Abbreviated

Codes of Practice on

CONTAGIOUS EQUINE
METRITIS (CEM)
KLEBSIELLA PNEUMONIAE
PSEUDOMONAS AERUGINOSA

EQUINE VIRAL ARTERITIS (EVA)

EQUINE HERPESVIRUS-1 (EHV-1)

---

Guidelines on

STRANGLES

These Codes of Practice aim to help horse breeders PREVENT and CONTROL contagious diseases significant to the equine breeding industry.

• These diseases are contagious and can affect ALL breeds of horse and pony. The diseases can cause sickness and abortion, and some may be fatal.
• Always consult your veterinary surgeon about implementing the Codes OR if you suspect the presence of disease, OR if you are in doubt about any aspect of these diseases.
• Whenever these diseases occur, always notify the owners of other horses which could have come into contact with the infected animal(s). This is very important to help stop the spread of infection.
• CEM and EVA are notifiable and must be reported to DEFRA by law. Your veterinary surgeon will know what to do, or can quickly find out

The full text of the Codes are available, free of charge, from:

Thoroughbred Breeders’ Association, Stanstead House, The Avenue, Newmarket, Suffolk C88 9AA.
Telephone: 01638 661321.

British Horse Society, Welfare Department, Stoneleigh Deer Park, Stoneleigh, Kenilworth, Warwickshire CV8 2XZ.
Telephone: 01926 707700.

Horserace Betting Levy Board, 52 Grosvenor Gardens, London SW1W OAU.
Telephone: 0207 333 0043, or on our Website, www.hblb.org.uk (select “Veterinary Science and Education” then “Codes of Practice”).

These Codes do not imply any liability by the Horserace Betting Levy Board, the Veterinary Advisory Committee nor the Sub-Committee in the implementation of, nor responsibility for enforcement of, the Codes.

CONTAGIOUS EQUINE METRITIS (CEM) AND BACTERIAL INFECTIONS CAUSED BY KLEBSIELLA PNEUMONIAE OR PSEUDOMONAS AERUGINOSA

1. THE DISEASE
Venereal diseases caused by the CEM organism (CEMO), Klebsiella pneumoniae and Pseudomonas aeruginosa can be very contagious. They can cause loss of fertility in the mare. Infection is spread from stallion/teaser to mare or mare to stallion/teaser during mating or teasing. The bacteria can also be spread via semen collected for Artificial Insemination (Al). Furthermore, it can be spread via human contact with horses and via equipment and water. Good hygiene practices are therefore essential - ask your veterinary surgeon for further advice.

2. SYMPTOMS
Mares: In severe cases, there is an obvious discharge from the vagina. In other cases, mares may be infected with less obvious symptoms, or with no symptoms at all. Any mares coming into season early, or breaking early in their cycle, should be viewed with suspicion.

Stallions/Teasers: Infected stallions/teasers do not usually show any symptoms at all.

3. DISEASE PREVENTION
Ask your veterinary surgeon to take swabs from your mares/stallions/teasers every year after January 1st but before starting mating/teasing, or collecting semen for Al, or inseminating semen.

The swabs should be sent to a laboratory approved by the Horserace Betting Levy Board for culture. Do not use the horse for mating, teasing or semen collection or insemination until the laboratory results are available. If the results are negative, the horse is not infected and can be used. If the results are positive, the horse is infected and must not be used for mating, teasing or semen collection or insemination until the infection has been treated successfully under veterinary supervision. Further swabs will be needed to demonstrate that the infection has cleared up.

Mare owners: do not put your mare to a stallion or teaser or accept semen for Al unless the stallion/teaser has an up-to-date negative Laboratory Certificate.

Stallion and teaser owners: do not accept mares unless they have up-to-date negative Laboratory Certificates.

Swabs Required - Mares
For most mares (‘low risk’ mares), 2 types of swab should be taken before the first mating in any year:

• ‘Clitoral swab’: samples taken to determine if the clitoral fossa and sinuses are free from infection.
• ‘Endometrial swab’: a sample taken through the cervix when the mare is in season.

A further endometrial swab should be taken when a mare returns into season again and is to be presented for repeat mating.

For ‘low risk’ mares, the stallion stud manager may, on veterinary advice, allow mating to proceed on the basis of satisfactory results from aerobic culture of endometrial swabs if adequate clitoral swabbing has already been carried out and disease is not suspected. Positive microaerophilic endometrial swab results must be reported to the stallion stud as soon as they are confirmed so that disease transmission may be limited. When a positive result is confirmed, the results of all previous swab tests conducted at the stud farms concerned must be made available for disease tracking.

