Vaccinations
 Vaccinations at Wilmington Animal Hospital


For the past 12 years, Wilmington Animal Hospital has adopted a very conservative vaccination policy. Our goal is to minimize the number of vaccines given to any one patient. We have found that this has resulted in a reduction of problems in our patients. In short, we believe that vaccines can prevent diseases, but they never make you healthy.

How we do it:

We have found that by carefully evaluating each dog’s and cat's risk of exposure to infectious diseases, we can safely limit the number of vaccines that each patient requires.

We have also undertaken a very critical review of all of the vaccinations available for our patients. Working with experts at the veterinary schools of Cornell University and the University of Wisconsin, we have determined which vaccines are safe, which are effective, which are not necessary, and which ones pose a higher risk of reaction than the actual risk of the disease. 

Most of our puppies receive 3-5 vaccinations (for parvovirus, distemper virus, and rabies) and most of our kittens receive 4-7 vaccinations (combination vaccination for feline distemper, herpesvirus, and calicivirus given once or twice depending on risk; and rabies). Contrast this to the more common vaccination schedules in which puppies receive anywhere from 24 to over 50 vaccine agents by 5 months of age, and kittens receive anywhere from 7 to over 14 vaccine agents!

What we do:

At the first annual exam, all dogs are evaluated for risk and vaccine requirements. For example, dogs boarding at certain kennels may be subject to certain vaccination requirements. Whenever possible, we begin measuring immunity to parvovirus and distemper in our patients. These tests that measure immunity are called “titers.” More and more kennels are accepting titers and minimal other vaccines (usually kennel cough and rabies vaccines) for boarding requirements. 

At each annual exam, we reevaluate and do the titer tests according to the dog's risks and requirements. Most of our patients that either do not board or who board at Wilmington Animal Hospital are able to stop all vaccines (except rabies) and titers by the age of 10, when the risk of contracting infectious diseases is virtually zero.

Similarly, for cats we evaluate their risks and vaccine requirements. Cornell University's Feline Health Center has performed studies evaluating duration of immunity in the feline distemper/herpesvirus/calicivirus vaccine. The American Association of Feline Practitioners has been very proactive in developing vaccine recommendations for cats. Consequently, many boarding kennels and veterinary facilities no longer require annual feline booster vaccinations. 

For our patients that have no risk of exposure to infectious diseases, booster vaccinations are usually not recommended. (except rabies according to state law). These cats include solo indoor cats who never board or never go to grooming facilities.

For our patients who have a risk of exposure to infectious diseases, booster vaccinations every 3-5 years are recommended for the distemper/herpesvirus/calicivirus vaccine. These include cats that go outside, cats living in households that will be bringing in new, stray, or rescue cats, and cats that board or go to grooming facilities. Occasionally, we will run titers on these cats if we have concerns for risks posed by vaccination.

Rabies vaccination is recommended in compliance with state laws. According to the vaccine label, the vaccine is only licensed to be administered to healthy animals. Medical exemptions can be given when the patient is not healthy enough to receive the vaccination. However, in the event of a human exposure, state public health laws override individual medical exemptions. For example, if a cat has been given a medical exemption but goes outside and receives a bite wound of unknown origin, this cat will still be required to undergo a six-month quarantine or be euthanized. If an unvaccinated dog or cat bites a human, including a member of a veterinary staff, this pet will be required to undergo a 10-day quarantine at the owner’s expense, even if the pet had not been healthy enough to be vaccinated. 

What we have found:

We feel that our patients are healthier with the judicious use of vaccines. For example, a study published in the American Journal of Veterinary Research in 2005 showed that cats inoculated with the feline distemper/rhinotracheitis/calicivirus vaccine developed antibodies to feline kidney tissue. Although none of the eight cats in the study developed kidney disease during the 56 weeks of the study, a direct connection between kidney disease in cats and the three-in-one vaccine was not ruled out. Restricted use of the vaccine can only have positive benefits in this regard. (Am J Vet Res 2005;66:506–511) 

We see very few vaccination reactions in kittens. We attribute this to our policy of only giving one injection every 3-4 weeks at most to kittens.

