The World Small Animal Veterinary Association issued a report (Recommendations on Vaccination for Asian Small Animal Practitioners: A Report of the WSAVA Vaccination Guidelines Group) and on page 15 states that:
Increasing the frequency of vaccination does not provide greater protection to an
individual animal and may increase the risk of
an
adverse reaction. In areas of high
infectious disease pressure, it is much more important to ensure that as many of the target
population as possible are vaccinated (i.e. increase herd immunity) than to increase the
frequency of
vaccinations given to individual animal.
I've outlined some of the possible side effects. There are some additional possible side effects not covered here, but I haven't had time to sort through them yet. I'll add them when I can.
Short Term Side Affects
According to the American Veterinarian Medical Association, the following side effects are common after a rabies vaccine. If they persist longer than 2 days or cause significant discomfort then go see your vet, otherwise don't worry about it.
- Discomfort and local swelling at the vaccination site
- Mild fever
- Decreased appetite and activity
- Sneezing, mild coughing, "snotty nose" or other respiratory signs may occur 2-5 days after your pet receives an intranasal vaccine
The following symptoms are rare, and the AVMA states that these
reactions can be life-threatening and are medical emergencies. Seek veterinary care immediately if any of these signs develop:
- Persistent vomiting or diarrhea
- Itchy skin that may seem bumpy ("hives")
- Swelling of the muzzle and around the face, neck, or eyes
- Severe coughing or difficulty breathing
- Collapse
The AVMA's information also matches the guidelines given by Cornell's Veterinary College.
Long Term Side Affects
Injection Site Sarcoma (ISS), previously called Vaccine Associated Sarcoma (VAS) is a particularly invasive form of cancer that is believed to form at any injection site that may have some inflammation (Woodward 2011). However, the only proven causes of ISS are prior administration of killed, adjuvanted rabies or leukemia vaccine (Wilcock 2012).
Adjuvanted vaccines have an ingredient that increases the inflammation (to force an immune response to the disease ingredients in the vaccine), and it is believed that that inflammation plays a key role in the development of sarcomas. Adjuvanted vaccines should be avoided for that reason.
The second recommendation can be applied to all injections, and that is that injection sites should be located in an area where if a sarcoma develops, it can easily be removed. That is generally recommended to be the leg (which can be amputated if a sarcoma develops), but I spoke to a vet tech earlier this year who works with an oncologist who recommends the stomach because the chest wall is easy to remove the sarcoma from.
For any injection, I generally weigh the risk of developing an ISS against whatever illness I'm treating. When my cats got a steroid shot for itch relief while the flea medication killed the cheyletiella mites, I requested it in their legs just to be safe. If I was giving fluids to a cat in renal failure, I would not worry about the chance of developing cancer in a few years.
References
Kevin N. Woodward
ISRN Veterinary ScienceVolume 2011 (2011), Article ID 210982,
Origins of Injection-Site Sarcomas in Cats: The Possible Role of Chronic Inflammation—A Review
web abstract
Brian Wilcock, Anne Wilcock, and Katherine Bottoms
Can Vet J. Apr 2012; 53(4): 430–434.
Feline postvaccinal sarcoma: 20 years later
web abstract
