When to see a vet urgently
Seek emergency veterinary care if a cat with respiratory symptoms has any of the following:
- laboured breathing or breathing with its mouth open;
- bluish mucous membranes;
- severe weakness and an inability to get up;
- worsening breathing and rapidly deteriorating general health in a kitten.
Overview
Bordetella bronchiseptica infects the respiratory tract, causing inflammation of the windpipe and bronchi. Infection spreads through droplets when an animal coughs or sneezes, and through shared food bowls and care equipment. The illness can be mild or severe, particularly if the cat's immune defences are weak.
Bordetella infection is not confined to the windpipe and bronchi: it can also cause upper respiratory symptoms. Signs affecting the nose and throat, and inflammation of the lungs, are possible manifestations of the same infection with different levels of severity. Not every infected cat develops pneumonia.
The bacterium attaches to the ciliated surface of the airways. Cilia normally help move mucus and foreign particles out of the respiratory tract. Factors produced by the bacterium can impair their function and damage them, disrupting airway clearance. Bordetella can cause disease on its own, but other respiratory infections may be present at the same time.
How infection develops
The main cause is Bordetella bronchiseptica. Factors increasing the risk of infection include:
- contact with sick animals,
- crowded conditions in shelters or boarding facilities,
- stress and reduced immunity,
- concurrent viral infections, including herpesvirus and calicivirus,
- unfavourable environmental conditions, such as damp, cold and draughts.
Cold, damp or draughts alone do not cause Bordetella infection without exposure to the bacterium. There is limited information about their independent importance as risk factors for feline Bordetella infection. Frequent animal contacts, crowding and concurrent respiratory infections are better established factors.
A dog can also be the source: Bordetella bronchiseptica can pass from a dog with a respiratory infection to a cat. Tell the vet about both cat contacts and coughing in dogs at home. Oral and nasal secretions from an infected cat spread the bacterium, and shared care equipment should not be considered separately from direct contact between animals.
Risk factors
- kittens and young cats with weak immune defences,
- cats living in shelters or boarding facilities,
- animals with chronic respiratory diseases,
- cats weakened by stress, surgery or illness.
Severe pneumonia occurs particularly in young kittens, but can also affect older cats. The risk of becoming infected and the risk of severe disease are not quite the same: frequent contacts facilitate transmission, while age and other aspects of health affect how well an animal copes with illness. A carrier without symptoms can also be part of the same chain of infection.
Symptoms
The symptoms of Bordetella infection can resemble other respiratory infections:
- a dry or mucus-producing cough,
- sneezing,
- clear or pus-like nasal discharge,
- wheezing and crackling breathing sounds,
- fever,
- loss of appetite and lethargy,
- shortness of breath and respiratory failure in severe cases.
Some cats may have no symptoms but can still infect other animals.
At home, pay attention to breathing effort, appetite and energy as well as coughing. The colour of nasal discharge alone does not identify the microbe responsible. In mixed infections, the typical features of individual pathogens may be obscured. Symptoms therefore cannot reliably distinguish Bordetella infection from viral cat flu, for example.
In pneumonia, breathing difficulties are associated with inflammation in the lungs and impaired oxygen uptake. The cat may be subdued and not eating, and coughing may not be the most obvious problem to the owner. Do not continue monitoring breathlessness at home simply because earlier nasal symptoms were mild.
Possible complications
Without appropriate treatment, Bordetella infection can lead to:
- bronchopneumonia,
- chronic respiratory infections,
- a substantial weakening of immune defences,
- death in kittens and debilitated animals with severe disease.
Severe pneumonia is a recognised complication, but the weakening of immune defences listed does not mean every infected cat develops permanent immunodeficiency. A decline in general condition must be distinguished from an underlying disease affecting immunity. Many cats with uncomplicated infection recover well when the cause is identified and treatment suits the situation.
Diagnosis at the vet
Diagnosis may involve:
- a clinical examination,
- bacterial culture of respiratory samples,
- PCR testing to identify Bordetella bronchiseptica,
- chest X-rays to rule out complications.
Other causes of similar symptoms
Bordetella is one possible cause of respiratory symptoms. Herpesvirus and calicivirus are common causes of cat flu and can occur together. Herpesvirus may involve corneal damage, while oral ulcers may be seen with calicivirus. These findings help guide investigations, but the diseases cannot always be distinguished from their clinical appearance.
Persistent nasal symptoms may also require investigation of changes to nasal structures caused by previous inflammation. In that situation, active Bordetella infection does not explain every ongoing symptom. Conversely, several pathogens occurring together can make disease more severe. The aim is therefore to identify the whole problem requiring treatment, rather than simply obtain one positive or negative test result.
