Wednesday, 18 August 2010

Treatment when skin testing

Dianne Summers of the Camelid TB Support group has asked us to post this article.

When I did my very first skin test on my herd my AHO and my vet told me not to use any treamtent on my herd between the skin test and reading date but it appears from the communication with my fellow members of the Tb Support group that not everyone is made aware of this.

Anyway, below are 2 statements from leading industry specialists experienced in Tb testing, one of them is a retired DEFRA DVM..

1. The tuberculin test takes 72 hours to work. During that time it is inadvisable to treat the animal with anything that could affect the test - this applies to any species being tested, because:
Substances that reduce inflammation may cause a positive reaction to be missed (the test produces an inflammatory response, which is then measured).
Substances that produce inflammation at the injection sites could cause a false positive reaction - and many anthelmintics etc are injected near these.
There is also the possibility that other drugs might interfere and enhance or reduce the reaction.

This applies to all species where the test is used, including goats.

It is important that we get the correct result. With camelids it is particularly important not to miss positives as many of the animals that are positive to the test are badly infected - as you know.

2. I have no first hand information as to whether goat owners were specifically told not to treat goats in between injection of PPD and reading the test. However, as a general rule we would be under instruction to avoid treatment during that time unless it was an emergency. Corticosteroids, as being immunosuppressant, would be top of the list to avoid, but NSAIDs should have no immunosuppressive effect. However, if an animal had had a
serious illness "During" testing welfare considerations would demand that treatment took place. It would then be up for discussion as to what the degree of risk was that treatment might have interfered with the test, and therefore whether any retesting was appropriate under the individual circumstances.

So there you have it - please make sure you ask your vet or AHO if you need to treat during the test - as it may affect your reading. I was told I wasn't allowed to do any treatment. I was also told to ask my vet if I needed to do any treatment 2 weeks prior to my test date as this could also affect the test. It is better to be safe than sorry. The last thing we need is a false reading. We may get too many false negatives as it is.

I hope you found this useful.

Dianne Summers
01209 822422

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