are educated on how to safely handle the project. Through education about these organizations and the possibility of a humane form of control on cat populations, we can work together with these partnerships to provide effective TNR programs where they are needed.

Another option that has been explored to minimizing the effect of feral cats is trapping and euthanizing. The procedure costs between $45 and $150 per animal with an additional fee to dispose of the dead body (Havahart, 2017). With a projected 50-87 million free-roaming cats in the United States alone, the cost of euthanizing these cats would be substantial. Through TNR programs, the cost of trapping, sterilizing, vaccinating, ear tipping, and release per cat is $50-60. It would costs an estimated $16 billion to trap and euthanize community cats, while TNR programs cost $7 billion a year (Havahart, 2017, para. 20). A difference of $9 billion is very significant and given the success of these programs, TNR is worth every penny. Not only would euthanizing these cats be costly, but a ‘Vacuum Effect’ occurs once cats are removed from their environment. The empty habitat attracts new members to utilize the same resources, such as food and shelter, that were readily available to the previous population (McKinney, B. P. & Bester, M. N., 2011).With their vast reproductive capabilities, feral cats are able to return to their original population numbers quickly, making euthanasia a non-viable option.

Looking at the costs that zoonotic disease can bring annually, TNR is a fitting solution in both its cost and success. The implementation of TNR programs will progressively cut down these costs by reducing cat populations and eliminating the need for the expensive euthanasia procedures. As the years go on, there will be less and less kitten populations due to the sterilization of feral cats (Johnson & Cicirelli, 2014; Mendes-de-Almeida, et al. 2011; Nutter, 2005). TNR programs make a tremendous difference in both the safety of the human population and overall money spent on the treatment of diseases and euthanizations.

The spread of these various zoonotic diseases through feral cats needs to be controlled to contain this public health threat. The question as to whether feral cats pose a significant threat to the environment cannot be contested with the support of the aforementioned statistics. One of the most effective ways to combat this spread of disease by feral cats is by Trap-Neuter-Return programs. These TNR programs are proven to be successful across the globe. They are a human solution to this problem and as cat populations decrease, the cost of this programs will be alleviated as well. Therefore, TNR programs seem to be the most compelling method of disease control in feral cats.


Paul Bolduc – Building and Construction Technology

Brittany Washum – Plant, Soil, Insect Sciences

Abbey Kingston – Pre-veterinary Science


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  2. From above article i learned lot of things about rabies. Like what is rabies, how it transmitted, how to prevention rabies and many more.
    I saw many comments about rabies in dogs there is no body mention what kinds of animal carry a rabies virus and list of there.
    I found such as article where a list that carry rabies virus.

    The following animals are the main sources of rabies infection in humans:
    Dogs, Cats, Horses, Cows, Rabbits. Foxes, Monkeys, Skunks, Woodchucks, Bats, Ferrets, Raccoons, Coyotes, Beavers

    Not only that i found many question answer like:
    What is Rabies?
    Stages of Rabies
    Sign & Symptoms of Rabies
    Treatment of Rabies
    How to Prevent of Rabies

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