Interpreting sample results
Investigations assess whether disease is confined to the upper respiratory tract or whether pneumonia is possible. X-rays show lung changes but cannot identify Bordetella on their own. When needed, respiratory samples are examined for inflammatory cells and bacteria. Sampling of the lower airways is planned according to the patient's condition.
PCR looks for the bacterium's genetic material, while culture aims to grow live bacteria. Antibiotic susceptibility can be tested alongside culture. A positive nasal or throat sample does not always show that Bordetella alone causes all the symptoms: it can also be found in carriers or alongside other infections. A lower airway finding together with matching symptoms provides stronger support for its importance. Conversely, a negative culture or PCR does not reliably rule out infection.
Antibody testing does not usually establish the cause of acute disease, as antibodies may be present in the cat population for other reasons. When planning investigations, describe when symptoms began, animal contacts, any other affected animals in the group and previous medication. The sampling site and testing for other pathogens are chosen using this overall picture.
Treatment and recovery
When Bordetella infection is considered responsible for the symptoms, the vet selects antibiotic treatment. Even a patient with mild symptoms may need treatment because infection can progress into the lower airways. Susceptibility results guide medicine selection when available. Not all antibiotics work equally well, and resistant bacterial strains have been described. A concurrent viral infection does not remove the need to treat the bacterium, but antibiotics do not themselves cure viral disease.
A severely ill cat may need hospital care, supplemental oxygen and fluids. Adequate nutrition is also ensured. Treating pneumonia therefore involves more than a course of antibiotics at home. Follow-up may assess breathing and general condition, with repeat chest X-rays when needed. If your cat deteriorates, do not delay contact until the planned review date.
At home, provide a warm, dry and quiet place for recovery. Nasal and eye discharge can be cleaned gently according to the care instructions to reduce discomfort. Monitor whether your cat eats and drinks and whether breathing at rest looks more laboured than usual. If giving food or medicine is not possible, ask the vet for an alternative that fits the treatment plan.
Do not force food or fluid into the mouth of a cat with breathing difficulties. Material going down the wrong way can cause aspiration pneumonia: inflammation caused by material inhaled into the airways. Not eating and difficulty breathing need veterinary assessment, rather than more forceful feeding at home.
Improvement in symptoms and the end of bacterial shedding are different things. A recovered cat may still carry the bacterium, and antibiotic treatment does not reliably eliminate carrier status. The vet therefore also advises on restricting contacts. Do not judge a return to a group of cats to be safe solely because coughing has stopped.
Prevention
- vaccination, with Bordetella vaccines available in some countries,
- reducing animal density, particularly in shelters,
- regular disinfection of premises and care equipment,
- supporting the cat's immune system with balanced nutrition,
- early identification and isolation of sick animals.
Bordetella vaccination is not automatically part of every pet cat's vaccinations. It is considered particularly in groups where infection has been confirmed and exposure risk is high. Protection is incomplete, so reducing infection pressure is needed alongside vaccination. Discuss availability and suitability with your vet.
Remove secretions and other visible dirt before disinfecting. Cleaning and disinfection are separate stages, and the product must be suitable for an environment with cats. Follow the contact time in the instructions and do not mix cleaning chemicals. Reducing the transfer of secretions on care equipment and hands helps break chains of infection even when not every carrier is identified.
This text provides general information and does not replace veterinary care. If your cat develops symptoms, contact a vet.
Frequently asked questions
Can a cat catch Bordetella from a dog?
Yes. Bordetella bronchiseptica can pass from a dog with a respiratory infection to a cat. Tell the vet about dog contacts and coughing in a dog too, even if your cat's symptoms look like an ordinary runny nose.
Can Bordetella infection spread to people?
Human infections have rarely been reported, particularly in people with weakened immune systems. If someone in your household is affected by this, mention it to the vet and, when needed, their own healthcare team. This also affects assessment of the suitability of a vaccine containing live bacteria.
Does every coughing cat need a Bordetella test?
Tests are selected according to symptoms and exposure. Coughing can also be associated with many other respiratory diseases. Finding Bordetella is interpreted alongside the sampling site, clinical findings and other possible pathogens.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- GUIDELINE for Bordetella bronchiseptica infection in cats, European Advisory Board on Cat Diseases, accessed 2026-11-03.
- Respiratory Infections, Cornell University, accessed 2026-11-03.
- Overview of Respiratory Diseases of Dogs and Cats, Merck Veterinary Manual, accessed 2026-11-03.
- Pneumonia in Cats, Merck Veterinary Manual, accessed 2026-11-03.
- Non-core Vaccines for Pet Cats, AAHA/AAFP, accessed 2026-11-03.
- GUIDELINE for Disinfectant choice in feline veterinary hospitals, shelters and cat households, European Advisory Board on Cat Diseases, accessed 2026-11-03.
- Feline Respiratory Disease Complex, Merck Veterinary Manual, accessed 2026-11-03.