How might one write mental illness in animal characters? Like they can talk to eachother but they live as animals in the real world?
CW: Animal abuse, self injury, eating disorders (anorexia, binge eating),
Animal behavior is not my specialty, so this answer comes courtesy @scriptveterinarian ! If you have any followup questions, send them their way!
We don’t have access to an animal’s internal monologue so can’t tell what they think or feel exactly, we can only infer based on what they do.Mostly we see anxiety and compulsive disorders because they’re the easiest to notice as an observer.
Here are some behavioural and somatic signs of acute (short-term) stress in dogs and cats:
Dogs:
- Urination and defecation/diarrhoea (peeing and pooping)
- Increased motor activity
- Vocalizations (barking, growling)
- Salivation (drooling)
- Piloerection (hair standing on end)
- Trembling
- Polypnoea - (panting)
- Looking away
- Protrusion of the tongue (sticking out their tongue)
- Muzzle licking
- Yawning
- Paw lifting (front paw held at 45 degrees)
- Frequent shifting of body position
- Low postures
Cats:
- Urination, spraying, and defecation/diarrhoea (peeing and pooping)
- Trembling
- Might vocalize with hiss/spit on approach
- Hiding, withdrawal to back of cage
- Sitting on all four legs with head low
- Eyes wide open
- Pupils dilated
- Polypnoea (panting)
- Ears flattened
- Whiskers back
- Tail close to body
And some general signs of chronic (long-term) stress:
- Decreased behavioural repertoire (less variation in behaviour)
- Decreased exploratory behaviour
- Reduced social behavior and increased antagonistic behaviour
- Displacement activities
- Stereotypic behaviors
- Passivity / apathy
- Increased sleep, or disturbance to sleep patterns
- Anorexia or binge eating
Stereotypic behaviour is a big one, especially in zoo animals and prey animals. That means repetitive behaviour patterns that the animal repeats at any given opportunity, eg pacing, wind sucking. Actual behaviour will vary by species.
Destructive behaviours - can be directed externally (eg trashing the house) or internally (feather plucking, licking through skin) or both.
We do talk about dogs being ‘depressed’ but we mean obtunded- slow to respond, dull, flattened personality. Not depressed like we mean in humans.
It may also be worth mentioning Spaniel Rage syndrome, which is a sudden onset rage that dogs have no apparent memory of once it’s passed. It’s actually an epileptic type disorder.
But we don’t typically classify mental illness in animals to anywhere near the same extent and detail as humans, simply because we can’t.
Depending on what species the animal characters are will determine what’s abnormal for them too. The same amount of vigilance in a rabbit may be hypervigilant in a dog.
The point I’m trying to make is that the 'normal’ will be different for each species, and so will deviating from that norm.