Click on the Babel Fish to translate this page into French, German, Spanish, Italian or Portuguese   Click here to load a tiny floating currency exchange calculator, that will move with you from page to page.  Handy little gadget!   : )

Buckskin Tennessee Walking Horses
Custom Search
Contagious Equine Metritis (CEM) is a transmissible, exotic, venereal disease of horses caused by the bacterium Taylorella equigenitalis. Thoroughbred horses appear to be more severely affected by the disease than other breeds. Because animals may be asymptomatic, the disease is difficult to detect and control. There is no evidence that CEM affects people.

CEM is a serious disease because it is highly contagious. When coupled with the fact that mares can be bred only during certain seasons, CEM can have a devastating effect on equine reproductive efficiency. Should CEM become established in the United States, the horse industry would suffer great economic losses.


The first case was diagnosed in England in 1977. Because of the insidious nature of the disease, it is difficult to determine its origin or how widelyit is distributed throughout the world. Countries known to be affected with CEM include Austria, Belgium, Bosnia-Herzegovina, Croatia, the Czech Republic, Denmark, Finland, France, Germany, Great Britain, Greece, Guinea-Bissau, Ireland, Italy, Japan, Luxembourg, the former Yugoslavian republic of Macedonia, Montenegro, the Netherlands, Norway, Serbia, the Slovak Republic, Slovenia, Sweden, and Switzerland.

The first cases of CEM in the United States were diagnosed on March 9, 1978, on thoroughbred farms in central Kentucky. In April of the following year, an outbreak occurred in Missouri. The disease was rapidly eradicated from both States and has not subsequently been found in the U.S. horse population.


CEM is commonly transmitted directly during sexual intercourse between undetected CEM positive breeding mares and stallions. Transmission may also occur indirectly by artificial insemination or contact with fomites, such as contaminated hands or instruments. Outbreaks usually occur at breeding facilities following international horse shipments.

Undetected carrier mares and stallions are the source of infection for acute outbreaks of the disease. During the breeding season, a carrier stallion may infect several mares before the disease is suspected or diagnosed.

Clinical Signs

Initial exposure to the disease usually results in infertility. An infected mare may fail to conceive (revealed by an early return to estrus after breeding) or she may spontaneously abort. Abortions related to CEM are rare, however. Stallions exhibit no clinical signs but can carry the CEM bacteria on their external genitalia for years.

There are three general degrees of infection in mares.

  • Acute: Active infl ammation of the uterus causes an obvious thick, milky, mucoid vulvar discharge 10 to 14 days after breeding.
  • Chronic: Milder uterine inflammation causes less obvious vulvar discharge, and infection may be more difficult to eliminate.
  • Carrier: The bacteria are established in the reproductive tract. The mare, though asymptomatic, is still infectious and can remain a carrier for several months or longer.


Two of the most common genital infections in mares are caused by Klebsiella and Pseudomonas spp. bacteria. Differentiating these infections from CEM cannot be reliably done except by laboratory isolation of T. equigenitalis.

Swabs for bacteriologic cultures from mares are taken from the cervix or endometrium of the uterus during estrus, clitoral fossa, and clitoral sinuses. Swabs from stallions should be taken from the penile sheath, fossa glandis, and urethral sinus. Bacterial samples must be delivered in Aimes transport medium (with charcoal) under refrigeration (4 to 6 °C) to an approved laboratory within 48 hours.

In mares, various serologic blood tests may be used to detect antibodies to the CEM bacteria. In stallions, detectable antibodies do not develop.


The mare cannot be successfully treated until the CEM bacteria clear from the uterus, a process that may take several months. The external genitalia of the mare and stallion can be treated with disinfectants and antibiotics. Once daily for 5 consecutive days, the external genitalia should be gently scrubbed with 2-percent chlorhexidine in a mild detergent solution and rinsed with warm saline. The external genitalia should then be coated with an antibiotic ointment, such as nitrofurazone. Due to the effectiveness of this treatment, surgical removal of the clitoral sinuses is rarely required.

