cat acting weird after being outdoors
Behavioral Problems

Why is My Cat Acting Strange After Being Outside?

If your cat is acting different, you’re bound to be concerned. Changes to your cat’s personality can happen for all sorts of reasons. Going outside for the first time – or spending more time outside than usual – could certainly trigger a personality change.

Cats scare very easily, so they might become traumatized after going outdoors. Also, climbing high fences and fighting with other cats can cause ‘invisible’ internal injuries and extreme lethargy. Moreover, cats may contract viral infections from local wildlife, or exacerbate pre-existing health conditions such as asthma, allergies, or Hyperesthesia syndrome (skin hypersensitivity) by venturing outdoors.

If your cat is acting strangely after being outdoors, you might decide to keep them inside 24/7. But is that always the best action to take? We discuss how long these personality changes might last, whether they need to be treated, and whether or not it’s safe to let your cat outside again.

My Cat is Acting Differently After Going Outside

If your cat has changed after going outside, it’s often due to one of the following reasons:

First Time Outside

Perhaps you’ve moved to a new house, and your cat is exploring the local area for the first time. Or, perhaps your cat has always been a house cat, and this is the first time they’ve ventured outdoors.

In either case, encountering another cat, a dog, a busy road, or a large group of people could be very traumatizing.

First Time Outside Alone

Cats who live together will often go outside at similar times (even if they don’t stick together the whole time). If one cat decides to stay inside, the other may feel very exposed and unsafe.

More Time Outside Than Usual

Perhaps your cat wandered too far from home and struggled to find its way back through new territory; passing through another cat’s territory can cause fights. Or, perhaps the cat flap became stuck and your cat couldn’t get inside for many hours.

Being unexpectedly shut out of the house can have a significant impact on your cat – both physically and mentally. Not only will your cat be frightened, but it may also become very hungry, thirsty, cold or overheated.

If your cat’s personality has changed, it’s probably because they were stressed or frightened in some way. Thankfully, these periods of distress seem to pass pretty quickly.

Most cats are back to their old selves within 1-3 days. However, as we’ll explore, personality changes can occasionally be an issue for significantly longer.

Strange Behavior in Cats

So, what behavioral changes might you see in a cat who has recently been outside?

  • Excessive meowing and howling
  • Overgrooming – perhaps bald patches have developed
  • Pacing, walking in circles, chasing its tail, running around the house quickly
  • Excessive clawing and scratching
  • Unexplained aggression
  • Stumbling, unable to walk straight
  • Cat is acting lethargic, seeming less sociable, and looking ‘disconnected.’
  • Unable to go to the toilet
  • Eating inedible objects (Pica)

Some of these changes are quite natural responses to trauma, and they should pass within a couple of days. However, some of these changes indicate an illness or injury.

cat suddenly scared of me after being outside

Why Is My Cat Acting Weird After Going Outside?

As you are probably aware, there are some risks involved in letting your cat outside. The following four risks could cause your cat to behave strangely:


Diseases can be contracted from other cats, other animals, and potentially even other humans. Your cat will also be exposed to bacteria and fungi in the ground which could threaten their health.

When cats are sick, their personality and behavior can change significantly.


If your cat is injured, they may start to pace around the house, overgroom their fur, or meow more than usual. On the flip side, they might hide away and become very lethargic.

It’s important to remember that some injuries are ‘invisible’ to the naked eye, but subtle changes to their behavior can be a giveaway that they’re injured.

Fear & Stress

If your cat is suddenly very scared of you, or has become very aggressive out of the blue, this suggests they’ve been frightened by something in their environment.

This could be other cats, people, dogs, noisy roads, etc. Cats who spend time outdoors may become accidentally shut in other people’s houses or sheds – which can be extremely traumatizing. There are ways you can alleviate your cat’s stress, but it is important to be patient.

Extreme Hunger or Thirst

If your cat was outside for longer than usual (perhaps shut inside somewhere), they may have gone without food or water for many days.

In this case, you’d probably notice the following personality changes: extreme lethargy, yowling, and an inability to walk correctly. Cats who are dehydrated and who are struggling to take on fluids should see a vet immediately.

