Is it possible for a horse to get Lyme disease from eating a tick with his pasture grass, or from eating an infected tick or other source of the bacteria in his hay or feed?

I have checked with two colleagues here at the Gluck Equine Research Center, and we all believe that a horse would not contract infection following ingestion of a tick infected with Borrelia burgdorferi, the bacterial causal agent of the Lyme disease, or from eating a portion of an infected mouse (which could have been baled into his hay).

It is very probable that B. burgdorferi needs to be introduced either into the subcutaneous (just under the skin) tissue or directly into the bloodstream for the parasite to be successful in establishing infection in the horse. The latter is probably facilitated by various factors in the secretions of the tick's salivary glands, which are introduced at the site of attachment of the tick.

Since B. burgdorferi, like many other spirochetes, is not a highly resistant organism in the environment, it would probably be killed by the fluctuations in pH (acidity) in the stomach and small intestine and the effect of the respective digestive enzymes in the proximal gastrointestinal tract