Case of the Month: uterine cancer in Pet Pigs

Case of the Month: uterine cancer in Pet Pigs

This past Monday, CVC got to work in a 130 pounds 10 years old female pot-bellied pig named Piglet.  Her abdomen was really distended and her caretaker knew from the first time that this was probably due to an uterine neoplasia. The mass was growing fast but Piglet was just doing great and her caretaker was worried about the risks from surgery. 

The distended belly is due to the presence of two large masses weighing 34 lbs.

Piglet was finally seen at CVC and she underwent surgery. During surgery, she was spayed and we removed two large uterine tumors attached to  her uterine horns. Both masses and the uterus weighed 34 lb. This was about 25% of the total body weight of Piglet. These masses were likely to be leiomyomas.

Largest of the masses, it needed to people to support the weight of the mass

Smaller mass, it was about to baseball balls together

After a week post surgery, Piglet is now doing well. In the last two days, she has regained a lot of strength back and will be joining her other pig friends soon. 

Unlike commercial pigs, pot-bellied pigs tend to live very long with a life span estimated to be as long as 20-25 years with the majority of them (average) living of 10-15 years. Cystic endometrial hyperplasia (CHE) has been found to be the most common finding in older pigs with reproductive disease. This is a disease characterized by excessive proliferation of the inner lining cells of the uterus (endometrium). About 44% of those, CHE can be present in conjunction with a smooth muscle tumor. 

One study found that uterine tumors are very common (70%) in the 5 year old or older female pig. From those, 65% were leiomyomas+.  Leiomyomas are a benign smooth muscle neoplasm that very rarely becomes cancer (0.1%). They can occur in any organ, but the most common forms occur in the uterus, small bowel, and the esophagus. 

Uterine leiomyomas, commonly termed fibroids, clinically affect approximately 25% of women of reproductive age in the United States (over 30 years of age), with a subclinical (no obvious for the person to realize about the growth) incidence as high as 77%. Interestingly, the pig has become a medical model for this disease in woman as it has some similarities+. 

In pigs, clinical signs include abdominal distension or vaginal bleeding. Like in human, in many cases they are just identified during spay. Tumors can range from microscopic to 99 lb, are often multiple, and primarily involved the uterine horns.

To sump up, spaying really helps with this as females will jump on you, whine for hours, and forget their potty training during heat  (which will occur every 21 days for about 5-7 days). The health benefits of spaying or castrating your pet pig also include the prevention of reproductive related diseases such as cancer and infection. In one study done on pet pigs ranging from 4 months to 19 years of age, 75% had cystic endometrial hyperplasia (CEH) and 62.5% of those had cancer. Aging is a risk factor and cancer was found in pet pigs of 5 years old or older*.



+ Mozzachio K, Linder K, and Dixon D. Uterine smooth muscle tumors in potbellied pigs (Sus scrofa) resemble human fibroids: a potential animal model. Toxicologic Pathology 2004: 32, 402-407.
*Ilha MRS, Newman SJ, van Amstel S, Fecteau KA, and Rohrbach BW: Uterine lesions in 32 female miniature pet pigs. Veterinary Pathology 2010: 47(6) 1071-1075.