The immunization of puppies and adult dogs is mandated by laws and regulations, which are necessary to prevent diseases associated with high communicability and/or mortality. Modern animal vaccines are considered to be safe and adverse reactions to vaccines are not common; however, controversy exists concerning the number of vaccines necessary to prevent illness and frequency of boosters. Since veterinarians are not required to notify regulating authorities or vaccine manufacturers of adverse reactions, it is impossible to determine the number of animals who may have been adversely affected by vaccines.
A dog’s immune system builds up levels of antibodies against the virus antigen in the vaccine, providing protection against that specific illness in the future. Puppies are required to receive a specified number of vaccines, and follow-up boosters on a regular basis. Dogs may receive yearly immunizations with as many as 5 – 7 different vaccines. A number of vaccines are given in a combined polyvalent form, making it can be impossible to determine which vaccine was the cause of an adverse reaction or chronic illness. Polyvalent forms may overburden a dog’s immune system unnecessarily. Blood titers, which measure the level of antibodies that the dog has developed against a particular disease, are not always a reliable method for determining how well a dog will react when they are actually exposed.
Vaccine production is regulated by government agencies in most countries. Vaccines provide disease-specific antigens most commonly as dead, live, or attenuated forms of the virus. Dead forms of a virus are the safest, are easy to manufacture and store, but may not produce enough antibodies to provide protection and may require boosters. Adjuvants, added to the vaccine in order to increase the effect of the viral antigen, can cause reactions at the injection site. Vaccines containing live antigens may be contaminated with other organisms, are complicated to produce, and require strict storage conditions. Live antigen vaccines present the possibility of contraction of a milder version of the disease, especially in dogs with depressed immune system. Attenuated, or weakened viral antigens, are able to replicate, but are unable to cause the disease. The possibility also exists that an attenuated viral antigen may revert to its more virulent form, resulting in the development of full-blown disease in the dog.
Very little scientific proof exists to support vaccine boosters being given every year to dogs. Some vaccines may require boosters only every 2-3 years, and some vaccines may provide lifelong immunity. Minimal immunity duration has not been measured or determined, and measurements are currently unreliable. Humans generally receive boosters every 10 years; booster protection may last as long in dogs. Boosters may stimulate the immune system unnecessarily, may not increase antibody levels against the virus, and may increase the risk of side effects. Multiple doses increase the risk of development of hypersensitivity to the vaccine.
Nosodes are made from tissue or body secretions of diseased animals, and are used by some homeopathic veterinarians to provide immunity in dogs against communicable diseases. While some practitioners report good results from the use of nosodes, there is not enough scientific evidence to support the use. Nosodes should only be administered by a reputable homeopathic veterinarian.
Canine distemper is a very serious viral infection with a high mortality rate. The disease attacks a dog’s gastrointestinal, respiratory, and nervous systems. If a dog does survive the illness, irreversible brain damage will most likely be seen. Puppies are most at risk and should be vaccinated against this disease. The vaccine is usually given in a polyvalent form, and may soon be available to be given alone.
Canine parvovirus is a viral intestinal infection, causing severe vomiting, diarrhea, dehydration, and sometimes death in the infected dog with mortality rates as high as 15%. Puppies are most at risk of contracting the illness and should be vaccinated; in older dogs the infection is less severe. Parvovirus can live in an area for up to 3 years. This vaccine is usually given in a polyvalent form, but is also available to be given alone.
Coronavirus is a viral intestinal infection that is transmitted like parvovirus, but the resulting illness is much milder, unless parvovirus is contracted at the same time. Puppies are affected the most; signs of illness in older dogs may not be noticeable. This vaccine is usually given in a polyvalent form, but is also available to be administered alone. Puppies who receive parvovirus vaccine will only have mild symptoms if they contract coronavirus.
Kennel cough is an upper respiratory infection caused by bacteria, resulting in a dry hacking cough that can persist for weeks. Kennel cough is highly contagious and is mainly seen where there are large populations of dogs, such as kennels, dog shows, boarding facilities, or shelters. Kennel cough is treatable with antibiotics, and is not considered to be life-threatening.
