INTRODUCTION

Mammary neoplasms in dogs are second in frequency after skin tumors and they are the most common types of tumors in the bitch. According to the histological diagnosis, between 41 and 53 % of the mammary tumors that occur in the bitch are considered malignant⁵. Mammary neoplasms primarily affect older animals with a mean age of about 10 years. Most affected animals are intact females or females that have undergone ovariectomy late in life. Mammary tumors are rare in males and in young animals of either sex³.

Early ovariohysterectomy is strongly protective against the development of mammary tumors^2,3. Bitches neutered before the first estrous cycle are at no greater risk for mammary tumor than are males. After 2.5 years of age or after the second estrous cycle, ovariohysterectomy is no longer protective in bitches³.

MATERIALS AND METHODS

       The observation was done on a 10 years old, intact female Golden Retriever dog which had mammary tumor metastasized to the lungs. Signalment and medical history of the dog were evaluated.  Physical examination was performed, supported by laboratory test including complete blood count (CBC) and serum biochemical profile (SBP). Radiographic examination was also performed to evaluate the presence of metastatic tumors to the lungs. The positioning of the dog was right lateral recumbent and dorsoventral (sternal recumbent) Diagnostic images of the thorax confirmed pulmonary metastasis of mammary tumor that was suspected on the basis of the history and physical examination. Therapy chosen for the dog was palliative. The dog’s condition was observed for two months before the dog died. Then, a necropsy and histopathology examination were performed.

RESULTS AND DISCUSSION

A 10 years old, intact female Golden Retriever dog was examined at the 24 HRS Veterinary Clinic Drh. Cucu K. Sajuthi and Associate on January 21^st 2009. The third left mammary gland was firm and enlarged less than 5 cm in diameter. Cytologic evaluation revealed mammary lobular hyperplasia. This condition is common in intact bitches without any significant symptoms and can develop to be malignant.

A year later on February 25^th 2010, the dog was brought again to the clinic. The caudal mammary glands including 3 mammary glands on the left and 1 on the right, were significantly enlarged. Complete blood count (CBC) and serum biochemical profile (SBP) were analyzed, and showed all values within reference range. The surgical excision was chosen to remove the tumor and also the four mammary gland adjacent to the tumor. The surgery was performed on March 13^th 2010.

The tumor was noticed to regrow very rapidly within three months, followed with locally suppurative inflammation (pus) and some ulceration (Fig. 1). Abdominal respiration was also observed in this dog, and we then decided to redo the diagnostic test including thoracal radiograph (Fig. 2), CBC and SBP, as shown in Table 1. Based on the thoracal radiograph, known that the tumor metastasized to the lungs and led to worse prognosis.

The dog survived for 5 months post surgery before the animal condition declined slowly and the animal died on August 4^th 2010. A necropsy was performed and we found masses of tumor in the lungs (Fig. 3). Histopathology examination revealed papillary cystadenocarcinoma which spread to the lungs and the spleen. This case study reported that the progression of canine mammary tumor can be very aggressive.

Canine mammary tumor is very related with hormonal factors. It is well established that dogs spayed before their first estrous cycle have a greatly reduced risk of developing mammary tumor. The risk of developing mammary tumors, approximately 50% of which are malignant, rises from nearly 0% in dogs spayed prior to their first estrus to 26% for dogs that are spayed after their second estrus¹. Mammary tumors primarily affect middle-aged (9 to 11 years) female intact dogs, with an increased incidence beginning at approximately 6 years of age. Sexual steroid hormones (estrogen and progesterone) are thought to have their primary effect on target cells during the early stages of mammary carcinogenesis in dogs⁴. Early ovariohysterectomy is strongly protective against the development of mammary tumors^2,3.

Fig.1. Mammary tumor was notice to regrow very rapidly within 3 months, followed with locally suppurative inflammation (pus) and some ulceration

Table 1

Result of diagnostic tests including thoracal radiograph, CBC and SBP