Should my horse get a strangles vaccine?

Most horse people are familiar with the dreaded “s- word”: strangles. But if there is a strangles vaccine available, why isn’t vaccination essential for all horses, like the rabies vaccine?

What is strangles?

Equine strangles is caused by infection with the bacteria Streptococcus equi var equi, causing mild to severe upper respiratory infection. Complications from infection can occasionally be fatal, but most horses fully recover. Strangles is a high morbidity disease, meaning it is extremely contagious in susceptible populations.  Proper biosecurity measures are crucial to limit the scope of an outbreak.

Pony with Strangles shows swelling from abscessed lymph nodes

Signs of strangles include fever, swelling of the lymph nodes (especially in the throat latch area), loss of appetite, cough, and significant mucoid yellow nasal discharge. The bacteria mobilize to the lymph nodes and causes intense immune response, so frequently these lymph nodes abscess open and drain. The term strangles originated from the harsh respiratory noise heard when severe swelling and lymph node abscesses can impair the horse’s ability to breathe.

Most infected horses respond well to supportive care. Supportive measures include anti-inflammatories, hot-packing of abscesses, and rest. More severe cases may benefit from hospitalization and antibiotics. To prevent the spread of strangles, hospitalized cases are managed in the isolation unit.

How does strangles spread?

Strangles is easily spread by horse-to-horse contact and via contaminated surfaces, such as handler clothing and hands, grooming equipment, and water troughs. Most horses will clear the infection within 3-6 weeks, but it is possible for some horses to recover fully and remain shedders of strangles. These horses appear healthy but will shed the bacteria and continue to infect other horses. Upon recovering from strangles, horses will be protected against reinfection for variable periods of time, sometimes even a few years.

Strangles vaccine options

Two types of strangles vaccines are available. One is a “killed” vaccine, meaning it contains dead/inactivated strangles. This vaccine is administered intramuscularly.  Killed vaccines produce a weaker immune response, so it is still possible for a horse vaccinated with this vaccine to develop strangles if exposed. Per the American Association of Equine Practitioners, the killed vaccine should not be expected to prevent disease. It may be effective in lessening the severity of infection. There is also an increased risk of vaccine site reaction with this product.

The second type of vaccine is called a “modified live” vaccine. This vaccine type uses a weakened form of strangles to stimulate a stronger immune response. In order to accomplish this, the vaccine is administered intranasally to target the same tissues as natural strangles infection. However, it is also possible for this modified live vaccine to cause lymph node abscesses, much like natural strangles infection. Horses that have natural immunity to strangles (those who have recovered from infection) have a higher risk of adverse reactions to strangles vaccination.

Should my horse have the strangles vaccine?

The take-home point is that we currently lack a perfect strangles vaccine. If your horse is in a high-risk population, discuss the pros and cons of strangles vaccination with your veterinarian to evaluate if strangles vaccination is worthwhile. It is important to remember that vaccination does not guarantee that your horse will not get strangles. Proper biosecurity is essential to prevent and limit strangles outbreaks.

Horse Show/Travel Biosecurity

The arrival of spring means long-awaited opportunities for trail riding, clinics, and horse shows. However, travel, new stabling, and the mixing of horse populations can also provide the perfect conditions for the spread of disease. With a little planning and biosecurity awareness, you can minimize potential risks to your horse.

What is Biosecurity?

Biosecurity refers to the preventative measures taken to minimize spread of disease. The most commonly encountered infectious diseases include influenza (flu), rhinopneumonitis (equine herpes virus), and strangles. While many horses are vaccinated against these diseases, vaccination does not guarantee 100% protection and does not negate the need for biosecurity.

How do I take effective biosecurity measures?

Some biosecurity measures are common sense – such as not allowing your horse to have nose-to-nose contact with other horses. Other measures are more complex.

First, consider your destination. Horse show venues and campgrounds may have specific requirements for incoming horses, such as a current Coggins test, health certificate, and proof of up-to-date vaccination. Remember to keep your veterinarian apprised of your summer travel plans so that you have all required documentation prior to your departure. While it can be frustrating to manage differing requirements, remember they are put in place for the health and safety of the horse.

When arriving at a campground or show stable, examine the housing for your horse prior to unloading. Look for overall cleanliness – an area free of manure and old bedding. It’s worth asking the venue how facilities are cleaned between horses prior to your arrival. Dirt floors and other porous surfaces are much harder to disinfect since organic debris can inactivate cleaners such as bleach.

Simple and easy biosecurity measures:

  • Prevent all direct contact between your horse and others (no nose-to-nose!)
  • Avoid sharing equipment with others, including; tack, grooming supplies, wheelbarrow, pitchfork, etc.
  • Avoid communal water sources/sharing hoses between horses. Dropping the end of the hose into multiple water buckets can transmit disease.
  • Wash your hands frequently and after touching any other horses.
  • Pack your horse’s thermometer. If your horse appears “off” a fever may be present before he is contagious to others.
  • Don’t forget to clean and disinfect your trailer regularly too!

