Timely vaccinations are very important part of pet's health. Different types of vaccine shots are to be given at different times. Some people are against vaccination and some are in favor of vaccination, but the assertion is that there are risks involved with both. A firm statement cannot be passed on a broader level, instead the rules vary from one individual animal to another depending on the needs and tolerance levels of the animal. There are certain factors based on which the decision must be taken.

Young ones which have been separated from their mothers before six weeks and are bottle-fed are at a higher risk of getting diseases. This is because the animals, which feed on their mother's milk, get maternal antibodies, which protects them until their own immune system has been fully developed. The development of immune system can differ on the basis of amount and type of viruses they are getting exposed to, the potency of the virus and the body's ability to face the virus attack. Diet and nutrition also plays an important role in preventing diseases.

Animals, which aren't exposed enough also needs to be vaccinated so as to alter the system and help develop it, without causing illness. The quantity is also important, because a little more virus can actually infest the disease in the animal. The amount can be determined by analyzing whether the animal has a weak or strong resistance to the virus.

Age is also another important factor. Animals, which are older in age, react differently. One of the reasons is that the system will be obviously weaker because of the daily activities, when compared to the younger ones. Sine their immune system would have undergone different conditions; there could be a possibility of deposition of toxins in the body. Sometimes the healthier older animal won't be requiring vaccination at all if it has received adequate shots before.

Before vaccinating an animal, its history should be checked. The number of times a particular vaccination has been given should be checked against the records. There are breeders who give a weekly dose of vaccination to their animal, which is for sure an over dose. This leads to many problems such as thickening of blood because of the protein complexes released from the immune system. This can also damage other internal organs and might even result in the failure of the immune system. In worst circumstances, it could even lead to the death of the animal.

Pregnant females react differently to the vaccines when compared to their male and female counterparts. The pregnant females should never be injected with live virus vaccines or even exposed to other animals that have recently received them. Animals, which have been injected with dead-virus vaccines, are safe for the childbearing animal.

Animals, which are already suffering from a disease, should be examined more carefully, so that the vaccination doesn't aggravate the problem. Genetics also plays an important role. If the animal stands a chance of getting a disease because of hereditary reason, vaccinations can create an adverse reaction.

The environment also plays a major role. If the animal is kept in a sanitary and clean place, it is exposed to lesser viruses, which lowers it's chances of getting diseases. A dirtier environment not only spreads viruses and bacteria but also affects the immune system and other systems adversely as toxins begin to deposit in the body. The vaccination plan should be designed after analyzing the lifestyle of the animal.

Another major reason for difference in the quantity of vaccination is the improvement in the vaccinations itself. They have become safer and more efficient. No tests have proved the affective period of the vaccinations. Every state and country has different regulations about vaccination. Vaccination testing cannot only risk the life of the animal, but as well as that of a human.

For example, if a dog, which is being tested for rabies vaccination, bites a human, it can lead to the death of the human, in extreme circumstances. Many states in the United States demand vaccination when owners try to get permit for exotic animals. The facility vet decided which vaccines should be given and which should be exempted for the safety of the animal.