TL;DR: A firm lump in a cat's mammary area is often a tumor and requires a veterinary examination within 24 to 48 hours, though it is usually not an immediate emergency unless it is bleeding or painful.
What does a firm mammary lump on my cat mean?
Finding a firm lump in your cat's mammary area—the space along the underside where the nipples are located—can be a distressing discovery. These masses can represent several different conditions, ranging from benign cysts or localized infections (mastitis) to mammary gland hyperplasia. However, in cats, a high percentage of mammary lumps are found to be mammary tumors, which require professional diagnosis to determine if they are malignant or benign.
Is finding a mammary lump on my cat an emergency?
- The urgency level for a firm mammary lump is classified as Medium.
- It is generally not a life-threatening emergency that requires a midnight visit to the ER, provided your cat is eating, drinking, and breathing normally.
- Because feline mammary masses can progress quickly, you should schedule a veterinary appointment within the next 24 to 48 hours.
- If the lump is rapidly growing, bleeding, or causing your cat obvious pain, you should seek care sooner.
How can a photo of the mammary lump help my veterinarian?
- Capturing a clear, high-resolution photograph provides a visual baseline to help the vet assess the size, color, and precise location of the mass.
- A photo is particularly helpful if the lump changes appearance or size between the time you first notice it and your scheduled appointment.
- When taking the photo, part the fur clearly and include a common object, such as a coin, for scale.
Clinical Context (Merck Veterinary Manual)
When a mammary mass is detected during a physical examination in a cat, a mammary tumor should be suspected. Palpation of regional lymph nodes can help determine the extent of spread. Thoracic radiographs, preferably three views, should be taken to detect pulmonary metastases. Fine-needle aspirates may differentiate between inflammatory and neoplastic lesions, but may lead to erroneous conclusions and delay of surgery; histopathology is important in defining treatment and prognosis. Most feline mammary tumors are adenocarcinomas. Benign tumors are relatively infrequent, and the TNM clinical staging system is used. A distinct entity called feline mammary hypertrophy, marked by rapid growth of one or more mammary glands, affects primarily young, actively cycling, or pregnant cats, and has also been seen in neutered cats given exogenous progestational drugs. Mammary tumors are treated surgically, although there is no consensus as to the best procedure; radical mastectomy has increased the disease-free interval but not survival time.
Chapter: Oncology, Surgery
Source: The Merck Veterinary Manual, 11th Edition (Page 1404)