What is strangles?

Strangles is a disease caused by Streptococcus equi, a bacteria. The infection can range greatly in its signs and symptoms from no symptoms at all, or very mild symptoms, to severe and even fatal consequences. Affected animals can experience high temperature, above 38.5 degrees Celsius, a cough (which is not always present), poor appetite dull and depressed, nasal discharge and swollen or abscessed lymph nodes of the head which can appear as open sores. The swelling can be under the jaw; in the space between the head and neck or on the head or neck. Abscesses that form can burst, discharging highly infectious pus and in some cases glands swell so much they restrict the airways.

If the infection spreads to other parts of the body or respiratory tract the disease can be fatal.

A nasal discharge without the glandular swelling is sometimes all that is seen. Not all horses show the same signs, and some can go unnoticed.

How does an animal become infected with strangles?

The disease doesn’t discriminate – no matter whether your yard is large / small, or if you are experienced or a relatively new owner. It transmits through direct contact between animals or indirectly via equipment, people hands and clothing and can affect any age, sex, or breed of horse/pony.

Once the disease is on a premises it can spread very quickly therefore early diagnosis is extremely important. And no different to Covid the aim is then to break the chain of infection/ eliminate further in contacts/ exert great care in biosecurity/ and importantly to notify other in-contacts off the premises so that they too take due care and watch for symptoms also.

The incubation period between being infected with the bacteria and showing signs of disease can be anything from 3 – 14 or even 28 days.  An increase in temperature above 38.5 Celsius is often the first sign and therefore spotting those animals with increased temperature early is a huge help.

A small but very important proportion of horses that have recovered can become persistently infected with S. Equi for months or even years. These carriers although less susceptible to reinfection, may have no obvious clinical signs of disease but can intermittently shed the bacteria which can then infect other naiive horses. Vets can though help with these cases.

How are infected horses treated?

Treatment is devised on a case by case basis depending on the stage of disease and in consultation with the vet involved. Most animals recover in three or four weeks but can remain infectious longer after all other signs have ceased. Testing is therefore the only way to ensure animals are no longer infected / not a carrier and can be removed from isolation.

Is there anything that can be done to prevent infection?

It only takes one contact with a contaminated individual / equipment to initiate an outbreak. There are practices individuals can adopt to reduce the chances of strangles and indeed other diseases entering the farm.

• Do temperature checks regularly, particularly on horses that have been in contact with others from outside the herd – and isolate if over 38.5
• Isolate all new arrivals for at least two weeks and longer if possible while monitoring them closely for signs of disease
• Isolate individuals at the first sign of disease and contact the vet
  • Close the yard – no movements on or off the premises
  • Split equines present into three groups and manage these separately
    • Red – those showing clinical signs or have tested positive
    • Amber – those with known contact with positive cases
    • Green – those who had no contact with positive cases
    • Any equine in the amber or green group which develops clinical signs should be immediately moved to the red group, and if from the green group that group is then by default also now amber
    • Take rectal temperatures twice daily to check for fever
• Implement good hygiene, for example:
  • Don’t share water sources off the farm/don’t put hoses down into buckets
  • Implement excellent hand hygiene between horses
  • Allocate individual equipment to individual horses / clean and disinfect between use with different horses
  • Disinfect boots and change outer clothing after visiting other yards
  • Have a boot disinfectant tray and hand sanitising station for visitors to the yard
    • Staff who are interacting with other horses off the farm should be extra careful
• Ensure boundary fencing is secure and prevents nose to nose contact over fence lines
• Explain biosecurity measure / yard protocols to all personnel on the farm and erect appropriate well positioned signage for any visitors to the farm
• Blood testing to screen new arrivals and vaccination are additional effective measures – discuss with your vet

Implement regular cleaning and disinfection in high traffic areas on the farm including transport vehicles; walkers; handling stocks; and so on. Also clean and disinfect stables/ housing, remembering you can NOT disinfect properly over dirt.

Vaccination

Vaccination in conjunction with strict hygiene and biosecurity management can form a vital part of a comprehensive control programme. Vaccination is recommended if there is a risk of introduction of disease due to contact with horses from areas where this pathogen is known to be present. A live vaccine is available to reduce clinical signs and the occurrence of lymph node abscesses in exposed horses. It is recommended that all horses stabled together are vaccinated. It is advisable that you would consult with your veterinary practitioner before using the vaccine, to discuss the risk profile for your horse/horses and a possible vaccination programme.

Strangvac vaccine is available in Ireland. The vaccination can be administered in two doses, four weeks apart, and can be given to foals from five months of age.  Equines at high risk of S.equi should be re-vaccinated after two months. Your vet will advise on the appropriate re-vaccination schedule based on your horse’s specific risks and the vaccine’s protection level. Vaccination is most effective when combined with other disease prevention methods, such as good stable management and biosecurity procedures.

Why is it is important to talk about strangles?

Despite the disease being so prominent across the world it still carries with it an element of stigma/ reluctance by many to talk about it, and a further reluctance to acknowledge to others its presence on a farm/yard which is not at all conducive to reducing its prevalence.

As the disease is so transmissible having strangles on a premises can be a traumatic experience. Not alone physically caring for the horses involved, but mentally, emotionally and financially it can be really challenging. The fear factor associated with this disease is nearly as dangerous as the disease itself if individuals try to hide it and not inform others. Also, those that are experiencing living with equines suffering from strangles deserve support and help, not incrimination.