Bacterial Infections in Dogs and Cats

Information for cats and dogs to help with symptoms of canine and feline bacterial infections.

Select a Topic

  1. What are Bacterial Infections?
  2. What Causes Bacterial Infections in Dogs and Cats?
  3. Diagnosing Bacterial Infections in Pets
  4. Help for Pet Bacterial Infections
  5. More Information on Bacterial Infections

What are Bacterial Infections?

Bacteria are single cell organisms that reproduce by dividing. There are good and harmful bacteria. Good bacteria can benefit your health and the environment, while harmful bacteria can cause illness and infection. Pets, like humans, can develop bacterial infections.

If left untreated, these infectious diseases can lead to more severe health complications.

The symptoms and clinical signs of bacterial infections common in cats and dogs include:

  • Fever
  • Abscesses on the skin
  • Wound infections
  • Lack of appetite
  • Coughing
  • Runny nose or eyes
  • Vomiting
  • Inflammation and redness
  • Lesions
  • Pain and discomfort
  • Lethargy and weakness

What Causes Bacterial Infections?

There are various types of bacterial infections. They can affect different parts of the body, including the skin, eye, ear, urinary tract, kidneys, nervous system and respiratory system:

Bacterial skin infections also known as pyodermas are caused by staphylococci (staph bacteria) and affect both dogs and cats. The Staph bacteria usually live harmlessly on the skin, but infection occurs if a pet scratches its skin too much.

The common symptoms include yellow pustules, scabs, reddened skin and lesions. Fleas, ticks, allergies, weakened immune system, stress, poor diet and underlying illnesses may all contribute to bacterial skin infections. This type of staph infection is not contagious to humans or other animals.

Streptococcal infections are caused by streptococcus bacteria and commonly affect both cats and dogs. It is commonly affects very young and very old animals, because they have weakened immune systems. In young animals, the immune system is not fully developed and not strong enough to fight off infection. In older animals, the protective mechanisms have declined.

Staphylococcal infection is caused by staphylococcus bacteria, which can be found in the environment, in the upper respiratory system, or as a skin parasite. It affects both dogs and cats and can sometimes spread between animals and humans.

Leptospirosis infection is caused by spirochete bacteria and is highly contagious. It is spread through the contamination of water or soil and the urine of carrier animals. Symptoms include fever, vomiting, lethargy, reddening of the mucous membranes and conjunctivitis.

If not treated, it can lead to kidney inflammation. It affects dogs more than cats. Routine vaccinations are necessary to prevent the infection.

Actinomycosis infection is caused by actinomyces bacteria and is normally found in the mouth. Nocardiosis infection is caused by nocardia bacteria and is found in the soil. In both these infections, the bacteria enter through a skin wound and the lymph nodes become swollen. This infection may spread to the abdomen or chest where pus starts to build up.

Brucellosis infection is caused by brucella canis and is most common in dogs kept in kennels. This infection usually occurs during breeding season. It is spread through contaminated urine, vaginal discharge of a female or the semen of a male dog.

Infected male dogs may experience fertility problems or develop prostatitis. Infected pregnant females may abort their fetuses or the puppies may die shortly after birth.

Diagnosing Bacterial Infections

A veterinarian will diagnose bacterial disease in cats and dogs based on the symptoms, medical history and a thorough physical examination. They may run tests including blood tests, cultures, skin biopsies, sensitivity testing or allergy testing to determine the cause of bacterial infection.

In addition, they may want to perform additional tests to rule out other medical conditions.

Help for Bacterial Infections

Depending on the type of bacterial infection, your vet will recommend a course of treatment to clear the infection. Medications usually include antibiotics and anti-inflammatories in the form of drops or topical ointments.

In the case of bacterial skin infections, your vet may prescribe allergy shots and certain shampoos to relieve symptoms. Incorporating dietary changes and daily exercise can also strengthen your pet’s immune system and ward off infection.

More Information on Bacterial Infections

There are a number ways for pet owners to reduce their pets risk of infection:
  • Feed your pet a high quality, all natural diet that is free of additives, preservatives and colorants. Malnourished animals are more susceptible to infection.
  • Ensure that your pet always has fresh, clean water available.
  • Exercise your pet regularly.
  • Use stainless steel food and water bowls instead of plastic, and always wash bowls thoroughly with warm, soapy water.
  • Keep your pet’s living area clean, dry and regularly disinfected
  • Incorporate immune-building supplements into your dog or cat’s diet to boost their immune system
  • Always disinfect cuts or scrapes to avoid further infection
  • Detox your pet regularly to eliminate unwanted toxins
  • Visit your annually for a check-up
  • Avoid situations overcrowded with other animals such as boarding facilities, or pet shows as much as possible
  • If your dog or cat is showing any symptoms of a bacterial or fungal infection, contact your veterinarian.


The content provided is for informational purposes only. It is not a substitute for professional medical advice. If you have a health condition, please consult a medical professional and do not use this information to self-diagnose or self-treat.



  1. “Bacterial Infections in Cats.” National Animal Supplement Council. Accessed February 21, 2020.
  2. Ghasemzadeh, I. and Namazi, S.H. “Review of bacterial and viral zootonotic infections transmitted by dogs.” Journal of Medicine and Life. Accessed February 21, 2020.
  3. “Bacterial Infection (Leptospirosis) in Dogs.” PetMD. Accessed February 21, 2020.
  4. Gruenberg, W., Swerczek, T., Tabor, A. “Disorders Caused by Bacteria in the Digestive System of Dogs.” Merck Manual Veterinary Manual. Accessed February 21, 2020.
  5. “Anaerobic Bacterial Infections in Cats.” PetMD. Accessed February 21, 2020.
  6. “Zoonotic Disease: What Can I Catch From My Cat?” Cornell University College of Veterinary Medicine. Accessed February 21, 2020.
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