Skip to Content

Why is my dog hyper after neutering or spaying?

Why is my dog hyper after neutering or spaying?

Many pet owners consider spaying or neutering their dog part of responsible pet ownership. Unfortunately, many owners get their dog fixed in an effort to change their behavior or personality.  However, the reality doesn’t always live up to the hype. 

Neutering or spaying can actually have a negative impact on your dog’s behavior, including causing them to be hyper. Of course, there are still valid reasons to get your pet fixed, but you should be prepared for potential negative effects, including hyper activity. 

Why is my dog hyper after neutering or spaying?

Perhaps you heard that desexing your dog was the perfect way to calm them down. You pick them up from the vet, and then realize something isn’t right. Instead of calming them down, they are more hyper than ever. 

It’s also possible for them to seem fine when they first come home from the vet, but to be very hyper as they begin to recover. There are several reasons why your dog can be hyper after being fixed. 

Sedative or Anesthesia

Sedatives are meant to calm or sedate your dog. However, the after effects can be the opposite, causing your pooch to be hyper. Anesthesia is used to put your pooch to sleep during the procedure. 

These medications can cause your dog to be disoriented when they wake up, and for a day or two afterwards. This disorientation can cause them to be hyper, because they are nervous. 

The medication itself can also cause hyper activity for some pooches. If this is the cause of the hyperactivity, it should pass within a few days.  


Dogs can respond to pain in different ways. Soem will become lethargic. Others will become clingy, or whine frequently. Some dogs will go into the opposite direction. Instead of being lethargic, they will become hyper. 

It seems as if they will be constantly hyper or on the go in an effort to keep their mind off their pain. Have you ever hurt yourself but kept going? You probably discovered a lot more pain once you settle down. Your pooch can have the same experience. 

Changes in Hormone Levels

Changes in hormone levels can also cause your dog to be hyper. Neutering or spaying removes the sex organs, which produce sex hormones. After the surgery, testosterone in males and estrogen in females begins to fall rapidly. 

This change can cause lots of personality and behavioral changes. Unfortunately, these aren’t always positive. The changes in hormones can cause hyper activity, anxiety, and aggression. These are the same behaviors that owners often fix their dogs to curb. 

Lack of Activity 

Your pooch will need some time to recover after their surgery. This means their activity must be limited. You’ll need to keep them calm for the first few days after surgery. They will be on a restricted activity level for 10-14 days. 

All this rest can make some dogs hyper. They don’t have a proper outlet for their energy. If your dog is naturally highly active, there’s a good chance this is the reason why your dog is hyper. 

They can’t have their typical activities and exercise. If you’ve ever been confined to bed rest due to an injury or illness, you can sympathize. Before you get better and are allowed to return to normal activities, you’ll probably feel a little crazy. Being stuck in a bed can cause you to feel hyper, and crave action.  

Fear-Based Aggression After Neuter 

Fear based aggression is unfortunately common after neutering or spaying. It’s due to the changes in hormone levels. 

In males, testosterone is responsible for sex drive and related behaviors. This includes male on male aggression, and to an extent, territorial behavior. However, this isn’t the only type of aggression. 

Fear based aggression is actually more common, and much more problematic for pet owners. Sex related aggression is directed at a rival male, but fear based aggression can be directed at another pet or even a person. 

When animals are afraid, they are at their most dangerous. Fight or flight takes over, and for dogs, fight is often the choice. It can also be misdirected. Your dog may be scared by another animal or even a thunderstorm, but take out their fear on you or another family member. 

Fear based aggression increases after being neutering. This may seem counter-intuitive. After all, isn’t neutering supposed to reduce aggression? 

The truth is that it reduces or eliminates male on male aggression,  because of the drop in testosterone. However, testosterone is also responsible for your dog’s confidence and sense of well being. 

Without testosterone, your pooch can feel insecure and unconfident. This makes them much more prone to fear, and fear based aggression. 