Where mares have been in contact with CEM infection in the past, or have come from countries where CEM is endemic (‘high risk’ mares), 2 clitoral swabs and the endometrial swab should be taken and all results obtained and transmitted to the stallion stud before the first mating.

For definitions of ‘high risk’ and ‘low risk’, and for more detailed recommendations for mares ‘walking-in’ for mating, refer to the full Codes of Practice.

Swabs Required - Stallions and Teaser.
Swabs taken from the urethra, the urethral fossa and the sheath of the penis. Where possible, obtain pre-ejaculatory fluid too.

4. DISEASE CONTROL
Disease suspected/confirmed in main, stallions or teaser. BEFORE mating/teasing or Al:

• If the CEMO is suspected or confirmed, seek veterinary advice and notify the Divisional Veterinary Manager of the Department for Environment, Food and Rural Affairs (DEFRA, formerly MAFF) IMMEDIATELY.
• Isolate the mare or stallion/teaser and treat under veterinary supervision.

Disease suspected/confirmed in mares, stallions or teaser. AFTER mating/teasing or Al:

• If the CEMO is suspected or confirmed, seek veterinary advice and notify the DEFRA Divisional Veterinary Manager IMMEDIATELY.
• Stop mating/teasing and collecting and inseminating semen for Al.
• Isolate and treat the stallion or teaser and infected mare(s) under veterinary supervision.
• Check all other mares which may have become infected and treat as needed.
• Notify owners of mares which have already visited the stallion or teaser (including ones which have gone home) and which are due to visit him. Also notify people to whom semen from the stallion has been sent.

Resume mating/teasing and collecting and inseminating semen for Al only after the veterinary surgeon has confirmed that all infection has cleared up.

EQUINE VIRAL ARTERITIS (EVA)

1. THE DISEASE
EVA is caused by a virus. It can lead to severe sickness and abortion and can be fatal. It is spread via the semen of stallions and teasers (through natural mating and through semen used for Al), or through the respiratory route from any recently infected horse or through contact with aborted foetuses and other products of parturition.

2. SYMPTOMS
The symptoms vary. Sometimes they are obvious and sometimes none are visible at all. Those seen include:

3 DISEASE PREVENTION
a. Introduction
Preventing EVA depends on blood testing horses before use for mating, teasing or semen collection for Artificial Insemination (Al) to see if specific evidence of viral infection is present. Mares, stallions and teasers should not be used for mating, teasing or semen collection until test results are available. If a result is positive, the horse is potentially infected and/or infectious. DO NOT use it for mating, teasing or collecting semen for Artificial Insemination (Al) until your veterinary surgeon is satisfied that it is no longer infectious. In the case of a positive stallion that is a “shedder” (see below), it may be possible to obtain an official licence issued by the Department for Environment, Food and Rural Affairs (DEFRA; formerly MAFF) allowing the stallion to be used for breeding in Britain.

All blood test results should be recorded in the horse’s passport. If recording in a passport is not possible, the results should be retained securely.

After an infection, stallions and teasers may stay infectious for months, years or permanently by excreting the virus in their semen but without showing any symptoms of infection. They are known as “shedders” or “shedding stallions”.

The notes below are for horses that have not been vaccinated against EVA. For vaccinated horses, refer to the full Codes of Practice and consult your veterinary surgeon.

b. Domestic Stallions and Teaser.

• Ask your veterinary surgeon to take blood samples after 1st January but before the stallion is used for mating, teasing or collecting semen for Al.
• If the result is negative, the horse can be used for mating/teasing and collecting semen for Al.
• If the result is positive, isolate the stallion/teaser and notify the Divisional Veterinary Manager of DEFRA IMMEDIATELY. Consult your veterinary surgeon on the next steps.

c. Domestic Mares

• Ask your veterinary surgeon to take blood samples for testing within 4 weeks before mating or teasing.
• If the test result is negative, the mare can be mated.
• If the result is positive and the mare had not been previously demonstrated to be positive, isolate the mare and consult your veterinary surgeon. Ask the veterinary surgeon to take a second blood sample at least two weeks after the first one. The same laboratory should be used for the second test as the first. Consult the veterinary surgeon about the results. If the antibody titre is stable or declining, the mare is safe to be mated. For positive mares that had been previously demonstrated to be positive, refer to the Full Codes of Practice.
• If the result is positive unexpectedly, isolate all horses in contact with the positive mare; ask your veterinary surgeon to take blood samples for testing from all the in-contacts.

