PSSM & MIM Symptoms- Aggression & Depression

When it comes to PSSM & MIM symptoms, aggression & depression are two behaviours that owners commonly report within their PSSM & MIM horses. But what do these two behaviours mean when it comes to PSSM & MIM, and how can we prevent them?

What Is Aggression?

Aggression is when a horse reacts violently towards humans or even other horses, the horse will often react unpredictably, or out of character.

Karlo an N/P4 warmblood gelding displaying the symptom of aggression

What Is Depression?

Depression is when a horse has little to no interest in life, depressed horses will often lose that spark, and have a dull look in their eyes.

Nellie an N/P3, N/PX Thoroughbred mare displaying the symptom of depression

How Does The Aggressive Horse Behave?

The aggressive horse will typically display one or more of the following behaviours:

-Pinned ears flat against head
-Kicking out
-Lashing out
-Reacting violently to humans or other horses
-Unpredictable aggressive behaviour
-Unhappy about being touched, rugged or groomed

How Does The Depressed Horse Behave?

The depressed horse will typically display one or more of the following behaviours:

-Little to no appetite
-Dull coat
-Listless expression
-Pinned ears
-Lowered head
-Dull eyes/ eyes that have lost their spark
-Spending most of the day standing in one spot
-No interest in life horse seems like it’s given up

What Causes A PSSM Or MIM Horse To Become Depressed Or Aggressive?

Pain is the primary cause of PSSM & MIM horses becoming depressed or aggressive, how the horse reacts to this pain will depend upon the horse’s character and the severity of the pain. Some PSSM & MIM horses will become depressed with pain, while others will turn increasingly aggressive and lash out.

Can A Horse Be Naturally Depressed?

No, a horse cannot be naturally depressed. An event will have to occur to cause a horse to become depressed. A few examples of events that could cause depression are pain, the death of a herd member, or the loss of a foal.

Can A Horse Be Naturally Aggressive?

Yes, some horses can be naturally aggressive. These horses are usually older domestic horses or wild horses, who haven’t had any handling by humans until they are adults. Through fear some of these older horses can become dangerously aggressive.

How Can We Prevent The PSSM Or MIM Horse From Being Depressed Or Becoming Aggressive?

Management is the key to relieving depression or aggression in the PSSM or MIM horse, if management works for the horse it can help relieve some or all symptoms of aggression & depression in the PSSM or MIM horse.

But as we know management does not work for all PSSM & MIM horses especially those who are severely affected with multiple symptoms. In these severe cases, horses are often euthanized to prevent further suffering.

If PSSM or MIM management does not work for your aggressive or depressed horse, discussion with your vet is needed to discuss the horse’s quality of life and future.

For more information on the PSSM & MIM symptoms aggression & depression check out our YouTube video with examples of affected horses by clicking this link