Cystic Ovary Disease Average Cost

From 242 quotes ranging from $8,000 - 20,000

Average Cost


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What is Cystic Ovary Disease?

The hormonal changes can cause the mare to become violent. Therefore, even if your horse is not being used for brood, it is important to address ovarian tumors or cysts to ensure your horse’s behavior does not become altered.

In many cases, the ovarian tumors are cancerous and do require aggressive treatments such as chemotherapy, radiation therapy, and even an ovariectomy. If found early enough, the treatments for cystic ovary disease can be extremely successful.

Reproductive issues within horses are fairly common.  Mares have the highest occurrence of ovarian cysts than any other domestic animal. Ovarian tumors, in general, cause the mare to have fluctuations within her hormone levels. This will occur during the mare’s heat cycle. During a normal heat cycle, your mare’s follicles within the ovaries will be 4 to 6 centimeters in diameter. When cystic ovary disease is present, the follicles can grow to double and in some instances triple their normal size.

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Symptoms of Cystic Ovary Disease in Horses

It can be difficult to diagnose cystic ovary disease because there may be no outward signs that something is wrong with the mare. If there are any noticeable changes to your horse’s behavior that cannot be attributed to any outward source, a physical examination needs to be done by your veterinarian to find the cause of this change. Possible symptoms to watch for include:

  • Behavior changes, especially corresponding with fertility cycles
  • Refusing to accept a rider
  • Refusing to accept a stud
  • Erratic heat cycles
  • Infertility

Causes of Cystic Ovary Disease in Horses

There is no known cause of cystic ovary disease in mares. Researchers believe that an abnormality that the mare is born with contributes to the development of ovarian tumors. Cancer is formed within the ovary when cells begin to rapidly replicate, forming a mass or tumor. There is no definitive answer to why so many mares are diagnosed with ovarian tumors or ovarian cancer.

Diagnosis of Cystic Ovary Disease in Horses

First, your veterinarian will conduct a thorough physical examination to ensure that there are no external issues causing your mare to be having problems.  

Rectal Examination

After the physical examination, your veterinarian will perform a rectal examination. This will allow your veterinarian to feel along the uterus and the ovaries. An enlarged ovary is indicative of a tumor in that ovary and will be easy to find through the rectal examination.

Transrectal Ultrasound Examination

An image of the enlarged ovary will help your veterinarian determine what type of tumor has developed and the size of the tumor.

Additional Testing

Your veterinarian will run additional tests that will evaluate the blood hormone levels of your mare. This will help in determining the best treatment plan for your mare.

Treatment of Cystic Ovary Disease in Horses

Treatments for mares diagnosed with cystic ovary disease will vary depending on the size and the stage of the tumor found. Removal of the ovary will most likely be required. In some cases, both ovaries will be removed. 


Your veterinarian will discuss the surgical process that they will be using to remove the affected ovary. A traditional surgical approach may involve general anesthesia and a laparotomy. A laparotomy is when a large incision is made through the abdominal wall to gain access to the reproductive organs.

Some veterinary teaching hospitals have begun using laparoscopic techniques to minimize the size of the incision during an ovariectomy. This new technique is starting to gain popularity as new veterinarians are beginning to use it as general practice when performing an ovariectomy. 

Antibiotics and Other Medications

Antibiotics and anti-inflammatory medications may be prescribed for pain management and to keep the risk of post-operation infection low. Be sure to always follow the dosage instructions for all medications given to your horse. 

Chemotherapy and Radiation

In cases where the ovarian tumor is cancerous, chemotherapy and radiation treatments may be recommended for your mare. Your horse may need to be hospitalized during the first few weeks of treatments.

Recovery of Cystic Ovary Disease in Horses

Recovering from an ovariectomy will take time. This is major surgery, no matter which technique has been used on your mare. Follow all post-surgical instructions carefully and be sure to complete all follow up appointments with your veterinarian. Once your mare has begun the recovery process, your veterinarian will be able to let you know when to expect a full recovery. 

In cases where cancer was found, the prognosis is guarded following the ovariectomy. Your veterinarian will monitor your mare’s response to treatments and keep you updated on any progress that is made in treating the ovarian cancer.

Cystic Ovary Disease Questions and Advice from Veterinary Professionals

One Dashing Hawk
5 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Irregularly Long Heat Cycles
Lower Back Pain to the Touch
Hopping and Rearing While Mounting
Excessive weaving

I have a mare who is almost five. She has always had intense heat cycles but nothing like she's having recently. She's always been a weaver, but like her heat cycles its also gotten worse. She is very sensitive in her lower back. She has developed a bad habit of rearing when I get on or off and when try to bring her to a stop after a run, and she is a barrel horse and is really sensitive but she never had any issues like that before this. She turns twenty times worse to the left than the right. She is constantly bracing on the bit no matter how harsh it is. She recently went though the hot fence to go stand next to another mare and pee. It seems like she is always distracted and even when we try to drug her it doesn't work. Our vet says she may have cysts on her ovaries, and we are going to try Regime. She is extremely healthy otherwise and sound as can be. She is off the track too. She also is on a good diet as well as supplements.

This mare is "willing" to hurt herself and put you at risk because she apparently is in PAIN... "turns worse to the left" braces on bits "no matter how harsh (Um...harsher bits do not "treat" training problems), went through a fence, and is showing aberrant hormonal behaviors.
She hasn't "developed a bad habit of rearing when you mount"-she is in PAIN.
Help her out and get her to a vet that will do something for her...and stop blaming her issues on escalating attitude problems. This sounds WAY beyond supplemental "treatments."

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13 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Irregular Cycles
Hip Banging
Some sensitivity to right side

My mare is extremely abnormal in her cycles, and has been the 4 years I have had her. She seems to cycle fairly regularly and with this comes aggression and moodiness. She bangs her hips on walls and fences to do, what we assume, is relieving some type of pain. She has been flushed out, given hormones, and placed on supplements and nothing seems to be helping her. Whenever we take her to a horse show it seems a switch flips and she immediately comes into heat. I am really looking for an opinion on what my next move should be. We have moved passed the idea that she is a typical mare with her attitude. I am wondering if she is suffering from something more underlying with her symptoms. Thank you.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
In this case I would highly recommend a thorough examination by your Veterinarian including an ultrasound of the reproductive tract to look for any anomalies which may be causing this behaviour; without an examination I cannot think of anything constructive to tell you unfortunately. Regards Dr Callum Turner DVM

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Quarter Horse
9 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms

excessive urination
Doesn’t like saddle
Pain in area of kidneys
Very stiff in hind end

Are these symptoms of the cystic ovary disease I am taking her to vet Tuesday
Drinking a lot of water
Pain in area of kidneys
Won’t except a saddle
Kicks when touched in hind end
Walks very stiff
Bites at me when being saddled

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
From your description, it doesn’t sound like cystic ovary disease but may be attributable to spinal disorders, muscle pain, azoturia among other causes; read the article below about azoturia (Monday morning disease) in horses. If Lily is in a lot of pain you should call your Veterinarian out. Regards Dr Callum Turner DVM

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