A frightening experience has probably caused your cat’s personality change – and this emotional trauma should pass with time – but it’s important to be aware that illness and injury are occasionally to blame for personality changes.

Diseases that Cause Behavior Changes in Cats

Various contagious diseases can cause your cat to ‘act out.’ Alternatively, your cat may have a pre-existing health condition that flares up when they go outside. The following diseases can cause behavioral changes:

  • Urinary Tract InfectionsUTIs in cats can cause stumbling, lethargy, and urination problems. Poor hygiene can cause a UTI, as can stress, so spending more time outdoors could trigger a UTI.  Neutered males are most at risk of developing a UTI.
  • Viral Infections – Viral infections can cause conditions such as Feline Leukemia Virus, Feline Infectious Peritonitis, Feline Herpes Virus, and Feline Calicivirus. The ASPCA list ‘changes in behavior’ as one of the early signs of Feline Leukemia Virus. For example, you might notice lethargy, excessive meowing, howling, seizures, and overgrooming. Viruses can easily spread between cats who groom each other, fight with each other, or go to the toilet in the same area.  If you plan to let your cat outdoors, it is strongly advisable to vaccinate against these viruses.
  • Respiratory Infections – These can be caused by viruses (see above), but also by cat allergies or asthma. If your cat has spent more time outdoors than usual, consider whether their asthma or allergies have flared up (some cats are allergic to grass, mildew, weeds or cigarette smoke). Respiratory infections are often accompanied by excessive meowing, hyperactivity, and overgrooming.
  • Parasites – These can be picked up from other animals. Contracting a parasite might not cause your cat to act weird per se, but it could make them more lethargic.
  • Hyperesthesia syndrome – This is a chronic condition that can make cats hypersensitive to pain. If your cat is acting weird and running around, it could have Hyperesthesia syndrome (see below for further details). This condition is not contagious so your cat wouldn’t have picked it up from another animal. Nevertheless, going outside might have caused the condition to flare up, especially if you live in a place with extreme weather conditions.

As you can see, many different illnesses can be triggered by your cat going outside – whether that’s because your cat has contracted a contagious disease, or because being outdoors has aggravated a pre-existing illness.

What Is Hyperesthesia Syndrome?

Hyperesthesia syndrome occurs when a cat’s skin is hypersensitive. To manage this sensitivity, the cat may engage in obsessive behaviors. According to VIN, most vets consider hyperesthesia syndrome to be a type of compulsive disorder.

So, what can overstimulate a cat’s skin in the first place?

  • Petting – There is sometimes a ‘soft spot’ on the cat’s back where they are overly sensitive.
  • Grooming from other cats
  • The Weather – Strong wind, rain, and extreme temperatures can trigger a reaction.
  • Mites in Their Fur – This can cause this condition to flare up – and the sensitivity may linger even after the mites are treated.
cat acting scared after being outside

To prevent this pain/sensitivity from continuing, cats may:

  • Start to twitch or shudder
  • Frantically start grooming
  • Run around the house – perhaps chasing their tail
  • Meow and yowl

The behavior is considered compulsive because it may carry on for many minutes or even hours after the cat was triggered. This is one of the reasons why it is vital to stop petting a cat if they seem uncomfortable. If you don’t stop petting them, they may start to groom themselves compulsively.

If your cat is exceptionally restless and regularly grooming themselves after going outside, see if this behavior calms down within a day or two. Going forward, you might need to monitor the weather before letting them outside (i.e., don’t let them out in the wind, rain, or temperature extremes).

If the compulsive behavior continues for more than 2-3 days, you should see your vet, and if you see any signs of the following, you should see your vet immediately:

  • Self-mutilation
  • Seizures
  • Uncontrolled urination (often during a seizure)
  • Extreme aggression

Burmese and Siamese cats are most at risk of developing Hyperesthesia syndrome, but it has been seen in most breeds. It is a condition that can appear ‘out of the blue’ because different triggers may occur throughout the lifespan.

Is My Cat Injured After Going Outside?

