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10 TIPS TO HELP WITH THE CONTROL OF ALLERGIES IN HORSES

 

When a horse is found to be hypersensitive to a particular allergen, regardless of whether this is found in culicoides saliva, lurking in a dusty feed bin or is airborne such as a grass pollen, the most logical solution to prevent the horse reacting to it is to avoid the allergen in question. This sounds great in theory but in reality can prove a little more challenging. The tips below are designed to offer some both strategic and practical ideas that horse owners can implement to reduce exposure and help control the clinical signs.

Insect bite hypersensitivity

Horse in rug CircleFly-proof garments

Creating a physically barrier with fly-proof garments can be helpful. Knowing your enemy is beneficial here as certain insects will attack the belly or legs, whereas others target the ears or face. Within the culicoides species alone you find location preferences and variable clinical signs as a result. You can then provide strategic accessories to a fly rug such as ear nets, face masks, belly bands (to ensure the ventrum has no sneaky gaps) or tail covers. Make sure these fit properly as if too big or small they won’t work well and may rub, leading to additional problems. Face masks may need some tactical extra securement like attaching to the head collar (as long as this is safe to do). All garments should be changed frequently, hot weather combined with soiled material against the skin is a recipe for secondary infections.

Fly prevention

Check that fly prevention products are true repellents (>2% permethrin if this is the active ingredient) not just insecticides and also what residual efficacy they have. How much does the product adhere to the skin and will rain, sweat or UV exposure render it much less effective? Frequent reapplication is normally required. Following the manufacturer’s instructions for general good coverage, also target in particular any areas especially relevant to the flies known to be a problem. For head shy animals, and to avoid direct contact with the eyes, squirt sprays onto a cloth before application or use roll on products or creams for the head and ears to ensure this area is also well covered.

Turnout schedule

Modify the horses turnout schedule to minimise exposure to the type of flies causing the problem. For culicoides this means stabling when they are most active (dusk and dawn) but other flies are most bothersome in broad daylight, such as Stomyxs calcitrans (stable fly) or Tabanidae spp. (horse fly). Avoid fields with standing, stagnant water (slow running streams or muddy banks count too) where flies are more likely to breed. If you are in a hilly area chose the highest windiest field!

Stabling environment

You can improve the stabling environment by installing fine-mesh screens to keep insects out and also set up strong fans (if possible safely) in front of the stable, or entrance and exit points, as culicoides struggle to fly in wind. Turn lights off when possible at night as this will attract flies. Finally, consider sticky fly tape on the ceiling or fly traps which can also help you monitor the number currently hatched in your area.

General yard maintenance

General yard maintenance, such as removal of manure and also standing water when possible, disrupts insect breeding and will help reduce their numbers. Encouraging seasonal fly eating birds such as swallows and house martins is a novel approach!

 

Other environmental allergies

white horse in stable CircleIndoor allergens

If indoor allergens are suspected turn the horse out as much as possible. Source good quality forage with minimal dust and mould. Feed forage from the ground so the inhaled particles drop downwards rather than into the airways. Haylage or bagged grass is usually a better option than hay, if only hay is available soaking or steaming it will help minimise the dust.

When stabling is necessary low dust bedding for the affected horses stable and all other stables within the same airspace is a good idea (ideally they should not be fed dusty hay either). Ensuring adequate ventilation is also very important.

Storage mites

For storage mites always empty the feed from the original packaging into resealable plastic containers discarding the dust at the bottom of the bag. Clean these plastic containers regularly, again discarding any dust at the bottom and always do this before adding new feed. Keep the feed in dry, cool conditions. Wipe the horses muzzle with a damp cloth after finishing hard feed to remove any food residues.

Dust mites

Dust mites can take up residence in horse rugs so it is advised, if these have been identified as an issue, to frequently wash and dry the rugs on a hot wash ideally drying them in the sun afterwards (not always easy in the UK in winter) as mites struggle in hot/dry conditions. Old rugs are believed to often house both live and dead mites so before putting them away for the summer clean thoroughly as previously described and store individually in either an airtight container or sealed plastic bag.

