Laboratory diagnosis is essential to confirm the presence or absence of T.equigenitalis, K. pneumoniae and P. aeruginosa in swabs taken from mares and stallions.
Types of swab
There are two types of swab:
Clitoral swab: taken from two sites; the clitoral fossa and the clitoral sinuses, at any point during the reproduction cycle to demonstrate whether these sites are free from infection. In the case of pregnant mares who have had difficult foalings requiring veterinary attention and antibiotic treatments, additional clitoral swabs should be taken after foaling and more than 7 days after antibiotic treatment has finished, in addition to routine endometrial swabs, in order to rule out acquired P.aeruginosa and K.pneumoniae infections. Providing the pre-foaling clitoral swab was certified negative for T.equigenitalis, the additional post-foaling clitoral swab may be tested by aerobic culture only, or by PCR.
Endometrial swab: taken during oestrus from the lining of the uterus via the open cervix to demonstrate whether the uterus is free from infection.
Mare swabs taken for disease prevention purposes should be tested according to the recommendations in the Prevention section.
Note: These are minimum recommendations. Mare owners should check whether the stallion stud, boarding stud or local breeders’ association (eg NSFA) has any additional requirements.
Swabs should be taken from three sites; the urethra, urethral fossa and penile sheath, plus pre-ejaculatory fluid when possible. Separate swabs should be used for each site and tested by aerobic and microaerophilic culture and/or by PCR, in all circumstances.
All swabs should be taken by a veterinary surgeon, who should:
A list of laboratories in the UK, Ireland, France and Germany registered with BEVA for the purposes of testing for T.equigenitalis, K. pneumoniae and P. aeruginosa is available from the BEVA website.
Submitting swabs to BEVA Registered Laboratories
The Registered Laboratories must set up swabs for conventional microaerophilic culture for T.equigenitalis within 48 hours of them being taken from the horse as this organism is short lived, even in bacteriological transport medium. Veterinary surgeons submitting swabs by routine postal services are, therefore, advised not to take swabs on Fridays, Saturdays or Sundays as they may not arrive in time. If weekend or bank holiday swabbing is unavoidable, the veterinary surgeon should ensure that the laboratory is open and able to commence cultures within the 48 hours. In this event, a suitable courier service should be used to deliver the swabs. If a swab does not arrive in time, the laboratory should reject it and advise the veterinary surgeon to repeat the swabbing.
However, time constraints do not apply to swabs submitted to laboratories that are registered to run PCR tests for T.equigenitalis as specific DNA from non-viable organisms can be detected for long periods. Experience suggests that swabs cultured aerobically for K. pneumoniae and P. aeruginosa are not so time sensitive and these organisms have a long life in bacteriological transport medium, as they do in the environment.
Laboratory culture of swabs
Laboratories can culture swabs in two ways: aerobically and microaerophilically (see Glossary, Appendix 10). The results of culture will be returned by the laboratory on an official Laboratory Certificate. When planning the timing of breeding activities, breeders and veterinary surgeons should be aware that the results of microaerophilic culture results will not be available for at least seven days and aerobic culture results will not be available for 48 hours (to exclude the possibility of slow-growing P. aeruginosa organisms).PCR tests do not have these delays.
Other laboratory tests for T.equigenitalis
Polymerase chain reaction (PCR) testing of swabs for T.equigenitalis, K.pneumoniae and P.aeruginosa is now validated for industry screening purposes. PCR testing is not recognised for import/export testing in the UK. Breeders and veterinary surgeons may find PCR test results helpful, as they may be available within 24 hours of arrival at a laboratory that is able to undertake PCR testing. Positive PCR results will need to be further investigated by conventional culture to help determine their significance and, in the case of K.pneumoniae, for capsule typing unless being tested, in the same laboratory,for capsule testing by PCR test. Positive PCR results for T.equigenitalis must be reported to Defra. The immunofluorescence test (IFT) for T.equigenitalis, which is available only in France, is not acceptable on its own, although it may be used in addition to culture.
Note: The term 'at risk' relates to any horse which may have become infected as a result of direct or indirect transmission of the disease.
References to swab testing mean appropriate testing by culture and/or PCR, where a laboratory is registered with BEVA for this method.
Further information on how to collect equine genital swabs in stud practice for the prevention of venereal diseases, as recommended by the Codes of Practice, is available here.