What makes an aggressive dog? Cocker Spaniel research suggests it's the owners personality.

Cocker SpanielOK, don't get me wrong. If you start with a breed created for guarding or fighting, you are going to have an uphill battle to train it not to do those things. Having these kinds of dogs, unless you are a professional dog trainer is always going to require much more effort.

The article I am reviewing is a paper created in 1997, that tells people pretty much what Cesar Milan has been saying all along. Calm assertive owner energy is needed to create calm passive dogs. The amazing thing is that this research was based around the English cocker spaniel. The research shows a direct link between owner personalities or energies and the dog's aggression levels.

Now for people not across this breed, the English Cocker Spaniel was created centuries ago in Britain from a large spaniel. The large proto-spaniel was subsequently breed down into seven varieties one of which being the cocker spaniel. The breed came well before the American Cocker Spaniel, which is more of a show dog (has reduced hunting skills).

The English Cocker Spaniel is known as a  "hunting-gun dog" and was bred to work in very difficult terrain. This means in the cold we marshes as well as on dry land.  It was mainly bred to flush out the WOOD COCK bird and is excellent at retrieving game as well as not damaging it because of its gentle mouth. It can be well trained and makes a perfect family pet.

The reason that I find this research so interesting is that I own a spoodle/ cockapoo (cocker spaniel cross poodle). These dogs are ideally suited for crossing since they are both gun dogs bred for retrieving in similar environments. The major difference is that the poodle has the one of the highest intelligences of all dogs, and has much greater stamina.

What I have found is that my dominant spoodle can often decide to go 'alpha' on me when out on off lead walks when he decides that he doesn't like me separating him or my other dogs from another walker and their pack, or if he decides we should play and I wont listen to him. In these circumstances he pulls on my pant legs and jumps for my jacket or hand while barking, yes essentially my very social dog becomes aggressive, but only towards me.

The aim of the experiment was to find out if " aggression of pure-bred English Cocker Spaniels was related to demographics and owner interactions."


218 high aggression and 217 low aggression cocker spaniels had their owners answer dog aggression and their own behaviours on an extensive questionnaire.

The RESULTS were:

Owners of ‘low’ aggression dogs were

  • more likely to be: older (65 years +; ?2 = 18.753, P < 0.01)
  • more attached to their dogs (U = 20346, P < 0.001).


Dogs in the ‘high’ aggression group were:

  • significantly more likely to be of a solid colour (?2 = 38.13, P < 0.001);
  • more likely to have been chosen for pet purposes only (?2 = 25.161, P < 0.001);
  • more likely to have suffered an illness during the first 16 weeks of life (?2 = 14.899, P < 0.001);
  • groomed less often (t = 2.252, P < 0.05);
  • given less time for walks/exercise (t = 2.618, P < 0.01);
  • slow in obeying commands (U = 17967.5, P < 0.001),
  • more likely to pull on the lead (U = 16663, P < 0.001);
  • more likely to react to loud or high-pitched noises (?2 = 14.142, P < 0.001).

A note on statistical significance. The significance level relates to how likely an event is to occur.

In experimental terms, a sample of the whole population is taken (say 100 dogs out of the total dog population, and they are meant to represent what occurs in the total population.

For instance P < 0.1 means that 90% of the test subjects fell into the criteria.

IN this case, we see P < 0.01 or 99% of dogs

and P<0.001   means that 99.9%  of dogs fit into the criteria.

For example: Dogs in the ‘high’ aggression group were: significantly more likely to be of a solid colour (?2 = 38.13, P < 0.001); means that 99.9% of the dogs that were aggressive were a solid colour. That is a VERY strong correlation!

A note on high aggression  correlations and my spoodle

Yes, while he is only half Cocker spaniel, I am very interested in whether he fits the experimenters profile.

My dog is a solid colour. Tick

He was chosen for pet purposes. TICK. HOWEVER, he has for several years been the lead dog in my dog walking business. This has had several interesting outcomes. Initially my dog didn't like other dogs being put into the back of our vehicle. However he is very social when out, and while dominant, this social aspect means that he will only dominate other dogs that allow it. He does not do so with unrestrained aggression. Dominance and submission are both acceptable behaviour in dogs play, and it does not necessarily mean aggression. It just means dogs are sorting themselves out in the pack order.

My dog didn't suffer any puppy illness. NO TICK

He is washed once a week,  NO TICK. and can be shaved up to five times over summer. We made sure that we took all the puppy advice of touching him on the face and paws as a puppy to get him used to being handled. I can still nurse him on my lap as he lies on his back. He shows no form of aggression in these submissive posses.

He is walked at least twice per day, but mostly off lead.

He is slow at obeying commands, when there is prey about or once he has been groomed or is wet. More on lead training my resolve this.

He pulls on the lead, but for the first five minutes. Then the martingale collar does its job.

He reacts to noises (high pitched and low truck rumbles) but is not afraid of thunder.

But I digress.


The research found that factors often cited as causing aggression tendencies in dogs such as

  • feeding the dog before the owner eats
  • lack of obedience training,
  • playing competitive games with the dog

were NOT found to be significantly different between the two groups.



The questionnaire measure sixteen personality traits of the owners.

Of the 521 owners,  382 replied and 285 (84%) completed the questionnaire.  128 responses came from owners of 153 dogs in the low aggression group, while 157 came from people in the HIGH aggression dog group.

Most of the respondents were female (62% from the low aggression group, 70% from the High aggression group and most of them owned only ONE cocker spaniel.

Most of the dogs were around 3 years of age.


FOUR personality traits were significantly different (out of the 16 tested) between the two groups of owners.

Owners of HIGH aggression dogs were significantly more likely (versus low aggression dogs)

  • to be tense (P <000.1)
  • emotionally less stable (P<0.01)
  • shy (P<0.01)
  • undisciplined (P<0.05)



The experimenters admit that this self assessments could have owners biased against their dogs (syaing they were higher aggression) and admitting that they had these personality traits. BUT the very high statistical significance of the results over the large sample suggests otherwise.

The second reason they suggest for the correlation between dog aggression and owner personality traits is that the differences of the personality traits in the owners were an affect of their dogs aggression rather than the cause. This has been ruled out because the owners were all adults and over 34 meaning that it is unlikely that such dog interactions could be so powerful as sway the whole sample set.

The last reason is the most plausible for the Caesar Milan fans. They suggest that the most plausible explanation for the observed correlation is the "traditional dog trainer view that anxious, tense and neurotic owners sometimes cause their pets to become ore aggressive or badly behaved (woodhouse 1978).

However it does not necessarily explain cause and affect (which way the relationship flows).

While further research continues, it is interesting just to read the RAW statistics for owners of aggressive dogs.


Article by Bruce Dwyer. If you wish to use any of this information please use a LINK reference to http://www.dogwalkersmelbourne.com.au

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Aggressive behaviour in English Cocker Spaniels and the personality of their owners A L Podberscek, J A Serpell  Veterinary Record 1997


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