Outdoor allergies

If a horse’s outdoor allergies are aggravated by the pollens of summer pastures, when the pollen count is high move the horse inside. Again the devil is in the detail, if you know what to avoid there may be certain hacks you can steer clear of while particular crops are in flower. Using a pollen net or face mask may be beneficial.

Concurrent allergies

Check for concurrent allergies. It is now thought that the allergy threshold in usually made up of multiple different allergens rather than one single allergen. The more relevant allergens you tackle successfully the better the chance of getting below the threshold and the horse becoming asymptomatic. Avoidance and reduction of exposure to allergens, while playing an important role, is usually just part of the solution in helping control allergies in horses.

If you are a veterinary surgeon and you’d like to discuss other components such as allergen-specific immunotherapy please contact us for more information.

If you are part of the veterinary profession and would like to receive regular information regarding equine allergy or other articles specific to your areas of interest then please click here.

 

Pet Allergy Week 2016 – Harvey MacKay Case Study

Harvey 3 CircleHarvey suffered from repeated bouts of otitis externa, with occasional mild dermatitis and pruritus since January 2016. He was on Prednisolone treatment that helped to control the inflammation in his ears however, his owner didn’t want him to be on the steroids long term. Therefore Harvey’s blood was sent to Avacta Animal Health for a Complete Plus allergy test during PAW in June 2016. By using the results from SENSITEST Harvey started on immunotherapy and his diet was adjusted.

Click HERE to read the full story on Harvey’s PAW success story.

 

Therapy Guide of Dogs with Skin Allergies

Therapy imageAvacta Animal Health has published its latest aid for clients – ‘Therapy Guide for Dogs with Skin Allergies.’

The DL leaflet has been design to specifically help dog owners:

  • understand the treatment choices for dogs diagnosed with an allergic skin condition
  • explore both avoidance techniques and therapies
  • manage potential flare-ups
  • consider the pros and cons of each therapy through a direct comparison

Copies of the leaflet will be distributed in May to practices who have registered for our Pet Allergy Week pack. Alternatively, a PDF version can be downloaded here.

EQUINE ALLERGY

THE GROWING ACCEPTANCE OF TESTING AND SUBSEQUENT TREATMENTS

HORSE HIVES circleBoth allergen-specific immunotherapy (ASIT), and the use of environmental serological testing as an aid to the diagnosis of atopic dermatitis, are clinically well accepted within canine practice 1. This is not currently the situation for equine allergy cases, although ASIT in horses is becoming a much more accepted and frequently conducted treatment, with the benefits discussed at the World Congress of Veterinary Dermatology in Bordeaux last year 2,3.

Dr. Yu, who presented in Bordeaux, wrote in the proceedings of the American Association of Equine Practitioners convention 2015, these take home messages; 1) “Treatment of equine allergies requires a multi-modal approach including environmental control, topical, and systemic therapy, and allergen-specific immunotherapy”. 2) “Allergen-specific immunotherapy should be considered for all presentations of equine allergies including hives, heaves, scratches, and head-shaking as it is a cost-effective weight independent treatment option that is not banned by the FEI, has minimal adverse effects, and may eventuate a cure”.4

To enable ASIT, and also allow targeted avoidance, problem allergens first need to be identified. Much of the recent literature states that either serological testing or intra-dermal skin testing are acceptable methods for equine allergen detection in atopic dermatitis, respiratory allergies and insect bite hypersensitivity (IBH).2,5,6,7

Similarly to canine allergy diagnosis, judicious interpretation of either test result is critical as Marsella (2013) states; “the single most important aspect in formulating a successful immunotherapy is not which test is used but how the allergens are selected (i.e., emphasis is placed on correlating the results with the seasonality and environmental exposure of the individual patient to increase the likelihood of including clinically relevant allergens among the ones that tested positive”)8. With the recent advent of more relevant allergens available through our serological test (UK and Northern European panel), it is hoped more horses will now benefit from ASIT.

