What are some of the causes a cat would have one pupil bigger than other?

Anisocoria is the medical term for unequal pupil size. It is a common sign in cats, and it can be caused by a variety of underlying medical conditions. Some of the most common causes of anisocoria in cats include:

Horner's syndrome: This is a condition that affects the sympathetic nervous system, which is responsible for controlling the size of the pupils. Horner's syndrome can be caused by a variety of underlying medical conditions, such as:

* Trauma to the head or neck

* Ear infections

* Tumors

* Neurological diseases

Uveitis: This is an inflammation of the uvea, which is the middle layer of the eye. Uveitis can be caused by a variety of underlying medical conditions, such as:

* Infections

* Trauma

* Immune system disorders

* Cancer

Glaucoma: This is a condition that occurs when the pressure inside the eye is too high. Glaucoma can be caused by a variety of underlying medical conditions, such as:

* Narrowing of the drainage channels in the eye

* Overproduction of aqueous humor (the fluid that fills the eye)

* Blockage of the drainage channels by scar tissue or inflammation

Cataracts: This is a condition that occurs when the lens of the eye becomes cloudy. Cataracts can be caused by a variety of underlying medical conditions, such as:

* Aging

* Diabetes

* Trauma

* Inherited disorders

Drugs: Some drugs, such as atropine and scopolamine, can cause anisocoria. These drugs are used to dilate the pupils for eye exams or to treat certain medical conditions.

If your cat has anisocoria, it is important to take them to the vet for an evaluation. The vet will be able to determine the underlying cause of the anisocoria and recommend appropriate treatment.