BREAST TUMORS IN CATS

Mammary tumors are the third most common type of cancer in female cats. It is more common in cats that are middle-aged and older, have not been neutered, and are fed high-fat foods. Persian and Siamese cats are breeds prone to mammary tumors. Cat mammary tumors are neoplasms that are mostly malignant and tend to metastasize (spread).

Mammary glands; In cats, as in many other species, is responsible for milk production and feeding newborns. Cats have a complex of 4 mammary glands each, and they are present in the form of a chain. Each glandular complex contains a nipple. The breast complexes are located between the front and hind legs, at the chest and abdomen. As the tumor develops, mammary gland cells degenerate and proliferate uncontrollably, forming a nodule in the breast tissue. This type of tumor is also found in breast cancer in women. Early diagnosis and appropriate treatment are very important regarding the course of the disease.

Triggering Factors

 1-Age 

Mammary tumors are usually diagnosed in middle-aged or older cats. Mammary tumors in cats are seen more common after the age of 6, with the incidence being highest at the age of 10-12. The risk of cancer increases with age.

2-Steroid Hormones and Sterilization

 While the development of mammary ducts in cats is stimulated by estrogen, the lobulo-alveolar system develops with the support of progesterone. Hyperplastic and neoplastic formations seen in the breasts of carnivores may develop with excessive stimulation of these hormones. Since sexual steroid hormones affect the development of mammary tumors, unneutered or late neutered cats are particularly affected by this disease. Although rare, mammary tumors are encountered in male cats. Estrogen and progesterone play an important role in the development of mammary tumors in the cat, just like in dogs and humans. 

Estrogen and progesterone are produced mainly in the ovaries. These are removed during the neutering operation. Therefore, cats that are neutered early have a lower risk of developing mammary tumors. Especially; The risk of formation of mammary tumors is greatly reduced in cats neutered during the prepubertal period, but this risk increases in unneutered cats which are regularly administered progesterone. Therefore, it is necessary to avoid the use of progesterone to suppress oestrus.

3-Nutrition 

In carnivores compared to herbivores and in carnivores kept in limited areas compared to those living in nature, the higher incidence of cancer in emphasizes that nutrition and reproductive history are important risk factors. Obesity, foods high in fat and low in fiber, and  Early sexual maturation due to good nutrition may be the reason for this difference.

4- Breed Predisposition

 Some cat breeds have a genetic predisposition to mammary tumors. For example, Siamese cats are twice as likely to develop mammary tumors than the other breeds. Almost one hundred percent of the mammary tumors encountered in this breed are malignant. In addition, the age at which breast tumors occur in this breed is lower than other breeds. Persian cats are one of the breeds at risk, although the rate is not as high as in Siamese cats.

Symptoms of Breast Tumor

-Nodules having a harder consistency than the surrounding glandular tissue

-The tendancy to lick the area clean if they have an open wound

–One or more mammary masses in cats who are past the middle age

–Swelling of the nipple and presence of an exudate

–Dyspnea, cough (pulmonary metastases are the most common cause of death), lymphatic edema in one or more legs, laminitis (foot inflammation), and paresis (paralysis) at the back of the body.

-Symptoms such as loss of appetite, high fever, lack of interest in the environment, pain, and anemia may also occur in cats. 

-Inflammation and/or ulcerative lesions in the breast lobe

If your pet is showing these symptoms, you should consult your veterinarian as soon as possible, even when you notice masses the size of lentils or rice!!! Some tumor types are prone to rapid growth, so the diagnosis needs to be confirmed as early as possible.

BREAST TUMORS IN DOGS 

Mammary tumors are the most common tumor type in dogs, and approximately 53.3% of these tumors are malignant. Although the causes of mammary tumors in canines are not well understood; steroid hormones, prolactin, GnRH and its receptors, some growth factors, the animal’s age, breed, nutritional status, and genetic factors are among the factors that play a role in the formation of this condition. It is thought that the progesterone hormone, which is administered exogenously to suppress oestrus, also affects breast tumor formation. Mammary tumor formation is more common in some dog breeds. As in cats, feeding high amounts of fat and obesity increases the risk of mammary tumor formation. For this reason, nutrition plays a big role in prevention. The breeds that are under the most risk are Daschund, Spanish Cooker, Terrier and German Shepherd Dogs.

Predisposing Factors

 1-Age 

Age is one of the factors  that affects the formation of breast tumors. The incidence of mammary tumors is higher in middle-aged and older dogs. While the average age of presence of benign mammary tumors is 8.9 years, the average age of malignant mammary tumors has been reported to be 10 years. In addition, the dogs with the highest risk of malignant mammary tumors are 13-year-old female dogs.

 2-Neutering 

Neutering dogs at an early age greatly reduces the risk of mammary tumor formation.

3-Growth Factors 

The growth of normal and tumor breast tissue is stimulated not only by steroid hormones but also by growth factors. These factors are synthesized locally and regulate tumor growth.

 4- Breed Predisposition

 Breeds at high risk of mammary tumor formation in dogs vary depending on geographical location. Toy Poodle, Miniature Poodle, English Springer Spaniel, Cocker Spaniel, Pulis, English Setter, Pointer, German Shepherd, Maltese, Yorkshire Terrier and Dashund are the breeds with the highest risk of developing mammary tumors.

5-Nutrition and Obesity 

As in humans, the factors that contribute to the formation of mammary tumors in dogs include eating fatty foods. The risk of mammary tumors is high in dogs fed homemade food and red meat. Obesity in young dogs that are over a year old is another risk factor that triggers the formation of mammary tumors at later ages. Another factor can be shown as a diet with high amounts of beef and pork and low amounts of chicken. In this way, feeding with protein containing high cholesterol accelerates tumor development. In addition, the possibility of breast tumors may increase due to genetic factors and some physical and chemical stimuli.

Symptoms of Breast Tumor 

–One or more palpable masses (usually firm and nodular) under the skin of the abdomen 

–Bloody, inflammatory or serous discharge from the nipple 

-If the tumor has metastasized (spread to other parts of the body), weakness, loss of appetite, weight loss, and difficulty breathing may occur.

–Ulceration or inflammation may occur.

Differential Diagnosis 

• Fibroepithelial 
• Hyperplasia 
• Mastitis 
• Abscess
• False pregnancy 
• Abdominal – Inguinal hernia

This blog post has been verified by Doctor of Veterinary Medicine Mert SARILAR.

PHOTOS

Breast Cancer in Cats and Dogs

https://www.sciencedirect.com/journal/journal-of-feline-medicine-and-surgery/vol/8/issue/6

SOURCES

Günay Uçmak Z, Kırşan İ. Kedilerde meme tümörlerinin patofizyolojik seyri ve tedavi al ternatifleri. Kırşan İ, editör. Köpek ve Kedi lerde Meme Tümörleri ve Güncel Yaklaşımlar. 1. Baskı. Ankara: Türkiye Klinikleri; 2021. p.56-64. 

Günay Uçmak Z, Enginler SÖ. Köpek meme tümörlerinin oluşumuna etkili faktörler ve ko ruyucu yaklaşımlar. Kırşan İ, editör. Köpek ve Kedilerde Meme Tümörleri ve Güncel Yakla şımlar. 1. Baskı. Ankara: Türkiye Klinikleri; 2021. p.93-100.