The Lyme vaccine is controversial. In the U.S., 3 vaccines are currently available, representing 2 basic forms. Two types are made from the whole bacteria (bacterin) and the other, a recombinant vaccine, is made from the only protein (rOspA) needed for protection from the bacteria. Bacterins in general tend to cause more reactions, and adjuvanted vaccines, (both of these bacterins contain adjuvants) are intended to elicit more immune response (and can elicit side-effects in the process). Subunit vaccines like the rOspA one are considered to be safer as they only introduce one antigen (foreign protein) into the body. 

 

In some areas where Lyme disease is prevalent, over 70-90% of dogs (healthy as well as sick) will test positive. Over 95% of these dogs that are exposed to the Lyme organism are not genetically predisposed to develop serious illness. Some of these dogs may develop non-serious symptoms that resolve within a week on their own. Those dogs that do develop Lyme arthritis, (less than 5% of those that are exposed), are easily treated with safe and inexpensive antibiotics. A less common but more serious form of Lyme disease that tends to affect Labrador Retrievers, Golden Retrievers, and Shelties can include the joint form (arthropathy) as well as eventual kidney disease. This is probably due to an immune-mediated condition because of genetic risk, and vaccination might actually increase the risk of this problem if the dog is later exposed. In addition, once these dogs test positive, vaccination is not recommended, as it may actually increase the risk of these dogs developing immune complex deposition in target tissues such as synovia (the lining of the joints) or glomeruli (parts of the kidneys). Interestingly, in one study almost 30% of dogs that had putative Lyme nephropathy (the kidney form of the disease) had been vaccinated.  

Finally, the efficacy of the vaccine has been called into question. Response to the vaccine can be measured in 2 ways. First, “seroconversion,” or the ability to make the intended antibodies, can be measured. In one study, 90% of the dogs made the antibodies to the bacterin, and 60% to the rOspA vaccine. The other measurement of response is to see how many vaccinated dogs later become ill with Lyme disease. In another study, 78% of dogs vaccinated with the bacterin were protected, and out of those, 58% were seropositive, 86% were seronegative. In both of these studies, however, dogs had not been evaluated for exposure to the Lyme organism before vaccination, complicating the interpretation of the data presented. In any case, the vaccines did not appear to confer protection to 100% of the dogs vaccinated in real-life situations. 

Lyme vaccine references:

1. Meryl P. Littman, lecture at Penn Annual Conference 2006

2. Meryl P. Littman, “The Lyme Test is Positive: Now What?” lecture at ACVIM 2007
 
3. Littman MP et al. ACVIM Small Animal Consensus Statement on Lyme Disease In Dogs: Diagnosis, Treatment, and Prevention. J Vet Intern Med 2006;20:422-434.
 
4. Dambach DM et al. Morphologic, immunohistochemical, and ultrastructural characterization of a distinctive renal lesion in dogs putatively associated with Borrelia burgdorferi infection: 49 cases (1987-1992). Vet Pathol 1997;34:85-96. 

Leptospirosis is a growing concern in dogs…or at least a growing market for the vaccines. There are three important issues related to this vaccine.
1. First, at least four serovars (types) of Leptospirosis are most likely to infect dogs. A vaccine that only protects against two serovars might be missing the one that could infect your dog.

2. The second concern is duration of immunity, or how long the vaccine lasts. For most of the Leptospirosis vaccines, duration of immunity varies from 3-12 months, and varies with different serovars, some creating longer-lasting immunity than others. 

3. Leptospirosis is significant because it is a disease that can be transmitted to humans. The actual protection to dogs and their exposed humans after vaccination is the third concern. Ideally, the vaccine should prevent the dog from getting infected by the leptospirosis organism. However, studies have shown that vaccinated dogs that are exposed to leptospirosis, while not necessarily getting sick themselves, still "shed" the organism in their urine. This could pose a false sense of security to dog owners and actually increase their risk of contracting the disease.

