(The following article, reprinted with permission, was taken from the 2008 Canine Breeder's Symposium, sponsored by the Society for Theriogenology and the American Kennel Club Canine Health Foundation. The Society for Therinogenology will be holding another Breeder Seminar on August 29, 2009 in Albuquerque, New Mexico. It will be a one day seminar and you can find more information and registration requirements posted on their website at http://www.therio.org in the near future.)
Mastitis and Common Mammary Disorders of the Bitch
Anne M. Traas, DVM, Diplomate ACT
Mastitis is inflammation of the mammary gland associated with infection. Mastitis
can occur anytime during lactation including lactation at the end of false
pregnancy. The most common bacteria isolated are coliforms, staphylococcus
sp. and streptococcus sp. These bacteria are normal inhabitants of the intestines
and skin of dogs.
Bitches housed in dirty environments or unhygienic conditions, bitches in
poor body condition, and bitches that are heavily parasitized or systemically ill
are all predisposed. Puppies with long nails can predispose the bitch to infection
due to trauma from the nails. In addition, galactostasis (see below) can
predispose a bitch to mastitis.
Typically, affected glands are reddened, firm and painful. Mastitis may
involve only a portion of a gland, one whole gland or several glands. Milk from
the affected glands can be normal in color (yellowish white if colostrum or white
in normal lactation), greenish-yellow, brown or red and can have flakes or clots
Abscessation and/or gangrene of the glands can be present in severe
cases and can occur rapidly (this is an emergency). In these cases the glands
may also appear dark or black in color. This type of disease can rapidly lead to a
systemic infection, also known as sepsis.
If the bacterial infection in the glands is severe enough the bitch may have
systemic signs of illness. The signs can include depression, neglect of pups,
anorexia, lethargy, fever and/or shock.
Chronic or sub-clinical disease:
Failure of puppies to thrive can be a sign of sub-clinical disease. It is not
known how common this condition is in dogs. It is important to note that mastitis
does not appear to be the cause of “toxic milk syndrome” (see below) in puppies
Microscopic examination of milk confirms the presence of pus instead of
milk (milk may have a few white blood cells naturally but should not be made up
of entirely them) and bacteria can be seen. Culture and sensitivity should be
performed. CBC (complete blood count) may show signs of response to infection.
Ultrasound may be helpful in diagnosis and in locating areas of abscessation .
Treatment is focused on management of the infection of the gland. The
patient is started on broad spectrum antibiotics until culture and sensitivity results
are available. The choice of antibiotic is important, as a drug that will enter and
hopefully concentrate in the milk is needed. Many factors influence the choice of
antibiotic including, lipid solubility, drug pH, integrity of the blood-milk barrier, and
a drug’s safety for puppies if they are nursing.
The gland should be hot packed or soaked in warm water, and milked out
twice a day if the puppies are avoiding the mastitic glands. Puppies do not need
to be weaned unless the bitch is septic, the gland is abscessed, the antibiotic
needed is unsafe in neonates or the bitch is neglecting them. Continued nursing,
will in fact, prevent engorgement.
The risk of septicemia to the puppies from the mother has not been well
studied. One study found the same bacteria in both septicemic puppies and
mastitis in the mother, though it is possible that the puppy introduced the bacteria
into the teat causing disease in the mother and not the other way around . In
addition some antibiotics, although safe for the puppies, may inhibit the normal
bacteria in the intestinal tract, causing diarrhea. The weights of puppies should
be monitored daily to be certain they are gaining appropriately.
Systemically ill patients should be stabilized first, and then if abscessation
or gangrene is present the infected and dead tissue should be surgically
removed and drains placed. The entire gland may need to be removed in rapidly
progressing cases, especially in the case of gangrenous mastitis.
Cooked white cabbage leaves applied to the glands then wrapped with vet
wrap for two hours is anecdotally reported to help draw out fluids and infection.
The author has not used this therapy and no studies have been done in dogs and
cats however a few promising studies have been done in women .
Unpublished anecdotal reports suggest it may help.
Keep whelping areas very clean. The bedding in the box should be
replaced 1-2 times a day and the box scrubbed and disinfected once a day.
Toenails of puppies should be kept trimmed to avoid trauma to the gland. Glands
should be checked by the owner daily as part of the routine post-partum care of
the bitch and her puppies.
Also called pseudocyesis or false lactation, false pregnancy is a normal
occurrence in the bitch due to the natural fall in progesterone at the end of
diestrus. It can also be observed if a bitch is spayed in diestrus or if progesterone
drugs are withdrawn. It perhaps should have been called “false lactation” as this
is why owners often present the dog.
If clinical signs are noted they typically occur 2 months after the end of
estrus. Some bitches will have no clinical signs whereas others will gather stuffed
animals, “nest”, and begin to lactate.
The diagnosis is based on clinical signs and a history of the bitch being in
heat 2 months ago. A thyroid profile can be helpful as elevated TSH levels may
increase prolactin secretion in a bitch with hypothyroidism.