Increased Aggression After Spaying

Unfortunately, increased aggression can also occur after spaying. It’s believed that it’s the result of low estrogen levels, along with lower levels of oxytocin. These hormones are linked to nurturing and mothering behaviors. 

When the hormone levels drop, it can lead to females becoming more aggressive. The hormones also have a calming effect. The absence of them can increase fear and nervousness, as well as aggression. 

The good news is that spaying a female later, at 12-18 months or later, reduces the increase in aggression and fearfulness. 

The Statistics 

Despite the large number of sources that still claim that spaying or neutering can solve behavioral problems, two large scale studies have shown some startling effects from desexing. 

Aggression can increase by 20-200%, depending on the type of aggression, in both sexes. Fearfulness increases by 31%, and touch aversion increases by 33%. There’s also an 8% increase in excitability. 


The stress of the procedure and recovery can also cause your pooch to  be hyper. Imagine yourself in your dog’s place. You go to a strange office, and are put to sleep. You wake up disoriented and in pain. 

You may realize that you have a wound on your body, but you don’t know what happened. Your normal routine is out the window, and you aren’t allowed to do the things you normally do and enjoy. 

All of this would be intensely stressful. In fact, it would be both cruel and illegal to do this to a human without their knowledge or consent. Of course, we have to decide what’s in our dog’s best interest, and this can include desexing surgery. However, it’s important to keep in mind your pooch’s perspective. 

Dogs react to stress in different ways. Your dog may have potty accidents. They may lose their appetite, or whine frequently. They may want to be left alone, or be very clingy. They may bark excessively. 

They may become hyperactive simply because they are highly stressed, and don’t know how to settle down. 

Is it normal for a dog to be hyper after neutering or spaying?

This depends on your definition of normal. It does seem to be common for dogs to become hyper after neutering or spaying. However, this isn’t a desirable effect, or one most owners expect. 

In fact, most owners don’t know the potential risks of spaying their dog. Hyperactivity after desexing may be more common than we realize, because many owners may not realize it can be a side effect of the surgery. 

How long are dogs hyper after neutering or spaying?

It really depends on the reason they are hyper. If it’s caused by the sedative or anesthesia, it should wear off in a few days. If it’s caused by the stress of the procedure, it may fade within a few days to a few weeks.

However, if it’s caused by the changes in hormone levels, this can last for the rest of their lives, without proper treatment. 

How to calm a dog after neutering or spaying?

After spaying or neutering, your pooch will need to take it easy for 10-14 days. This means you’ll need to keep them calm and well occupied. After they’ve recovered, calming them becomes a different matter. 

After Surgery 

After surgery, keeping your dog calm centers on keeping them relaxed and occupied. You may find it helpful to put them in a low traffic area, so they can rest. If your dog wants to be near you, you may want ot let them recover in the living room or your bedroom. 

Try to keep the activity going on around your dog to a minimum. This isn’t the time to have a barbeque or a birthday party. Keep things low key and relaxed. 

Give them plenty of toys and treats. In addition to chewies, you can give them puzzle toys. These don’t require a lot of physical activity, but provide mental stimulation. You may also find it helpful to turn the TV on for your dog. 

It’s common for your dog to be given pain medication after the surgery. This can help keep them calm in the first few days after surgery. 

If your pooch can’t seem to be still during recovery, your vet may recommend sedative medication. Too much activity after surgery can cause injuries or slow their recovery. 

After Recovery 

Your pooch has recovered from their surgery, but they are hyperactive or experiencing other behavior problems. Your vet may recommend obedience training, and if that fails, antidepressant medications. 

The problem is, this doesn’t address the actual issue. Your pooch is likely affected by the lack of hormones. Hormone replacement therapy can help your dog become themselves again. 

They will still be sterile, but HRT can relieve many of the physical and behavioral negative effects of spaying. If you are unhappy with the changes in your pooch, this can be a lifesaver. It may give you back your companion, the way they should be.