or Infection of the Mammary Glands
Dogs & Cats

A Service of the FoxNest Veterinary Hospital....Seneca, South Carolina...and the

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Mastitis or infection of the mammary glands... a fairly frequent problem for the 1-2 months after delivery

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Introduction to Reproduction in Dogs & Cats

Whelping or Delivering Puppies

Alternatives to Spaying and castration for birth control

Newborn Care for Puppies and Kittens

Momma Dogs who won't nurse.  Agalactia (no milk) 

Dystocia or problems giving birth

Pyometra (infection of the uterus)

False Pregnancy

Undescended Testicles

Birth Control Alternatives to Spaying
and Castration

Brucellosis This disease causes abortions.  This serious disease is also contagious to humans and other mammals.

Reproductive Surgery:

Spays (Ovariohysterectomies) in Dogs, Cats, and Other Pets

C Sections
Includes an interesting short history about a women doctor pretending to be a man performing the first modern C Section

Castration in Dogs, Cats, and Other Pets.  Includes recipes for Rocky Mountain Oysters, Montana Tendergroins, and Swinging Beef.  What Viagra is made from.

On Other Pages about other topics:

Declawing Cats

Ear Cropping


Cancer and Mass Removal

Fracture Repair

Abdominal Surgery

Using the Omentum

Soft Tissue Surgery

Referral Veterinarians, Specialists, and Veterinary Colleges at your service

Hernia Surgery

About the Treatment of Injuries, Abscess', ETC

Tuberculosis, Plague, and Brucellosis. Pasteurella, Encephalitis, Samonella, e-coli, and Cryptosporidium: a brief review of these zoonotic diseases that you can get from pets

Diseases people get from pets from mosquitos, fleas, ticks, and lice
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Denistry: why oral hygiene and health is so important and what you can do about it

Dermatology: How I treat skin diseases in pets

Orthopedics: How I treat arthritis, pannus, hip dysplasia, and other problems of the bones and joints

Ear problems and the miracle treatment Zymox

Ophthalmology: Eye Problems discussed

Diseases of the blood

Metabolic Diseases like Diabetes, Cushings Disease, Addison's Disease, and Thyroid Disease

Cardiology: Heart problems in cats and dogs

History of Veterinary Medicine in the United States

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Diseases People get from Pets

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Mastitis in Dogs and Cats: What to expect when you take your pet to the vet
(Of course, your veterinarian may treat this problem a little differently)
by Roger Ross, DVM

Mastitis refers to swelling, inflammation, and infection of the of the many things that can go wrong during the pregnancy, birth, and nursing process.  Having babies is a fairly high risk venture in all species, and of all the potential problems that can occur, mastitis is usually fairly easy to treat ...but not always: this disease can be deadly. 

Yet another reason to recommend spaying  female pets unless you really want a litter and are willing to take on the responsibility and expenses of when things go wrong.

Some Basics:

Mastitis refers to the swelling, inflammation, and infection of one or more mammary glands (breast tissue)...a problem that sometimes occurs while nursing puppies or kittens. 

Think about it; the spongy glands of the breasts have been recently stimulated by hormone changes to swell and produce milk and colostrum...full of nourishing fats and sugars...A NEAR PERFECT situation for bacterial growth.  All a bacteria has to do to gain entrance into the milk enriched gland is find a way up the teat canal...which very likely might be swollen and raw from being suckled and gnawed on by greedy little infants.

If the bacteria can't make it up the nipple, it can possibly gain entrance from the blood ; after all, it's common to have an extra high bacteria count in the uterus, the vagina, and the near-by urinary tract for a few weeks after delivery...AND NOT ONLY THAT, but the mom's immune system is often out of whack during the massive hormone changes of pregnancy and nursing.  So, bacteria might gain entrance into the blood stream, evade the immune system's defenses...and settle happily into the milky goo of the mammary glands.

To top it off, the intestinal system...the number one source of bacterial invasion into the blood more likely to be raw and inflamed during nursing.  Why?  Because the hormones of pregnancy stimulate intestinal worms to come out of dormancy and feast on the intestinal tract...AND...GI upset (inflammation) is very common post delivery due to the mom eating all those nasty placentas,  cleaning up all that vaginal discharge, and licking all those puppy or kitten butts.

After reading the above, you might not be surprised to know that ALL (100%)  nursing dogs and cats get bacteria in their breast tissue.  Luckily, most of the time, the immune system is successful at keeping the bacteria numbers low enough so as not to cause obvious disease needing medical treatment. 

But sometimes the immune system is not up to par...often due to poor nutrition, poor parasite control, or poor vaccination protection...and sometimes due to poor dental care. (Inflamed gums are a major source of bacterial entry into the blood stream)  Sometimes the immune system is simply overwhelmed:

This article is about what to expect if your pet happens to get an infection of the breast tissue during nursing...a disease known as MASTITIS


The most obvious symptom is a swollen mammary gland (breast, tit, teat, boob etc) that is either more red, discolored, painful, firm, or lumpy than the other breasts on the pet.
The breast may discharge pus...or milk that looks different from the other breasts.

Other symptoms might include:

    Fever (rectal temperatures greater than 103 F in both dogs and cats)
    No or poor appetite
    Dying pups or kittens
    Poor energy level

Note: the above symptoms are not exclusive to mastitis; they could be caused by other or additional problems.

