Cancer in Horses

Cancer in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

Most common symptoms

Bleeding / Diarrhea / Odor / Poor Appetite / Vomiting / Weight Loss

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Rated as serious conditon

2 Veterinary Answers

Most common symptoms

Bleeding / Diarrhea / Odor / Poor Appetite / Vomiting / Weight Loss

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Cancer in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

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What is Cancer ?

As the cancer begins to spread throughout the body it begins to metastasize and create additional masses. Some forms of cancer become apparent only when the cancer is in an advanced stage and outward symptoms begin to present. 

Gray horses are very susceptible to nodular masses known as melanomas. These masses are usually seen under the tail, behind the jaw or in the eye. Most melanomas remain harmless to the horse, but there have been instances where they grow into invasive tumors and spread through the body.

In our society cancer is becoming more and more prevalent, not just in humans, but also in our animals. Horses are not the exception. Cancer occurs when normal cell growth changes and cells begin to multiply in a chaotic manner. These multiplied cells begin forming masses that will disrupt the normal functions of the body. Cancer can affect any part of the body.

Symptoms of Cancer in Horses

If you suspect that your horse may have developed some form of cancer, schedule an immediate appointment with your veterinarian and have a full assessment done including bloodwork and biopsies, if possible. Signs to look for when suspecting cancer in your horse include:

  • Evidence of a mass 
  • Enlarging or changing masses
  • Swollen lymph nodes
  • Chronic weight loss
  • Distended abdomen
  • Chronic vomiting
  • Bleeding 
  • Chronic diarrhea
  • Dry cough
  • Difficulty urinating
  • Lameness
  • Foul breath or odor from the mouth
  • Refusal to eat or drink

Causes of Cancer in Horses

Just like in humans, it is difficult to determine the cause of most equine cancers.  Researchers have determined that in the case of melanomas, the horse’s coat color is linked to a cell mutation that causes the melanoma to form. 

Researchers are still working to understand why cells start rapidly multiplying causing mutations or masses to form. Some claim genetics plays a role, while others claim environment is the cause. Until researchers finally determine why cells begin mutating, cancer will still remain somewhat of a mystery.

Diagnosis of Cancer in Horses

Your veterinarian will begin with a full physical examination and will do several palpations along your horse’s body, searching for any masses that can be felt.  After the initial assessment is finished, additional testing will be required to fully diagnose your horse.

CBC

Routine bloodwork will show if there is an elevation of the blood calcium concentration.  An elevated blood calcium concentration is called hypercalcemia. If elevated, it could point toward cancer.

Imaging Tools

Your veterinarian will want to do some form of imaging to see exactly where the mass or masses are located and if it has metastasized; X-rays and ultrasound may be utilized.

Biopsy

A biopsy will be taken of the mass to determine the type of cancer. This will give your veterinarian an idea of how advanced the cancer has become. By taking a biopsy of the lymph nodes or the actual mass, it can be determined if the mass is malignant.

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Treatment of Cancer in Horses

It has been determined that many of the same treatments used in humans for cancer work for horses diagnosed with cancer. This includes surgical removal of the mass, chemotherapy, and radiation.

Surgery

Depending on the location and size of the mass, surgical removal may be an option. Your veterinarian will determine through testing and imaging if your horse is a good candidate for surgery. Laser surgery has been used with success in the treatment of cancer in horses. It is used to cut out the mass and seal the blood vessels, thus promoting faster healing. 

Chemotherapy Drugs

Researchers have developed a serum that is tissue based and made from the cells of your horse’s mass. This serum has had great success in treating melanomas. There has been limited success in treating other forms of cancer in horses. 

Radiation Therapy

Radiation has been used to shrink existing masses and reduce the chances of the cancer spreading.

Recovery of Cancer in Horses

Horses diagnosed with cancer will always be given a guarded prognosis. If the cancer has been found while still in the early stages and immediate treatments have begun, your horse has a much better chance of fully recovering. Follow the treatment plan set by your veterinarian to ensure the best possible prognosis for your horse. Keep your veterinarian informed of any changes to your horse’s health so the treatment plan can be modified. 

In horses that have been diagnosed with cancer that is in the later stages or has already metastasized, supportive care is suggested to keep their quality of life as high as possible. In these cases, the treatments would probably have little to no effect on the cancer and eventual euthanasia will be recommended.