Prevention and Control

  • Quarantine and test all imported fillies, mares, and stallions of foreign origin, and mares and stallions not previously bred in the United States that are older than 731 days (2 years).
  • Quarantine and test the first three mares bred to a stallion of foreign origin.
  • Quarantine all suspects until all test results are negative.
  • Avoid breeding any CEM-positive horses until they have been successfully treated and certified CEM negative.
  • Maintain strict hygiene when handling mares and stallions (e.g., use disposable gloves, change gloves between horses, and thoroughly clean and disinfect instruments).

Report Suspicious Cases

Veterinarians and equine owners who suspect an animal may have CEM or any other foreign animal disease should immediately contact State or Federal animal health authorities.

For more information, contact
U.S. Department of Agriculture
Animal and Plant Health Inspection Service
Veterinary Services, Emergency Management
4700 River Road, Unit 41
Riverdale, MD 20737
Telephone (301) 734–8073
Fax (301) 734–7817

Current information on animal diseases and suspected outbreaks is also available on the Internet; visit the APHIS Web site at

The U.S.Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, largeprint, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720–2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326–W, Whitten Building, 1400 Independence Avenue, SW, Washington, DC 20250–9410 or call (202) 720–5964 (voice and TDD). USDA is an equal opportunity provider and employer.

“Doc – What’s the Fuss About Some Disease Called C.E.M.?"
© A.J. Neumann, D.V.M.
published in The Draft Horse Journal, Summer 2000
Most of us who read the DHJ pay little or no attention to what might happen to our horses, should certain governmental agencies of the U.S. Dept. of Agriculture fail to be alert in performing their duties as required by law.

Having stated that, let me explain a little about what you have just read.

There are many diseases of livestock, including horses, which are found in some foreign countries. Were they to be introduced into our animal populations, they would utterly devastate and destroy our livestock operations.

Most livestock people have heard or read about foot-and-mouth disease, which infects cloven-hooved animals. It has been reported in the U.S. several times and has been stamped out by a vigorous control program, including quarantining animals in the affected area and slaughtering them. The disease, itself, can be found endemic in many countries, including some in our own hemisphere. It is found in Mexico, where outbreaks occur from time to time, and the U.S. Department of Agriculture works with the Mexican government in controlling the disease. If it should spread into the U.S. and become established in the cattle, sheep and hog populations, it would be devastating to the numbers of these species.

The same can be said for Venezuelan Equine Encephelomylitis or V.E.E., which appeared in Texas a few years ago, apparently coming from Mexico. It is a highly fatal disease of horses. Stringent steps were taken by state governments to ban the import of horses from the stricken areas, and vaccination efforts were undertaken to produce immunity against the disease in those horses living in or near these afflicted areas. Often states will cooperate with the Federal government in the control or abolishment of these diseases when they are introduced accidently from some outside source.

It is the job of certain agencies of the U.S. Department of Agriculture to monitor the presence of some of these diseases in foreign countries and to quarantine and test them in animals such as horses, imported into the United States. That is simply why horses which are imported must spend a given amount of time undergoing testing and surveillance at quarantine areas so designated upon arrival in the States from some other point of origin. This fact is often resented by the purchaser of the quarantined horse or horses, since the period of quarantine may last for many days or several months, depending on the animal’s origin and the disease-screening process.

Everyone involved in this process of quarantining a horse must realize that even though it is a lengthy and expensive one, it serves the best interests for the horse industry by possibly keeping out a disease which could ruin the entire horse business.

As I have mentioned before, individual states also have laws regarding importation of horses into their territories. Occasionally states will pass laws, when the emergency arises, banning the importation of animals from other states where a disease is known to exist in their stock.

There are some diseases of the horse, which are found in parts of the world, which we never want to import into the country. For any reason we do not want these conditions to become established in our own equine populations. To list a few, they are: Glanders; Dourine; African Horse Sickness; and Contagious Equine Metritis or C.E.M.

