Registry Services -
Genetic Disorders
HERDA
This webpage provides you information about
• HERDA – What is it? NEW
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The Genetics of HERDA NEW
• The Role of AQHA in Managing HERDA NEW
• AQHA’s New Rules Regarding HERDA NEW
•
Testing For HERDA NEW
• Frequently Asked Questions NEW
• Procedure For HERDA Testing NEW
HERDA – What is it?
Hereditary Equine Regional Dermal Asthenia, also known as Hyper Elastosis Cutis or HC
 Big words, yes, but bear with us and we shall explain as simply as possible what it all means – only bringing in science where necessary!
HERDA is a painful but rare skin condition characterised in afflicted horses by skin lesions. It most often occurs along the back, particularly the saddle area and the neck but has also been known to show up on other parts of the body, including the legs.
As with all animals, the skin of the horse is the largest organ that effectively acts as a protective multi-layered cover. The top layer of skin is called the epidermis, the middle layer, the dermis and the deepest layer, the sub cutis.
Basically, a HERDA afflicted horse’s skin has ‘faulty’ or defective fibres which act to prevent the three layers of skin binding together properly. The weakened fibres cannot stand up to any external stress or strain. Consequently, when the skin is damaged, it fails to heal properly leaving it open to infection and can in the most extreme cases ‘de-glove’ the horse - effectively skinning it alive. Unfortunately, because of the nature of HERDA and the weakened state of the fibres, the skin cannot be stitched back together.
 In most cases horses don’t show any visual signs of the disease until they are around 2 years of age and have begun their initial training. Occasionally, HERDA does become apparent earlier if an afflicted horse becomes injured in the paddock or even after it has been innocently rolling.
Tragically, there is no cure for HERDA as it is a genetic disorder. Most horses diagnosed as afflicted with the disease are euthanized because they can no longer be ridden due to the injuries they suffer whilst saddled. Anecdotally, most afflicted horses are unlikely to have an extended lifespan.
However, after extensive expert scientific research, what we DO know is that HERDA is a recessive genetic disease so both sire and dam must possess the recessive gene in order for offspring to possibly be afflicted with HERDA.
There is still a great deal of misinformation surrounding HERDA being spread within the Quarter Horse industry and this booklet sets out to provide clear and concise information.
The Genetics of HERDA
There has been considerable research into the genetics of HERDA and with the advent of reliable DNA screening it can now be decisively concluded afflicted with the disease.
Sounds confusing? Now would be a good time to explain the terminology so that the table below is fully understood.
A normal horse is a horse that carries no copies of the gene and in genetic terms is depicted as N/N.
A carrier horse is a horse that carries one copy of the HERDA gene and in genetic terms is depicted as N/Hr. It is important to note that carrier horses do not show the symptoms of HERDA.
An afflicted horse is a horse that carries 2 copies of the HERDA gene and in genetic terms is depicted as Hr/Hr. It is important to know that an afflicted horse will, at some stage, display the symptoms of HERDA and in a large majority of horses this will ultimately be fatal.
Now that we have established the terminology we will explain the various mating possibilities outlined in the table below.
When a normal (N/N) is mated with a carrier (N/Hr) scientific research indicates that 50% of the offspring will be carriers (N/Hr) and 50% of the offspring will be normal (N/N).
When a carrier (N/Hr) mates with another carrier (N/Hr), scientific research indicates that 50% of the offspring will be carriers (N/Hr), 25% afflicted (Hr/Hr) and 25% will be normal (N/N).
When an afflicted (Hr/Hr) is mated with a carrier (N/Hr), scientific research indicates that 50% of offspring will be carriers (N/Hr) and 50% will be afflicted (Hr/Hr).
When an afflicted horse (Hr/Hr) breeds with a normal horse (N/N) 100% of the offspring will be carriers (N/Hr). And on it goes….
At this point in time it is apparent that Quarter Horses diagnosed with HERDA (either carrier or afflicted) have been genetically linked to the famous American Quarter Horse sire, POCO BUENO.
The Role of AQHA in Managing HERDA
AQHA’s prime responsibilities are to act as custodian and protector of the stud book which includes responsible policy on the management of genetic disorders by providing reliable information for AQHA members and Quarter Horse enthusiasts generally.
With this in mind we have produced this booklet in an attempt to dispel misinformation currently being circulated and to give people an understanding of HERDA in ‘layman’s terms’ and how it may affect the individual and the Quarter Horse industry as a whole.
As we have already noted, there are a number of people within the industry who are spreading misinformation and causing panic without proper knowledge or research. These people are having a very negative effect on what should be a positive and proactive approach by all.
