Honking Dogs - The Kennel Cough Complex

A cough can be caused by different things and can sound different depending on what causes it. For instance, a deep, productive, wet cough may be more typical of pneumonia (in the UK, I saw this referred to as a "chesty" cough). Tracheal irritation will cause a typical "goose honk," non-productive kind of cough. Debris on the larynx (like post-nasal drip or laryngitis) will usually cause of hacking kind of non-productive cough. (Think croup in children)

I wanted to specifically mention Infectious Tracheobronchitis (ITB), a.k.a Kennel Cough, a.k.a. Contagious Canine Cough Complex. The names alone should suggest that it is not as simple as a single bacteria or virus causing it. We are talking about a complex of diseases.

The most famous culprit is Bordetella. This bacteria is WICKED contagious and can cause all kinds of upper and middle respiratory issues. It is a very close cousin to whooping cough in people. Other known causes of the ITB complex include:
Parainfluenza
Mycoplasma
Strep equi (var zooepidemicus)
Canine herpesvirus
Canine respiratory coronavirus
Canine influenza virus
Canine adenovirus type 2
Canine distemper virus (CDV)

The above list includes a paltry three bacteria with the rest being viral. The most common cause of all appears to be the parainfluenza virus. Bordetella is often blamed, but is not often the cause. It is also important to note that these viruses don't always act alone. A co-infection with bordetella when you already have parainfluenza can cause a nasty infection where either alone may be harmless.

Because ITB is infectious, it is most commonly associated with animals in a high-density setting. This includes boarding, grooming, shelters, play parks, daycare, or dog shows. HOWEVER, because it's so stinkin' contageous, it's not uncommon for me to see a dog with typical "kennel cough" that has not stepped foot in a kennel in months! Cats or dogs coming through the yard, visiting dogs coughing on the fence, or dogs sharing a patch of grass at the park or in the apartment building shortly before your dog does can all be sources of infection.

When I am presented with a dog who is otherwise healthy (no history of respiratory, cardiac, or immune system disease) and ONLY has a tracheal cough, I rarely treat with antibiotics. If they are very young, very old, or have other issues, I may use an antibiotic. Why? Because the infections are nearly always self-limiting. If I treat with an antibiotic, the patient will nearly always get better in 5-7 days. If I don't use an antibiotic, they patient will nearly always get better in 5-7 days. There are exceptions to every rule, and if the patient isn't responding or gets worse, I will intervene earlier.

I try to reserve the use of antibiotics to only those times I feel there is evidence that antibiotic use is necessary. The goal is to prevent antimicrobial resistance. For me, that's a pretty danged important goal.

That's how I handle it. I have many colleagues that treat all coughing dogs with antibiotics and I can't fault them for it. The argument for antibiotics include:
1) It can't hurt
2) The problem may resolve faster with antibiotics
3) I can't prove it is viral, so I should protect against the possible bacteria that can cause more severe infection.
4) That doctor's local population of animals seem to get particularly nasty infections and regularly require antibiotics.

Because these guys usually have WICKED coughs, I will give a cough suppressant to help everyone get some sleep. The most effective cough medications are narcotics (i.e. hycodan), but there are others that may work well. Our supply of narcotic cough medications has been dicey at best over the past few years, so we use what we can when we have it. An alternative to hycodan if it is not available is tramadol.

Vaccination:

Here's a hot topic! We can vaccinate for Bordetella, Parainfluenza, Influenza, and Adenovirus. None of these vaccines are perfect and we consider them likely to protect against severe disease, but NOT ALWAYS protective against infection. There's just too much variation in the wild-type bacteria and viruses. So YES, a vaccinated dog can get "kennel cough." It doesn't mean the vaccine wasn't given correctly or failed. There are just too many variables.

The influenza vaccine is new and in my opinion, the jury is still out on whether it will be worth using much. I've had two requests to blog on influenza virus. I'll get the rest of my data together and post on that one soon.

How often should a pet be given a "bordetella" vaccine? That depends. Some vaccines peter out after 6 months. Some have been proven to last one year. The most common protocol you will find is every 6 months. Even when I was using a vaccine that I felt worked for at least one year, groomers and boarding facilities required it every 6 months. I disagreed with them, but I was just the doctor. It's their facility. Is it hurting to give it every 6 months? Doesn't appear to be, but this goes back to the discussion of how many vaccines are enough and how many are too many.

Religion, Politics, and Vaccination - topics never to be discussed in mixed company ;)

Moral of the story:
I have LOTS of cases of "kennel cough" come to me every year. Most are viral, some are bacterial, and (in my hands) nearly ALL of them go home with cough medications only. A few end up with antibiotics. Think of it as the common cold for dogs. You just have to ride it out. Annoying, but rarely more than that.

AMH