Vancouver Feline Hospital - Cat Veterinary Clinic

Feline Mammary Hyperplasia

The lumps/enlarged gland(s) are firm and non-painful. There are generally no concurrent signs of illness.

It happens to young, intact, cycling or pregnant queens, or spayed cats, as well as cats of either gender receiving endogenous progestogen (e.g. megesterol acetate (Ovaban), birth control pills).

The veterinarian will confirm the diagnosis and consider the following alternative conditions:

1. Mastitis - mastitis occurs when the queen is lactating - the mammary glands are red, swollen and painful; she is often critically ill, feverish, oozing pus; her kittens may be fading or have died from septicaemia.
2. Mammary neoplasias - older cats - differentiate by biopsy. CBC, blood chemistry, urinalysis will be normal.

To differentiate these three conditions, the veterinarian will suggest doing a Fine Needle Aspirate of the lump and sending the slides to the lab for cytology. In FMH, cytology is of a non-inflammatory or non-diagnostic type. If any fluid can be expressed, that may also be sent for analysis.

If the veterinarian is concerned because sometimes FMH can be a precursor to mammary cancer, a biopsy may be suggested - this involves surgery and the risks and benefits of that will be discussed then. Biopsy results will definitely confirm the diagnosis if they read something like "benign fibroglandular proliferation".

For all breast lumps, veterinarians prefer to collect a "minimum data base" - basic information that can significantly help in diagnosis, staging and decision-making. This data-base includes a complete blood count, biochemistry screen, FeLV and FIV test, thyroid hormone test and chest x-rays (3 views). You need to discuss costs with your veterinarian so that decisions can be made that allow a diagnosis to be made and optimum care for your cat.

Therapy options:

1. Wait for progesterone levels to fall - the mass will disappear by itself.
2. Spay the cat.
3. Stop any progesterone-type medication.
4. Treat with aglipristone, a progestan-antagonist. 3
5. Surgery to excise affected gland only if single gland affected.
6. For the lactating spayed cat/ false pregnancy queen:
   1. Prevent self-suckling or self-mutilation if she is lactating (a head cone)
   2. Bromocryptine or cabergoline (prolactin inhibitors) - these drugs are not approved in Canada and have some severe side effects.
   3. Check regularly - watch for any of the signs of mastitis - she may need antibiotic treatment and warm compresses.
   4. Keep the area clean to decrease the chance of infection.

Supportive Therapy:

1. Anti-inflammatories and analgesia (pain killers) - especially if multiple glands involved.

2. Appetite stimulants and nutritional support may be necessary.