Several cases of pneumonia in dogs have been reported at various vet practices recently, relating to a specific type of bacterial infection. This pneumonia can be fatal for many animals. Whilst it’s not an epidemic, we still thought it would be worth covering the cause of this condition as well the treatment options, in case a pattern is emerging.

What is pneumonia?

Pneumonia is a broad term used to describe inflammation of the lungs and airways. It causes breathing issues and a lack of oxygen around the body (hypoxia). Secondary effects can also occur due to the spread of toxins into the bloodstream from the affected lungs.

Causes of pneumonia are most commonly viral, with secondary bacterial infections. Sometimes parasites or fungal infections can cause pneumonia too. Aspiration pneumonia can also be seen, usually due to issues with the way an animal eats or because it has inhaled its own vomit.

What is causing these new cases of pneumonia?

Streptococcus equi subspecies zooepidemicus is the cause of the recent cases of pneumonia that we will be discussing. This is a bacterium that was previously associated with infection of the reproductive tract of horses. However, cases have been identified in dogs with the bacteria causing serious cases of pneumonia. 

Transmission from horses to dogs may be possible, but it seems that it is usually spread by dog-to-dog contact. This means the disease is most likely to happen when dogs are kept close to each other such as kennels, greyhound tracks or rehoming centres. The disease is most likely to occur in dogs with a weakened immune response. This is possibly because they are already suffering from another lower grade respiratory infection.

Are there any symptoms?

Affected dogs usually have mild non-specific symptoms, to begin with, such as an increase in discharge from the nose, and a cough. This can look like common ‘kennel cough’ (infectious tracheobronchitis). This is usually a self-limiting illness that doesn’t require treatment in normal fit dogs. So, the true cause of the dog’s disease may be initially missed, until they start to develop other symptoms.

As the disease progresses, the dog may start to show additional signs such as a fever, lethargy, fast respiratory rate and a poor appetite. These signs are a key indicator that pneumonia is developing. Pneumonia associated with Streptococcus equi subspecies zooepidemicus also often means bleeding can start to occur. The infection damages the blood vessels in the lungs causing a bloody discharge from the nose in some animals.   

What is the treatment for this pneumonia?

Diagnosis of the condition may be made by examining the dog and taking swabs for bacterial culture and analysis. Blood samples may also be taken. Post mortem examinations may confirm the disease in animals that have sadly died, allowing measures to be put in place for other dogs at the kennels.

Treatment usually involves a combination of antibiotics and fluids by a drip. This will help improve your dog’s blood pressure and hydration status; which is particularly important if your dog is starting to show signs of shock. Unfortunately, the condition often progresses rapidly, so dogs may still die despite treatment.

How can I prevent my dog from getting this type of pneumonia?

There are no vaccinations currently available for the bacterium S. zooepidemicus, so prevention usually revolves around limiting the spread of the bacteria. If a case has been diagnosed in a kennel environment, then staff should take care to isolate affected animals and wear protective clothing when handling the dog. Equipment that has been used by ill animals should be disinfected thoroughly before being used elsewhere (e.g. food bowls, toys and leads).

There is also a potential risk to humans, with the bacteria causing respiratory disease of septicaemia. So good hygiene and lots of hand washing is important when handling suspected cases.


Sadly many cases of pneumonia caused by the bacteria S.zooepidemicus are fatal, especially as the disease looks similar to other milder respiratory infections in the early stages. Prompt diagnosis of the condition will mean measures can be put in place to limit the spread to other dogs, as well as helping keep staff safe. More research is being carried out into this infectious disease so we are still learning about it. Dogs that are housed in kennels in close proximity to each other are most at risk, but you should always speak to your vet if you have any concerns about your dog.

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