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Bacterial Infection (Streptococcus) in Dogs

What Is Streptococcus Bacterial Infection in Dogs?

Streptococcal bacterial infections can affect both humans and animals, including dogs. Among dogs, Streptococcus canis is the primary bacterial species involved. These bacteria typically inhabit various parts of a healthy dog’s body such as the throat, gastrointestinal tract, reproductive organs, and skin.

Under certain circumstances, streptococci can penetrate a dog’s natural defenses, infiltrating tissues and causing a range of health issues. These may include skin and ear infections, pharyngitis, pneumonia, urinary tract infections (UTIs), and arthritis.

In severe instances, the infection can escalate into critical conditions like necrotizing fasciitis (NF) and streptococcal toxic shock syndrome (STSS).

Given that S. canis is a usual inhabitant in a dog’s system, infections are not uncommon but typically arise when a dog experiences a wound or has a weakened immune system. Most affected dogs exhibit only mild to moderate symptoms associated with the infection.


Symptoms of a Streptococcus bacterial infection in dogs can manifest in various parts of their body. The specific area affected determines the symptoms associated with S. canis infection, including:

  • Fever
  • Lethargy
  • Decreased appetite
  • Coughing
  • Redness and pain at the site of a wound
  • Discharge and an unpleasant odor at the wound site
  • Ear pain, along with discharge and an unpleasant odor
  • Pain during urination
  • Stiffness, particularly noticeable after periods of rest


Causes of Streptococcus bacterial infections in dogs differ from those affecting humans with strep throat, as clarified by the Infectious Disease Society of America. The bacterium responsible for strep throat in humans is distinct from the one affecting dogs.

Currently, there is no scientific evidence indicating that the strep throat-causing organism in humans can infect dogs. A dog’s susceptibility to developing a streptococcus infection depends on the following factors:

  • Age: Puppies have underdeveloped immune systems, while senior dogs often experience immune system weakening. This diminishes their ability to combat infections, making them more vulnerable to streptococcus infection.
  • Wounds: S. canis typically resides on the skin and can infect open wounds. Although dogs typically don’t develop an S. canis infection from chewing or licking a wound, it’s advisable to discourage such behavior to prevent other types of infection.
  • Immunosuppression: Dogs with weakened immune systems, such as those undergoing chemotherapy or dealing with underlying health issues, face a higher infection risk compared to healthy dogs.
  • Allergies: Dogs with conditions like atopy, characterized by chronic allergic skin reactions, or other allergic skin issues, are at an elevated risk of infection due to compromised skin barriers.

Complications of Streptococcus Bacterial Infection in Dogs

Complications stemming from Streptococcus bacterial infections in dogs, particularly severe cases related to S. canis, are relatively rare occurrences. Potential complications of S. canis infections include:

  • Streptococcal toxic shock syndrome (STSS): STSS is a severe streptococcal infection that induces sudden shock, organ failure, and abnormalities in bleeding throughout the dog’s body.
    Symptoms of STSS comprise fever, vomiting, unexplained bruising, bleeding from the nose or rectum, and collapse. In extreme cases, death from STSS can transpire within as little as 48 hours.
  • Necrotizing fasciitis (NF): NF is another severe streptococcal infection that penetrates deep skin layers, leading to tissue necrosis.
    NF often originates from a minor wound and can escalate to tissue death within 24 to 72 hours. Typically affecting the limbs, symptoms include localized warmth, swelling, and discharge from the wound.


While most cases of S. canis infection in dogs do not constitute emergencies, it’s prudent to schedule a veterinary appointment promptly upon noticing symptoms in your pet.

However, certain symptoms may necessitate immediate veterinary attention. Take your dog to the vet urgently if they exhibit any of the following:

  • Difficulty breathing
  • Significant warmth, swelling, or pain associated with a wound
  • Unexplained bruising or bleeding
  • Fever exceeding 105 degrees Fahrenheit

When assessing a potential bacterial infection, your veterinarian may conduct the following diagnostic tests:

  • History: Your vet will inquire about your dog’s symptoms and when they first appeared. Providing details about any underlying health conditions your dog may have is crucial.
  • Physical exam: A thorough physical examination will be performed by your veterinarian.
  • Bloodwork: Blood tests, including a complete blood count (CBC) and a biochemistry profile, may be conducted to evaluate your dog’s overall health and detect signs of infection.
  • Urinalysis: If a urinary tract infection (UTI) is suspected, your vet may recommend a urinalysis.
  • Swab: If your dog exhibits symptoms of a skin or ear infection, your vet will likely obtain a sample from the affected area for culture and cytology analysis. This aids in identifying the causative agent, enabling the prescription of an appropriate antibiotic.
  • Skin scrape: In certain instances, a skin scrape or biopsy may be performed by your veterinarian to identify the infectious organism or to rule out other skin conditions.


Treatment of streptococcus bacterial infection in dogs varies depending on the location and severity of the infection.

Potential treatment options include:

  • Fluid therapy: If your dog is dehydrated, your veterinarian may opt for hospitalization to administer intravenous (IV) fluids.
  • Antibiotics: Typically, S. canis is susceptible to antibiotics, and your vet will select an appropriate medication accordingly.
  • Tissue removal: In cases of infected wounds, your vet may need to excise dead tissue to facilitate healing.
  • Bandaging: To safeguard the infected area and prevent your dog from licking it, your veterinarian may apply a bandage to the wound.
  • Ear wash: For streptococcal ear infections, your vet is likely to suggest ear cleaning along with prescribed ear medications.

Living and Management

Uncomplicated streptococcal ear, respiratory, and urinary tract infections typically clear up within five to seven days after your dog begins receiving the appropriate antibiotics.

During the recovery period, it’s essential to keep your dog well-hydrated and ensure they get plenty of rest. For dogs with streptococcal infections in wounds, recovery duration hinges on the severity of the infection and may extend over several weeks or even months.


Preventing streptococcus bacterial infections in dogs is challenging as many cases are not preventable.

However, you can reduce the risk of infection by scheduling regular wellness visits for your dog. This allows your vet to detect any underlying health issues early on.

Additionally, it’s important to monitor your dog’s wounds or minor injuries closely for signs of infection such as heat, swelling, excessive pain, or discharge. If any of these signs occur, seek veterinary care immediately to address the issue promptly.

Bacterial Infection (Streptococcus) in Dogs FAQs

Is a streptococcal infection in dogs contagious?

Yes, S. canis is contagious and can transmit from one dog to another. However, a dog usually doesn’t contract an infection unless their immune system is compromised. While dogs rarely transmit this infection to humans, it’s advisable to practice good hygiene, especially frequent hand washing, when your dog is unwell.

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