Freedom from Disease

Next » « Previous  

Following infection with any of the three bacteria, breeding activities should only be resumed with approval from the attending veterinary surgeon, and in the case of T. equigenitalis, APHA, who must be satisfied that infected and in-contact horses have been investigated, treated as appropriate and subsequently cleared on the basis of negative swabs.


The first post treatment swabs should be taken seven or more days after treatment has ended. All post treatment swabs should be tested by aerobic and microaerophilic culture and by PCR. All positive isolates of K. pneumoniae should be capsule typed where they are identified on post-treatment samples, irrespective of whether pathogenic K. pneumoniae was isolated prior to treatment. All positive K. pneumoniae PCR results will need culture tests also performed to provide bacteria for capsule typing, unless being tested, in the same laboratory, for capsule typing by PCR test.

As PCR is able to detect bacterial DNA remnants from non-viable organisms as positive for a period of time after treatment in mares or stallions when the corresponding cultures confirm that there is no evidence of viable bacteria, consequently only the third of the set of three consecutive negative cultures will be required to also test negative by PCR. Experience in various parts of the world from treating CEMO in mares and stallions, highlights that this may predispose to subsequent colonisation by K. pneumoniae or P. aeruginosa and, therefore, it is very important that screening post-treatment of one type of infection continues to include swabbing and testing for all three pathogens. It is emphasised that endometrial swabs, which are required for confirmation of freedom from disease, can only be successfully collected when the mare is in oestrus.

Mares

Starting not earlier than seven days after cessation of treatment for infection has ended, three clitoral swabs should be taken at intervals of at least seven days. For K. pneumoniae (capsule types 1,2 and 5) or P. aeruginosa two endometrial swabs should be taken during two oestrous periods and tested by both aerobic and microaerophilic culture and by PCR tests, but for T.equigenitalis three endometrial swabs should be taken during three oestrous periods and tested by both aerobic and microaerophilic culture and by PCR tests.

In respect of maiden mares whose pre-screening clitoral swab only (i.e. endometrial swab negative) was positive for P. aeruginosa, pre-treatment, three clitoral swabs must be taken but only one endometrial swab (taken in oestrus) is required. All swabs should be tested by both aerobic and microaerophilic culture and by PCR tests.

For mares to be considered to be free from disease, three consecutive sets of swab samples should all have returned negative culture results and at least the last of these must also be negative by PCR.  If any result is positive, further investigations should be undertaken in conjunction with the attending veterinary surgeon and for T. equigenitalis with Defra/APHA or the BEVA AVS (see Appendix 11).

 

Stallions

Starting not earlier than seven days after cessation of treatment for infection, three sets of penile swabs (see Diagnosis – types of swab) should be taken at intervals of at least seven days and tested by aerobic and microaerophilic culture and by PCR tests and negative results confirmed. All results in treated stallions must be negative before any breeding activities resume.

For treated stallions to be considered to be free from disease, three consecutive sets of swab samples should all have returned negative culture results and at least the last of these must also be negative by PCR.

Thereafter, the first three mares mated naturally by the stallion should have clitoral swabs taken three times at intervals of at least seven days, starting two days after mating and tested by both aerobic and microaerophilic culture and by PCR tests. If any result in the mated mares is positive, breeding activities should cease again immediately, and further investigations should be undertaken in conjunction with the attending veterinary surgeon and, for T. equigenitalis, with Defra/APHA or the BEVA Approved Veterinary Surgeon (AVS) (see Appendix 11). For stallions intended solely for semen collection for artificial insemination, in addition to the set of penile swabs confirming freedom from infection, raw semen (i.e. with no semen extender and/or antibiotic added) should also be collected and tested by both aerobic and microaerophilic culture and by PCR tests, with all negative results confirmed before any semen is used for artificial insemination in mares.