Most bitches will resolve spontaneously in about 2 weeks. Bitches should
be prevented from self stimulating the glands through licking, which will prolong
the lactation. A child size T-shirt or ace wraps can be applied to keep her from
licking. The glands should not be manipulated, hot or cold packed as this often
In bitches that do not resolve within 2-3 weeks medical therapy may be
necessary. Withholding food and rationing water to ½ of normal intake for 24
hours can help her “dry up”. Cabergoline (dopamine agonist) is an expensive but
effective treatment with few side effects. Bromocriptine is a similar drug that is
less expensive than cabergoline but can have the unwanted side effects of
vomiting and/or diarrhea. These side effects are minimized by starting at a low
dose and increasing slowly over a few days and by administering with food.
Mibolerone can be used but is an anabolic steroid hormone and also can have
side effects, however they are less common and different than with
bromocriptine. Progestogens (i.e. progesterone) should not be used as the signs
will recur when the drug is withdrawn.
Pain medication can be given to very uncomfortable animals, but sedation
with phenothiazine tranquilizers should be avoided as they can increase prolactin
secretion leading to increased milk production. Recurrence is common as this is
a normal process, but can be prevented with a spay once signs have resolved.
AGALACTIA / HYPOGALACTIA
Agalactia is the inability to produce milk and is rare in the bitch. It is
sometimes seen in bitches on progesterone supplementation for suspected
A more common scenario is inadequate milk production, hypogalactia.
This may be seen in maiden or nervous bitches, bitches that whelp prematurely,
bitches with small litters that are not being stimulated adequately, bitches with
inadequate water or food intake, bitches in poor body condition or bitches that
are heavily parasitized.
Oxytocin is unlikely to be effective in true agalactia as it only helps with
milk letdown and not with milk production or gland development. It may help in
cases of nervous or new mothers who are reluctant to nurse a litter especially
when used as in combination with phenothiazine tranquilizers (these can
stimulate prolactin secretion). Although injectable oxytocin has a very short half
like, the combination allows the puppies to nurse and then stimulate normal
oxytocin production by nursing. Domperidone (a dopamine antagonist) can be
used to promote mammary development with few, if any, side effects (soft stool
may develop). Metoclopramide, a drug normally used to enhance gastrointestinal
motility and reduce vomiting, also indirectly increases prolactin levels. It may be
used if domperidone is unavailable, but has the potential to cause some
neurologic side effects (excitation, anxiety) especially when administered at
higher dosages because it does cross the blood-brain barrier. If metaclopromide
is used, the bitch’s behavior should be carefully monitored. These medications
may also be used in combination with oxytocin to stimulate milk letdown,
especially in nervous bitches.
This is the build up of milk in the mammary glands due to delayed
passage of milk out of the teat ducts. It can be due to the normal weaning
process, when there are no puppies to nurse or if puppies are removed abruptly.
Anti-inflamatory pain medications can be used to increase comfort and
reduce inflammation. Engorged glands should not be milked out as this will only
continue or increase milk production. Therapies that decrease milk production
can be used as described above in the treatment for false pregnancy. Wrapping
the glands may help to decrease milk production due to hormonal feedback to
the brain and also keeps the bitch from self stimulating .
If decreased milk production is not desired because the puppies would be
put back on the bitch in a short period of time, the glands should be regularly
milked out by hand and medications should not be used unless mastitis
TOXIC MILK SYNDROME
This diagnosis is often used when the cause of death of pups can not or is
not determined. It is easy to “blame” the milk when puppies die unexpectedly,
however, there are many causes of neonatal death and disease. It is important to
perform diagnostic tests (necropsy, blood tests, cultures etc.) to determine the
actual cause of death. Some of these puppies may in fact be dying of diseases
that can be transmitted via the milk however, they may also be suffering from
treatable or preventable diseases, such as herpes virus or hypothermia for
example. This term is not discussed in modern human medicine and it is the
author’s opinion that this diagnosis should no longer be used in veterinary
Mammary cancer is the most common cancer in female dogs. 50% of canine
mammary tumors are benign (most commonly fibroadenoma) and 50% are
malignant (most commonly adenocarcinoma). Adenocarcinoma commonly
metastasizes to the regional lymph nodes and lungs. The caudal glands are most
One or more lumps in the mammary glands of the intact or spayed bitch is
a sign of mammary cancer. Rapid growth of a mass or the presence of a large
mass more commonly indicate malignant disease than benign disease. In rare
cases a condition called inflammatory mammary adenocarcinoma may present
similarly to mastitis with red, painful glands and systemic disease .
Initial diagnosis is made by palpation of one or more masses in the
mammary glands. Multiple masses are common. Fine needle aspirate or touch
prep cytology of ulcerated masses can often give a preliminary diagnosis.
However, a negative cytology does not mean that a tumor is not malignant since
many mammary tumors do not readily shed cells making an accurate diagnosis
difficult with cytology alone. Tissue should always be sent for histopathology
(microscopic analysis) to confirm the diagnosis. Radiographs of the chest and an
abdominal ultrasound to check for metastasis should be performed when
malignancy is diagnosed.
