It is quite common for dogs to cough and there are several reasons why this may happen. Before we list the main causes it is important to note that if a dog is coughing but is otherwise bright and well, then it is probably not necessary to immediately seek veterinary attention. You will see from the following information that many of these cases will recover within a couple of weeks without any treatment.

Reasons as to why your dog may begin to cough. We will list the causes here then say a little about each in turn later.

- Kennel cough or infectious tracheobronchitis

- Chronic bronchitis

- Allergic bronchitis

- Heart disease

- Inhalation of a foreign body

- Laryngeal paralysis

- Lung worm

- Brachycephaly (flat faced dogs such as Pugs and French Bulldogs)

- Tracheal collapse

- Lung disease including cancer.

Kennel cough or infectious tracheobronchitis

This is probably the most common reason an owner may seek advice about a cough.

Kennel cough is caused by a variety of bacteria and viruses often in mixed infections and it leads to irritation and inflammation of the upper airway, mainly the trachea or windpipe.

The lungs are very rarely involved.

This cough is typically harsh (honking)and persistent, it starts suddenly and dogs may appear to gag or vomit at the end of a bout of coughing as the increased mucus is difficult to shift.

Although this can produce the most dramatic coughing signs in dogs, they are usually quite bright, well in themselves and prepared to exercise and eat normally.

Occasionally some kennel cough cases do have more serious signs, they can develop a fever (rare in most cases) and can be lethargic and off their food. A very small number of dogs may develop a bronchopneumonia which affects the lungs. These more serious complications are more likely in the very young, the very old, dogs with underlying health problems or those with a weakened immune system.

Kennel cough is very infectious and is spread in the air through aerosol particles but can also be contacted from contaminated surfaces or via the hands of people who have been in contact with infected dogs.

The syndrome gains its name because it is most likely to occur and spread where several dogs are sharing the same air space. In recent times, there has been a huge increase in the socialisation of dogs and with this there are increased opportunities for this condition to occur and spread e.g. doggy day care and professional group dog walking services. With this in mind dog owners are often required to have their dog vaccinated against kennel cough by these service providers.

Sometimes there may be no history of contact with other dogs and it is certainly not the case that a dog must have been in kennels to become affected by kennel cough.

Prevention of kennel cough or the reduction of spread requires a combination of vaccination (ask your vets advice about timing etc), excellent hygiene and the isolation of affected animals from unaffected ones.

Most dogs recover well from kennel cough without treatment but you should have your dog examined by a vet if it appears unwell or if the cough persists for more than 2 weeks without improvement.

If your dog is distressed by the constant coughing then your vet may be able to recommend treatment to suppress or reduce the severity of the cough symptomatically.

Rarely one of the organisms associated with kennel cough, Bordetella Bronchiseptica, can persist and the cough may continue for several weeks or even months.

The signs of kennel cough can often be significantly reduced by using a harness instead of a collar as this reduces the pressure on the windpipe.

Any dog that coughs persistently for more than 2 weeks should be seen by a vet.

Chronic bronchitis

This can present as a persistent cough usually in older dogs that may appear quite bright and normal otherwise even for years. Chronic bronchitis usually involves coughing during at least two of the last 12 months but is often persistent all year round. In its later stages it can lead to more serious problems. It is caused by gradual damage to the lining of the airways. The precise cause of chronic bronchitis is not fully understood but factors may be the prolonged inhalation of irritants such as cigarette smoke.

In the later stages dogs may become less willing to exercise and show increased effort breathing. 

Dogs which cough recurrently or persistently beyond three weeks should be seen by a vet.

Allergic bronchitis

Dogs with allergic bronchitis will present similar to those with chronic bronchitis however following investigations an allergic component is discovered. The allergy may be triggered by something the dog has inhaled but also by parasites in the lungs such as lung worm. These cases may be identified when a vet investigates any persistent cough.

Heart disease

This is usually a problem with older dogs but occasionally an issue for young dogs and can be more likely to affect younger large breed dogs. This is usually a soft cough and will normally be associated with other signs of heart disease such as increased tiredness with less willingness to exercise and possibly fainting or collapse.

The coughing in these cases is caused by enlargement of the heart in response to the heart disease which in turn causes the heart to “knock” on the windpipe particularly when the dog is exercising vigorously or becomes excited.

As before because this cough will persist your dog should be examined by a vet. The urgency increases if there are any signs of weakness, tiredness, fainting, breathing difficulties or collapse

Inhalation of a foreign body

This is a very rare cause of coughing but owners tend to suspect this when dogs actually have kennel cough because they sound as if they are trying to clear their throat and it comes on so suddenly. If a dog has something substantial in the back of its throat it will have difficulty eating or swallowing, if this is the case when your dog is coughing you should seek veterinary attention as an emergency. Smaller foreign bodies that have entered further into the respiratory system may be identified during the course of an investigation of a persistent cough.