Leptospirosis is contracted from the urine of infected animals, especially opossums, raccoons, or skunks. This illness causes liver or kidney disease, with death occurring in 10-20% of dogs. The kidney failure may continue long-term. Dogs who have contact with wildlife, herding dogs or dogs who have contact with livestock, dogs who roam, or drink from contaminated water are at highest risk of contracting this illness. Leptospirosis vaccines are associated with the highest rate of adverse reactions, especially in miniature breeds, and may suppress the immune system in dogs less than 16 weeks of age. Different strains of leptospirosis exist; a vaccine may not protect against the strain that is in your area.
Lyme disease is transmitted to dogs by a spirochete that is carried in certain species of ticks, resulting in fever, lethargy, and arthritis. Further development of the disease may cause kidney failure, nerve damage, and heart problems. Contraction of Lyme disease appears to depend upon the immune system status of each individual dog. Only vaccinate if you live in an area where the disease is prevalent, and your dog is exposed to ticks. Lyme vaccine may cause adverse reactions at the injection site, and some veterinarians suspect a possible development of kidney disease and arthritis from the vaccine. Your best defense against Lyme-carrying ticks may be the use of tick control products, preventing your dog from roaming, maintaining short grass and removal of leaves in your yard, and checking your dog for ticks when they come inside.
Rabies is an untreatable viral infection that affects the central nervous system of all mammals, and inevitably results in death. Dogs that have contact with wildlife are at highest risk of contracting this disease, from the bite of an infected animal. Local laws mandate the frequency of rabies vaccinations and boosters in dogs. Some veterinarians believe that behavior problems or the development of chronic illness may be the result of rabies vaccines. Do not give the vaccine to an ill dog, or one who has had previous adverse reactions to the vaccine. Talk with your veterinarian; you may be able to receiv
e exemption status for your dog, if this is available in your area.
The stress from a vaccination reaction may be enough to activate sub-clinical infections, especially since some vaccines may cause mild suppression of a dog’s immune system. Existing stress due to illness, temperature extremes, pregnancy, malnourishment, or fatigue can reduce a normal immune response. Some chronic illnesses, which include autoimmune diseases, may be caused by the over-vaccination of dogs. Proven problems with vaccines are allergic reaction, either localized or systemic leading to anaphylactic shock, development of the disease for which the dog is being vaccinated, hair loss at the site of injection, or nerve damage. The dog may enter a carrier state, where the dog will test positive for the disease but have no symptoms. Possible problems with vaccines are allergic skin disease, behavioral problems (especially aggression), chronic pain, fertility problems in female dogs, kidney failure, thyroid dysfunction, and seizures. Some symptoms that have been observed following immunization are chronic diarrhea associated with inflammatory bowel disease, cystitis, behavioral and emotional changes, seizures, skin eruptions, and thyroid disease.
Contact your veterinarian immediately if your puppy or dog exhibits signs of an allergic reaction after vaccine administration. Dogs are different from humans and other domesticated animals, in that the organ most affected by an anaphylactic reaction is the liver, not the lungs. Gastrointestinal symptoms are the result of severe anaphylactic reactions, and include salivation, abdominal pain, vomiting, restlessness, excitement, facial swelling, watery eyes, difficulty breathing, shock, convulsions, and possibly death.
Breeds which appear to have increased susceptibility to adverse reactions from vaccines are:
- American Eskimo
- Cocker Spaniel
- Fox Terrier
- Harlequin Great Dane
- Parson Russell Terrier
- Springer Spaniel
What to do?
Inside dogs may be able to receive less frequent immunizations, as well as dogs with limited contact with other dogs or wild animals. Dogs with chronic illness, or a previous adverse reaction to vaccines in the past, those who are being treated with immunosuppressive drugs for autoimmune diseases, pregnant dogs, and very young puppies should not be immunized. It is up to you to make an informed decision after weighing risks versus benefits of immunization, the age and condition of your dog, and the prevalence of diseases in your area. Discuss your concerns with your veterinarian before deciding upon a course of action, whether it be less frequent boosters, pre-medication with antihistamines and/or corticosteroids, or possibly no boosters at all.
Good health and a strong immune system is your dog’s best defense against all illnesses and development of chronic diseases. To strengthen and maintain your friend’s immune system provide a balanced diet, adequate water, exercise, nutritional supplements, and, of course, lots of love and attention.
Allegretti J, Sommers K DVM. The Complete Holistic Dog Book: Home Health Care for Our Canine Companions. Ten Speed Press; Berkeley, CA; 2003.
Vaccines and Immunotherapy. The Merck Veterinary Manual. Available at: http://www.merckvetmanual.com. Accessed February 26, 2009.
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