Mammary gland disease

• Mammary neoplasia - overview

  50% of mammary tumours in the dog are malignant and up to 50% of these have metastasised by the time of presentation.

  85% of mammary tumours in cats are malignant.
• Pre-disposing factors to mammary gland neoplasia

  Previous use of progestogens (usually benign lesions).

  Early ovariectomy reduced the risk of mammary neoplasia.

  Protective benefit of neutering:

  • 0.5% if spayed before 6 months.
  • 8% if spayed before 6-18 months
  • 26% if spayed after 18 months
  • No protections is spay after 2 years

  Obesity increases the risk of mammary neoplasia.

  It is not clear if lactation/ pseudopregnancy have any impact.
• Signs that indicate a poorer prognosis for mammary gland neoplasia.

  Rapid growth

  Poor delineation/ infiltration into adjacent tissue.

  Inflammatory changes (lymphoedema of vulva or limbs).

  Ulceration

  Metastasis to regional lymph nodes or lung, liver, bone.

  Tumour size at presentation:

  • In dogs less than 3cm has better prognosis
  • In cats greater than 0.75cm has poorer prognosis.
• Presented with a mammary tumour - should I take a biopsy?

  Small modules: yes (excise it)

  Suspect inflammatory carcinoma: yes

  But generally:

  • Therapy does not alter based on the biopsy
  • Sometimes it is just as easy to remove the gland as to biopsy it.
  • Better to spend the money on time and staging
  • Examine the local lymph nodes (FNA)
  • Both lateral thoracic radiographs
• Options for surgical techniques in mammary neoplasia

  Lumpectomy (removing lump from within the gland).

  Single mastectomy (one gland)

  Regional mastectomy (more than one gland)

  Complete mastectomy (all glands - either unilateral or bilateral).
• Mammary neoplasia - size of tumour

  Masses less than 1 cm in diameter and firm on palpation can be treat by lumpectomy.

  Masses greater than 1 cm and those attached to skin or deeper tissue should be treated by single mastectomy.

  Masses greater than 1cm with indistinct border should be treated by mastectomy which may be regional or compete unilateral depending on the clinical staging.

  Multiple masses can be treated with regional meastectomy or complete unilateral depending on clinical staging.
• Mammary neoplasia - location of the tumour

  Anatomy of the lymphatics

  • Axillary and inguinal lymph nodes
  • Lymphatic drainage runs cranial and caudal
• Mammary neoplasia - regional mastectomy

  Glands may need to be removed in groups if lymphatic spread is possible (i.e. based upon clinical staging).
• Mammary neoplasia - reported growth rate

  Rapid growth indicative of aggressive nature.

  You should not be considering lumpectomy but a higher order procedure.
• Mammary neoplasia - condition of the animal

  Clinical condition:

  • Bitches are more likely to be in poor condition of there are metastases.

  Consider staging the disease

  • Minimum database
  • Right and left lateral thoracic radiographs.
  • Lymph node assessment (palpation/FNA).
• Overall treatment in mammary gland neoplasia in the dog and cat

  Always treat cat mammary tumour more aggressively

  • Radical mastectomy is recommended
  • Increases chance of removing all affected tissue.
  • Decreases chance of local recurrence.
• Mammary gland neoplasia - surgical techniques

  Lumpectomy - removing the lump from within the gland

  Single mastectomy (one gland)

  Regional mastectomy (more than one gland)

  Complete mastectomy (all glands - either unilateral or bilateral)
• mammary gland neoplasia - closure and post-op

  Good sterile technique it’s important

  Keep the facial surface moist with saline during reconstruction

  Close the dead space meticulously - especially in the caudal inguinal fat pad.

  Closure - drains.

  Monitor recovery carefully

  • Consider effect of fluids/ blood loss in older patients
  • Calculate and maintain fluids into post-op
  • Consider concomitant renal/hepatic disease.
• Other treatments for mammary gland neoplasia

  NSAIDS (COX-2) have both anti-inflammatory and anti-neoplastic often given prior to surgery.

  OVH is often recommended to prevent exposure to oestrogen and progesterone, sometimes this is done at the same time as the mammary surgery.

  Chemotherapy may be used in non-respectable or stage 4 or 5 tumours. Combined therapy with more than one drug is often recommended.
• What are common conditions of the mammary gland?

