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Home > Cats > Cat Hormones 101: Vet Explained Disorders & Care

Cat Hormones 101: Vet Explained Disorders & Care

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Dr. Maria Zayas Photo

Written by

Dr. Maria Zayas

Veterinarian, DVM

The information is current and up-to-date in accordance with the latest veterinarian research.

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Most people have had an experience when their hormones went a little crazy, but what does that really mean? What’s a hormone? Do they drive our pet kitties crazy too? How serious is a hormone imbalance for a cat, and how does it happen?

We will go over everything you need to know about your cat’s hormones and the most common hormone disorders they may experience. So, the next time something seems wrong, you can tell if they’re just hormonal, sick, or both.


Hormones and the Endocrine System

Everybody, including cats, needs a way for different parts and systems to communicate with each other. The body accomplishes many smart ways, but the endocrine system is the driving force behind it all. The endocrine system is mostly a series of glands across the body that produce hormones (though other tissues can also make hormones). Hormones are protein or steroid chemical messengers. This means they are sent from one type of tissue to others to let them know when to do certain functions, to what level, and when to stop.

For example, insulin is a hormone produced by the pancreas. Insulin tells cells around the body when to take sugar from the blood to use for energy, and the body controls its release through a feedback system that monitors the sugar levels of the blood, so they won’t grow too high or fall too low.

Here are the most important components of the endocrine system in cats:

  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Pancreas
  • Adrenal glands
  • Ovaries (female cats)
  • Testes (male cats)
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Image Credit: arturs.stiebrins, Shutterstock

Important Cat Hormones

Now that we know what a hormone is and why the body has them, what kinds of hormones do cats have? Well, cats have the same hormones that we do. These are some of the most important hormones in cats and which part of the endocrine system produces them, but this is by no means an exhaustive list.

  • Insulin – Pancreas
  • T4 (thyroxine) – Thyroid gland
  • Growth hormone – Pituitary gland
  • Cortisol – Adrenal glands
  • Progesterone – Ovaries
  • Estrogen – Ovaries
  • Testosterone – Testes

What Makes These Hormones Important in Cats?

Every hormone plays a critical role in the body, but in cats, some endocrine disorders are far more common than others, and some hormones related to the daily maintenance of normal body functions are more useful for a cat’s way of life than other species. Here is what makes those day-to-day upkeep hormones important in cats.

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Image Credit: Azovsky, Shutterstock


This hormone is released when a cat is stressed. It tells their body to create more energy they can burn, keeps their blood sugar level, and decreases inflammation. Cats are predators, but due to their small size, they can also be prey. Their lifestyle relies on a ready, quick response to stressors, and maintaining appropriate cortisol levels is a top priority for a feline endocrine system.


Estrogen is the main reproductive hormone of female cats. It can control the release of other reproductive hormones, controls what the organs of the female reproductive system do, and levels of estrogen signal stages in a cat’s life, such as puberty.



This female reproductive hormone is most related to pregnancy. It tells the uterus when to prepare for pregnancy, helps maintain that pregnancy, and tells the mammary glands to prepare for lactation, too, so newborn kittens can nurse.


In the male cat, testosterone is an important reproductive hormone. It controls the development of male reproductive organs and physical characteristics.


Common Diseases of Hormone Dysfunction in Cats and How to Treat Them

The rest of the hormones on our list are important to know because they are related to the most common endocrine disorders in cats. Here are those disorders, which hormones are responsible for and how these disorders are treated.


Diabetes, the full name being diabetes mellitus, is a disorder in which the body fails to make enough insulin or the cells of the body are resistant to the insulin produced. Insulin is a hormone produced by the pancreas that tells the cells of the body to take in sugar from the blood to use or store for energy. Insulin levels are supposed to change based on the current level of a cat’s blood sugars.

Signs of diabetes are as follows:

  • Loss of appetite
  • Vomiting
  • Lethargy
  • Increased drinking and increased urination

Diabetes has several types of treatments, the most common of which is to introduce even more insulin into a cat’s body through daily injections for better communication with the cells around the body. Changes in diet and weight are also useful aspects of treatment and well-rounded diabetes treatment plans can often cure diabetes in cats.

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Image By: stokerolga, Shutterstock


In cats, hyperthyroidism is almost always due to a benign thyroid tumor that results in overproduction of the iodine-containing thyroid hormone thyroxine. Thyroid hormones control a cat’s metabolism. When their metabolism becomes overactive due to high levels of thyroids hormones, signs can include the following:

  • Weight loss
  • Increased energy or vocalizations
  • Increased drinking and urinating
  • High heart rate
  • Significant increases in appetite (ravenous eating but losing weight)

A blood test with a veterinarian that shows an elevated T4 (thyroxine) level is enough to diagnose hyperthyroidism, though sometimes the enlarged thyroid gland can also be felt on the neck of a cat.

The most common treatment is to give a medication every day that helps block the production of thyroid hormones. Since this doesn’t treat the underlying problem, this is a life-long treatment. The best way to cure hyperthyroidism is via a radiation treatment that will destroy just the extra thyroid tissue of the tumor rather than the whole thyroid in most cases, returning a cat’s thyroid hormone production to normal.

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Image By: Andy Gin, Shutterstock

Feline Acromegaly

Acromegaly is a disorder in which tumors in a cat’s pituitary gland (located in the brain) lead to the overproduction of growth hormones. In adult cats, signs of acromegaly would be adult cats that gain weight quickly, including developing a larger skull, muscles, heart, feet, organs, and more.

Almost all cats with acromegaly will also have uncontrolled diabetes due to insulin resistance, and so signs may also include increased drinking and urination and lack of response to treatment for diabetes.

The best way to diagnose acromegaly in cats is with a CT scan of the pituitary gland to find the tumor(s), paired with increased growth hormone levels on blood work and a history of insulin resistance. While there are some treatment options for feline acromegaly, such as daily medication and radiation therapy or surgery for the pituitary tumors, in most cases, unfortunately, treatment only involves treating symptoms, like insulin therapy for diabetes.

The long-term prognosis for feline acromegaly is poor, with most cats developing heart disease that progresses to heart failure. It is important to note that while feline acromegaly is one of cats’ more common endocrine disorders, it is not a common disorder of cats in general.



A cat’s endocrine system uses hormones to communicate between body systems. This allows the body to coordinate complicated processes that don’t just stop and go but can fine-tune how active the process should be. Breakdowns in these communication relays can cause over or underproduction of hormones which can leave a cat very ill, very quickly.

It helps to know the signs of the most common endocrine disorders of cats so that you can report these to your veterinarian when you see them, and they can perform the necessary tests to get your kitty started on the path to feeling better.

Featured Image Credit: santypan, Shutterstock

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