What to Expect When you go to the Vet:

A good exam.  It's tempting to simply look at an obviously infected breast and make
the diagnosis of mastitis...and start treatment.  But it's not that simple.  There are usually multiple problems and a good vet will go over the entire pet checking out all the major body systems to see what we're up against.  Here are some examples of problems that are often associated with gross infections of the mammary glands:

High fever and all the secondary vascular changes that can occur with high fevers to include blood clots and an often deadly conditon called DIC
Toxic Shock and Sepsis
Stress, bacterial invasion, and resulting dysfunction of the liver, kidney, and lymphatic systems.
Toxic Milk
Gangrene (from gas producing organisms)
Moderate to severe Intestinal upset and inflammation resulting from the fever and infection...or as mentioned in the introduction the cause of the problem.

And remember...nursing is a time when multiple problems can happen together: Milk Fever (Calcium-phosphorus imbalances), protein deficiencies, post delivery diabetes and other blood sugar irregularities, as well as immune system suppression, greatly increased parasitism, and to some extent hormone induced depression.

The take home message: a good professional exam by a veterinarian is important even though it's usually not difficult to determine that your pet has mastitis.

Lab work your vet might recommend:

As you might gather from reading the above...lab work isn't usually needed to make a diagnosis of mastitis.  But lab work might very well be needed to determine how badly the rest of the body is faring.  Also:  Many mastitis cases require anesthesia and surgical draining and debridement (cutting away of dead, putrid, and damaged tissue).  Therefore, to minimize the risk of anesthesia and surgery, your vet may recommend:

Blood Work:  (usually a CBC and Blood Chemistry).  These common tests flag sepsis, diabetes, anemia, kidney, liver, and pancreatic diseases, dehydration, and electrolyte problems.

Fluid analysis with microscopic evaluation of the milk or any discharge.  What the vet will be looking for is a high white blood cell count of the milk, free or encapsulated bacteria, and a type of white blood cell called degenerate neutrophils. Milk pH might also be considered as different antibiotics work better at differ pH levels.

Aspirate (inserting a needle and syringe to remove a sample of material) and cytology of solitary masses

Bacterial culture and sensitivity of the fluid to allow better choice of antibiotic

Bacterial culture of the blood if sepsis is suspected

Urinalysis: useful anytime a patient acts weak and sick as a screening test for dehydration, diabetes, debilitation, and kidney function.


Treatment options will depend on how sick the patient is in general and how extensive the local damage to the breast tissue.  Mastitis can be a minor, inexpensive nuisance or a major, life threatening disease requiring a big commitment.

Probable treatments will include:

    Antibiotic injections followed by oral antibiotics

    Some type of anti-inflammatory medication to reduce swelling.  This usually means
    some sort of short acting steroid...our most effective treatment...but also one with
    potential problems that needs to be monitored.

    Lancing and draining of the infected breast...either without anesthesia for minor
    cases or as part of a major surgical procedure involving debridement and surgical
    drains.  Sometimes complete surgical removal of the breast is needed.

    Topical wound cleaners, compresses, ointments, wound healing enhancers, and
    various soothing remedies  (each vet seems to have their favorites)

    Supportive care of the whole patient if needed:  IV Fluids, antioxidants, electrolytes,
    pain meds, etc.
   Knowing when and how aggressive to get with supportive care for each different case
   is where experience and the practice art become so important.  Too little and the
   patient suffers or dies.  Too aggressive and we waste your money and lose your
   respect for making a mountain out of a mole hill.

   Time to heal and good home treatment by the pet owner.  Once bacteria gets
   established in such a perfect growth media as a milky breast it won't be easy to kill it
   off...It's critical that you administer the pet's antibiotics faithfully for at least 10 days.
   Even if your vet does everything right, mastitis is a potentially fatal disease and
   there's a fair chance that the initial medical treatment won't be entirely successful
   and more aggressive treatment and/or surgery will be needed.  You can greatly
   increase your chance of initial success by making sure you give the prescribed meds
   even if difficult or inconvenient to do so.

   Clean bedding.  A pet with a draining breast shouldn't be lying on wet, urine soaked,
   filthy bedding.  Nor should the bedding be irritating.

   Recheck/follow up exam if it's not obvious that all better.  Some people seem to think that
   the vet somehow failed if a treatment plan doesn't go perfectly.  Hey...this is a
   serious disease with lots of complicating factors.  A certain percentage of cases will
   need additional work.

Some Other Treatments or Things that your vet may consider:

Early weaning of the pups or kittens to allow the mammary glands to dry up or to prevent death of the babies.  Sometimes we recommend total separation (different buildings) so that the momma pet can't smell or hear their babies which stimulates lactation.  Another reason for early weaning is if the momma pet is simply too weak to both fight off her mastitis and nurse.  There are negatives to early weaning the decision will be based on each case like so many other situations in medicine.

Supplemental feeding of the puppies or kittens.  A sort of compromise of early weaning.

Shaving the hair from around the teats and clipping the toe nails of the puppies or kittens.

Manual milking of the infected breast to keep it draining.

Herbal and other "Alternative" treatments.

Caution: Disorders that might be confused with mastitis include:

Insect or snake bite wounds to the breasts.  This is, technically, still mastitis, but
treatment would also include antihistamines etc.

Mammary gland enlargement caused by advanced pregnancy, lactation or pseudo-pregnancy. Sometimes there is an excessive accumulation (galactostasis) of milk in the glands, and they may become warm and somewhat painful. In other words...just because the breasts are firm and tender doesn't necessarily mean they're infected.

Mammary hypertrophy is a benign growth of the mammary tissue causing a firm swelling.

Mammary gland tumors are fairly common in older animals and could be confused with mastitis especially if they are draining.