Surgical removal of the masses along with spay is highly recommended
but spaying may not be an option in valuable breeding animals. Even benign
tumors can become quite large and uncomfortable, making them difficult to
remove. Several surgical procedures have been recommended but there is no
evidence that any individual procedure correlates with increased survival time. A
more radical surgery, such as an unilateral mastectomy may be associated with
decreased recurrence at the site. Unfortunately, studies have demonstrated that
the type of surgery has no effect on the cancer free interval [7-8]. Total
mastectomy (removal of all glands with or without the lymph nodes is rarely
performed as there is not usually enough skin left to close the incision and only
one paper has shown improved survival . If a spay is performed at the same
time as surgery to remove a tumor, the spay should be done first to prevent
seeding the abdomen with neoplastic (cancer) cells. Chemotherapy and radiation
therapy are not well characterized in the dog although protocols do exist.
Surgical procedures used are as follows:
- Lumpectomy – removal of mass only, with or without wide margins
- Simple mastectomy – removal of the entire gland containing the
- En bloc dissection – removal of the entire gland containing the
mass and the regional LN and lymphatics
- Unilateral mastectomy – removal of the entire chain of glands with
or without the regional lymph nodes
The prognosis is very good for benign masses. Malignant masses <2cm
have a fair to good prognosis after surgical removal. After surgical removal, dogs
whose tumors were less than 3 cm in diameter had a significantly increased
duration of survival, with a median of 22 months versus 14 months for dogs with
tumors greater than 3 cm in diameter .
Dogs spayed before the first estrous cycle have 0.5% the risk of
developing cancer when compared to intact dogs, dogs spayed between estrus 1
and 2 have 8% the risk, those spayed after 2 cycles have 26% risk. After the
second cycle it is unclear what the exact benefit of spaying is on risk of
mammary cancer, but it is believed that there is some reduction in incidence
even with aged bitches. Pregnancy has no effect on the risk of developing
mammary cancer. . Exogenous progesterone administration (typically used
for keeping a dog out of heat) can increase the risk. [11-12]
Mammary cysts, also called fibrocystic disease of the mammary gland or
blue dome cysts, may have a hormonal basis. Is occasionally possible to aspirate
clear to brown fluid from the mass. The major concern with this condition is
making sure that the masses felt are cysts and not lumps. The best way to do
this is by removing them or taking a tissue sample from them. Fine needle
aspirate may also help but is not as good as biopsy. The ability of these cysts to
develop into cancer is not known 
 Ververidis HN, Mavrogianni VS, Fragkou IA, et al. Experimental
staphylococcal mastitis in bitches: clinical, bacteriological, cytological,
haematological and pathological features. Vet Microbiol. 2007;124(1-2):95-106.
 Johnston, SD, Root Kustritz MV, Olson PN. Pariparturient disorders in the
bitch. In Canine and Feline Theriogenology. W.B. Saunders 2001. p. 129-143
 Trasch K, Wehrend A, Bostedt H. Ultrasonographic description of canine
mastitis. Vet Radiol Ultrasound 2007;48(6):580-4.
 Schäfer-Somi S, Spergser J, Breitenfellner J, Aurich JE. Bacteriological status
of canine milk and septicaemia in neonatal puppies--a retrospective study. J Vet
Med B Infect Dis Vet Public Health. 2003;50(7):343-6.
 Ayres JF. The Use of Alternative Therapies in the Support of Breastfeeding. J
Hum Lact 2000;16(1):52-56.
 Momont H, Barber JA. Mammary disorders. In: Root-Kustritz MV, editor.
Small Animal Theriogenology. Butterworth/Heinemann; 2003. p. 421–446.
 Misdorp W, Hart AAM: Prognostic factors in canine mammary cancer. J Natl
Cancer Inst 1976;56:779–783.
 Allen SW, Mahaffey EA. Canine mammary neoplasia: Prognostic indicators
and response to surgical therapy. J Am Anim Hosp Assoc 1989;25:540-546.
 Wey N, Kohn B, Gutberlet K: Mammary tumours in the bitch: clinical follow-up
study (1995–1997). Kleintierpraxis 1999;44:565–578.
 Philibert JC, Snyder PW, Glickman N, Glickman LT, Knapp DW, Waters DJ.
Influence of host factors on survival in dogs with malignant mammary gland
tumors. J Vet Intern Med. 2003 Jan-Feb;17(1):102-6.
 Sorenmo KU, Shofer FS, Goldschmidt MH. Effect of spaying and timing of
spaying on survival of dogs with mammary carcinoma. J Vet Intern Med. 2000
 Misdorp W. Progestagens and mammary tumours in dogs and cats. Acta
Endocrinol (Copenh). 1991;125 Suppl 1:27-31.
 Johnston, SD, Root Kustritz MV, Olson PN. Disorders of the mammary
glands of the bitch. In Canine and Feline Theriogenology. W.B. Saunders 2001.
Last Updated: 02/16/2009, 10:27 am