Request your FREE Equine Lunch and Learn here.

(1) Olivry, T., DeBoer, D.J., Favrot, C., Jackson, H.A., Mueller, R.S., Nuttall, T & Prélaud, P. (2015). Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee
on Allergic Diseases of Animals (ICADA). BMC Veterinary Research, 11:210
(2) Mueller, R.S., Janda, J., Jensen-Jarolim, E., Rhyner, C. & Marti, E. (2016). Allergens in veterinary medicine. Allergy 71: 27-35
(3) Loewenstein, C. & Mueller, R.S. (2008). A review of allergen-specific immunotherapy in human and veterinary medicine. Veterinary Dermatology 20(2): 84(15)
(4) Yu, A.A. (2015). Treatment of Equine Allergies. In: Proceedings of the 61st American Association of Equine Practitioners convention, Las Vegas, 2015
(5) Fadok, V.A. (2013). Update on equine allergies. Vet Clin North Am Equine Pract. 29(3): 541-550
(6) Jensen-Jarolim, E., Einhorn, L., Herrmann, I., Thalhammer, J.G. & Panakova, L. (2015). Pollen allergies in humans and their dogs, cats and horses: differences and similarities. Clinical and
translational allergy 5:15
(7) Stepnik, C.T., Outerbridge, C.A., White, S.D and Kass, P.H. (2012). Equine atopic skin disease and response to allergen-specific immunotherapy: a retrospective study at the University of California
Davis (1991-2008). Veterinary Dermatology, 23(1):29-3
(8) Marsella, R. (2013). Equine allergy therapy: Update on the treatment of environmental, insect bite hypersensitivity, and food allergies. Vet Clin North Am Equine Pract. 29(3): 551-557

BSAVA Congress 2017

congress-2017-exhibitor-email-footer-808

Avacta Animal Health are delighted to be exhibiting at the BSAVA Congress in Birmingham from 6 – 9 April 2017. Come along to stand 808 to say ‘Hello’

Whether you want to know more about our allergy services or our non-allergy products and innovations such as our canine lymphoma multi-marker algorithm-based test, there will be someone available to answer your questions.

At our stand you have the chance to win a £100 Amazon gift card by completing the exhibition voucher in the delegate packs, and whilst you’re there you may like to show off your creative skills by entering our ‘Name the PAW Pets’ competition.

Finally, there will be the opportunity to register your interest and get an exclusive look at this year’s Pet Allergy Week pack!

We look forward to seeing you there!

REGISTER NOW – FOOD ALLERGY WEBINAR – FRIDAY 21ST APRIL, 1PM

FREE FOOD ALLERGY WEBINAR – GETTING THE BEST FROM DIET TRIALS.

Presented by Dr Tim Nuttall, BSc, BVSc, CertVS, Phd, CBiol, MRSB, MRCVS

DATE: Friday 21st April at 1pm

Equine AFR Cat AFR_ Resized 

This webinar will review the developed awareness of adverse food reactions and how these affect the skin. It seems that adverse food reactions are relatively common in atopic animals and probably underdiagnosed. Unfortunately, we’ve also learned that they are more complex than first thought; recognition, diagnosis and management of adverse food reactions can be challenging. This webinar will discuss the following:

  • Defining food allergy syndromes
  • Clinical features of adverse food reactions
  • Selecting appropriate foods using history, serology and other tests
  • How best to follow up diet trials
  • Hidden allergens in foods, novel foods and food cross-reaction
  • How hydrolysed does a food need to be?
  • The role of the gut microbiome and probiotics

We’ll present the latest evidence and do some myth-busting along the way!