AQHA has been working tirelessly behind the scenes to facilitate testing for its members and will soon have a testing kit available at a cost effective level, which uses the same testing process as AQHA’s current DNA Testing Kit. This means that members will also be familiar with the process.
At this time, the only official statements that have been published by AQHA are those that are supported and substantiated by scientific fact and responsible rule implementation. Any further statements, or rule changes, will be made after proper investigation and evaluation. These will reflect a responsible and proactive approach whilst also taking into account the broad cross section of views that may be expressed.
In the meantime, if you are not sure – or need to clarify – any information in this booklet, please contact AQHA so we can assist you with any concerns or questions you may have.
Don’t guess – be informed.
AQHA’s New Rules Regarding HERDA
Registry Services Update - HERDA
22 January 2008
Anna Stevenson
AQHA have been successfully facilitating the HERDA testing procedure through Cornell University in the USA for the last 2 months. We have received a wonderful response from members, who have been ordering HERDA testing kits through our office for the special discounted price of $55 which AQHA negotiated with Cornell for our members. The most encouraging thing has been members ordering kits for their breeding mares, even though AQHA have not requested it at this time. This shows us that members are keen to support our steps to control the progression of HERDA and ultimately eradicate this crippling disease in Australia.
AQHA have implemented the new requirements for HERDA testing, which have come into effect since 1 January 2008. We hope that members will continue their support by adhering to the below requirements. It is important to note that horses already registered with AQHA that test positive (N/Hr or Hr/Hr) to this disease will not be de-registered. At this point all new registrations coming through for horses born in Australia that test positive (N/Hr or Hr/Hr) will be accepted for registration. Only imported horses testing positive (N/Hr or Hr/Hr) will be affected by the new HERDA requirements for 2008. Please see points below.
- Effective 1 September 2007, any horses purchased or embryos harvested overseas prior to 31 December 2007 will be accepted for Registration with the Association but will require HERDA testing not later than 31 March 2008 and have the result marked on their Certificate of Registration.
- Effective 1 January 2008, any horses purchased or embryos harvested overseas after 31 December 2007 must be tested for HERDA by 31 March 2008. Any horse testing positive to HERDA (N/Hr or Hr/Hr) will not be eligible for AQHA registration.
- Effective 1 January 2008, AQHA will only accept the results of HERDA testing facilitated by AQHA through Cornell University. Results received from testing done by members direct through Davis, Cornell or any other testing facility will no longer be accepted. If you would like to test your horse for HERDA and have the results accepted by AQHA, you must have been issued an AQHA HERDA testing kit. These are available for $55 through the office.
- Effective 1 January 2008 all stallions registered with AQHA as approved breeding sires (IBF endorsed or AQHA classified) will be required to have their HERDA status on record with the Association and printed on their Certificate of Registration by 31 July 2008. Any breeding sire without HERDA testing having been completed by this date may have Stallions Returns held or have their registration suspended form 1 August 2008 until testing has been carried out. AQHA is in the process of putting HERDA results up on the online stud book for all Classified or IBF approved breeding sires. Results for colts, fillies, geldings or breeding mares will not be advertised at this point, however members can chose to have the result printed on their horses Certificate of Registration if they wish.
- Effective 1 January 2008 all new colts and stallions going through the IBF process will be required to have HERDA testing done before they will be accepted as a breeding sire with the Association.
- Effective 1 January 2008 all new Foundation Stock recording applications will require HERDA testing on top of the already required DNA, OLWS and HYPP testing. A negative test must be achieved before they will be accepted into the Foundation recording system.
Members with breeding mares that have linage to the stallion POCO BUENO (USA 3044) are encouraged to test for HERDA so they can make educated decisions when choosing a stallion to send their mares to for the 08/09 season. AQHA would like to stress that this disease is active within all Quarter Horse disciplines and warn that HERDA testing of all breeding stock with lineage to POCO BUENO will become mandatory within the next 3 years to help put a stop to the progression of this debilitating disease in Australia.
If you have any queries in regard to the new regulations or would like to discuss HERDA or our method of testing, please contact the AQHA Registry Department on (02) 6762 6444.
Testing For HERDA
AQHA has negotiated a very favourable price for its members for HERDA testing facilitated through Cornell University in USA to test their horses. Testing kits are AU$55 including GST and can now be ordered by phoning AQHA on (02) 6762 6444, fax (02) 6762 6422 or via email to: qhorse@aqha.com.au, giving authority to debit your credit card or, alternatively, by mail with payment by cheque or money order or authority to debit your credit card. This fee includes handling and air freight of samples to the USA and management of the data in our office. Anyone who choses to test other than through AQHA from 1 September 2007, could see themselves paying extra and will not have their test results accepted.
