Aggressive Behaviour Flashcards
Aggression
A physical act by one individual with the actual or potential result of harming, limiting or depriving the “fitness” of another
Agonistic Behaviours
Broader term, includes all forms of behaviours associated with a conflict between animals, including both aggression and submission. Also includes all competitive behaviours before and after interaction.
Aggressiveness
A personality trait shaped by genotype and early experience, and modulated according to psychological (win-loss ratio), physical (presence of horns, antlers, etc.) and physiological (hormonal status, health status, etc.) characteristics.
- A costly behaviour so important for animals to learn/ give up when necessary
- Animals with more success will be more likely to continue the behaviour and passed experience will shape what behaviours the animal chooses to display
Types of aggressive behaviours
- Offensive (Territorial, sex-related, instrumental aggression)
- Defensive (fear-induced, maternal)
- Other behaviours fall within a mixture of both defensive and aggressive (predatory, organic origin, mock fighting)
Offensive aggressive behaviours
Individual trying to gain access to a specific resource
- Territorial: occurs in an area in which the animal has established itself. 40-60%
- Sex related: stimulated by the proximity of 2 males not familiar with each other. Elicited by the same stimuli that elicit sexual responses
- Instrumental aggression: learned response (reinforced)
Ex. fight between dogs- shown behaviour due to dominance, but it has been reinforced by performing the behaviour and will do it more often
Defensive aggressive behaviour
Avoidance of an external intrusion.
- Fear-induced: characteristic of confined or cornered animals that feel threatened, is preceded by escape movements
- Maternal: elicited by the proximity of some agent that is threatening to a females young
Aggressive behaviour from a mixture of both offensive and defensive behaviours
- Predatory: initiated by a hungry individual in the presence of a prey item
- Organic origin: irritable state elicited by a broad range of health issues (stress/frustration, pain, brain tumors, rabies)
- Mock Fighting: A feature of social reactivity, is a variant of play behaviour. No harm is caused, but it’s a good experience to refine their motor skills
How to tell Offensive vs. Defensive behaviours apart?
Can tell behaviours apart based on both the origin of the behaviour AND the body signals that an animal displays.
Offensive- make their body bigger, try to intimidate
Includes: Ears up, hackles raised, tail raised and stiff, lips curled, body leaned forward, legs stiff, forehead wrinkles, nose wrinkled, teeth and gums visible
Defensive- make the body smaller
Includes: Tail tucked, body lowered, head low, mouth corner pulled back, lips slightly curled, teeth might be visible, pupils dilated, nose wrinkled, ears back
Key points when differentiating aggressions
- Posture: is not voluntary, is triggered by the neurons activated with each type of aggression behaviour
- Circumstances: when approached, when food is around, when you want to touch them
- Who is the aggression directed to. Is it at Owners, one individual in particular, other dogs/animals.
Aggressive behaviours in dogs
Huge problem for dogs… main cause of euthanasia (greater than 5yrs old) and abandonments
- Danger to humans
2-5 million people bitten per year, 1 millions requiring hospitalization
280 deaths in 15 yrs
Particularly in children (40%) - In most cases, no obvious triggering cause
Destructiveness
can be considered a redirected aggressive behaviour
Cause of aggression in farm species
- Mixing of unfamiliar animals
- Competition over food
- Spatial factors and overcrowding
- Frustration, boredom, fear, pain
Differences between species in terms of aggressive behaviours
Important to identify and understand that the normal behaviour for aggression is different for different species
Aggressive behaviours of pigs
Pigs: slash with tusks at opponents neck and shoulder, bites directed towards shoulder, neck, front legs and ears, some head knocks against opponent (no kicking)
Aggressive behaviours of Cattle
Cattle: uses horns and head to butt neck, shoulder, flank, buttocks. Kick with hind legs to the side (no biting)
Aggressive behaviours of sheep
Sheep: butt head, often back up and charge – clashing head on. Do not kick or bite
Aggressive behaviours of goats
Goats: similar to sheep, butt heads, rear on hind legs and clash heads on downward thrust (goats do not kick or bite during fighting)
Aggressive behaviours of horses
Horses: bites directed towards neck, shoulders, flank and legs, kick with hind legs. May defend front legs from bites by kneeling
Aggressive behaviours of chickens
Chickens: face each other with raised hackles and direct pecks at head and body. Scratch with feet and spurs as they fly towards opponent
Consequences of Animal aggression
- Physical injury (to humans and conspecifics)
- Physiological effects
Different physical harm that can occur as a consequence of aggressive behaviour
Lacerations: provide avenue for infections; skin damages and bruising results in reduced revenue. Leads to increased cut outs and downgrading of meat products
Injuries: the most common reason for culling bulls used in community during male-male fighting
Different physiological effects that can occur as a consequence of aggressive behaviour
- Natural activation of HPA axis, which may lead to immunosuppression
- Pigs: carrying a genetic defect can be lethal (sudden death, Porcine stress syndrome) or cause a reduction in carcass value (PSE= Pale, soft, exsudative)
- Fighting (or stress) depletes glycogen stores in muscles, which results in high pH and dark cutters
Ways to control aggression
- Determine reason for aggressive behaviours: offensive, defensive, organic source
- castration- for offensive aggressions in males. May still need additional treatment
- Drugs- can be used to help implement other measures
- Behavioural training
- increase serotonin through diet, exercise, or drugs
- Make animal less successful at performing behaviour
- Environmental design- allow animals to have enough space to move away
- Provide sufficient food for group and feeding spaces
- Avoid mixing
Ways to make an animal less successful at performing behaviours to help control aggression
Does not remove the cause of the aggression, but provide long term benefits. Most under close examination
- Castration
- Dehorning
- Tail docking
- Teeth clipping
- Cover horns with something soft (pool noodle)
How is behavioural training used to control aggression?
- change dominance rank
- socialization
- flooding/habituation
