Bacterial Infection (Streptococcus) in Dogs

Published Dec. 13, 2023
A dog is examined by their vet.

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What Is Streptococcus Bacterial Infection in Dogs?

Streptococci are bacteria that can cause infections in both humans and animals. Streptococcus canis is the streptococcal species most commonly found in dogs. The bacterium is normally present in a healthy dog’s throat, gastrointestinal (GI) tract, reproductive tract, and skin.

In some cases, streptococci can breach a dog’s normal defenses, invading tissues and leading to various disease manifestations. This can result in skin and ear infections, pharyngitis, pneumonia, urinary tract infections (UTIs), and arthritis.

In severe cases, the infection can progress to potentially life-threatening conditions, including necrotizing fasciitis (NF) and streptococcal toxic shock syndrome (STSS).

Since S. canis normally colonizes in a dog’s body, infection is common, but it usually only occurs when the dog has a wound or suppressed immune system. Most affected pups experience only mild to moderate symptoms associated with the infection.

Symptoms of Streptococcus Bacterial Infection in Dogs

Streptococcus can affect many areas of a dog’s body. Depending on the body area the pathogen infects, symptoms of S. canis can include:

Causes of Streptococcus Bacterial Infection in Dogs

Some pet parents worry about passing their strep throat infection to their canine companion, but the Infectious Disease Society of America explains that the streptococcus bacterium causing strep throat in humans is different from the one that affects dogs.

Currently, there’s no scientific evidence that suggests the organism that causes strep throat in humans can infect dogs. A dog’s predisposition to developing a streptococcus infection depends on the following:

  • Age—Puppies’ immune systems are not fully developed, and senior dogs commonly experience a weakening of their immune systems. This decreases a dog’s ability to fight infection, making them more at risk of streptococcus infection.

  • WoundsS. canis is typically present on the skin and can infect open wounds. If your dog chews or licks a wound, they won’t usually develop an S. canis infection. However, you shouldn’t allow your dog to chew or lick a wound. This can lead to other types of infection.

  • Immunosuppression—Dogs with a weakened immune system, such as those undergoing chemotherapy or experiencing underlying health conditions, have a higher risk of infection than healthy dogs.

  • Allergies—Dogs with atopy (a chronic allergic skin reaction) or other allergic skin conditions face an increased risk of infection because their skin barrier is compromised.

Complications of Streptococcus Bacterial Infection in Dogs

Severe S. canis–related disease can occur, although these cases are rare. Potential S. canis complications include:

  • Streptococcal toxic shock syndrome (STSS)—STSS is a streptococcal infection that triggers sudden shock, organ failure, and bleeding abnormalities throughout a dog’s body.

  • Necrotizing fasciitis (NF)—NF is a streptococcal infection that invades the deep skin layers, causing tissue death.

    • NF often starts as a minor wound and can progress to tissue death in 24 to 72 hours. Lesions usually involve the limbs, and symptoms include localized heat, swelling, and wound discharge.

How Veterinarians Diagnose Streptococcus Bacterial Infection in Dogs

Most S. canis cases are not considered an emergency, but you should schedule an appointment with your vet or an urgent care facility as soon as you notice symptoms in your pup.

Some symptoms of streptococcus can be the cause of an emergency. Take your pup to the vet immediately if they experience any of the following:

  • Difficulty breathing

  • Significant heat, swelling, or pain associated with a wound

  • Unexplained bruising or bleeding

  • A fever higher than 105 degrees Fahrenheit

If your dog shows signs of bacterial infection, your veterinarian may perform one or more of these diagnostic tests:

  • History—Your vet will ask you to describe your dog’s symptoms, as well as when you first noticed them. Tell your vet about any underlying health conditions your dog may have.

  • Physical exam—Your veterinarian will perform a thorough physical exam.

  • Bloodwork—By performing blood tests, such as a complete blood count (CBC) and a biochemistry profile, your vet can assess your dog’s overall health, helping them determine whether your pup has an infection.

  • Urinalysis—Your vet may recommend a urinalysis, especially if they suspect your dog has a UTI.

  • Swab—If your dog has a skin or ear infection, your vet will likely take a sample from the problematic area to perform a culture and cytology. This test helps your veterinarian identify the cause of a skin or ear infection, so they can prescribe an appropriate antibiotic for your dog.

  • Skin scrape—In some cases, your veterinarian may perform a skin scrape or biopsy to help identify the infectious organism or to rule out other skin conditions.

Treatment of Streptococcus Bacterial Infection in Dogs

Treatment for streptococcus in dogs depends upon where the infection is located on the body, and how severe it is.

Potential treatments include:

  • Fluid therapy—If your dog is dehydrated, your vet may hospitalize them to administer intravenous (IV) fluids.

  • AntibioticsS. canis is usually vulnerable to antibiotics, and your vet will choose an appropriate medication.

  • Tissue removal—If your dog has an infected wound, your vet may need to remove dead tissue to help the area heal.

  • Bandaging—To protect the infected area and prevent your dog from licking it, your veterinarian may bandage the wound.

  • Ear wash—If your dog has a streptococcal ear infection, your veterinarian will likely recommend ear cleaning in addition to ear medications.

Recovery and Management of Streptococcus Bacterial Infection in Dogs

Most uncomplicated streptococcal ear, respiratory, and urinary tract infections resolve in five to seven days after your dog receives the appropriate antibiotics.

While your dog recovers, ensure they stay hydrated and get as much rest as possible. For a dog whose wound has developed a streptococcal infection, recovery depends on the infection severity and may take several weeks or months.

Prevention of Streptococcus Bacterial Infection in Dogs

Most streptococcus infections in dogs are unpreventable.

However, you can lower your dog’s risk of infection by scheduling your pup’s regular wellness visits, so your vet can detect underlying health issues in their early stages.

If your dog has wounds or even minor injuries, be sure to monitor them for signs such as heat, swelling, excessive pain, and discharge.

Seek veterinary care immediately if these signs occur.

Bacterial Infection (Streptococcus) in Dogs FAQs

Is a streptococcal infection in dogs contagious?

S. canis is contagious and can pass from one dog to another.

However, a dog typically doesn’t develop an infection unless their immune system has been compromised. Dogs rarely pass this infection to humans, but you should still practice good hygiene—especially frequent hand washing—when your dog is sick.

Featured Image: Dejan_Dundjerski/iStock / Getty Images Plus via Getty Images


Streptococcus Canis - an Overview | ScienceDirect Topics.”

Strep Throat?—Probably Not Correct to Blame the Dog.” Cornell University College of Veterinary Medicine, 5 Nov. 2019.

Themes, U. F. O. “Streptococcal and Enterococcal Infections.” Veterian Key, 10 July 2016.

Pagnossin, Davide, et al. “Streptococcus Canis, the Underdog of the Genus.” Veterinary Microbiology, vol. 273, Oct. 2022, p. 109524.


Jenny Alonge, DVM


Jenny Alonge, DVM


Dr. Jenny Alonge graduated from Mississippi State University College of Veterinary Medicine in 2002. She completed an equine medicine and...

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