Equine Rhinopneumonia

Rhino, EHV or Equine Rhinopneumonia are the names used for a virus that scares many horse owners. Rhino is known for causing large outbreaks with paralyzed horses and many abortions in mares.

Equine Rhinopneumonia is caused by the Equine Herpes Virus and is present worldwide. There are multiple forms of Rhino, each causing different symptoms.

Different forms of Equine Rhinopneumonia

There are two types of Rhino viruses that give rise to three different symptoms. Equine Rhinopneumonia is caused by a herpes virus (EHV1 and EHV4). The EHV1 virus causes the neurological and abortion forms of Rhino. The respiratory form (which is most common) is usually caused by the EHV4 virus, but can also be caused by EHV1. Unfortunately, science does not yet understand why EHV1 does not always lead to the respiratory form, but in some cases only to the neurological form. Almost all horses in the Netherlands have antibodies against EHV4 and around 30% against EHV1.

• Respiratory form: 2 to 10 days after infection, the first symptoms appear. Horses may experience one or more symptoms such as coughing, clear nasal discharge, suddenly swollen legs, fluctuating body temperature, and decreased appetite. Most symptoms disappear within a week with rest. In cases of reduced immunity, recovery may take longer. The respiratory form is common, but is often dismissed as a "little virus" that does not even involve the veterinarian. Horses generally recover well from this form.

• Abortion form: the nightmare for breeders. EHV1 can cause abortion in pregnant mares. It can also happen that a live foal is born, but it is very weak and fragile. These foals often die within a few days. Pregnant mares are usually infected several weeks to months before abortion. The prognosis for foals is very poor, but mares recover quickly and can become pregnant again.

• Neurological form: This form is the least common, but often has the most impact. In the neurological form, the horse's central nervous system is affected, leading to ataxia and paralysis. Typically, the first symptoms appear within 1-14 days after infection. Usually, there is only poor coordination, but actual paralysis can also occur. Paralysis of tail, anus, penis, bladder or legs has serious consequences for the horse. Some horses cannot defecate by themselves, cannot stand up, or develop bladder ruptures. Prognosis for the neurological form depends on the severity, but can last for months. Prognosis for horses lying down for more than 24 hours is very poor.

How does your horse get Equine Rhinopneumonia?

Many horses are already carriers of the Rhino virus. This means that they have a higher chance of getting Rhino when their immunity is lowered or they are stressed. They also shed virus particles and are a source of infection. Virus shedding occurs through nasal discharge, sneezing, and coughing. In the case of the abortion variant, the amniotic fluid, afterbirth, and the foal "cleaning" of the uterus are highly contagious.

The virus is also absorbed through the upper respiratory tract, inhalation, or contact with nasal secretions. Additionally, the virus remains active and contagious for several hours via water buckets, stables, equipment, etc.

An infection with Rhino cannot be prevented, but you can make your horse more resistant by maintaining high immunity. A high level of infection pressure is also needed to make the horse sick. Spending time outdoors and limiting contact with unfamiliar horses can help keep the virus at bay.