Prevention is by far the most important means of control of venereal disease for the horse population. The most important means of preventing infection are:
No vaccines against these bacterial diseases are available.
Freedom from infection
Establishing freedom from infection before, and checking that horses remain free from infection during, breeding activities involves a veterinary surgeon taking samples (‘swabs’) from the genitalia of mares and stallions for testing (‘culturing’ and/or PCR testing) in a laboratory. The laboratory will test for the presence of T. equigenitalis, K.pneumoniae and P. aeruginosa. If the results are negative, the horse is free from infection and breeding activities may take place. If the results are positive, the horse is infected and must be treated, re-tested and cleared. The horse must not be used for breeding activities at this time. If a swab is positive for the CEMO, the Notification Procedures on page 6 also apply, and an investigation of the source and extent of the disease will be undertaken.
No horse should be used for breeding activities until or unless all swab results are available and negative.
Different types of swab and culture are recommended for different circumstances in this Code of Practice. For further information on the types of swab, taking and submission of swabs, culture and return of results, see ‘Diagnosis’ on page 13.
More detailed recommendations for establishing freedom from infection in mares and stallions before breeding activities commence, and for checking that horses remain free from infection during breeding activities, follow.
Hygiene measures
Staff should be made aware of the risk of direct and indirect transmission of infection. They should always wear disposable gloves when handling the tail or genitalia and change gloves between each horse. Separate sterile and, where appropriate, disposable equipment and clean water should always be used for each horse.
Biosecurity protocols specific to AI are described in further detail in the Guidelines on AI.
Prevention recommendations
These are minimum recommendations. Mare owners should check whether the stallion stud, boarding stud or local breeders’ association (e.g. NSFA) has any additional requirements. If so, these should be respected.
After 1st January in any year and before a mare is mated, teased or inseminated, the following should be undertaken:
• Ascertain whether the mare is ‘high risk’ or ‘low risk’ (see Appendix 2);
• Complete a Mare Certificate (see Appendix 3) and send it to the stallion owner/manager;
• Arrange for a veterinary surgeon to take the appropriate swabs (see protocol on page 10) and send them to an appropriate laboratory for testing;
• Distribute the resulting Laboratory Certificates (see Appendix 4) in accordance with the protocol on page 10.
References to swab testing means appropriate testing by culture and/or PCR testing where a laboratory is registered by BEVA for this method following satisfactory Quality Assurance testing.
If the results are negative, the mare is free from infection and breeding activities may commence. If they are positive, she is infected and must not be mated, teased or inseminated until she has been treated and cleared from infection under the direction of the attending veterinary surgeon and, in the case of the CEMO, with Defra/APHA or the BEVA Approved Veterinary Surgeon (AVS) (see Appendix 11).
Swabbing protocol for mares temporarily or permanently resident at a stallion stud (pre-breeding)
| Mare status | Type of swab | When/where taken | Culture/PCR |
| Low risk | Clitoral | Home premises or stallion stud | Aerobic and microaerophilic |
| Endometrial | During oestrus at stallion stud | Aerobic | |
| High risk | Clitoral | Before arrival at stallion stud | Aerobic and microaerophilic |
|
(not known to have been infected) |
Clitoral |
On arrival at stallion stud (at least 7 days after the previous swab) |
|
| Endometrial | During oestrus at stallion stud | Aerobic and microaerophilic |
High risk (not known to have been infected) mares usually come from countries other than UK, Ireland, France Germany and Italy, i.e. the signatories for these Codes. For high risk (after treatment for infection) mares, please see Confirmation of Freedom from Disease.
Swabbing protocol for walking-in mares (pre-breeding) or for mares being presented for AI (considered as ‘low risk’)
The following applies to mares which will not be resident on the same premises as the stallion, but will be ‘walked in’, either from their home premises or from a boarding stud. If ‘high risk’ walking-in mares are going to a boarding stud, that stud should either be under the control of, or meet full approval of, the stallion owner/manager. The veterinary surgeons involved should liaise closely to ensure adherence to the Code of Practice and to arrange any additional precautions that may be required.
| Mare status | Type of swab | When/where taken | Culture/PCR |
| Low risk | Clitoral | Home premises or stallion stud | Aerobic and microaerophilic |
| Endometrial |
During oestrus at home premises or boarding stud |
Aerobic | |
|
High risk (not known to have been infected) |
2 x Clitoral |
At least seven days apart at home premises or boarding stud |
Aerobic and microaerophilic |
| Endometrial |
During oestrus at home premises or boarding stud |
Aerobic and microaerophilic |
Protocol for distribution of Laboratory Certificates
The timely provision of acceptable Laboratory Certificates is essential to satisfy the needs of stallion stud managers. Laboratory Certificates relating to pre-breeding swabs taken from mares at the home premises should be sent in advance to the stallion owner/manager and, where appropriate, to the boarding stud. For ‘walking in’ mares, acceptable Laboratory Certificates must at least accompany the mare at the time of presentation for mating.
Certificates relating to pre-breeding swabs taken from mares at boarding studs should be sent in advance to the stallion owner/manager.
Before a mare is mated, the mare owner/manager is advised to request a Laboratory Certificate confirming the stallion’s disease-free status in the current breeding season.
