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Health - Sterilisation

Animals affected

Dogs, Cats






Sterilisation is a procedure which aims to nullify the reproductive function. Nowadays they use solely and exclusively vasectomy and tubal ligation to prevent fertilisation. Other methods include orchiectomy, ovariohysterectomy and oophorectomy to eliminate the sexual cycle.

Most people who breed their dogs or cats have good intentions and high expectations for the puppies or kittens, but the truth is it’s very difficult to find homes for all of them, especially when it’s a big litter. It is even more difficult to find good homes for them, with families who will take care of them their whole life. Many of these puppies and kittens end up being abused or abandoned.

The decision to sterilise our pet is an act of responsibility towards him/her. It is a basic decision which foresees and avoids health problems and promotes general wellbeing (emotional, physical and hormonal). It also helps the rest of the animals of the same species. With sterilisation thousands of dogs and cats will not be abandoned or need to be put down.

Nowadays the surgical techniques mean that sterilisation is a minimally-invasive procedure. The animal recovers in 24-48 hours, the post operation treatment is minimal and the animal gets back to its normal life in a short period of time.

In this section we will debunk the persistent myths surrounding sterilisation in pets and we will see the advantages that this responsible decision brings.

Benefits of sterilisation

A longer and healthier life:

  • In females, sterilisation (or spaying) helps to prevent uterine infections and breast or womb cancer (cysts and ovarian or breast tumours). It eliminates the heat cycle and psychological pregnancies disappear.
  • In males, sterilisation (or neutering) prevents testicular cancer (cysts, brucellosis, and testicular, prostate and anal tumours). It prevents unwanted and dangerous behaviour like running away or fighting.
  • Sterilisation also prevents contagion of diseases such as leukaemia and feline immunodeficiency.

Population control: Avoids unwanted pregnancies and having an uncertain future for the offspring. It reduces the amount of dogs and cats which are abandoned or have to be put down and increases the number of animals which are adopted from shelters and dog’s homes.

If females are sterilised before their first heat the chances of her getting mammary cancer are almost zero. However, if it is done after their first heat the likelihood increases to 7%, going up to 25% if it is carried out after the second heat.

Behavioural improvement:

  • It eliminates the appearance of heat. When a dog is on heat fights can break out between males or if the animal escapes she could get lost, knocked down, etc.
  • Marking and occasional aggressive behaviour disappear in males. Sterilised animals centre their attention on the family and are more docile.

An economically viable decision: the cost of sterilisation is less than having and looking after puppies and the cost of treating the diseases non-sterilised animals could suffer from.

A responsible decision: allowing a pet to breed without having the intention of looking after them afterwards is irresponsible. Sterilisation is preventative and also improves the physical and psychological quality of life of the animal and contributes towards the population control of the species.

It avoids overpopulation: sterilisation helps to avoid unwanted births, the result of which often end up abandoned on the streets only to later flood the animal rescue centres or end up in a place where it will be quickly put down.

Myths and legend regarding sterilisation

  • Sterilised animals put on weight: sterilising animals does not make them prone to obesity. It is necessary that the animal continues with the same lifestyle, as long as it is adequate for their age, sex, size, and they get enough exercise. As long as the animal gets enough exercise, it should not gain weight. There is also specific feed for sterilised animals.
  • It changes their character: cats and dogs are not affected negatively by sterilisation, their nature doesn’t change. Some aggressive males can improve, since the aggressiveness may be related to high levels of testosterone. Females no longer exhibit heat behaviours like irritability, aggression or escaping to find a male to mate with.
  • It is good to breed once during her lifetime: it is false that females have to breed once in their life to be healthy. There is no conscious relationship of reproduction as a necessary part of their emotional wellbeing. Their sexuality is different from that of humans and it is completely dictated by hormones, therefore they don’t express emotions such as frustration or wish to have offspring at a conscious level. If the surgery takes place before the first heat possibilities of having breast cancer are almost zero, but if it takes place after, it increases the chances to 7%, going up to 25% if it takes place after the second heat.

Table: reproduction statistics of dogs and cats

Taking into account that a female only has two litters in her life and assuming that half of the babies are female that will breed at the same ratio as their mothers (twice in their lifetime) and that the survival rate of those females is 100%:


1 Cat

1 Dog
















Advantages of sterilisation

  • For the animal: because it will enjoy having better physical and psychological health.
  • For you: because it helps to save problems and money in the future.
  • For the feline and canine species: because you will help control the population and decrease abandonment.
  • For animal protection organisations: because you help reduce the entry of animals in the animal shelters that are overcrowded.
  • For society: because abandoned animals can be a danger to themselves and to people, because dealing with them represents a public expense and because encouraging respect towards sentient beings is an issue of universal justice.


Our action

  • In Catalonia and others CCAA we carry out a yearly sterilisation and identification campaign aimed at the pets of private individuals at reasonable prices: Soy Responsable (I'm Responsible).
  • On our web page Soy Responsable, you will find up-to-date information about veterinary centres which offer good rates for families who can prove a lack of resources.
  • From FAADA we inform about the benefits of sterilization in companion animals and its consequences in case of not doing so.

What can you do?

  • Choose sterilisation for the animals that live with you.
  • Inform your acquaintances about the advantages of sterilising your pets.
  • Spread information on the sterilisation campaigns that you know about, so more people can sterilise their pets.

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