If you have any queries in regard to obtaining a hair sample from your horse, please click here or contact AQHA on (02) 6762 6444. The sample collection process is the same as AQHA’s current DNA sampling process.
NOTE: It is CRUCIAL that you follow the instructions for DNA sampling to the letter to ensure an accurate test and result. See inside back cover for details.
Frequently Asked Questions
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Do only Quarter Horses get HERDA? |
| A: |
No. Other breeds and species have been found to exhibit a similar condition. Other breeds with some Quarter Horse bloodlines have been diagnosed with the disease including Paints and Appaloosas. Non Quarter Horse breeds, Hanoverian and Halflinger horses have also shown up as possessing the HERDA gene. In addition, HERDA – or HERDA like conditions - occur in other animals such as cats, dogs, cattle and sheep. There is even a very similar inherited skin disease seen in humans – Ehlers Danlos Syndrome (EDS). |
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| Q: |
Is HERDA contagious? |
| A: |
Absolutely not. HERDA is a genetic disorder. The disease has to be inherited from one or both parents. It is not transmitted through air or touch like strangles. |
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| Q: |
Do I have to have my horse tested for HERDA? |
| A: |
Notwithstanding the current rule changes for imports or breeding sires, no, however AQHA does recommend you have your horse tested if you have any reason to believe your horse may be a carrier or afflicted or if it affects the eligibility for registration of your horse. You may also wish to have your horse tested for your own peace of mind. |
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| Q: |
What do I do if I think my horse has HERDA? |
| A: |
Don’t panic! There are many other skin diseases that could be mistaken for HERDA. See your Vet first to determine whether a test should be taken, the last thing anyone wants is the unnecessary destruction of a young horse with some other symptomatic skin irregularity. However, if you are at all unsure, testing can either ally your fears or confirm them. |
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| Q: |
What is AQHA doing about HERDA? |
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AQHA has spent many long hours speaking to eminent and respected scientific experts regarding HERDA and has already altered its Rules and Regulations to responsibly attempt to manage and control the condition. However, it is an ongoing process and we are continually seeking further information so we can best protect and inform our members. |
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| Q: |
I have read and heard a lot of conflicting information about HERDA – who do I believe? |
| A: |
This booklet contains the most, up to date, accurate information that AQHA has currently available and should be viewed as an authoritative source. Please contact AQHA with any further queries. |
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| Q: |
Where did HERDA come from? |
| A: |
HERDA was initially diagnosed in the United States of America; however it has now been diagnosed in a number of countries including Australia. It is only coming to the fore now due to the development of a reliable genetic test and what appears to be an increase in cases being diagnosed in the United States of America. Much has been said about HERDA in the past and breeding continued without the knowledge or ability to determine the HERDA status of horses. Now, with a reliable test available, breeders can make educated decisions when planning to purchase or breed. |
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| Q: |
What can I do to prevent my horse from getting HERDA? |
| A: |
As HERDA is genetic only and not contagious, your horse cannot ‘catch’ HERDA from either a carrier or an afflicted horse. Its HERDA status will already be genetically determined. Therefore, be sure to check the breeding of your horse; look for clinical signs (bearing in mind that carriers do not display any) and have your horse tested for peace of mind. |
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| Q: |
Is AHQA going to de-register horses that are found to carry HERDA? |
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No. Deregistration is not an option as far as AQHA is concerned. However, as part of AQHA’s responsible management, we will require a certain number of horses be tested, their HERDA status printed on their Certificate of Registration and noted in the horses’ information on the AQHA website. |
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| Q: |
What are the chances that my horse carries HERDA? |
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If your horse has lineage to POCO BUENO then there is always a chance, but this chance is minimal unless there are a number of crosses of this stallion on both sides of your horses’ pedigree - the more crosses, the greater the chance. Only testing will determine for certain. |
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| Q: |
Will I be able to breed with my mare if she has HERDA? |
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If your mare is a carrier of HERDA then breeding is still possible. However, you will have to monitor what stallions you serve her with to avoid producing an afflicted foal. With a carrier mare, by avoiding mating with carrier stallions your offspring could be normal (N/N), but there is a 50% chance of their offspring being a carrier due to your mare being a carrier. |
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| Q: |
Should I avoid purchasing HERDA horses? |
| A: |
This is a personal choice. If a horse carries HERDA it will present as a healthy horse and will be able to perform in the ring and possibly in a breeding program – (once again this is a personal choice). When breeding with a horse that carries HERDA, you have to make sure the horse you mate it with is not a carrier, so it comes down to an educated and monitored breeding decision. |
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| Q: |
Should I avoid sending my mare to a stallion that carries HERDA? |
| A: |
Once again, this is a personal choice. You should avoid stallions that carry the disorder if you mare is also a carrier. If your mare is not a carrier and you put her to a stallion that is, remember, you have a 50% chance of your foal also being a carrier, which will present as a healthy foal.
