Stud demands for Strangles tests....

[Alec Swan]

Late in the season, though this may be, it's being offered as a warning to others........

We own a half bred mare which was imported from Ireland as a five year old. The mare is now 14 years old. We bought her from a friend. She is booked in to visit a Stud.

The Stud owner said, as an aside, "don't forget about a strangles test". I thought little of it, until I 'phoned the previous owners and mentioned this, and the response was that the mare had contracted the disease 7 years ago. I went cold. I'm tempted to say, "If only I'd read the small print", but the print was big and bold.

The mare was blood tested and threw up a positive result. The second test showed an increased response. Now the mare needs a guttural pouch wash out and culture test. It's my understanding of the problem, from my own vet, that blood tests are rather inaccurate. The low positive first test and the increased result from the second test, could just as easily have been reversed.

The mare is displaying NO symptoms of any sort and she appears to be an entirely healthy mare.

I have no problem whatsoever with the demands of the Stud owners. If a mare of mine came back from a Stud, with Strangles, then I'd be spitting blood, and what's fit for the goose is fit for the ferret. I applaud their conscientious approach.

There is no reliable vaccine, so I'm told, for Strangles, and having looked on the websites of the more reputable Studs, they all seem to now be demanding the test. I'm just wondering how many well travelled mares are going to become a liability. It's all rather worrying.

If a horse which I owned ever passed on this dreadful disease to an innocent party, then I would never forgive myself.

I, for one, would welcome the thoughts of the more experienced.

Alec.

 

[GinnieRedwings]

Alec, the blood test shows that she has antibodies against strangles (effectively, she vaccinated herself when she got strangles 7 years ago), which basically means she is less likely to contract the disease or be a carrier - a bit like you getting chickenpox as a child and then being able to be around a child with chickenpox without catching it, and you certainly can't pass it on to anybody else because you have antibodies against it. That is all the blood test shows. A better way of determining whether she is a carrier is to do a nasal swab and culture, which tells you whether she has it NOW - which is all the stud really ought to need to know!

Another thing about strangles is that some of the healthy carriers, called shedders, have no symptoms, and can come back negative on the blood test & the swabs because they somehow have natural immunity and never actually had the disease - just carry it. Those horses are impossible to detect and this is why strangles is so difficult to erradicate, no matter what precautions the stud takes, there will be some shedders passing through their doors without anyone knowing, unless another horse becomes ill!

The gutural pouch flush is probably overkill. If she comes back with clear swabs, she is probably clear (and immune!!!).

 

[sallyf]

Nasal swabs are notoriously unreliable as it will depend on the skill of the person taking them and if they get enough discharge for a good culture.
Hence why vets such as ours (Rossdales so i trust there word)would recommend a gutteral pouch wash to get a culture.
Of all the mares that have had to be double tested coming through here only one has needed a gutteral pouch wash and culture and that came back fine.

 

[GreedyGuts]

I think it's perfectly reasonable to test all mares before allowing them on a stud. The test is an accurate indicator of previous exposure; if a mare comes back positive then, as you have found, further tests can be done to ensure that she isn't a carrier.

Presumably the stud would accept swabs instead of a guttural pouch wash, but as it requires 3 clear swabs rather than 1 clear GP wash to show a horse is clear this would be more time consuming.

 

[chestnut19]

As I understand it the strangles blood test identifies antibodies to S. equi (Strangles causing bacteria) specific antigens. Horses that have been exposed to S. equi will develop antibody titres to these antigens and have a positive result on the ELISA test.

If the test result is positive for either or both antigens (antigens A and B), the horse is likely to have been exposed to S. equi in the recent past. This does not necessarily mean that it is currently infected with S. equi and could indicate any of the following:

•Exposure to S.equi and incubation of the disease
•Acute phase strangles in which case the horse may show clinical signs such as nasal discharge or abcessation of the lymph nodes of the head or neck
•Infection with S. equi in the previous 6 months, with or without clinical signs, followed by full recovery
•Infection with S.equi in the past, with or without clinical signs, resulting in immunity to the disease in the face of recent exposure
•Past infection with S.equi which has resulted in the horse becoming a carrier

Horses that recover from infection and have no residual carrier state can remain seropositive on the ELISA test for up to 6 months (due to the time it takes for antibody levels to naturally wane). It is important to remember that the ELISA test indicates exposure to S. equi only and does not determine whether the animal is actively shedding bacteria or not. To detect bacterial shedding further testing using culture or PCR is required. These techniques can be performed on nasopharyngeal swabs or guttural pouch lavage material.

