E. Coli Infection in Cats

Healthy adult cats rarely experience issues related to E. coli, but kittens, older cats or those with compromised immune systems can become sick when exposed to the bacteria. The presence of pathogenic E. coli can make cats critically ill in several different ways. For example, the majority of feline urinary tract infections (UTIs) are caused by E. coli. Certain strains of E. coli generate gastrointestinal problems. Intact female cats can develop the uterine infection pyometra, and newborn kittens can suffer from an extremely serious form of E. coli infection called colibacillosis.

Escherichia coli, abbreviated to  E. coli, is a bacterium that is commonly found in the lower gastrointestinal tract of most mammals, including humans and cats. There are hundreds of different strains of E. coli, and the majority of them are not dangerous. E. coli is known to cause problems, however, when it enters parts of the body where it does not belong, or when a harmful strain of the bacterium is introduced to the system. Cats with E. coli infection can exhibit a variety of symptoms including lack of appetite, vomiting, urinary distress, excessive thirst, and fever. Because E. coli is a bacterial infection, and also because symptoms of illness caused by E. coli can vary greatly, laboratory tests are required in order to obtain a definitive diagnosis.

E. coli causes different types of infections, and symptoms will vary based on the strain and location of bacteria involved. 

Urinary tract infection

E. coli is one of the most commonly diagnosed causes of UTIs in cats. Typical symptoms include:

• Frequent urination
• Urinating outside the litter box
• Pain while urinating (sometimes indicated by vocalization)
• Blood in the urine
• Foul-smelling urine
• Straining to urinate
• Tenderness in the abdomen
• Fever

Gastrointestinal

• This type of E. coli infection is often caused by ingesting contaminated food, causing symptoms such as:
• Lack of appetite
• Vomiting
• Diarrhea, sometimes with blood

Pyometra

A disorder of intact females, pyometra is a uterine infection that usually occurs after a heat cycle that did not result in pregnancy. Symptoms can be difficult to spot, but may include:

• Lethargy
• Poor appetite
• Distended abdomen
• Vaginal discharge
• Increased thirst
• Excessive panting

Colibacillosis

A condition seen in newborn kittens, colibacillosis is characterized by the sudden onset of symptoms including:

• Lack of appetite
• Vomiting
• Lethargy
• Severe diarrhea
• Low body temperature
• Dehydration

While all E. coli infections are caused by an overgrowth of pathogenic strains of the bacteria, each manifestation of the disease has its own method of transmission. 

With UTIs, introduction of bacteria from the anus to the urinary tract is often thought to be caused by the routine act of a cat performing normal grooming, such as licking one spot and then the next. While this does not generally cause a problem, the bacteria may grow beyond normal proportions in older cats with weaker immunity, or those with underlying diseases.

Gastrointestinal E. coli can usually be traced to the ingestion of undercooked or raw foods. Outdoor cats who hunt and eat prey are particularly prone, but commercial pet foods are sometimes to blame. Raw meat diets can also be problematic, and many veterinarians warn against feeding raw meat.

Pyometra occurs when there is a bacterial overgrowth in the uterus triggered by hormonal changes. Pyometra has been known to arise even when no external source of exposure can be identified.

Newborn kittens sometimes develop colibacillosis after E. coli exposure, which can occur in a number of ways:

• In utero (in the womb) via bacteria in the mother's system
• During birth from bacteria in the birth canal
• While nursing from infected mammary glands
• When housed in unsanitary conditions

If your cat is exhibiting symptoms of an E. coli infection, you should consider it a medical emergency and get your cat to your veterinarian immediately. Diagnosing E. coli infection requires laboratory tests, and time is of the essence. 

Your veterinarian will ask you to describe any symptoms that you have observed, and will need all of the history that you can provide. If your cat is female, the vet will want to know if she is spayed, pregnant, or nursing kittens. You may be asked whether your cat lives indoors or outdoors, what it eats, whether it is on any type of medication and for what condition. Your vet will perform a physical examination, including palpating your cat's abdomen to check for distended or thickened membranes of the intestines, uterus or bladder. Laboratory tests will be conducted to check for the presence of bacteria and to screen for potential underlying diseases. These tests may include:

• Blood tests
• Urinalysis
• Fecal exam
• Vaginal swab
• X-rays
• Ultrasound

Two additional steps that your veterinarian is likely to take to ensure an accurate diagnosis and eventual treatment are:

• Bacterial culture to confirm the presence and type of bacteria
• Antibiotic sensitivity test to find which antibiotic is most effective against the isolated bacteria

The last two steps are key, both because different types of bacteria besides E. coli can cause infection, and because some bacteria, including E. coli, are becoming resistant to certain strains of antibiotics. 

Many cases of E. coli infection can be treated on an outpatient basis, with follow-up visits to check progress.

Antibiotics

Regardless of the location of the infection and the type of illness involved, antibiotics are the universal treatment choice. Simple infections require a normal course of antibiotics lasting 10 to 14 days. Complicated infections may need antibiotic treatment for up to six weeks.

Additional Treatments

More serious cases may require hospitalization, especially with very young kittens. Supportive therapies and additional procedures may be necessary, such as:

• IV fluids for dehydration and hypoglycemia
• Monitoring of body temperature to avoid hypothermia
• Hand feeding or bottle feeding in place of nursing

Ensuring your cat receives the full schedule of antibiotic treatment is critical. Stopping the medication too soon could result in a recurrence of the illness, or worse, contribute to antibiotic resistance. If the infection is a case of pyometra, spaying the intact female is urged. Cats with UTIs may need a prescription diet, and they should be encouraged to drink as much as possible, since more frequent urination will help keep bacteria flushed from the bladder and urinary tract. Outdoor cats with gastrointestinal E. coli should be brought indoors to eliminate the killing and eating prey, and raw meat should be avoided as a food source.

Your veterinarian will schedule follow-up visits to repeat some of the lab tests after the antibiotics have been administered to ensure that the bacteria is out of your cat's system.