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  Discussion on Possitive Coggins with Rhino vaccinated horses?
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Posted on Thursday, Feb 3, 2000 - 2:57 pm:

I have been given second hand information that a horse that was recently vaccinated for Rhino tested possitive to the Coggins test - but the horse turned out to be negative? Could this be true, has there been any research on this? I am having my herd Coggins tested next week, we have a breeding operation and all of the horses are vaccinated regularily with Rhino, especially the mares - 5,7 & 9 months! Do I need to be concerned?

Posted on Thursday, Feb 3, 2000 - 4:18 pm:

Hello Lanna,
I would suggest you go to the article on EIA that Dr. O has on this site. I will try to help out what I can with information that I have available. As you probably are aware the Coggins test is a blood test for EIA (Equine Infectious Anemia). This disease is caused by a Retrovirus. Infected horses remain virus carriers for life. The infected horse is the only known reservoir for infection. Transmission in nature is via insect carriers--horseflies and deerflies are the most important. The virus may be transmitted by transfer of infective blood or blood products on contaminated instruments or syringes, that is why blood donor animals should be Coggins test negative and care with veterinary practices should be observed.
On the other hand, Rhinopneumonitis is caused by equine herpesvirus. So, you can see that the two conditions are not caused by the same virus family. Therefore, vaccination for Rhinopneumonitis is not a cause for EIA. I vaccinate all my horses for Rhino-Flu every 90 days and the mares at 5,7, and 9 months. I hope this information helps. Dr. Woodworth

Posted on Thursday, Feb 3, 2000 - 4:23 pm:

Hello Lanna,
Just a postscript to the previous message. I use "Pneumabort K" vaccine at 5, 7, & 9 months in my pregnant mares. Dr. Woodworth

Posted on Thursday, Feb 3, 2000 - 6:16 pm:

Thanx Dr. Woodworth, I realize that the two diseases are not related and that is why I couldn't understand why it would throw the test. I too, use Pneumabort K for the pregnant mares at the 5th,7th & 9th month gestation periods. Normally, I only vaccinate once before spring for everybody else with the Rhino, is that enough? You mentioned that you do it every 3 months? Also,I'm new to Coggins testing and have been unsure of whether or not to test, I've been receiving alot of negative feedback on testing, I've read the article you spoke of, could you enlighten me a little more?

Posted on Thursday, Feb 3, 2000 - 10:47 pm:

I'm not a veterinarian, but a human doctor. We frequently see "false positive" results after vaccinations of many types for reasons we can't explain. Although the viruses are different, the immunoglobulins against them (which is what the commonly used screening tests actually measure) apparently can look enough alike to confuse the test. (The most recent cases we saw were false-positive HIV tests after flu vaccine, which occured with the vaccine given several years ago). When you go back and test the blood by a different method, you find that the tests are negative (normal), and so you reassure the patient and just don't worry about it. The false-positive results are usually short-lived--just a few months--and then go back to normal. I suspect that if you did get a positive Coggins, pretty much the same thing is going on. If I'm right, doing a second test which assesses by a different method should rule out EIA, though.

Posted on Thursday, Feb 3, 2000 - 11:24 pm:

Hello Lanna,
The reason I vaccinate for Rhino-flu every 3 months is for two reasons: 1.) That is the protocol that was taught and still is recommended by Kansas State University Veterinary Medicine, where I went to school. The main reason they make this recommedation is number 2.) The effect of the rhinoflu vaccine lasts for 60 to 90 days, so horses that are competitive, (i.e. showing, exposed to other horses frequently) need this boostered regularly since they are constantly exposed to the viruses. KSU also recommends that if you have a backyard horse, (horses that do not travel to meet other horses, and do not have exposure to new horses in their environment) can be vaccinated every 6 months for rhinoflu and usually get along just fine.
I am an avid team penner and take several of my horses traveling and so that is why I vaccinate for rhinoflu every 3 months.
As to the Coggins test, I test all my horses annually because it is a simple blood test and I need the paper work in order to team pen. The test is recognized by USDA and all states and accuracy approaches 100%. I have confidence in the testing procedure. Hope this enlightens you a little more. Dr. Woodworth

Posted on Friday, Feb 4, 2000 - 8:02 am:

Oh the things you can hear on the internet! I am not judging the story Lanna, just want to remind everyone that the internet can be a bit like a fire: it can illuminate or it can burn the house down. This story is more remarkable for what we do not know than for any useful information it provides.