In many cases, it will be obvious if your cat is injured because they may be limping, bleeding, or unable to stand up. However, less severe injuries are not always obvious to the naked eye. Changes to behavior and personality are often the first signs of a less severe injury. For example, internal bruising and joint inflammation can cause changes to your cat’s personality and behavior. A cat with internal bruising or joint problems may suddenly become:

  • Lethargic
  • Meow excessively
  • Be extremely nervous or aggressive all of a sudden (will not tolerate being touched at all)

So, how might a cat develop bruising and/or joint injuries?

  • Falling or Jumping from a Tree – Inexperienced climbers tend to climb up high but then are too afraid to come down. Sometimes, your cat might be stuck in a tree for several hours or even days before they dare to come down. If they fall on the way down, this can result in an ‘invisible’ injury.
  • Road Accidents – Not all road accidents are fatal to the cat involved.
  • Cat Fights – Catfights will often result in visible wounds, but that’s not always the case. Cats who share territories learn to ‘time share’ the area – so one cat gets it in the morning, and one gets it in the afternoon. If you let your cat out at a different time to normal, this might spark a cat fight.

If you’re worried that your cat might have an internal injury, see if they have a fast, shallow heartbeat, increased pulse, or they are purring more than usual. If so, it’s advisable to see a vet as soon as possible.

What Else Could Have Harmed My Cat?

As mentioned, there are some risks involved in letting your cat outside. If your cat goes outside very infrequently, some of these risks do increase because your cat won’t necessarily know how best to protect themselves. These risks include:


Antifreeze spillages, rodent poison, and certain plants can be toxic to cats.

A cat who has ingested a toxic substance may start to pace around and become hyperactive. Their muscles will tremor, and they will eventually enter a coma.


Cats who rarely go outside might not be very good at managing their body temperature or knowing when to find shade. British Shorthair, Himalayan, and Persian cats are prone to heatstroke so their time in the sun should always be limited.

A cat with heatstroke will stagger/stumble and become very lethargic. You should see a vet immediately if you suspect this condition.

Tooth Problems

Biting into something hard can cause a tooth injury. House cats who go outside and get an opportunity to hunt for the first time may harm their teeth when biting into their prey.

Alongside excessive saliva and bad breath, cats with tooth problems will withdraw, may be lethargic, and will usually refuse to eat.

Why Is My Cat Aggressive After Going Outside?

Cats can be aggressive for all sorts of reasons. ‘Redirected aggression’ is one of the more serious forms of aggression because it can be difficult to anticipate.  This occurs when a cat sees something threatening in their environment and responds by redirecting their fear/anger/aggression onto their owner.

Redirected aggression can occur hours or even days after the incident. This could explain why your cat has an aggressive outburst days after going outside. Triggers for redirected aggression include:

  • Seeing a stray cat in the garden or close to the house.
  • Seeing or encountering dogs or other threatening animals.
  • Being stroked/petted outside – many cats who enjoy being petted inside do not feel safe being touched outside of the home. Even if they tolerate it at the time, it could cause them to become aggressive later.
  • An unsuccessful attempt to catch prey – this could lead to frustration.
  • Encountering loud noises (i.e., fireworks, large groups of people, busy roads, sirens)
  • Not being able to get back into the house when they want to.

Many of the above scenarios trigger the ‘fight or flight’ response in cats. This explains why some cats may respond in an aggressive manner (fight), whereas others will shy away from human interaction and become very withdrawn (flee).

Why Is my Cat Scared Suddenly Scared of Me?

The outside world can be a scary place for cats. While the outdoors can trigger aggression it some cats, it can cause others to become very distant from their owners. Cats who are bred for their docility (i.e., Siamese, Ragdoll) are more likely to become withdrawn than aggressive.

As mentioned, going out for the first time, or spending longer outside than usual can unnerve your cat, but what else could have been frightening for your cat?

  • You let your cat out at a different time (perhaps during the night when they’re used to going out in the day or vice versa).
  • Your cat is overweight or elderly and felt very vulnerable outside.
  • Your cat got trapped in or on something – sometimes collars can get stuck in fences, for example.
  • Your cat fell asleep under a vehicle, and the engine was started – given them an intense fright.
  • There are new animals in your area – has your neighbor got a new dog, for example?
  • Someone tried to catch your cat.
  • Another cat tried to re-enter through your cat flap.