A veterinarian in the course of a month’s time will receive a good many pieces of literature or bulletins from colleges of veterinary medicine, veterinary periodicals, and reports from various federal and state governmental agencies, all dealing with information regarding diseases and conditions of animals, their treatment, and their occurrences in the states and country as a whole.

In the past several months there has been quite a bit of information released about Contagious Equine Metritis and its importance to the equine industry. This has been prompted by the very recent discovery of some stallions with C.E.M., which were imported into this country, and a C.E.M. positive-test mare found at an approved C.E.M. quarantine facility in Florida. Apparently the infected mare had been test-bred by a stallion which had just recently been imported from Germany.

As a result, the state of Florida has announced some additional testing on all breeding-age stallions and mares being imported from countries where C.E.M. is known to exist. This is in addition to testing being done at the Federal level at their own quarantine stations.

Contagious Equine Metritis (C.E.M.) is a true sexually transmitted disease of the horse and ass family. It is generally held that there are only two other sexually transmitted genital infections of these species. One is a Klebsiella infection and the other a Pseudomonas infection of the genital tract.

C.E.M. is caused by a coccus-type bacteria sporting the grand name Taylorella equigenitalis. This disease is found today in about 25 countries, including most nations of Europe. The very first outbreaks in 1977 appeared on stud farms in Ireland and England. Two outbreaks occurred in this country in 1978 and 1979. They were in Kentucky and Missouri, and, I believe, involved Thoroughbreds which were traced back to carrier stallions which had been imported from somewhere in Europe. At that time very stringent methods were adopted by federal and state agencies, and the disease was eradicated. The U.S. has been free of the condition until these cases were discovered as the horses entered quarantine facilities in the United States (federal) and Florida (state).

Most countries with C.E.M. have control programs in place which try to detect breeding animals which are infected and, therefore, prevent the disease from spreading. To our credit we have rigid import regulations and quarantines for those horses coming from countries which are deemed not to be C.E.M.-free.

This disease, where it flourishes, is very economically devastating to the equine industry. It happens like this: an infected stallion, who, by the way, shows no symptoms of the ailment, will breed a mare. Two to ten days later the mare will have developed an infection of the vagina, the cervix, and the lining of the uterus. These are known as vaginitis, cervicitis, and endometritis, respectively. The mare will also exhibit at this time a very nasty so-called muco-purulent discharge.

Of course when this happens, the conception rate plummets, as much as 50 percent or more. Some mares will recover on their own and conceive upon a later breeding. Other mares may show little or no signs of the infection, but will probably be infertile for a while.

In any case, many of these so-called recovered mares will be carriers of the ailment for several months or longer. The clitoral sinuses and fossa will harbor the infection for a long period of time, and these mares will show no clinical symptoms of the disease.

The diagnosis of the condition is based upon recovering the causative bacteria from the cervix, uterus, endometrium, or the clitoral sinus or fossa. Collection and growth of the bacteria are not easy procedures, so there is some room for a margin of error. With the present culture techniques it is feared that some carriers may slip through the net and go undetected.

Antibodies against the bacteria which are circulating in the blood can be detected by any one of several serological tests. However, these tests are not 100 percent accurate, so they seem to have a limited value, especially in diagnosing the chronic carrier.

Another test to detect the presence of the causative bacteria, using a polymerase chain reaction, may be the best yet. It has only recently been approved.

At the present time all horses imported into the United States from countries with C.E.M. are quarantined. Three negative samples taken seven days apart from the endometrium, clitoral fossa, urethral fossa, and cervix, for the presence of T. equigenitalis, are required. At least one set of samples must be taken from the quarantined mare at the time of estrus.

The pregnant mare is kept in quarantine until she delivers. Upon delivery she must have three negative culture samples at seven day intervals, the same as other mares, in order to be released from quarantine.

