Laurie Anne Walden, DVM
Dogs often receive vaccines during their veterinary wellness visits. But what are all of those shots for? This article describes the diseases that canine vaccines help prevent.
Vaccines save lives and are safe, but your dog might not need every vaccine available. Vaccination is a medical procedure, and the choice of vaccines to use is specific to each dog. Talk to your veterinarian about your dog’s risk factors. The American Animal Hospital Association (AAHA) lifestyle-based vaccine calculator is a good starting point.
Canine vaccines fall into 2 categories: core vaccines, which are recommended for all dogs, and noncore vaccines, which are recommended for dogs whose lifestyle and environment put them at risk of infection.
Rabies vaccination is mandated by law in the United States. In North Carolina, all dogs, cats, and ferrets older than 4 months must be vaccinated against rabies. Rabies is caused by a virus that is spread through the saliva of infected mammals. After an incubation period that can last up to several months, the virus attacks the brain. Infection is almost always fatal once symptoms begin.
The rabies vaccine is an example of an animal vaccine that also protects human health. Read more about rabies in the blog post about NC rabies laws.
Canine distemper virus, canine adenovirus 2, and parvovirus
Vaccines against canine distemper virus, adenovirus 2, and parvovirus are included in a single combination vaccine.
Canine distemper virus infection causes fever and respiratory symptoms (runny nose and coughing) before it proceeds to the nervous system, resulting in seizures and possibly death. Dogs that survive the initial infection can have nervous system abnormalities for the rest of their lives.
Canine adenovirus 1 causes infectious canine hepatitis, a potentially fatal liver disease that also affects blood clotting ability. The vaccine against adenovirus 1 can have unwanted effects, so the currently recommended vaccine targets canine adenovirus 2, a variant that causes respiratory illness. The adenovirus 2 vaccine protects against both virus variants.
Canine parvovirus is a highly contagious, sometimes fatal infection spread through the feces of infected animals. Puppies and incompletely vaccinated dogs are most likely to be infected. Parvovirus causes severe intestinal disease (diarrhea and vomiting) and disrupts immune function.
Antibody tests (vaccine titers) are available for canine distemper virus, adenovirus 2, and parvovirus and may be an alternative to vaccination for some dogs.
Bordetella bronchiseptica and canine parainfluenza virus
Infectious tracheobronchitis, or kennel cough, is a highly contagious respiratory disease caused by a variety of viruses and bacteria. Bordetella bronchiseptica (a bacterium), canine parainfluenza virus, canine distemper virus, and canine adenovirus 2 are some of the organisms that cause kennel cough. Kennel cough is usually mild, but some dogs develop more serious illness. Kennel cough vaccines target Bordetella and sometimes parainfluenza virus. Parainfluenza virus vaccine is also included in some combination distemper/parvovirus vaccines.
Leptospirosis is caused by infection with Leptospira bacteria. This infection is zoonotic: it can spread between animals and humans. Leptospira are carried by many animal species, including wildlife and farm animals, and are usually transmitted through urine. Animals become infected through any contact with infected urine, including exposure to contaminated water or soil. Leptospirosis ranges from mild illness to kidney failure, liver failure, and death.
Canine influenza virus
Like kennel cough, canine influenza is a very contagious respiratory illness. Most dogs develop the mild form of flu, but the disease progresses to pneumonia in some dogs and can be fatal. Two strains of influenza virus are known to cause canine flu. AAHA recommends vaccinating at-risk dogs against both strains.
The bacterium Borrelia burgdorferi is responsible for Lyme disease, a tick-borne disease that causes fever and lameness in many animal species, including dogs and humans. North Carolina is currently on the border of one of the geographic areas with a high risk for Lyme disease.
For more information
Canine vaccination guidelines (AAHA)
Vaccinations (American Veterinary Medical Association)
Photo by Jay Wennington
Laurie Anne Walden, DVM
Are dogs’ mouths really cleaner than humans’ mouths? Definitely not! You may have read the recent news story of a Wisconsin man who required multiple limb amputations after contracting a bacterial infection from dog saliva. This type of severe infection is extremely rare, but dogs' (and cats’) mouths do harbor quite a variety of bacteria, some of which can make people sick.
The organism responsible for the Wisconsin patient’s infection was Capnocytophaga canimorsus, which is common in dog and cat saliva. Many different Capnocytophaga species normally live in the mouths of healthy dogs, cats, and humans. Up to 74% of dogs and 57% of cats have Capnocytophaga in their mouths. The types of Capnocytophaga that live in human mouths are usually different from those in dogs and cats.
Capnocytophaga canimorsus is one of the bacteria that cause infections in people who are bitten by dogs. Although it is usually spread through bites, it’s possible for a person to contract the infection after being licked by a dog. The Wisconsin man was reportedly licked, not bitten. A case report published in 2016 described an older woman who developed serious illness from Capnocytophaga canimorsus that likely came from contact with her own Italian greyhound. She recovered fully after 2 weeks of intensive care and antibiotics.
The vast majority of people exposed to this bacterium do not become ill. (Think of all the times you’ve been licked by a dog and haven’t gotten sick.) People who have had their spleen removed, use alcohol to excess, or have compromised immunity (from cancer or HIV infection, for example) are at increased risk of Capnocytophaga infection. Infection can cause severe sepsis (blood infection), gangrene, and inflammation of the heart lining, eyes, lymph nodes, and brain membranes. Infection in a pregnant woman can spread to the fetus. A 2015 review article reported a fatality rate of about 26%.
Of course Capnocytophaga are not the only bacteria in our pets’ mouths. Oral cavities—everyone’s, humans included—contain hundreds of different species of bacteria. Most of these bacteria are not zoonotic; that is, they are not spread between animals and people. The ones that do cause illness in people are usually transmitted by bites. However, one study found that several oral bacteria species could potentially be transmitted by close contact between pet dogs and their owners.
For most people, the risk of contracting a severe infection after being licked by a dog is incredibly low. But if your dog has zoonotic parasites like hookworms or roundworms, eats a raw meat diet, or eats feces (including foraging for snacks in the cat’s litter box), it would be a very good idea not to let him lick you in the face.
The Centers for Disease Control and Prevention recommends taking extra precautions around animals if you have an increased risk of infection. And everyone should take steps to prevent dog bites, which are much more likely than doggie kisses to cause an infection.
Photo by James Barker
Laurie Anne Walden, DVM