Guidelines: Outbreak Rhinopneumonia
Rhinopneumonia occurs almost every year in Belgium. An infection can spread quickly to other horses. Usually horses that get this infection only have to deal with a mild cold. Unfortunately, horses can also become seriously ill after an infection. Some possible consequences are damage to the respiratory system, paralysis of the hindquarters and abortion in pregnant mares. Rhinopneumonia is caused by the Equine Herpesvirus 1 (EHV-1). The Equine Herpes Virus occurs worldwide and is animal species specific. So EHV-1 is not dangerous to humans or other animal species.
Sick animals can spread large amounts of virus. Transmission occurs through close and direct contact with other animals. Therefore stables with sick animals are blocked for at least three weeks to avoid contact with other horses. Saliva, hair or nasal discharge through a person, clothing, material,… can also end up from one horse to another, and this also counts as direct contact. Although the virus is not that resistant, other horses could be infected this way. The virus can only spread over a few meters via the air. It is therefore impossible to transfer from one house to another by air. In other words, companies in the vicinity run little risk, as long as there is no close contact with the affected company or has not been recently.
Fortunately, the majority of these infections go without serious symptoms and are limited to mild flu-like symptoms (fever and nasal discharge, usually combined with swelling of the limbs for a few days). There are, however, a few exceptions. Pregnant mares are at risk of abortion after infection. When the virus settles in the uterus, a vascular infection develops in the innermost layer of the uterine wall and the placenta (placenta) and the fetus are rejected. The susceptibility of the uterine wall to such an infection is much greater at the end of the pregnancy than at the beginning of the pregnancy.
Less frequently, horses can start to show the dreaded paralysis symptoms. where the virus has lodged in the nervous tissue of the spinal cord or brain. As a result, the sick horse can show all kinds of (neurological) nerve symptoms. The symptoms of the neurological form usually start suddenly and can vary widely:
- Floppy tail
- Overflowing bladder that is about to leak
- Mild ataxia (unstable standing / walking)
- Complete paralysis
Clinical symptoms usually progress to their most severe form within two to three days.
If you think you recognize a case of rhinopneumonia, you should notify your veterinarian immediately and, pending a diagnosis, make sure that the affected horses do not come into contact with other horses. If you have touched a suspicious or sick horse, it is best to change your clothes and take a shower before going to another horse.
For the examination, the vet will draw a nasal swab and blood. In the event of an abortion, a swab of the mare’s vagina, a piece of the placenta and / or a piece from the lungs of the aborted foal can be sent in. This will be examined in a laboratory by means of a PCR test.
It is very important that a stable where disease occurs, takes responsibility, communicates the situation to other horse owners and stops all contact with other farms.
With the cold form, the sick horses usually recover without treatment. Sometimes, however, bacteria play an additional role and veterinary treatment is necessary. With the abortion form, the mare does not need any further treatment. However, it is wise to isolate the mare immediately and not let her cover immediately. In the neurological form, the treatment is much more extensive, both in the field of medication and in the field of care.
There are many measures that increase the chances for a horse with the neurological form of rhinopneumonia, but often help from the veterinarian is needed:
- Stable the horse in a spacious box with a soft bottom so that the horse can stand up more easily and be helped with this if necessary
- Regularly walk by hand if the horse can still do so, possibly with extra help at the tail and next to the legs
- At least twice, but preferably three times a day, empty the bladder with a urinary catheter after thorough cleaning of the vulva or penile tip (and rinse with, for example, Betadine® dissolved in physiological saline); In geldings and stallions with neurological symptoms, it is usually possible to grasp the penis without anesthesia
What if the horse can no longer stand?
If the horse can no longer stand, it must be carefully discussed with the veterinarian how to proceed. If the horse is still attentive, wants to drink and eat and has strength in the legs, an attempt can be made to hoist the animal in an adapted girth. In the first instance, this should be done with the veterinarian, because when hoisting, especially if a horse resists, enormous forces are released and the situation can quickly become very dangerous.
After the hoist, the horse must want to remain standing on its own. The horse can also be rolled on the other side every 4 to 6 hours for 1-2 days. Sometimes they can then suddenly get up on their own. This is only possible if the horse ‘accepts’ the lying down and does not ‘fight’. Furthermore, it should be realized that horses that need all of this will usually not fully recover. Sometimes the result ‘can only be used as a pasture horse’ must be accepted by an owner. Euthanasia is often an honest attitude towards the horse at this stage and is really necessary if the horse no longer wants to eat or drink.
What if the horse just can / cannot get up?
For these horses, only running loose in an indoor arena, a paddock or small pasture with good fencing is essential. They then have more space to get up themselves or to be helped at the head and at the tail. A birth alarm girth can be of great use here if continuous monitoring is not possible.
As stated earlier, direct contact between horses must be strictly avoided. Infected horses should be separated from uninfected horses. When taking care of the horses, it is best to provide separate caretakers per group of horses. If this is not possible, it is best to start with the care of the ‘healthy’ horses and end with the infected horses. Hygiene and disinfection of the material remains an essential factor here.
The following tips apply for correct barn cleaning and disinfection:
- Remove all bedding (straw, sawdust or flax) and dispose of it from the farm as soon as possible
- Thoroughly clean the floor and walls by scrubbing with a brush and soap and water (do not use a high-pressure cleaner for cleaning, as the virus can then spread in the air via small water droplets, unless stables are completely empty)
- Allow the floor and walls to dry properly (viruses cannot tolerate dehydration)
- Then disinfect with Halamid® or another suitable disinfectant in the concentration prescribed for viruses and let it work for twenty minutes
- Then rinse well with water
- Finally let it dry well
Prevention – Vaccination
Every year there are outbreaks of rhinopneumonia worldwide. However, it is possible to reduce the number and extent of those outbreaks through vaccination. This means a primary vaccination course from 5-6 months of age of two injections 4-6 weeks apart and then repeat twice a year. Abortion is less common in well-vaccinated groups, although breakthroughs (ie abortion does occur) may occur. No vaccine claims to provide 100% protection against the neurological form of rhinopneumonia and outbreaks occur in both unvaccinated and well-vaccinated groups. Vaccinated horses, however, excrete less virus in the event of an infection, which reduces the risk of spreading.
Vaccinating the horses regularly maintains a fairly good resistance to the virus. As a result, on the one hand, they will infect less other horses and they themselves are better protected against infection from other horses. The keywords here are “regular vaccination”. If we only vaccinate when there is an outbreak, we will be too late. If everyone vaccinates their horses regularly, there will be significantly fewer problems with rhinopneumonia. We can regard a consistent vaccination policy as a form of civic duty among horse lovers.