d. Imported Mares and Stallions (including returning ‘shuffle’ stallions)

• Ensure that the horse has tested negative for EVA shortly before it leaves the country of origin.
• When the horse arrives from abroad, place it in isolation for at least 21 days.
• Ask your veterinary surgeon to take blood samples for testing on the horse’s arrival and at least 14 days later. Use the same laboratory for the tests.
• If both test results are negative, it is safe to mate the horse (includes teasing and semen collection for Al in the case of stallions).
• If a result is positive, the rules are the same as for Domestic Stallions/Teasers and Domestic Mares above.

e. Artificial Insemination
To prevent infection, mares must not be inseminated with semen from infected stallions. The virus survives in chilled and frozen semen.
Therefore:

• If you plan to inseminate your mare with semen from a domestic or imported stallion, ensure that the stallion/semen tests at b. and d. have been carried out, with negative results, before accepting any semen.
• If you plan to import or use any chilled semen from an overseas stallion, check that the semen is accompanied by papers certifying that a blood sample was taken from the stallion and tested with a negative result shortly before the semen was collected. If the imported semen is frozen, it must be accompanied by papers certifying that the stallion or semen have been tested negative after the collection was made. Additionally, it should be tested on arrival in this country.

Under EU legislation, it is not permitted to import semen from shedding stallions.

4. DISEASE CONTROL
If EVA is suspected or confirmed in mares or stallions:

• Seek veterinary advice and notify the DEFRA Divisional Veterinary Manager IMMEDIATELY.
• Stop mating/teasing and collecting and inseminating semen.
• Stop movement of horses on/off the premises.
• Isolate all horses with symptoms of infection and all horses which have been in contact with them.
• Notify owners of all horses which are on your premises, which have recently been at your premises or which are due to visit. Also notify your breeders’ association and recipients of semen from the premises.

For further action needed, refer to the full Codes of Practice and consult your veterinary surgeon.

EQUID HERPESVIRUS-1 (EHV-1)

1. THE DISEASE
EHV-1 is caused by a virus. It can lead to abortion, respiratory disease and paralysis. It spreads via the respiratory route and from aborted foetuses and associated tissues/fluids.

2. THE SYMPTOMS
These include mild fever, coughing and discharge from the nose as well as abortion and paralysis. Mares and stallions can be carriers of the virus without showing any symptoms at all.

3. DISEASE PREVENTION
EHV-1 is a very common virus so avoiding it can be difficult. However, you can avoid individual abortions and outbreaks of abortion through good management, hygiene and vaccination.

Management
Minimise stress in pregnant mares:

• Foal them at home if possible (given adequate facilities and staff) before sending them to the stallion.
• If they are going to foal at the stallion stud, send them there at least one month before the foaling date.
• Avoid transporting them with other stock.

At the stallion stud:

• Put healthy pregnant mares in small groups, separated from ALL other horses on the premises.
• Isolate mares in late pregnancy and mares from sales yards and abroad.
• Isolate any foster mare coming onto the stud until you are sure that her foal’s death was not caused by EHV-1.

Hygiene

• Clean and disinfect stables, equipment and vehicles used for horse transport regularly; use approved disinfectants and steam cleaning.
• Separate staff should attend to separate groups of horses if possible. If not possible, deal with pregnant mares first each day.

Vaccination

• Vaccination of all mares and other stock on your premises is recommended.
  NB: vaccination cannot replace good management and hygiene.

4. DISEASE CONTROL
If a mare aborts, or a foal is born ill or dead, or a foal becomes ill within 14 days of birth:

• Seek veterinary advice IMMEDIATELY.
• Isolate the mare or mare and foal; send samples and the foetus/carcase to a competent laboratory for diagnosis, as instructed by your veterinary surgeon.
• Stop movement on/off the premises; notify owners of mares due to visit the premises.
• Disinfect and destroy bedding. Clean and disinfect stables and vehicles used for horse transport.
• Isolate all mares in contact with the suspect mare/foal into small groups to minimise the spread of any infection. NB: other pregnant mares may still abort.

If laboratory results confirm EHV-1:

• Maintain the infected mare/mare and foal and other in-contact mares in isolation and maintain the movement restrictions and hygiene measures for at least one month.
• Notify all of the following: (i) your breeders’ association; (ii) owners of horses on your premises; (iii) owners of horses due to visit your premises; and (iv) those responsible for the management of premises where horses have been sent from your premises and to which horses are to be sent from your premises (refer to the Full Code for additional requirements).

