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Study: Shared Water Sources Contribute To EHV Transmission

A study has found that equine herpesviruses are able to replicate in freshwater sources in the wild and remain infectious to spread among animals, especially during drought conditions. In the wild, many species of animal will congregate around freshwater sources to drink, potentially allowing for virus transmission between species.

Drs. Anisha Dayaram, Peter Seeber, Alexandre Courtiol, Sanatana Soilemetzidou, Kyriakos Tsangaras, Mathias Franz, Gayle McEwen, Walid Azab, Petra Kaczensky, Jörg Melzheimer, Marion East, Oyunsaikhan Ganbaatar, Christian Walzer, Nikolaus Osterrieder and Alex Greenwood sampled water holes in areas of Africa and Mongolia that had significant dry seasons. They determined that EHV can remain stable and infectious in water under these conditions.

The team reported that animals forced to congregate around water supplies become stressed. Stressed equids can shed viruses like EHV, which enter the water supply when the animal drinks. Rhinos have tested positive for EHV when they share watering holes with zebras in the wild.

The EHVs found in Africa and Mongolia are nearly identical to those found in domestic horses, suggesting EHVs have changed very little over time. The research team suggests that additional research be done to determine other viruses that may use water as a vector to spread among animals.

Equine Herpes Virus-3 Confirmed In Icelandic Herd Closed To The Outside World For Centuries

Prior to 2021, only three strains of equine herpes virus (EHV) had been confirmed in Icelandic horses living in their native country, which has been a closed herd for more than 1,000 years. Now, four strains have been reported to affect the native population: EHV-2, EHV-4, EHV-5 and EHV-3, the newest strain to be detected.

Scientists had previously speculated that the absence of EHV-1 in Icelandic horses suggested that the virus was not as common in Medieval Europe as it is today. However, with confirmation that EHV-1 does exist in the closed herd, it appears that the virus was common in horses in Europe in the 9th or 10th Century.

EHV is a family of viruses: EHV-1 can case neurologic problems, respiratory disease, abortion, neonatal death. EHV-4 causes nonfatal respiratory disease in foals and EHV-3 causes venereal disease that doesn't affect fertility.

Drs. Lilja Thorsteinsdóttir, Gunnar Örn Guðmundsson, Höskuldur Jensson, Sigurbjörg Torsteinsdóttir and Vilhjálmur Svansson took samples from a 3-year-old Icelandic mare that had blisters on her vulva. Testing was positive for EHV-3.

EHV-3 is non-invasive; lesions typically heal in 10 to 14 days. Infected horses may be dull, have a fever or go off their feed.

Researchers speculate the appearance of the new viral strain in the closed population may be connected to the growing popularity of Icelandic horses, which has led more horse people to travel to the country and interact with the population of Icelandics there.

Read the communication here.

Horses May Need Up To Three Weeks Of Recovery After A Virus

It's not just humans that should take it easy if they're ill: experts say horses that have had the flu or other respiratory issues should rest for at least three weeks to allow their bodies to heal. Though lower-level exercise isn't necessarily harmful, high-intensity exercise can suppress immune system response and increase the horse's susceptibility to disease.

Intensely exercising a recovering horse can also cause him to lose weight and tire more quickly, as well as have a harder time recovering. Exercising does not affect virus duration or the duration of virus shedding.

It takes a minimum of three weeks for the respiratory epithelium and the mucociliary apparatus to heal, so allowing horses to rest or complete only low-level exercise is imperative. If exercise is begun and the horse seems distressed, it should be stopped immediately. Open communication with the treating veterinarian is key to creating a return-to-work plan tailored to the horse and his specific health issue.

How Horses Helped With the Creation Of A COVID-19 Vaccine

People across the United States and Canada began receiving the COVID-19 vaccine this week, less than a year after the novel coronavirus that lead to a worldwide pandemic was first identified. The equine industry played a small but relevant role in this amazing scientific feat.

West Nile Virus first emerged in the United States 1999; in 2005, Fort Dodge Animal Health created a vaccine to protect horses from the mosquito-borne disease. This vaccine was the world's first DNA vaccine approved for human or animal use—and the technology used to make it became key to creating the COVID-19 vaccine.

Conventional vaccines used a killed or inactive form of a virus that teaches the body how to mount an immune response to it. DNA vaccines use small pieces of genetic material from a virus; the material itself is injected into the recipient and their cells transcribe the DNA into messenger RNA, which creates distinct proteins to jumpstart the body's immune response. This immune response will defend against the entire virus. Gene-based vaccines are faster to develop and manufacture than traditional vaccines.

Manufactured by Pfizer, the new COVID-19 vaccine is the next generation of genetic vaccines; it's a novel mRNA vaccine that directly translates into proteins once the cell incorporates it. The equine West Nile DNA vaccine was a beginning step for the creation of this vaccine, proving that nucleic acid-based vaccines were safe and effective.