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If your mare is a carrier and you put her to a HERDA carrier stallion, you have a 1 in 4 chance of getting a foal that will be afflicted, which will not be eligible for registration and may have to be put down. |
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| Q: |
My horse has been tested and is a HERDA carrier. Should I sell it or put it down? |
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This is again a personal choice. However, AQHA would not like to see healthy carrier horses euthanized. If your horse is a carrier, it will function as any healthy horse and the only way the horse can pass on the HERDA gene is if it breeds. If your horse is a breeding sire or mare, the best course of action is to ensure that it does not breed to another carrier. |
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| Q: |
My horse has been tested and is HERDA afflicted. Should I sell it or put it down? |
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This is an extremely hard question and a decision that only you can make in consultation with your vet. Life for an afflicted horse can be a painful and heartbreaking one, especially in the knowledge that the vast majority of afflicted horses will ultimately die prematurely as a result of the condition. |
AQHA’S PROCEDURE FOR HERDA SAMPLING
You will need to contact AQHA to request and pay for a HERDA sampling kit/s. Once received your HERDA testing kit/s should contain the following:
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Green HERDA hair sample card (uniquely numbered)
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Plastic snap-lock bag
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2 labels with your horse’s details
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A HERDA Identification Certificate
STEP 1 – Make sure the number in the bottom right corner of the label matched the number in the top right hand corner of the green card and that the details of the horse are correct. If the details are incorrect you will need to return the kit to AQHA to have a replacement kit issued with the correct information.
STEP 2 – Select at least 40 mane hairs well forward of the withers, or in the case of young foals, tail hairs. Wrap the hairs around your finger or a comb, as close as possible to the skin and then pull firmly and swiftly upward. This will ensure that roots stay with the hair. Remember to keep the sample dry and handle the hairs as little as possible to avoid contaminating or damaging the hair roots. It is important that the roots are attached to the hair as broken off or cut off hair is not acceptable.
STEP 3 – Place the hair shafts on the front of the green card included in your HERDA kit, making sure the hair follicles are on the right hand side and inside the area marked 1. Secure them by sticking the horse identification label vertically over the shafts of hair in the area marked 2. Trim off the excess length of hair at the area marked 3. DO NOT TRIM THE HAIR ROOTS OFF.
STEP 4 – Insert the prepared sample card into the resealable bag supplied with the HERDA kit. Ensure that the special seal is closed by firmly pressing both sides together. Insert only one card and hair sample per sealable bag.
STEP 5 – Place the sealed sample bag into an envelope, seal and post immediately back to AQHA. If you have multiple HERDA samples to send, a standard DL sized envelope can hold up to three individually sealed sample bags.
STEP 6 – Place the second HERDA identification label in the top left hand corner of the green HERDA ID Certificate supplied with the kit. You will need another person to witness you taking the hair sample. Complete the green HERDA ID Certificate fully with all the horses’ markings and details, sign the declaration at the bottom of the form and have the person who witnessed the taking of the sample also sign where indicated.
STEP 7 – Send hair sample/s and green HERDA ID Certificate/s it to AQHA, PO Box 979 Tamworth NSW 2340. If the sample is for a horse already registered with AQHA, and you are updating its registration details, you will need to send the original Certificate of Registration as well. We will update your horses’ record and registration certificate to include your horses HERDA status and send the registration certificate back to you.
If the HERDA kit is for a stallion as part of the IBF process, an Examination for Initial Breeding Fee Form must also be completed by your vet and returned to the AQHA along with the original registration papers and the appropriate fee (including GST) which is as follows:
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Initial Breeding Fee process COMPLETED prior to first service taking place – $550.00
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Initial Breeding Fee process COMPLETED after first service taking place – $2,200.00 plus $550.00
To avoid the $2200 penalty fee being imposed, please ensure your stallion has been fully endorsed as a breeding sire prior to the first service taking place.
Please note: All hair samples submitted for HERDA testing will be subject to Parentage Verification (PV), DNA comparison testing and other genetic testing.
Click here to download the HERDA booklet (PDF - 290KB).
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