Even if such an occurence happened, always be supicious of the temporal (time relationship) correlation. Just because A happens before B does not mean that A causes B. Then again Dr Walker's point about increase positives on immunological tests following vaccination makes perfect sense. I do want to reiterate the Coggins (an AGID test) test is very dependable but though it approaches 100% the consequences of a positive are so serious making doubly sure is important. As far as I know all horses that test positive are retested before any action other than quarantine is taken.
DrO

Posted on Friday, Feb 4, 2000 - 11:57 am:

Dr. O--I agree with you all the way. I certainly wouldn't forego a rhinoflu vaccine for fear that a Coggins would become positive, nor would I forego Coggins testing if its indicated. My intention was to reassure that yes, you can get immunological cross-reactivity in certain instances, but that with additional testing it can be shown to be just that and no more, and need not condemn a horse if it should occur.

Posted on Friday, Feb 4, 2000 - 7:15 pm:

Dr. O--- I too agree with your statements. Also, I too would retest any horse that came up Coggins positive before I did any other action other than quarantine. Sincerely, Dr. Woodworth

Posted on Tuesday, Feb 8, 2000 - 1:39 pm:

Thank you so much, everyone for the great responses! I've since had all my horses tested yesterday & will wait approx. 10 days for the result of those blood tests. Just days before the tests, two of my mares received their 9 month Pneumobort shots and another received her 4-way vac being that she is 6 weeks away from foaling! Hopefully the information I was given is incorrect & the vaccines won't throw the test & yes, I was assured that with registered or performance type horses, they will do a second test to confirm, before any action is taken. My other concern is if one of my pregnant mares tests possitive, apparently there is a chance that the foal may not carry it, but you have to wait for the foal to be weaned and 6 months of age before you will get an accurate test? Is this true?

On the other topic, Rhino flu, I have only vaccinated once a year with that, but thank you for the info, as I plan to do it every 6 months for the horses that don't travel or have outside contact & every 3 months for the ones that do!

Thank you again for all of your information, it is nice to have a site like this to ask questions and have them answered so quickly!

Posted on Tuesday, Feb 8, 2000 - 4:26 pm:

Hello Lanna:
My answer comes from the Current Therapy in Equine Medicine text: Mare to foal transmission of EIA: Chronically infected mares--the virus crosses placental barrier. Infected mares with clinical signs of EIA will probably; (1) Be Barren
(2) Abort or (3) Give birth to an infected foal.
Now the infected mare that DOES NOT show clinical signs of EIA during the entire gestation will probably deliver a foal that is not infected.
Foals from infected mares can show a "false positive" Coggins because of colostral antibodies they received. These foals "go negative" usually by 6-9 months of age as the passively acquired antibodies are lost. This is why the wait til the foal reaches the above age.
I hope this information helps and I will be interested to hear Dr. O's comments as well.
Sincerely, Dr. Woodworth

Posted on Wednesday, Feb 9, 2000 - 1:27 pm:

Thank you Dr. Woodworth, I will let you know when I get the results of my tests! I sure appreciate all the feed back I've been getting - I will keep you informed.

Posted on Thursday, Feb 24, 2000 - 11:52 am:

Good news everyone! All my horses tested negative to the Coggins test, as well as my neighbors horses! I will now request a negative test for any mares coming in for breeding & will be more careful when buying new horses & have them tested as well! What a relief, hopefully we are one step closer to ridding horses of this disease! Thank you again for all of the advice.
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