Up to 10% of affected animals continue to shed S. equi intermittently for prolonged periods after clinical signs have resolved. This 'carrier' state is probably caused by incomplete drainage of pus from the guttural pouches and/or sinuses following rupture of abscesses formed in the retropharyngeal lymph nodes at the back of the horse’s head. Over time the pus dries and with the movement of the horse’s head forms discrete bodies called chondroids that can remain in the guttural pouch for several years.

Carriers shed S. equi intermittently and may be culture negative over several weeks or even months and so the culture of wash samples collected from the guttural pouch is now considered the gold standard for carrier detection. Once identified carriers can usually be treated very successfully through the removal of chondroids using a basket snare and subsequently instilling a penicillin gel into the guttural pouch to kill any remaining bacteria.

 

[GinnieRedwings]

I think it's perfectly reasonable to test all mares before allowing them on a stud. The test is an accurate indicator of previous exposure; if a mare comes back positive then, as you have found, further tests can be done to ensure that she isn't a carrier.

Presumably the stud would accept swabs instead of a guttural pouch wash, but as it requires 3 clear swabs rather than 1 clear GP wash to show a horse is clear this would be more time consuming.

I do completely agree that it is more than perfectly reasonable for the stud to ask to know with a reasonable degree of certainty whether a mare is a carrier or not. I was just saying that the testing process is often flawed. If, as SallyF (and Rossdales) suggests (and that makes a lot of sense to me so I am feeling myself moving away from my previous statement of "overkill"), the GP wash & culture is the most reliable method of determining whether a horse is a carrier, then why bother with the blood test (which doesn't show whether a horse is incubating the disease for instance, but would show a positive result for an immune non-carrier) or the nasal swabs?

 

[GreedyGuts]

Collecting a blood sample for serology is a simple procedure in contrast to scoping a horse and obtaining GP washes, which is quite a bit more involved and costly. Swabs are simpler to collect, but to guarantee freedom from strangles with the same certainty as a single GP wash 3 swabs taken at 7 day intervals need to be cultured so quite time consuming.

Prior to the blood test becoming available studs/yards did very little to protect themselves against strangles being brought on to the premises because it was not seen as practical to do so. The introduction of the blood test enables horses to be screened for exposure, and will pick up the vast majority of horses that have come into contact with Strangles in the previous 6 months (antibody levels reduce below a cut off point in most horses after this time). I agree that the weakness of the test is that it takes about 2 weeks for horses to seroconvert so recently infected animals may not test positive. Some studs insist on an isolation period to overcome this problem.

In reality most horses haven't been exposed to Strangles in the past 6 months, test negative and are admitted to stud. The small proportion that test positive are subject to further more invasive tests to ascertain whether they are carriers. It's not a perfect test (none are) but as a relatively simple means of reducing disease transmission it works pretty well.

 

[Aredis]

Last year we sent a mare to stud and a strangles test was requested prior to being admitted.

I found it reassuring that my mare was entering an enviroment that was as safe as could be expected.

 

[Andalusianlover]

Hi there. I had to have my two horses strangles tested to take them to a livery yard. One of them tested positive in as far as he'd come in to contact with strangles at some point in his 2 year old life. I then had to have the gutteral pouch thingy done on him which came out ok, he wasnt a carrier. The vet advised me (whilst flushing out his gutteral pouches) that even if the test came back positive that one of my horses was a carrier then it could be treated with antibiotics then another gutteral pouch flush and this process repeated until the horse tested clear. I was always under the impression that once a carrier always a carrier but I was told at the time this is not the case. It could be very expensive but can be eradicated.

 

[tikino]

the stud i use does the strangles test and whenyou think how much there stallions and other stock are worth and the inpact it would have on the stud if they has strangles it is totaly reasonable to expect to be asked for the test

 

[Alec Swan]

tikino, nobody is arguing about whether horses should be tested or not. If a stud demands those tests, then that's the end of that. Conditions, are just that, and there's no argument from me.

Ginnie, Chestnut, Sally et all, thank you for your advice. The mare will come home over the weekend, for my own and competent vet to do the whole nine yards, of the guttural and cultured test. With luck, that should give us a definitive answer.

So that I can better understand the situation, one final question. Let us assume that a horse is a carrier. Would you expect her to show any outward signs of ill health? Is it possible for a horse to be a carrier, which is expelling contagious spores, whilst at the same time remaining "silent" ? ( for want of a better word).

Is a horse, which has previously been so infected, likely to erupt, and produce contagious spores, but intermittently, at say, times of stress?

Would you consider that the mare in question, who's shown NO signs of ill health, for the last 7 years, would still be a risk? and if so, then will she always be so?

Will the mare in question, be subjected every year to the tests? Why is it that this mare who has been with us for well over a year now, and lived out with two other mares, foaled, lived with those mares and foals, and still there has been nothing untoward?

