By Teresa Garden, DVM
Core vaccines are those that have been developed to protect dogs from diseases that are common and have relatively high morbidity and mortality. Core vaccines, such as Distemper, Parvo, and Adenovirus should be offered to all puppies at 9 weeks, 12 weeks, and 16 weeks of age. A booster is needed a year later and then titers can be performed yearly to check for ongoing long-term protection. Rabies is a core vaccine and should be given to puppies at 3 to 6 months of age. That vaccine will give protection for 1 year. Adult dogs can be given a Rabies booster that is labeled for 3 years of protection. It is extremely important that puppies and dogs have immunity against these dangerous diseases.
In spite of widespread vaccine practices since the 1950s, infections and outbreaks of Distemper Virus still occur. Contact with wildlife, especially racoons, may lead to infection in our pet dogs. Distemper is highly contagious with variable morbidity and mortality. The virus is found in large population in respiratory secretions and is spread in air via aerosolization. The virus is also found in urine and other bodily fluids. Younger dogs and puppies are most susceptible. Older dogs not adequately vaccinated, stressed, or immunosuppressed are at risk.
Distemper virus attacks the respiratory system, GI tract, and nervous system. Symptoms of illness include cough, ocular and nasal discharge, fever, lethargy, vomiting, diarrhea, and seizures. Many victims of the virus will die from dehydration, sepsis, shock, and encephalitis. Some may recover with intensive supportive treatment.
Parvovirus is another very important core vaccine due to its high morbidity and mortality. It generally infects dogs less than 1 year old with poor vaccination history. Older, immunocompromised dogs are also at risk. Dobermans, Rottweilers, German Shepherds, and English Springer Spaniels are genetically predisposed and more seriously affected with the disease. The virus has a fecal – oral route of infection. Signs of Parvovirus are vomiting, bloody diarrhea, hyper or hypothermia, dehydration, and abdominal pain. A majority of dogs may survive with early diagnosis and aggressive treatment. Some will die due to septicemia, shock, and coagulopathy. Viral organisms remain outside the host for 5 months and can be transmitted by fomites (shoes, bicycle tires, flies). Parvovirus in the environment is thought to be the most important source of transmission. Most common disinfectants fail to inactivate the virus. If dogs recover from the illness, they can still shed Parvovirus in their feces for weeks. These dogs can have permanent damage to cells lining their intestines and heart. Studies have shown unvaccinated dogs are 13X more likely to be become infected than vaccinated dogs.
Canine Adenovirus-2 is a core vaccine that is usually combined with Distemper and Parvo when administered. It is also known as Canine Hepatitis Virus because it attacks the liver. Young dogs are most at risk. Symptoms of infection are vomiting, diarrhea, abdominal pain, and jaundice. It can also cause severe disease in the eye resulting in corneal edema and anterior uveitis.
Rabies Virus is still a threat to domestic pets and people worldwide. The virus is present in wildlife in the USA. Wildlife reservoirs for the virus include raccoons, bats, foxes, and skunks. Infected raccoons pose the greatest threat to dogs due to likelihood of contact even in suburban areas. Rabies results in a fatal encephalitis. Thus, it is an essential core vaccine for dogs. The virus is transferred in saliva via bite wounds or contamination of mucous membranes or open wounds with saliva of an infected animal. Virus is shed in saliva 5 to 10 days before the onset of symptoms. Neurological symptoms start 2 to 4 weeks after exposure. In dogs, the disease can cause a “furious” form or a “paralytic” form of disease. The furious form presents with behavioral changes, hyperexcitability, hyperesthesia, aggression, ataxia, seizures, and then death. The paralytic form has symptoms such as paralysis of facial muscles, the larynx, and pharynx. This is followed by hypersalivation, respiratory paralysis, and death. Treatment of Rabies is unsuccessful and it is invariably a fatal disease. Euthanasia of infected animals is often required by law due to serious public health implications. This is why state law mandates vaccination against Rabies for pet dogs and cats.
Noncore vaccinations will be discussed in our next article.
Dr. Teresa Garden is owner/chief veterinarian of Animal Health & Healing, a full-service conventional and holistic veterinary clinic located in the Richmond Heights/Maplewood area. 314-781-1738.