Saturday, February 13, 2010

Sat. Feb 13, 2010: Vaccination Protocols

Vet tip of the Day: Selecting Appropriate Vaccines
Key Words: West Nile, Tetanus, Influenza, Rhinopeumonitis, Encephalitis, Rabies, Strep Equi

Diseases are like brush fires.  Some smolder for awhile and are easily extinguished, others flare up and have devastating effects.  Choosing vaccinations for your horse has a lot to do with the nature of each disease we are attempting to prevent.  Toward this goal, here are the answers to yesterday's questions.  

Note: The answers about likelihood of exposure are only pertinent to horses in Northern Nevada.  Consult your veterinarian for other geographic regions.

1.     How likely is it that this horse will be exposed to Disease A?
  • West Nile:  Likely
  • Tetanus: Unlikely
  • Influenza: Very Likely
  • Rhinopnuemonitis: Very Likely
  • Encephalitis: Very Unlikely
  • Rabies: Very Unlikely
  • Strangles: Likely
2.     Is Disease A a deadly disease, such as Tetanus? (this assesses risk to this horse)

  • West Nile: Yes, 40% mortality
  • Tetanus: Yes, 80+& mortality
  • Influenza: No
  • Rhinopneumonitis: No, but high risk abortion in pregnant mares
  • Encephalitis: Yes, 85+% mortality
  • Rabies: Yes, uniformly fatal
  • Stangles: No, 10% complication rate, with fatality uncommon
3.     Is Disease A highly contagious, such as Influenza? (this assesses risk to neighboring horses)

  • West Nile: No, is not transmitted horse to horse. Disease is transmitted from infected bird, to mosquito, to horse
  • Tetanus: No, is not transmitted horse to horse. Tetanus bacteria lives in soil and usually gains access to horse through deep puncture wound that creates an oxygen free environment where bacteria can proliferate.
  • Influenza: Yes! Transmitted directly horse to horse by aerosole (cough) and direct contact.
  • Rhinopneumonitis: Yes! As for influenza.
  • Encephalitis: Moderately, disease is not transmitted directly horse to horse, but is carried from horse to horse by a "vector", which for this disease is the mosquito.
  • Rabies: No, is not transmitted horse to horse
  • Stangles: Yes! Primarily transmitted by direct contact horse to horse AND by contact with contaminated "fomites": halters, lead ropes, hands, feet, water buckets, etc.
4.     Is the vaccine used to protect against Disease A highly effective?

  • West Nile: Yes, Intervet DNA vaccine extremely safe and effective with minimal side effects
  • Tetanus: Yes, killed vaccine 95+% safe and effective
  • Influenza: Vaccines against influenza currently available are moderately effective, with relatively short lasting immunity provided. 
  • Rhinopneumonitis/Equine Herpes type I and IV: There are 2 main Equine herpes viruses that cause upper respiratory disease in horses. They are also responsible for abortion and a neurologic disease which can be fatal.  Currently available vaccines are very effective in preventing abortion, moderately effective in preventing upper respiratory disease, and of questionable efficacy against the neurologic form of herpes virus.  More discussion on this in a later vet tip post.
  • Encephalitis: Yes, killed vaccine very safe and effective
  • Rabies: Yes, killed vaccine very safe and effective
  • Stangles: The intranasal vaccine against Strep equi bacteria is moderately effective, and of all the vaccines discussed here has the highest complication rate.  We will discuss Strangles in more depth in a later vet tip post.

5.     What is the cost vs. effectiveness vs. safety value of the vaccine for Disease A?

  • West Nile: Excellent
  • Tetanus: Excellent
  • Influenza: Moderate
  • Rhinopneumonitis: Moderate, except very good against Equine Herpes induced abortion
  • Encephalitis: Very Good
  • Rabies: Excellent
  • Stangles: Fair

 With this information, consider the following:
Your horse's age: the young and the old are always more susceptible to disease
Your horse's lifestyle: travel, stress of competition, and exposure to other horses always increase the risk of disease

Now decide which vaccines you think are appropriate for your horse.

More on Monday.  Have a wonderful weekend.


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