4. The safety of the vaccine has come into question. All of the vaccines have been shown to cause a hypersensitivity reaction that can last up to four years. (Personal communication with Dr. Ronald Schultz, School of Veterinary Medicine University of Wisconsin-Madison, October 2005 and November 2007)

In our experience, this disease is extremely rare in our area, and is found mostly in dogs with severely immunosuppressed systems. We have not diagnosed a case in years. 

The Feline Leukemia Virus (FeLV) vaccine remains controversial because of a serious risk posed by the killed type of vaccine and because of the lack of risk posed by the virus to adult cats. We do not recommend this vaccine for most cats. 

First, the killed form of the FeLV vaccine has been linked to tumors (fibrosarcomas) at the vaccine site. Second, the risk of contracting feline leukemia virus declines markedly after 16 weeks of age, and is extremely low, according to one prominent vaccine researcher, by one year of age. In one unpublished study, 300 susceptible cats were injected with a high dose of the virus directly into the abdomen. Only one cat developed a persistent infection. (Personal communication with Dr. Ron Schultz, School of Veterinary Medicine University of Wisconsin-Madison, December 2006.) Other studies proving the efficacy of this vaccine relied on suppressing the immune system in order for the cats in the control groups to succumb to the virus. 

The risk of contracting the Feline Leukemia Virus increases with concurrent infection with FIV (Feline Immunodeficiency Virus) and with prolonged direct contact with infected cats. For cats that go outside, this would include sharing similar food and water dishes. In other words, adult cats not only need to have marked exposure to the virus, but also need a compromised immune system to develop a persistent infection with the virus. For these and other reasons, we feel that most of our patients would not benefit from this vaccine, and might actually engender a risk from receiving it.
The Canine Influenza vaccine is a relatively new vaccine for a disease that has been recognized for a few years. Canine flu appears in most dogs like regular kennel cough. 20% of dogs can be infected with no clinical signs. 5% mortality has been documented. Deaths are from severe bacterial pneumonia and can occur in previously healthy young dogs. Pneumonia usually shows up 10-12 days after exposure.
 
It appears that infection after casual contact with an infected dog is not a major concern, as the virus is not shed at high levels and is not readily transmitted. Three to four days of continuous contact (like that seen in boarding kennels, for example), is needed for an infected dog to transmit the virus to a susceptible dog. Dogs that play in dog parks or participate in outdoor activities are unlikely to contract the flu virus in these environments.
 
After exposure to the virus, dogs start shedding the virus in secretions within 24 hours. They stop shedding the virus by 7 days after exposure. Clinical signs usually start by day 2-5 after exposure. Coughing, when present, can last for 30 days.
 
 In one study of 700 dogs, the vaccine was “reaction-free,” most likely meaning without immediate reactions like fevers and injection site pain. The vaccine has not been in widespread use as of yet to determine further side effects; and of course, like most vaccines, it is difficult to connect chronic problems with any one vaccine that has been given. This is a killed vaccine with an adjuvant (like the rabies vaccines).
 
Currently we are suggesting that clients consider this vaccine only if their dogs will be at high risk for Canine Influenza (H3N8). Outbreaks have been noted in Delaware, and are mostly from boarding facilities and shelters. Accordingly, if your dog will be boarding, showing, doing obedience trials, or being placed in other situations of prolonged contact with many dogs at once, you might want to consider this vaccine.
 
Two doses given 3 weeks apart are required for the vaccine, and immunity does not occur until 2 weeks after the second dose.
 
This vaccine, while effective at inducing immunity, does NOT prevent infection. In other words, dogs can still contract the virus and spread it to other dogs, although the amount of virus that is shed is reduced. Like the human flu vaccines, it may reduce the severity of an infection.


Many more vaccines exist and are marketed to veterinarians. We are happy to discuss any vaccines you might be interested in for your pet.

For more information on vaccinations for dogs and cats, visit UC Davis VMTH Canine and Feline Vaccination Guidelines.
 
For more information on vaccines and potential links to autoimmune diseases, visit:  www://vonhapsburg.homestead.com/haywardstudyonvaccines.html.