Space and Funds

At the end of the day every euthanasia decision made boils down to one of two things, lack of space, and/or lack of funding. If shelters had unlimited (and well funded) space, or more adoptions, they would be able to keep more animals alive. It is that simple. While the public often criticizes shelters for their alarming euthanasia rate (in the USA 3-5 Million animals are euthanized every year in shelters). As more animals come in on a weekly basis than leave through adoptions or claims (as when pets come in as strays and are recovered by their owners) the shelter is forced to make a decision. The lack of space and funds force shelters to deal with the excess pet population. Only a few shelters have the luxury of turning pets away when they are full, the rest have no choice, when they are full they MUST make room for incoming pets.

Euthanasia is NEVER an easy option.  So, when you run a shelter and are full, with more animals coming in, how do you decide who lives, and who dies?  Shelters have to guess which pets will be more adoptable.  Below are the criteria shelters often use to decide which animals to keep and which to euthanize. They are in no particular order as shelters decide which criteria are more important themselves.

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Age

When it comes to picking a pet to adopt very few people consider the older animals. Most want kittens or puppies. A few might take an adult animal, but not that many are willing to adopt senior pets. Some shelters try to encourage adoption of older pets by lowering the adoption cost or waving it altogether. At the end of the day, when a shelter is full, and an elderly pet, suffering from problems associated with age, is often on the list for euthanasia.

Time at the Shelter

Although members of the public often hear that shelters only keep pets for 72 hours, this is totally false information. 72 hours is the length of time shelters must keep stray pets until they are considered the legal owner of the pet. Once the decision has been made to put the pet up for adoption it is vet checked, vaccinated, and dewormed. At that point the shelter has invested money into the pet and euthanasia is never a desired option. Still sometimes pets sit waiting to be adopted for months. They are passed over again and again.  At a point the shelter staff must make a tough decision, to put down one of their friends to give another animal a chance at getting adopted.  So they might decide to give a new pet a chance.

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Health

A sick pet may put the health of other animals in jeopardy. Some diseases such as Parvo, in dogs, and distemper in cats, can rip through a shelter like wildfire. Because shelters house stray animals that may or may not be vaccinated, and they usually cannot ship all their sick pets to the veterinarian, and they cannot always afford the cost of helping some sick pets, emergency euthanasias are performed. Some pets have ongoing health issues that may prevent them from getting adopted. Diabetic pets, for example, may require insulin shots twice daily, and few owners would choose to adopt such a pet over a healthy one.

Temperament

Dangerous pets are often euthanized. Keeping such animals risks injury to staff and volunteers and not every shelter has the ability or time to work with and rehabilitate aggressive pets. Additionally pets with behavior problems for which the shelter cannot retrain and which would make them difficult to adopt, may be considered for euthanasia when other facts are considered.

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Signs of Stress

Some animals simply cannot cope with living in a cage for a prolonged period of time. They may become depressed, and withdrawn. This hurts their chances of getting adopted. Some develop negative behaviors such as pacing in their kennel. Not all shelters have the luxury of allowing pets to live in foster homes and as such chose to euthanize animals who are not thriving in the shelter.

All Ready Have Many Similar Pets for Adoption

Sometimes a shelter will have several pets that are relatively similar, such as eight border collie dogs or two dozen black cats. When shelters have unique pets, such as unusual breeds, those pets often get a preference in comparison to a pet type that the shelter already has many of.

In dogs preference is usually given to the ones with the best manners, and training. An unruly dog has a poor chance of getting adopted.   Some areas also know that certain sizes of dogs are more adoptable.

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Preference for Keeping

Animals who are already spayed or neutered, and who are fully vaccinated, and are surrendered to the shelter by their owners, have a better chance at being kept by a shelter (and going for adoption), than a stray with unknown history when all other factors are the same. This is because the pet only needs a behavioral assessment where as the shelter still has to pay for the stray pet to be brought up to date medically speaking. Shelters do not get veterinary care for free. Also when a pet is surrendered the owner can pass on information such as whether or not it is good with kids and other pets. Even if these answers are negative, having the answers is often better than having only questions.

Summary

It all boils down to adoptability in relationship to the shelters resources. 

Again we must realize that if shelters had more funding, more space, more adoptions, and fewer animals being brought in all the time, there would be no need for euthanasia. If people took more time to train their animals rather than surrendering unruly pets to the shelter, if they took more time considering what pet was right for them before getting one on a whim, if they spayed or neutered their pet rather than allowing it to have a litter, shelters would not have to deal with excess, and unwanted, pets.

Please note that while some shelters call themselves No-Kill shelters, these are places that generally do not allow unlimited admissions of pets.  They only take pets in when they have space. 

Related Reading

What the 72 Hour Law Means to your Pet

Why we need Animal Shelters

Reasons Why People Surrender their Pets to Animal Shelters

How to Start an Animal Rescue

How to Adopt a Pet