Laryngeal Paralysis

Mostly affects older large breed dogs but can be congenital (i.e. present from birth) in some breeds.

Where laryngeal paralysis develops later in life it is known as idiopathic because the cause is not clear but it may be related to more generalised neurological disease.

In this condition some of the nerves to the larynx do not work properly and this means that the larynx cannot be pulled open enough to create a wide airway which is needed for normal breathing. This can cause particular problems when trying to exercise and during hot weather. Dogs need to pant in order to control their body temperature.

Dogs affected by laryngeal paralysis can undergo surgery to hold the larynx open but this does increase the risk of inhaling food which can cause a form of pneumonia.

Idiopathic laryngeal paralysis is a progressive disorder that mostly affects older large breed dogs.

Dogs with laryngeal paralysis may have an unproductive cough and noisy breathing particularly when exercising. The bark may alter and they may have reduced ability to exercise and even collapse in warm/hot conditions. If you suspect your dog may have laryngeal paralysis you should consult your vet and be very careful to avoid the dog exerting itself in hot weather. 

Lungworm

Lungworm in dogs is still a quite rare cause of disease in the UK but it is more common in hotspot areas within the UK. This condition is however more prevalent in Lungworm-endemic countries and taking dogs on holiday abroad or to a UK hotspot may mean that they have a higher risk of being exposed to Lungworm. There are a couple of different parasites involved which can cause coughing and one of them in particular (Angiostrongylus vasorum) can have more serious health consequences which are more dangerous than coughing. Your vet can advise of risks and preventative measures or testing and treatment if they suspect your dog to be affected.

Brachycephaly

This is the term used to describe the conformation of dogs with shortened muzzles and flatter faces. These dogs are at risk of a variety of respiratory and breathing problems and some of those may involve an increased tendency to cough. These dogs when affected by any of the other causes of coughing may present with more serious signs because of their underlying narrowing of the airways.

Collapsing Trachea

This is a problem that largely affects small breed dogs. When a dog is breathing in through the mouth a negative pressure is generated in the windpipe (trachea) by expansion of the lungs. This negative pressure would tend to collapse the windpipe but it is usually kept open because it is supported by a series of ‘c-shaped’ rings of cartilage along its length rather like the hose of a vacuum cleaner.

Sometimes these rings do not develop properly which results in  part of the wall of the windpipe being soft and weak. As a result, the wall of the windpipe tends to be sucked in, thereby narrowing the airway when the dog breathes in. The dog will then often cough to open it up again on the out breath.

This type of cough will tend to be recurrent and persistent and may be worse when the dog is excited or exerting itself. 

As this condition is progressive it often has to be managed rather than cured and your vet will be able to discuss the options for reducing the severity of the impact on your pet’s quality of life if the condition is diagnosed or suspected.

Lung disease (including cancer)

There are several progressive diseases of the lungs that can lead to chronic persistent coughing, they are not common and may require a variety of tests and investigation to identify and treat appropriately, they may be the consequence of other long term conditions such as chronic bronchitis.

Lastly, the one everyone is most worried about - cancer. Fortunately it is not very common and usually a disease of old age.  As with humans lung cancer can be secondary i.e. spread from a tumour elsewhere or primary in that it has originated in the lungs. Affected dogs will usually cough and lose weight, they may be increasingly lethargic and show increasing breathing difficulties. The signs associated with this disease will depend on the nature of the cancer but will gradually become more obvious and debilitating as time goes on.

Occasionally younger animals, particularly the very large breeds may get cancers which spread to the lungs.

This most serious of diagnoses is one of the first things a vet will want to try and rule out when investigating a persistent cough.

In summary

If your dog is bright, active, eating normally and generally behaving normally despite coughing, especially if the signs developed very suddenly, it is unlikely to be of serious concern unless it persists beyond two weeks, other signs are present or the general condition of your dog deteriorates.

Any cough persisting beyond two weeks should be seen by a vet.

Any dog coughing that is also showing signs of breathing difficulties, weakness, loss of appetite or collapse should be treated as an emergency.

Great care should be taken with any dog showing any respiratory signs during warm or hot weather. Until you are sure what is causing the problem, affected dogs  should be kept cool with the minimum of exertion.

All respiratory disease and most conditions causing persistent coughing are made much worse and much harder to manage if your dog is overweight. Some conditions can be greatly improved  with a return to optimum body condition and weight so that medication is no longer required or can be substantially reduced.