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Cancer Average Cost

From 210 quotes ranging from $15,000 - $30,000

Average Cost

$20,000

Cancer Questions and Advice from Veterinary Professionals

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Vixy

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Appaloosa & Arab

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21 Years

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Mild condition

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0 found helpful

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Mild condition

Has Symptoms

Mass To Eye

I am considering adopting a rescue appaloosa/arab gelding. He has a mass/tumor the size of a small tangerine above his right eye and another very small patch of carcinoma on his chest. What is the prognosis for him and how will I know when the cancer metastasis? He has had a vet evaluation but I am concerned i wont know when he is more ill. Currently he acts as if he is perfectly healthy

June 20, 2018

Vixy's Owner

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3320 Recommendations

Generally the first sign of metastasis is when new symptoms develop due to the growth of a secondary tumour, these symptoms can vary depending on the specific location of the secondary tumour; the rate of spread of skin cancers in horses is slow but the risk is higher in horses with large tumours. There is no set rule or time frame and is really a wait and see approach that is normally taken, the Veterinarian which performed the evaluation would be able to tell you more. Regards Dr Callum Turner DVM

June 21, 2018

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Iris

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Oldenburg

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17 Years

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Critical condition

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0 found helpful

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Critical condition

Has Symptoms

Colic

Recently my Oldenburg mare had to be put down do to a tumor wrapped around her small intestine. How long would it take for something like this to develop? Why didn't I notice any major symptoms? I took her to the vet that morning due to colic symptoms but I hadn't noticed anything more than that. Any advice for what to look for in the future?

March 6, 2018

Iris' Owner


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Dr. Michele K. DVM

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1611 Recommendations

Thank you for your email. I'm sorry for the loss of your Iris. Some tumors grow very slowly, and show very little signs. If she was healthy up until she had this episode, you can rest easy knowing that the tumor did not affect her until the end.

March 6, 2018

My horse had a sudden death today, i owned him for nearly two and half years, was a rescue with not much background. in the last few months he had many of the symptoms listed above. Vet came out and thought he may of had a hidden tumour.

July 18, 2018

Kendra

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Big Red

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Quarter Horse

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23 Years

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Moderate condition

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0 found helpful

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Moderate condition

Has Symptoms

Diarrhea
Weight Loss
Coughing
No Weight Gain
Etc

Hi,my horse is 22-23 years of age. He is a Quarter Horse and has some signs of cancer or some other medical issue. He doesn't gain weight and we currently have him on 9 pounds of SafeChoice daily. He coughs when being excersyised and doesn't drink much water. He had manure that is so funny that it splatters when hitting the ground. Does anyone one know what this would be? He also is lame in his front right leg

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Sam Cat

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Quarter Horse

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10 Years

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Serious condition

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0 found helpful

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Serious condition

Has Symptoms

Swollen Eye, Loss Of Balance

My horse started out with a serious sinus infection. Within a week, his eye swelled. He seemed to lose depth perception and had problems with balance. A blood test was negative. When he walked he only turned in circles to the left. He was constantly running into things so it was difficult to put him in s stall. The day he died he was having seizures. He only lasted about 5 weeks from the time he had the sinus issues. Without a cat scan we cannot be certain but our vet thought it must have been a tumor that pressed on his optic nerve and then the brain.

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Flash

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Tennessee walker

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20 Years

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Serious condition

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0 found helpful

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Serious condition

Has Symptoms

Swollen Chest

My horse was healthy when I bought him Nov 2018. Last week (Thursday) he had a very low head and not himself. Friday he was still low head and did not poop all afternoon and all evening. Vet advised Banadine. I gave it to him and he pooped. Saturday he seemed ok - but his head was low, eating and drinking. Sunday he became swollen in the face neck and chest. Sunday night he seemed to be in a ton of pain. Gave him Bute until vet came on Monday. Vet took blood on Monday - the numbers were so high (white count 75 where 14 is normal) Lab said get another test this can't be right. Wednesday the 2nd Blood test showed white 95 where 14 was normal. He started to show "sailor legs" in back weak and feet under his belly. He has a huge lump on his chest that has been moving downward. We moved him back to the original owner pasture to be with his old herd. He was diagnosed with Lymphatic Cancer. 2 vets both said he has 1 week to live. He is currently head high - and does not seem to be in pain. Outside all day and night with run in shed (huge like garage) He is eating and drinking normally. The previous owner and I have been devising a natural healing plan for him that is in the works. When he makes it past 2 weeks we will test his blood again. We both refuse to do steroids due to damage is can cause.

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Murphy

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Shire x thoroghbred

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23 Years

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Critical condition

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0 found helpful

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Critical condition

Has Symptoms

Enlarged Lymph Nodes

My horse is being put to sleep this afternoon , he's 23 and I've had him 19 years . Mortified and numb but yes been diagnosed with lymphoid leukaemia which i understand is very rare. He had bloods taken 6 years ago and they did not pick this up but did say he had cushins. He does not appear as a cushins horse or present with the normal symptoms. Could they have got it wrong and it was the start of the leukaemia,are the tests similar for what they look for . Doesn't change anything but would be nice to know .

Cancer Average Cost

From 210 quotes ranging from $15,000 - $30,000

Average Cost

$20,000

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