Mammary Gland Disease

Question 1

Clinical Examination of the Mammary Gland

Answer 1

Examination of the gland skin

Palpation of the gland
Number of glands and teats
Basic structure
Size
Texture / firmness
Evenness

Examination of the teat (nipple) and teat canal
Skin crusting / ulceration / etc
Discharge

In lactating animals - expression of milk
Colour
Odour

Milk production data

Question 2

Possible tests to investigate mammary Gland Disease

Answer 2

California mastitis test (cow side indicator of somatic cell count)

Ultrasound examination of the gland

Fine Needle Aspiration (FNA)

Question 3

properties of the normal Mammary Gland

Answer 3

Has normal non-diseased skin
Is appropriately sized and maintained by the gland (udder) suspensory system
May vary in size (increases in size when progesterone is elevated)
Is not hot or painful
Is even in texture
Has a single teat with non-diseased epithelium
May (if lactating) allow the expression of normal coloured milk (or colostrum if shortly after birth)
Milk production data will conform to expected stage of lactation

Question 4

What causes mammary gland enlargement/lactation in dogs

Answer 4

Elevated progesterone and prolactin occur in every non-pregnant dog after ovulation. This results in mammary enlargement and often lactation with behavioural changes that are often termed pseudo-pregnancy

Question 5

Common Mammary disorders (10)

Answer 5

Diseases of the local skin or mammary skin

Damage of the udder suspensory apparatus (dropped udder)

Damage to the teat skin (e.g. milking machine trauma),

Damage to the teats

Inverted nipple

Skin disease
Warts
Ulcerative mammillitis (Bovine Herpes Virus 2)

Mastitis (all species but common in those which are milked). Different classification systems used e.g. cows:
Sub-clinical mastitis
Clinical mastitis
Acute mastitis
Acute gangrenous mastitis
Chronic mastitis

Mammary gland enlargement
Normal under progesterone
Due to milk engorgement at weaning
Mammary hyperplasia (e.g. hormonally induced in Queen with fibroepithelial hyperplasia)

Mammary neoplasia (common in dogs)

Lack of milk (Agalactia)

Question 6

Which species see the most mammary neoplasia
what is staging system called

Answer 6

Bitch and queen

50% of mammary tumours in the dog are malignant and up to 50% of these have metastasized by the time of presentation
85% of mammary tumours in cats are malignant

Classification and staging – TNM system
E.g. 4cm tumour with no spread to the local node and no metastasis found on lung radiographs = T2,N0,M0 = Stage 2

Question 7

what is agalactia

Answer 7

No milk

Question 8

2 mechanisms of agalactica

Answer 8

Can be a failure of milk production
There will be inadequate mammary development
Caused by early caesarean
Treated by administration of metoclopramide (a prolactin agonist)

Or, failure of milk letdown
Seen in nervous dams where adrenaline blocks oxytocin release
Treated by administration of oxytocin

N.B. Metritis, systemic infection and mastitis can lead to agalactia and requires treatment of the underlying cause

Question 9

What hormone controls milk production

Answer 9

Prolactin

Question 10

What hormone controls milk release

Answer 10

Oxytocin