In many cases, this anxiety will die down in a day or two, but occasionally, the emotional effects can be longer-lasting.

cat acting weird running around

How to Comfort Your Cat

If your cat is suddenly scared of you, there are things you can do to help them feel more at ease:

  • Give Them Somewhere to Escape To – It’s important for cats to feel they can escape. Clear a room for them (ideally with some high-up spaces as cats feel safe if they can look down on their environment). Alternatively, some cats like to hide-out under the sofa or the bed. Either way, allow your cat to have some private time.
  • Take Their Lead – If your cat hasn’t run off to hide, try to pet them gently but pay close attention to their response. If they seem uncomfortable, don’t force any affection on them.
  • Food and Water – If your cat was outdoors for longer than usual, they’re probably hungry and thirsty. In times of stress, cats will suppress their appetite, so they might not ask for food and water – but make sure it is available to them. As mentioned, if you see the signs of dehydration, you should consult a vet.
  • Quiet – Keep noise to an absolute minimum.
  • Catnip Catnip may improve your cat’s mood.
  • Pheromone Plug-in – Pheromone plug-ins can help a cat to feel calm and relaxed.

Remember to be patient as some cats can take longer to recover from a traumatic experience than others.

Should I Let My Cat Outdoors Again?

If your cat shows an interest in going outside in the future, there’s no reason why you can’t let them out. To make their outdoors experience as pleasant as possible, you might want to follow these precautions:

  • Microchip Your Cat – If your cat gets lost and can’t find its way home, you’ve got a better chance of being reunited.
  • Neuter/Spay Your Cat – This will reduce the chances of your cat fighting with other cats.
  • Vaccinate Your Cat Regularly – To protect against disease.
  • Routine – Try and let your cat out/ call them in at the same time each day. This will allow them to ‘time share’ territory with other cats if necessary, but it will also help them learn how much traffic to expect on the roads. If a cat is usually let out in the early hours of the morning, but you decide to let them out during rush hour for a change, they may become overwhelmed by the traffic.
  • Check the Weather – Limit your cat’s sun exposure to prevent heatstroke and if your cat has Hyperesthesia syndrome learn about the triggers (i.e., wind, rain).
  • Cat Flap – Check the cat flap is working regularly; it can become trapped by snow or ice.
  • Enclosure – If you’re worried about the risks of letting your cat outside, and you want to protect the local environment, consider enclosing your garden so that most of the wildlife is kept out.

Remember, if you want your cat to enjoy spending lots of time indoors, too – you’ll need to provide enough stimulation and attention. If you play with your cat regularly, you may even reduce their desire to hunt for prey outside of the home.

Is Going Outdoors Always to Blame?

Although spending time outdoors can change your cat’s temperament, chronic illnesses can do that, too. It could be a coincidence that just as your cat develops a chronic illness, they also happen to be spending more time outdoors.

According to the Blue Cross, Feline Cognitive Disorder and Hyperthyroidism can both cause your cat’s personality to change quite drastically. These disorders can come on quite quickly, so it might appear as if a one-off experience (such as going outside) has triggered them.

Feline Cognitive Disorder occurs in older cats; it can make cats lethargic, unstable on their feet, and might cause them to yowl incessantly. Hyperthyroidism occurs when your cat produces too much thyroid hormone; it can cause restlessness, hyperactivity, and problems urinating.

Strange Cat Behavior Explained

Humans go through periods of trauma, injury and illness – and cats are no different. Trauma, injury, and illness can cause cats to act strangely. If your cat is acting different, it’s understandable that you’d want to get the bottom of it.

In many cases, going outdoors (or spending more time outdoors than usual) is a trigger for this strange behavior. This could be because your cat has been traumatized by another animal in the neighborhood – or perhaps contracted a disease from another cat. Alternatively, your cat might have an underlying health condition that flares up when they go outside.

Whatever the cause, it’s important to monitor your cat’s behavior, and limit their time spent outdoors if necessary. Most cases of trauma will resolve themselves in a couple of days, but don’t delay seeking professional advice if your cat is unable to ‘bounce back’ from their outdoor adventure.