This webinar is suitable for both vets and nurses that deal with food-allergic animals and their owners. To sign-up for the webinar, please click HERE

   Webinar Club logo

Avacta Animal Health 2016 Christmas opening hours

Please note over the festive period we will be closed for the national bank holidays. The customer services department and laboratory will be open for the normal working days between Christmas and New Year from 09.00 – 15.00.

All canine Lymphoma Blood Tests and Acute Phase Protein tests will be run as normal during working days.

Full working hours will resume on Tuesday 3rd January.

May we wish you a Happy Christmas and New Year from all the team at Avacta Animal Health.

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Visit us at London Vet Show 2016!

lvs-buttonWe are delighted to be exhibiting and supporting the London Vet Show holiday passport at this year’s event in its new home at ExCel. Come along to M63 to learn about our complete allergy service of tests and treatments, including our new enhanced equine allergy test.

We’ll also be showcasing our range of revolutionary multi-marker algorithm based tests, including the canine lymphoma blood test (cLBT), and you can enter our caption competition courtesy of Natural VetCare Prescribed and have your advert created in Vet Times and VN Times!

We look forward to seeing you there!

Presentation at this summer’s World Congress of Veterinary Dermatology by Avacta’s Senior Research and Development Scientist Jennifer Bexley

At this summer’s World Congress of Veterinary Dermatology (WCVD) in Bordeaux, Avacta Animal Health’s Senior Research & Development Scientist Jennifer Bexley, at her 3rd successive WCVD, presented her research on SEROLOGICAL CROSS-REACTIVITY BETWEEN BEEF, LAMB AND COWS’ MILK ALLERGENIC EXTRACTS IN DOGS, which was co-authored by TJ Nuttall, B Hammerberg and REW Halliwell (Veterinary Dermatology 2016, 27 (suppl) 7).

Here’s a summary from Professor Richard E W Halliwell and the implications this has on the selection of foods for the diagnosis and/or management of possible cases for adverse food reactions (AFR).

 

Summary: The immunopathogenesis of adverse food reactions (AFRs) in dogs is uncertain, but likely to involve both IgE and cellmediated hypersensitivity. Supporting this contention are previous studies which showed an excellent correlation between results of patch testing (which is indicative of cell-mediated hypersensitivity) and results of provocation challenges with the same antigen. Similarly, in the same study, there was a high negative predictive value of both IgE and IgG serology and results of provocation challenges – i.e. if serology was negative, then there is little likelihood of involvement of that particular food (Bethlehem, Bexley and Mueller, Vet Immunol Immunopathol, 2012, 145:582-589). These studies have emphasised the need for knowledge concerning cross-reactivity of food antigens recognized by canine patients, so that potentially cross-reacting antigens can be avoided in the selection of antigens for inclusion in hypoallergenic diet trials.

The research reported herein was conducted by scientists at Avacta Animal Health and presented at the 8th World Congress of Veterinary Dermatology in Bordeaux this June. As a first step, results of serology for food antigen-specific IgE in sera from 469 dogs with suspected AFRs were analysed for evidence of statistically significant associations between multiple positive reactions within and across related antigen groups, i.e. mammalian, avian, fish and plants. It was found that there was a far greater likelihood of multiple positive reactions occurring to antigens within the same group, rather than between antigens in unrelated groups. Reactions to beef, lamb and cows’ milk were the most strongly correlated. However, this could be the result of co-sensitisation rather than cross-reactivity. Therefore in the second phase of the study, sera that were reactive to at least two of the three antigens (beef, lamb and milk) were selected for performing ELISA inhibition studies. In these, the addition of (say) beef antigen to a serum reactive to lamb (or milk) was assessed for the ability to inhibit the reaction, thus confirming true antigenic cross-reactivity. It was found that beef and lamb were highly cross-reactive, with milk also being cross-reactive although slightly less so.