  Galactostasis

  Agalactia

  Mastitis

  Mammary tumours

  Pseudopregnancy

  Fibro-epithelial hyperplasia in queens
• Mammary gland neoplasia - Galactostasis

  Congestion of the mammary gland.

  Seen close to parturition/ after weaning/ rarely in pseudopregnancy.

  Engorgement and pain of the gland.

  May lead to failure of milk letdown immediately post-partum.

  Treatment os reducing food intake, cold packs and encouraging of sucking or milking.

  May require cabergoline.
• Mammary gland neoplasia - Agalactia

  Can be a failure of milk production

  • Inadequate mammary development
  • Early caesarean
  • Treated by administration of metoclopramide.

  Or, failure of milk letdown

  • Seen in nervous bitches where adrenaline blocks oxytocin release.
  • Treated by administration of oxytocin.
• Mammary gland neoplasia - mastitis

  Common and associated with ascending bacterial infections with E.coli, Streps and Staphs.

  May be seen with prolonged galastostasis after weaning, following teat trauma and in poor sanitary conditions.

  Clinical signs are swelling, heat, pain.

  In severe cases abscessation may occur.
• Mammary gland neoplasia - mastitis treatment

  Broad-spectrum, bacteriocidal antibiotics should be chosen based on sensitivity understanding that they will be passed in the milk.

  • Tetracycline, chloramphenicol, or aminoglycosides should be avoided during lactation unless the neonates are weaned.

  Cephalexin and amoxicillin/clavulanate are recommended as initial therapuetic agents pending culture results.

  Hot-packing the affect gland encourages drainage and seems to relieve discomfort.

  Fluid therapy is indicated in animals with septic mastitis that are dehydrated or in shock.
• What causes pseudopregnancy?

  Caused by elevated prolactin which is the principle luteotrohic hormone.
• Pseudopregnancy - all non-pregnant bitches

  Have mammary enlargement

  Have some milk production

  Have some behavioural changes.
• Pseudopregnancy - described as overt of overt


  May or may not be noticed by the owner

  May or ay not be disturbing for the owner.

  May or may not be distressing for the bitch.
• Pseudopregnancy - signs of oestrus may persist for several months

  Anorexia

  Nervousness

  Aggression

  Nest making

  Nursing inanimate objects

  Lactation

  Occasionally pseudo-parturition
• Treatment of Pseudopregnancy

  Most cases require no treatment- initiation of treatment is often related to owner demands.

  Conservative options:

  • Sedatives - care if considering using phenothiazines as these are dopamine antagonists which may increase prolactin concentration.
  • Bathing the mammary glands - care as may stimulate further milk production
  • Diuretics and reducing fluid and food intake - care if bitch is already anorexic.
• Pseudopregnancy - treatment with Cabergoline


  Rapid resolution of behavioural changes

  Rapid reduction of milk production
• Pseudopregnancy - administration of hormonal preparations

  Before treatment ensure that bitch has pseudopregnancy and is not pregnant:

  • Prolactin inhibitors may/ will induce abortion
  • Progestogens may inhibit or delay parturition.
• What is fibroepithelial hyperplasia

  Significant mammary enlargement caused by local growth hormone production in response to progesterone (like a local acromegaly)

  • Young queens (pregnancy or pseudopregnancy)
  • Older queens (exogenous progestogens)

  Glands are very firm and may succumb to secondary mastitis or traumatic ulceration.

  Can be massive, oedematous, bilateral, ulcerated.

  Usually a clinical diagnosis but FNA shows epithelial cells and large numbers of spindle cells.
• Treatment of Fibroepithelial hyperplasia - intact female

  Spay

  Administer prolactin inhibitor (Cabergoline)

  Adminsiter progesterone receptor antagonist (Aglepristone)
• Treatment of Fibroepithelial hyperplasia - Female on oral progestogens

  Stop administration

  Administer prolactin inhibitor (Cabergoline)

  Administer progesterone receptor antagonist (Aglepristone)
• Treatment of Fibroepithelial hyperplasia - female on depot progestogens

  Adminster prolactin inhibitor

  Administer progesterone receptor antagonist.
• Treatment of Fibroepithelial hyperplasia - general treatements

  Surgery during acute phase not warranted as the condition normally will subside spontaneously.

  Progestogens should be avoided.