If paralytic EHV-1 is suspected in any horse: Seek veterinary advice immediately, isolate the horse(s) concerned, send samples to a competent laboratory for diagnosis and stop movement on/off the premises.
For further action needed, refer to the full Codes of Practice and consult your veterinary surgeon.

GUIDELINES ON STRANGLES

1. WHAT IS STRANGLES
Strangles is caused by the bacterium Streptococcus equi. The symptoms classically include high temperature, coughing, nasal discharge and swollen and abscessed lymph nodes of the head. The disease may be fatal if the bacterium spreads to other parts of the body. However, a nasal discharge without glandular swelling is frequently all that is observed, and the carrier state without any obvious clinical signs is also possible.

The incubation period is usually about one week but may be longer. The organism is shed from draining abscesses and the nose, and it survives in the environment and water troughs.

Direct contact with infected horses is the most important means of transmitting the disease. Good hygiene is essential in controlling the disease.

Infection can be controlled through the isolation of infected horses and shedders until they are free from infection. Shedding usually ends rapidly after recovery. However, shedding may be intermittent. Therefore, before any convalescent horse or any in-contacts of any infected horse can be considered likely to be free from infection, a series of negative nasopharyngeal swabs is needed.

2. DISEASE PREVENTION
All horses entering a stud should be monitored closely, particularly in the period soon after arrival. Any horses that develop a nasal discharge should be segregated and swabbed for the presence of S. equi.

3. DISEASE CONTROL
Spread of strangles can be limited by the early detection of shedders amongst newly affected horses and their in-contacts by taking 3 nasopharyngeal swabs at 5—7 day intervals over a 2-week period and culturing the swabs for S. equi. Three negative swabs indicate freedom from infection in the great majority of cases but not all. All young horses are most susceptible to infection and should be monitored closely.

All infected horses and their in-contacts should be placed under veterinary supervision in strict isolation with the highest possible standards of hygiene.

Horses should not enter an affected stud unless they can be kept in strict isolation from all sources of infection.

No infected or in-contact animal should be released from isolation or veterinary supervision unless 3 consecutive negative swabs have been taken over a 2-week period. Recovered cases may retain potential for carrier status in spite of undergoing 3 negative swab tests and it is recommended that the guttural pouch, sinus openings and trachea are examined carefully with particular reference to carrier status.

4. DISEASE NOTIFICATION
All confirmed cases of strangles and S. equi infection in Thoroughbreds or animals in contact with Thoroughbreds should be notified to the Thoroughbred Breeders’ Association.

It is important that nasopharyngeal swabs sample the back of the pharynx adequately. Swabs with extra long shafts and an enlarged absorbent head can be obtained from the Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU (Telephone 01638 552993).

TRANSPORT

There is potential for transmission of infectious diseases during transport.

Cleanliness and hygiene on board all forms of transport is the responsibility of the vehicle owner in private transport and the vehicle operator in contracted transport. The following notes are for guidance in either case.

• Vehicles should be cleaned and disinfected frequently and regularly, preferably using recognised viricidal disinfectants.
• Vehicles should be clean before horses are loaded.
• Prior vaccination of horses may reduce the risk of disease transmission during transport.
• When mixed loads are unavoidable, give careful consideration to the categories of horses which are transported together so as to minimise the risk (eg. risk to pregnant mares of EHV-1 infection).
• Horses should be healthy and fit to travel.
• Sick animals should not be transported except when they are traveling, under veterinary supervision, to obtain veterinary treatment. Where transport of such horses is unavoidable, they must not be put in mixed loads without the consent of the owners (or the agents) of the other horses in that load. Veterinary advice may be needed.
• If horses or their in-contacts are ill on, or shortly after, arrival at their destination, inform the transport operator at once. The operator should inform other clients with animals in the same load. Take veterinary advice on the sick horses, isolating them if necessary.
• Facilities should, if needed, be made available for cleaning/mucking out of lorries at premises where loading/unloading stops are made.

These abbreviated Codes are published annually as a supplement to the Full Codes of Practice which are also produced every year. For detailed recommendations, please refer to the Full Codes which are available from the Horserace Betting Levy Board, 52 Grosvenor Gardens, London SW1W OAU. Tel: +44 (0) 20 7333 0043; Fax: +44 (0)20 7333 0041.