Can Dogs Catch Colds or the Flu?
Does My Dog Have a Cold?
When we talk about the common cold, we are referring to an infectious virus or disease that affects the upper respiratory tract (nose, sinuses and throat). We know the symptoms of a cold—that sting in the back of the throat followed by sneezing, a runny nose and sometimes a cough. Dogs can also suffer from viral infections of the respiratory tract, but the germs that cause canine colds are not the same as those that cause human colds. Your dog cannot catch your cold, and you cannot catch his or hers.
In dogs, the term 'kennel cough' is used to describe a variety of viral and bacterial conditions that cause similar symptoms to the human cold. Thus, a dog with kennel cough is suffering from a type of canine cold. Kennel cough is highly contagious and is spread via contact with the saliva of the dog. Anything the dog has carried in its mouth, drooled on, eaten or taken a drink from can carry those germs and transmit the disease. Shared water bowls are a common way that the condition spreads, but it can also become airborne when a dog coughs or sneezes.
Any place dogs come into contact with each other puts them at risk of catching kennel cough—this might be the park, a training class or even going to the vets. It is so easily spread that it is almost impossible to avoid, just like when humans try to avoid catching the common cold.
Kennel cough can take up to 10 days to develop or present in a dog. Unfortunately, before a dog shows symptoms, they will already have been shedding germs and could have infected other dogs without showing signs of being sick. In fact, some dogs catch it but may develop no symptoms, yet they can still spread it to other dogs they meet.
What Causes Colds in Dogs?
Kennel cough is caused by a variety of different germs—some viral and some bacterial. It can be the result of a single infectious agent, or it can be a combination of germs It usually begins when a viral agent infects the dog. The dog's immune system is then compromised, and he or she may be at higher risk of secondary infections from other viruses or bacteria. In some dogs, this can lead to serious complications.
There are multiple viral agents that can trigger the condition, including the canine distemper virus, canine parainfluenza and canine herpes. However, some of these only trigger true kennel cough when they combine with certain types of bacteria. Canine parainfluenza, for instance, when contracted on its own, has different symptoms than kennel cough.
The two most common infectious bacterial agents to trigger the condition are Bordetella bronchiseptica and the various species of Mycoplasma bacteria. Bordetella bronchiseptica is closely related to the bacteria that causes whooping cough in humans, and it can pass to other animals including pigs, horses and cats. There are a known 15 varieties of this bacteria that can be picked up by dogs.
Most owners only realise their dog has contracted a cold when it develops a dry, persistent cough (hence the name 'kennel cough'). The cough may be accompanied by the dog bringing up phlegm or bile, and some pups will also appear lethargic or have a temperature. Other dogs will show no symptoms except for the cough and will appear otherwise fine in themselves.
This condition is highly contagious, and in a multi-dog household, it is very likely to spread through all the resident canines. It is important to keep your dog away from other dogs while they are poorly, to prevent it from spreading further. Dogs can remain infectious after the cough stops, and it is advisable to continue to keep your dogs away from others for two to three weeks. Many training clubs and kennels have a rule that if your dog has had it or has been around dogs with the illness, they must not attend the club or be boarded for 21 days.
Can I Treat Kennel Cough at Home?
As with the human cold, the condition is usually self-limiting and does not require a vet visit. Dogs should be allowed to rest and be offered plenty of fresh water. They should be kept warm and may be offered honey to soothe a throat made sore from coughing.
Dogs that normally eat dry kibble may need their food moistened with water to enable them to consume it or have to switch completely to wet food. Most dogs will bounce back within a few days.
Puppies under six months, elderly dogs, dogs with heart or respiratory problems or dogs that have a compromised immune system, may develop complications from the illness. One common complication is pneumonia, which causes the dog problems breathing and can be serious if left untreated. If your dog does not stop coughing after a few days, then a vet visit may be in order. Equally, if your dog develops a high temperature, stops eating, becomes increasingly lethargic, struggles to breathe or has an upset stomach, you should seek professional veterinary advice.
Although kennel cough is generally not a severe illness, it is inconvenient and pet owners naturally look for ways to prevent it. There is a vaccine, but its effectiveness is questionable because there are so many varieties of the germ that it is impossible to create a vaccine to cover them all. Dogs can still catch it after being vaccinated if the strain they are infected with is different from the one they were vaccinated against.
Dr Ronald Schultz, professor and chair of pathobiological sciences at School of Veterinary Medicine, has been studying the effectiveness and longevity of canine vaccines since the 1970s. He has stated that Kennel Cough is not a disease that can be vaccinated against, and he has questioned whether it is even necessary. He says:
Most pet dogs that do not live in breeding kennels, are not boarded, do not go to dog shows and have only occasional contact with dogs outside their immediate family, rarely need to be vaccinated or re-vaccinated for kennel cough.
However, many boarding kennels and even some training clubs do insist on dogs having the vaccine before attending them. In all likelihood, your dog has been exposed to kennel cough on many occasions and their own immune system has prevented it from affecting them. Even if they do contract it, a healthy dog should recover in a few days and some will not even show symptoms. With plenty of rest and care, your dog should be right as rain in no time, and there should be no need for a trip to the vets.
What About Canine Flu?
Doggy flu can be caused by canine parainfluenza, or by the influenza viruses H3N2 or H3N8. Parainfluenza is different from the H3N viruses and a vaccination for it is sometimes included in the standard injections your pet receives. The parainfluenza vaccine does not protect against ordinary influenza. To cause extra confusion, when parainfluenza combines with other viruses or certain bacteria, it then may cause kennel cough.
Parainfluenza can affect pigs, monkeys and even humans, along with dogs, however, there is no evidence that dogs can pass the flu to humans or vice versa. On its own, parainfluenza only causes mild symptoms in a dog, such as sneezing.
H3N8 is a relatively new flu virus to appear in dogs. It first appeared in horses about 40 years ago. In 2002, two foxhounds in the UK were suspected to have caught the virus and were isolated before it could spread. Then, in 2004, it was discovered in racing greyhounds in the United States that shared a racetrack with horses. As flu viruses are constantly evolving, it is not surprising that H3N8 has managed to jump to a new species. Since 2004, H3N8 has spread throughout the canine population and is now considered endemic in the US, however, it is not yet considered a major problem in the UK.
H3N2 started in birds, then spread to dogs and cats. The first cases in dogs were identified in North Korea in 2007, then cases emerged in Thailand, China and Canada. H3N2 was first seen in America in 2015. There have been suspected cases in the UK, but as with H3N8, it is not yet considered an epidemic.
Symptoms of canine flu can include:
- runny nose
- lethargy/excessive sleeping
- loss of appetite
For most dogs, flu is a minor problem that resolves with rest and keeping the dog hydrated—the same as in people with flu. They should be kept away from other dogs to prevent the disease from spreading. Occasionally, a vulnerable dog may develop complications that need to be addressed by a veterinarian. As with kennel cough, the most common problem is pneumonia. If your dog develops breathing difficulties or is sick for over a week, then you should consult a vet.
In the US, there are vaccines for canine influenza and parainfluenza, however, it is debatable how effective they are and whether they are really necessary. In the majority of dogs, flu is rare and only causes mild illness.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
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© 2020 Sophie Jackson