Preventing E. Coli Infections in Dogs

E. coli infections can cause serious illness in both humans and dogs. Here’s what you need to know.

By: tys720
E. coli is already in the gut. By: tys720

With E. coli’s reputation for causing serious illness, you may be surprised to learn that you are already intimately acquainted with this bacterium.

This is because E. coli (Escherichia coli) is a normal inhabitant of the lower bowel in many mammals — including humans.

Why it makes some animals ill, but not others, is poorly understood. The most likely explanation is the strength of the host’s immune system in fighting off infection. This would also explain why very young, very old or already-sick animals are most likely to become seriously ill from colibacillosis (infection from E. coli).


Newborn puppies and kittens are especially vulnerable to E. coli, which can cause blood poisoning that can in turn lead to organ failure. These very young animals are cold, weak and frequently have diarrhea.

If a puppy or kitten is a little older, then sickness and diarrhea are the most likely signs — but be aware, these can also be symptoms of many other conditions. Having diarrhea is not a diagnosis in itself.

Elderly animals will show different signs depending on what bodily organ is infected. Diarrhea is a common sign, but animals can potentially have cystitis, mastitis, endometritis or pyelonephritis (respectively, infection of the bladder, mammary gland, womb or kidney).


This bacterium normally lives in the gut where it doesn’t cause problems because the host’s immune system keeps it in check. But if the animal eats contaminated meat or drinks from a puddle containing E. coli, this massive extra dose can overwhelm the immune system and make the pet ill.

If a nursing female dog has E. coli in her bloodstream, the bacteria could circulate and settle in her mammary glands, causing mastitis. The milk can then infect the puppies with E. coli when they suckle.

Because puppies’ immune systems are not yet fully formed, E. coli makes them vulnerable to serious, sudden onset illness and death from colibacillosis.


Making a definitive diagnosis can be tricky. There is little point in screening feces for E. coli because it is a normal gut inhabitant. And routine blood tests give a general picture of dehydration rather than a specific diagnosis.

The most conclusive test is to culture E. coli from blood or tissue — this can be difficult in very small puppies and kittens, and it may mean taking tissue samples at post-mortem to give an answer posthumously.


Key to successful treatment is replacing fluids lost through diarrhea, giving antibiotics to kill the E. coli and first-class nursing care.

Young animals in particular are prone to low blood sugar levels and losing heat; thus, giving regular oral glucose supplements and keeping youngsters warm can make the difference between a successful outcome or not.


There are a number of things that help decrease the chances of young puppies and kittens acquiring a serious E. coli infection.

It is vital that they suckle colostrum within a few hours of birth. This highly nutritious milk is antibody-rich and primes their immature immune systems. Likewise, it helps if the dam is in good health and is not harboring a low-grade infection before she whelps which she could then pass onto her pups.


Factors such as a dirty environment or overcrowded kennels add to the background level of contamination and should be avoided.

Regular disinfection of whelping facilities and keeping the number of animals down in any particular kennel is a basic requirement. And don’t forget, humans can become infected, so regularly washing our hands after any contact with animals, especially before eating, is key.


  • Small Animal Internal Medicine. Nelson & Couto. Publisher: Mosby. 3rd edition.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 17, 2018.