Effect of sterilisation on body weight, metabolic rate and glucose tolerance of domestic cats

This short post is based upon a study published online in March 1997. The concern is quite a well discussed topic, that of domestic cats putting on weight after they've been neutered (males) or spayed (females). I am only able to see the study's summary.

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This study found that "the castrated males gained more weight as fat than the sexually intact males". And "the neutered males gained significantly more weight than the entire males".

Further, "There was a significant increase in daily food intake after neutering.".

Neutered males gained weight faster than entire (unsterilised) females.

The scientists also said that "Spayed females underwent a significant decrease in fasting metabolic rate". I take this to mean that the spayed female cats had a slower metabolic rate when they were not eating i.e. fasting. It is not stated in the study but it would seem reasonable to conclude that with a lower metabolic rate there is a greater chance of fat being stored because less energy is being used and therefore the food is being burnt up at a slower rate.

They found that there was no or little effect from sterilisation on glucose tolerance. I take that to mean that there is no impact on domestic cats in terms of a predisposition towards Type II diabetes but that is my personal interpretation and it is not stated in the study.

The term 'gonadectomy' is often used by scientists to mean the removal of female testes and the female's ovaries. In other words, sterilisation of both sexes of cat.

Comment - my views

The advice given by veterinarians is to modify your male and female cats' diet after the neutering and spaying operations. I think the operation will affect different cats differently. My cat did not put on weight and was always relatively skinny and only now when he is in middle age is he putting on a little bit of weight. I delayed his neutering operation as long as possible but was pressured by the veterinarian to have it done as soon as possible. I resisted that pressure.

Extruding penis

There is another study online which says that neutering a pre-puberty male cat can leave the cat unable to extrude his penis which would be a scientific way of saying having an erection! I'm not sure this is true although the study was completed by a PhD student. She said that 100% of male cats neutered before puberty were unable to have an erection. I don't believe that at all. 

I have first-hand evidence because my cat gets boners all the time and he was neutered after puberty but there may be an issue here is to whether you neuter a male cat before or after puberty which is about seven months of age in order to allow the male cat to retain some normal malfunction and appearance. In this instance I'm talking about the facial appearance specifically the jowly, square, larger face of the intact male tomcat.

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P.S. please forgive the occasional typo. These articles are written at breakneck speed using Dragon Dictate. I have to prepare them in around 20 mins.

Study: Effects of neutering on bodyweight, metabolic rate and glucose tolerance of domestic cats. Link to the study: https://doi.org/10.1016/S0034-5288(97)90134-X.