Wishing you a safe, happy, and healthy riding season!

Core Vaccines

***This blog was originally written in January of 2020, and as of today, March 24th, 2020, times have changed significantly.  With Covid-19 causing the issues that it is, we feel it necessary to add the following statement.

Governor Polis on 3/20/2020, in Colorado Executive order 2020 009, made veterinarians part of the list of essential workforce to continue with “necessary procedures.”  For the safety and welfare of horses, the Mobile Veterinary Services vaccination schedule will continue as planned.  If delayed 3 or more months, depending on conditions, our horses will become susceptible to deadly diseases.  

As always, at MVS, we strive for clear client communication.  We will keep everyone informed to the best of our abilities as to the orders placed on us as veterinarians.  Please feel free to call with individual questions that you may have. ***

There is a long list of vaccines available to give our horses.  Owners and even veterinarians can get bogged down in the details, and that’s just based on the vaccines available. 

Then we start to talk about schedules for each group of horses.  Groups like Adult horses vaccinated in the past, Adult horses with no known or no history of vaccines, Foals (of vaccinated mares), Foals (of unvaccinated mares), oh yeah, and the broodmares!  Whew, I think that covers the horse population!!!

Really quickly a discussion of “just vaccines,” gets complicated.  Mobile Veterinary Services will always fall back on, “talk with your veterinarian to make a plan for YOUR herd and their individual needs.”  Here, we would like to discuss “core vaccines.”

What is a core vaccine? 

As defined by the AAEP (American Association of Equine Practitioners) a core vaccine “protects against diseases that are endemic to a region, are virulent/highly contagious, pose a risk of severe disease, those having potential public health significance, and/ or are required by law.  Core vaccines have clearly demonstrable efficacy and safety, with a high enough level of patient benefit and low enough level of risk to justify their use in ALL equids.”  It’s a mouthful, but what does it mean?  In the end, it means that they are safe, low risk, and designed and developed to protect horses and humans alike. 

These are the Core Vaccines recognized by the AAEP:

Tetanus:  Should be given annually.  If there is a question as to the status of a horse, they should receive a 2-dose series (4- 6 weeks apart).  Colts should receive a 3 shot series beginning around 6 months of age, second dose 1 month later, and another dose at 1 year old. 

EEE/WEE (Eastern Equine Encephalitis/ Western Equine Encephalitis):  Just like the Tetanus, it should be given annually, and they should go through an initial 3 dose series.  Conveniently, tetanus is often in a combination vaccine with these two. 

West Nile Virus:  As with the two above, West Nile should be given annually.  This is often in combination with WEE/EEE and Tetanus and can be given to colts and fillies in one shot on the same 3 dose schedule. 

Rabies:  Rabies is 100% fatal, in ALL species.  All youngsters should receive 2 vaccines starting around 6 months old (second one about 1 month later).  Then, every horse, every year should receive a booster. 

Every horse should receive at least these vaccines, every year.

It is important that these vaccines are handled correctly and managed at the appropriate temperature and environment to ensure that the vaccine is an effective and SAFE one.  This is the biggest reason that we recommend that you receive your vaccines from a licensed veterinarian.   If you ever have questions about your herd’s (no matter how big or small) vaccination protocol, please feel free to reach out to MVS!

Coronavirus and Veterinary Medicine

As we all hunker down for a few weeks of self-quarantine and social distancing, we want to alleviate any concerns our clients may have as it pertains to the potential transmission of coronavirus between horses and people.  While equine and bovine coronavirus has been present in the agricultural industry for quite some time, the disease is of gastrointestinal origin (diarrhea) and is not related the human respiratory virus (pneumonia) currently circulating our continent. 

As more research is conducted on this current respiratory coronavirus impacting human patients, it has become clear that the viral particles remain active outside of a human host for up to nine days.  This means that if one of your family members has COVID and sneezes directly onto your horse’s neck and you proceed to immediately rub your nose in that site on the horse’s neck, the horse could act as a fomite, thus delivering viral particles to you.  Otherwise, your horse is not a carrier of COVID and you cannot transmit the virus back and forth between each other. 

Here at MVS, we are still working at full capacity while taking measures to practice social distancing amongst ourselves and our clients.  If you are sick or feeling under the weather, please know that our doctors travel with a technician and can complete the appointment in your absence.  If you wish to be present, feel free to reschedule your appointment.

If you have any additional questions or concerns, please don’t hesitate to reach out to one of the MVS docs.  We’re here to help!