Stallions from countries with a C.E.M. problem must be quarantined upon arrival in the U.S. for at least 45 days. Cultures are taken from three areas: the prepuce, urethral fossa, and the urethra. They must test negative for the causative bacteria.

In addition to the above cultures, the stallion is required to breed three mares, and they, in turn, must have negative cultures on the three different occasions taken seven days apart. For the trial mares this same procedure as described previously for the quarantined mares.

Now, one can understand why the authorities in Florida were disturbed and announced additional testing requirements for all breeding-aged stallions and mares imported into Florida from countries affected by C.E.M. No one in his or her right mind wants an infected stallion or mare to slip through the tests and be dumped out into our horse populations.

Florida’s C.E.M. emergency rule, which has been put into place, requires imported mares to have additional testing over and above the federal tests. Not only are there more tests, but there are also more culture locations. Also, the post-breeding test of most mares has been extended from 15 to 21 days.

In addition, C.E.M. serological testing must be done on the first three mares bred to stallions after their release from quarantine.

With this emergency rule in place and operational it should make the possibility of a carrier mare or stallion much less likely to slip through the screen undetected.

I decided to write this article for two reasons, the first being that I wanted to demonstrate how some of our governmental agencies are working hard to protect the livestock industry, including the horse business. We often do not realize what a responsibility the men and women who work in these agencies have resting on their shoulders. A mistake on their part could cost, in this case the horse industry, millions, if not billions, of dollars in losses.

Many draft horse breeders today are entering the “warm-blood” market, and raise draft-Thoroughbred or draft-Morgan or draft-Quarter Horse crosses, to name a few. Even though many animals of the draft breeds are not imported, I am sure there are plenty members of the so-called “hot blood” breeds that are. So a draft breeder could get caught up with C.E.M. by purchasing an imported stallion or mare of some “hot blooded” breed.

The second reason is that in the last two months I have just clocked 18 phone calls and letters, mostly from subscribers to the DHJ, who have asked about C.E.M. Among the 18 received is a page from the Florida Market Bulletin by the Florida Department of Agriculture and Consumer Services with the following headline: “Disease testing increased–Florida moves to protect horse industry.” Then there follows a discussion of C.E.M. Well, guess who sent it. None other than Mr. Lynn Telleen, the editor of the DHJ!

I will say, I had most of the reading and research done for this article when his letter arrived.

I hope I have answered most, if not all, of your questions about Contagious Equine Metritis. And it’s sure great to report that there are some real dedicated government employees out there watching out for the horse and mule industry!

Canada has just announced restrictions on the importation of semen and horses due to the CEM disease. They announced it this morning, January 20, 2009.

DEFRA Report on CEM
Silobreaker: North Dakota Mare Exposed to CEM Disease
DeGraff Stables - CEM Outbreak & Updates
The Horse: Prevent CEM, Other Infectious Diseases Through Strict Hygene Practices
DHJ:: Doc– What’s the Fuss About Some Disease Called C.E.M.?"
Defra, UK - Disease surveillance and control - Notifiable diseases
Canadian Food Inspection Agency - Animal Health - Disease control
contagious equine metritis - Intute: Health and Life Sciences
CEM - STD of Horse World | NowPublic News Coverage
CEM Investigation Underway | Blog
Northern Broadcasting System - AGRICULTURE - Headlines - MT AND ND
Texas Among 27 States Testing Horses for Contagious Equine Metritis
CEM contagious equine metritis: a transmissible disease with international implications.
Review of Common Horse Diseases - Symptoms and Treatment
Beginner Basics
Breeder of Buckskin Tennessee Walking Horses
Jim Holmes
113 Cty Hwy 840
Sikeston, Missouri 63801
Cell 573-620-0784
Email Holmes Farm 
Directions to Our Farm
  Last Updated: December 28, 2016  
  Website maintained by
Website designed by
Website & Graphics Copyright 2005© by Thunder Valley  Walkers.

eXTReMe Tracker