Mare owners/managers should not accept semen for AI without obtaining evidence that the donor stallion was free from infection when the semen was collected. In the UK, this evidence would be provided by a Laboratory Certificate confirming the stallion’s disease-free status in the current breeding season. When importing semen, it should be accompanied by documentary evidence of freedom from infection with all three bacteria and the original import certificate.
If the mare does not conceive on first (or subsequent) matings, and her return to oestrus is normal, she should be swabbed again before being re-mated to check that she is not infected as a result of the previous mating or indirect transmission, according to the protocol below.
The mare may be re-mated on the basis of negative swab results. If the results are positive, she is infected and must not be mated, teased or inseminated until this has been investigated, she has been treated and cleared under the direction of the attending veterinary surgeon, and, in the case of T. equigenitalis, with Defra/APHA or the BEVA Approved Veterinary Surgeon (AVS) (see Appendix 11).
Swabbing protocol for mares temporarily or permanently resident at stallion stud (repeat matings)
| Mare status | Type of swab | When/where taken | Culture/PCR |
| Low risk | Endometrial | During oestrus at stallion stud | Aerobic |
| High risk | Endometrial | During oestrus at stallion stud | Aerobic and microaerophilic |
Swabbing protocol for walking-in mares (repeat matings)
The following swab recommendations apply to mares which will not be resident on the same premises as the stallion, but will be ‘walked in’, either from their home premises or from a boarding stud. If ‘high risk’ walking-in mares are going to a boarding stud, it should either be under the control of, or meet full approval of, the stallion owner/manager. The veterinary surgeons involved should liaise closely to ensure adherence to the Code of Practice and to arrange any additional precautions that may be required.
| Mare status | Type of swab | When/where taken | Culture/PCR |
| Low risk | Endometrial | During oestrus at home premises or boarding stud | Aerobic |
| High risk | Endometrial | During oestrus at home premises or boarding stud | Aerobic and microaerophilic |
Protocol for distribution of Laboratory Certificates
Laboratory Certificates relating to repeat swabs taken from mares at the home premises should be sent in advance to the stallion owner/manager and, where appropriate, to the boarding stud. For ‘walking in’ mares, acceptable Laboratory Certificates must at least accompany the mare at the time of presentation for mating. Certificates relating to repeat swabs taken from mares at boarding studs should be sent in advance to the stallion owner/manager.
If any mare returns to oestrus at an unusual (especially shorter than normal) time (in the opinion of the attending veterinary surgeon), this may be because she is infected. Repeat clitoral and endometrial swabs should be taken and cultured under aerobic and microaerophilic conditions or by PCR test.
If any mare changes stallions between matings, repeat clitoral and endometrial swabs should be taken at least seven days after mating by the original stallion and cultured under aerobic and microaerophilic conditions or by PCR test.
These are minimum recommendations. Mare owners should check whether the stallion stud, boarding stud or local breeders’ association (e.g. NSFA) has any additional requirements, e.g. requirements for microaerophilic culture or PCR testing for repeat matings.
After 1st January in any year and before a stallion is used for mating/teasing or semen collection, the owner/manager should:
• ascertain whether the stallion is ‘high risk’ or ‘low risk’ (see Appendix 2);
• arrange for swabs to be taken by a veterinary surgeon in accordance with the protocol below;
• ensure that a Laboratory Certificate (see Appendix 4) confirming the mare’s disease free status in the current breeding season, and a current Mare Certificate (see Appendix 3) are received for each mare to be mated, teased or inseminated at the stallion’s premises;
• ensure that a Laboratory Certificate confirming the stallion’s diseasefree status in the current breeding season is made available to mare owners/managers.
References to swab testing means appropriate testing by culture and/or PCR testing where a laboratory is registered by BEVA for this method following satisfactory Quality Assurance testing.
Protocol for swabbing (pre-breeding)
After 1st January and before any breeding activity is commenced, two sets of swabs (see definition on page 13) should be taken from all stallions at an interval of no less than seven days and cultured aerobically and microaerophilically or tested by PCR.
If the results of swab testing are negative, the stallion is free from infection and breeding activities may commence. If they are positive, he is infected and must not be used for mating, teasing or semen collection until he has been treated and cleared under the direction of the attending veterinary surgeon and, in the case of the CEMO, with Defra/APHA or the BEVA Approved Veterinary Surgeon (AVS) (see Appendix 11).
The following should be carried out during the breeding season to check that the stallion has not become infected:
‘High risk’ stallions and any other stallion(s) standing at a stud for the first time warrant additional precautions. The first four mares mated with them should be screened for T. equigenitalis, K. pneumoniae (capsule types 1, 2 and 5) and P. aeruginosa by taking a clitoral swab two days after mating. If the mare subsequently returns to oestrus, an endometrial swab should be taken at that time. These swabs should always be tested aerobically and microaerophilically or by PCR test.
In stallions, bacterial growth or PCR detection of T. equigenitalis is generally more easily achieved after mating. Swabbing of all stallions after their first few matings in any season should therefore be considered in conjunction with the attending veterinary surgeon. In addition, mid-season swabbing should be considered for all stallions and teasers. These swabs should always be tested by aerobic and microaerophilic culture and/or by PCR testing.
Remember: 'stallion' means mating stallions, teasers and stallions used for AI
References to swab testing means appropriate testing by culture and/or PCR, where a laboratory is approved by BEVA for this method