One final question, has turned into about 9. I apologise!!

Alec.

 

[GinnieRedwings]

So that I can better understand the situation, one final question. Let us assume that a horse is a carrier. Would you expect her to show any outward signs of ill health? Is it possible for a horse to be a carrier, which is expelling contagious spores, whilst at the same time remaining "silent" ? ( for want of a better word).

Is a horse, which has previously been so infected, likely to erupt, and produce contagious spores, but intermittently, at say, times of stress?

I think the answer to those 2 is: yes, in theory.
What I don't know is if a guttural pouch antibiotics flush would stop that from happening.

 

[tagalog]

I know it is a pain and extra cost but the gultural pouch will show she is all clear I'm sure. I have to go through this every time with my mare. My mare tests positive, why? Not because she contracted the disease but because I gave her the vaccine that was on the market a few years ago. The vaccine was then removed from the market - why? Because it was giving some horses strangels. Don't see the pharm. comapny picking up my extra bills each year though!

 

[Alec Swan]

Chestnut 19,

having read, and then re-read your response, and in an attempt to clarify my thinking, another question. Your last paragraph, but one; "...discreet bodies called chondroids that can remain in the guttural pouch for several years". Could they remain in place for 7 years?

I asked my own vet, and I suspect that he covered his tracks with an even more Latinised response than yours. Yours, I sort of understood, his I didn't!

Further to the post of tagalog, I'm assuming that if this is going to be an annual occurrence, and that whenever I have a stud who need a Strangles test, then this particular mare will have to go through the whole routine again. I'm also assuming that a horse which has actually had the disease, can never be considered "clean", am I right?

Alec.

 

[chestnut19]

Let us assume that a horse is a carrier. Would you expect her to show any outward signs of ill health? Is it possible for a horse to be a carrier, which is expelling contagious spores, whilst at the same time remaining "silent" ? ( for want of a better word).

Is a horse, which has previously been so infected, likely to erupt, and produce contagious spores, but intermittently, at say, times of stress?

Would you consider that the mare in question, who's shown NO signs of ill health, for the last 7 years, would still be a risk? and if so, then will she always be so?

Will the mare in question, be subjected every year to the tests? Why is it that this mare who has been with us for well over a year now, and lived out with two other mares, foaled, lived with those mares and foals, and still there has been nothing untoward?

One final question, has turned into about 9. I apologise!!

Alec.

In answer to the first question, most carriers would not show any signs of ill health as they are effectively immune to the disease, so yes, they are 'silent' carriers.

In your second question your assumption is also correct, carriers tend to emit the contagious particles intermittently, although, when and why they emit them is not fully understood (I believe), and so it is highly plausible that it could be during times of stress but it may also be completely random.

If the mare in question is a carrier then yes, even after 7 years she could still pose a risk to others. However, the guttural pouch wash, with removal of any chondroids (which sometimes necessitates transendoscopic removal), followed by topical treatment of the guttural pouch with specific penicillins should cease carrier status. In some cases IV infusions of specific antibiotics have been found more effective than the topical treatment.

I would be hesitant to give a judgement on whether or not it is likely that your mare is a carrier as normally antibody levels should drop within around six months of exposure to S. equi. However, since she has been around plenty of other horses with no ill effects it seems unlikely that she is.

Horses who have had strangles and are completely clear should show up negative on the test. Carriers who have been 'cleaned' for want of a better word! should also show up negative after approximately 6 mnths post chondroid removal. I am afraid I do not know why your mare has shown a positive result so long after contracting the disease (unless she is a carrier) although I believe that it may be possible for some horses to be 'non-active' carriers, which would mean they do not shed any contagious bacteria, but further research is still being carried out on this. Hopefully there will be someone else on here who could let us know?!

 

[Alec Swan]

Right, an update!

The mare K, has had her guttural pouches washed out, and for those who've been kind enough to show an interest, I'll let you know the outcome.

Then there's the mare L. She's in foal, and is going away to foal, at the same Stud as K, and then she'll be re-covered. The same conditions apply, and guess what? She's thrown up a positive result! She will have her second BT, and if that shows an increased response, then we're back to the guttural pouch wash, with her too, and I really don't like the idea of immobilising heavily in foal mares. In fact, if that's the case, then she can stay here and foal with us.

There are no words which can adequately explain to you just how P****D OFF, I am. Isn't it so much easier, when there's some one to blame?

Rant over! for now, and I'm truly grateful to those who've taken the trouble to offer advice.

Alec.

 

[lucydelaroche]

Alec,

I'd just keep the mares at home & AI them instead!

May just require a re-think if your chosen stallions are only available by natural covering.