Comments: These findings have important implications for the selection of foods for the diagnosis and/or management of possible cases of AFR. Thus if dietary history indicates that beef has been fed, lamb and dairy products should also be avoided in the selection of the most appropriate hypoallergenic diet trial. Similarly, if the history specifically implicates one of these antigens, all three should be avoided.Although antigenic cross-reactivity was only proven in respect of these three antigens, the fact that positive reactions in multireactive sera were significantly associated within rather than across related antigen groups suggests that further studies will likely show additional cross-reactions within antigen groups. In the light of this it would be prudent to formulate diets that avoid all antigens within the relevant group. So if a mammalian food has been fed, the trial diet should come from the avian, fish or plant group and vice versa. Of course, if serology is undertaken, then the existence of any possible cross-reactivity in the individual patient will become evident, and dietary selection can be optimised by choosing antigens with no serological reactivity.

To rule in or rule out – that is the question…

By Mark Dunning, MA VetMB CertSAM PhD DipECVIM-CA MRCVS, Clinical Associate Professor in Small Animal Internal Medicine, School of Veterinary Medicine and Science at the University of Nottingham.

Sensitivity and specificity remain the statistical measures by which veterinary surgeons select their tests in an attempt to reach a confident diagnosis. These values are (usually) determined from ‘pure’ populations of animals with and without a particular disease using the gold standard reference test. In the ideal world sensitivity and specificity would both be 100%. This would mean that the test was perfect at both ruling out (excluding) and ruling in (diagnosing) a particular disease. Whilst this is desirable, in reality this is almost impossible to achieve. In reality what is achieved is a compromise between each measure. We will return to this concept in a future article.

Sensitivity represents the true positive rate – i.e. the number of animals correctly identified with the condition. Specificity represents the true negative rate – i.e. the number of animals correctly identified as not having the condition. Whilst applying sensitivity and specificity measures, we must remember that these have (usually) been determined in a pure population of affected and unaffected animals. This aspect must be considered in order to understand how these tests perform in particular clinical settings where the population is poorly defined……

Clearly when trying to diagnose a particular disease, we do not know whether it is present or absent, hence the reason for the test (!). Test performance becomes heavily influenced by the individual case and setting. The strengths of each measure must therefore be considered when attempting to interpret the test. So, to consider the terms slightly differently:

    • sensitive tests are best at ruling disease out (SeNsitivity OUT – SNOUT)
    • specific tests are best at ruling disease in (SPecificity IN – SPIN).

Therefore, if we want to use each test to the best of its capability we must refine our clinical approach and choose whether we want to exclude or diagnose the condition. This may seem obvious, however in many clinical situations vets are looking to diagnose a particular condition when they may be better excluding it. This is particularly true when seeing a case for the first time, as many different diseases are often being considered at this point. Unless a multitude of clinical signs are present at the time of first presentation (raising a very strong suspicion for one particular disease), a rule-out approach has the greatest strength.

It is therefore important to refine the clinical question that needs answering in order that the test result is reliable. In order to get the best out of the tests you are using it is desirable to know whether you should be trying to rule out a particular disease or rule it in. So using the little aide mémoires of SNOUT and SPIN, let’s use hyperadrenocorticism as an example:

If we consider dog 1 that is only suffering with PU/PD we would want to exclude it from our list of differentials as the likelihood of this being the cause is reasonably low when only one clinical sign is present.

If we consider dog 2 presenting with PU/PD, polyphagia, a pot-belly, lethargy and alopecia we would be highly suspicious of hyperadrenocorticism and therefore we would look to diagnose the disease not rule it out.

Under these situations, a sensitive test would be most appropriate for dog 1 whilst a specific test would be most suitable for dog 2 (SNOUT and SPIN).

We hope this helps with some aspects of your clinical decision-making and in selecting the most appropriate test for your case. This will help to avoid errors in result interpretation and ultimately misdiagnosis. We will follow this up in the next newsletter and discuss the importance of predictive values which are an essentially ‘applied’ sensitivity and specificity.