Equine viral arteritis - Symptoms and treatment

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Equine viral arteritis is a infectious disease that affects horses and is generally associated with racetracks and breeding or reproduction centers of this species. Its origin, as its name suggests, is viral. The virus, in general, does not usually give serious forms and much less with high mortality, it is only usually more serious in certain age and risk groups. The clinical signs that will appear in horses will be mainly as a consequence of inflammation in the smaller blood vessels. The virus mainly targets the respiratory system and causes abortions in pregnant females..

In this AnimalWised article we will address the equine viral arteritis, your symptoms, your diagnosis and your treatment. Read on to learn more about this disease that our horses can suffer from.

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  1. What is equine viral arteritis?
  2. Causes of equine viral arteritis
  3. Symptoms of equine viral arteritis
  4. Diagnosis of equine viral arteritis
  5. Treatment and prevention of equine viral arteritis

What is equine viral arteritis?

Equine viral arteritis (EVA) is a infectious and contagious disease affecting equidae. It is caused by a virus that mainly targets the placenta or the respiratory system, causing miscarriages or inflammatory lesions in the arterioles of acutely infected animals..

It affects equidae, but there is some evidence that alpacas and llamas can also be affected. It is a disease that it is not transmitted to humans, that is, it is not a zoonosis.

Many of the cases of infection by this disease are subclinical, so that they do not produce clinical signs, although it depends on the virulence of the strain. The most serious forms of the disease that can end the life of the horse usually occur in very young foals or foals with congenital disease, but also in immunosuppressed horses or with some other pathology.

Causes of equine viral arteritis

EVA is caused by an RNA virus, the equine arteritis virus (VAE), belonging to the genus Arterivirus, family Arteriviridae and order Nidovirales.

¿How the equine arteritis virus is transmitted?

This virus is transmitted from respiratory secretions, fresh or frozen semen, placenta, fluids, and aborted fetuses. That is, the two main forms of transmission are:

  • Airway: by exudates and secretions when they cough or sneeze or leave secretions in feeders and drinkers. It is of greater importance during the acute phase of the disease.
  • Venereal route: during riding, when the stallion or mare is infected, as well as during artificial insemination.

The disease can also be transmitted congenitally from mother to young..

Symptoms of equine viral arteritis

In the pathogenesis of equine viral arteritis, the virus multiplies in the arterioles, causing edema and cell death (necrosis). Clinical signs begin after 3-14 days of incubation, being earlier if the infection has been through the respiratory route and later if the transmission has occurred through the venereal route.

Once the disease develops, Clinical signs that can be observed are the following:

  • Fever.
  • Depression.
  • Anorexy.
  • Mucosal congestion.
  • Petechiae.
  • Conjunctivitis.
  • Epiphora (tear discharge).
  • Runny nose.
  • Moderate cough.
  • Dyspnoea.
  • Stomatitis.
  • Diarrhea.
  • Colic.
  • Urticaria.
  • Edema of the foreskin, scrotum or mammary gland.
  • Peri or supraorbital edema.
  • Edema in distal areas, especially in the hind limbs.
  • Abortions if there is massive fetal infection and necrosis of the placenta.

Generally, horses shed the virus for 28 days after illness, but in mature males it presents a lot of persistence in the prostate and seminal vesicles, making the period in which they are infectious can even last their whole life.

¿What injuries it produces in the organs of a sick horse?

The lesions that occur in the organs of horses show a distinct blood vessel injury. Specifically, disseminated vasculitis appears in smaller arterioles and venules, leading to hemorrhages, congestion, and edema, especially in the subcutaneous tissue of the abdomen and extremities, as well as peritoneal, pleural, and pericardial fluid..

In foals killed by this virus, pulmonary edema, emphysema (air in the lung), interstitial pneumonia, enteritis and heart attacks in the spleen have been observed.

Diagnosis of equine viral arteritis

In the presence of the clinical signs that we have commented on in horses, we must make a differential diagnosis among other pathologies that affect equidae and can give rise to similar symptoms:

  • Equine influenza.
  • Equine rhinopneumonitis.
  • Equine adenovirus.
  • Hemorrhagic purpura.
  • Equine infectious anemia.

In the blood test a leukopenia (reduction in total white blood cell count) may be seen. The definitive diagnosis will be given by the laboratory. For this, samples must be obtained to be sent to it and they can perform the appropriate laboratory tests for diagnosis..

The samples They must be obtained as soon as possible after the peak of fever appears or when infection is suspected due to the appearance of clinical signs indicative of CVA, and they are:

  • Uncoagulated blood and serum.
  • Semen.
  • Nasopharyngeal or deep nasal swabs.
  • Conjunctival swabs.
  • Placenta, lung, liver, and lymphoreticular tissue from the aborted fetus.

When EBV-related abortions are suspected, virus detection and isolation should be done with fetal fluids and tissues from the placenta, lungs, liver, and lymphoreticular tissues..

The tests to be carried out according to the type of sample are:

  • ELISA.
  • Seroneutralization.
  • Complement fixation.
  • RT-PCR.
  • Virus isolation.
  • Histopathology of arterioles.

Treatment and prevention of equine viral arteritis

The treatment of equine viral arteritis is only carried out in endemic areas of the disease (which have it) and is symptomatic with the use of antipyretics, anti-inflammatories and diuretics.

Correct control and prevention of the disease must always be carried out with a series of preventive measures. This seeks to reduce the spread of the virus in breeding horse populations to minimize the risk of miscarriages and deaths in young foals, as well as to establish carrier status in stallions and foals. The control measures are:

  • Semen analysis prior to the entry of new stallions.
  • Quarantine of the new stallions.
  • Good management in equine breeding centers.
  • Identification of carrier horses.
  • Isolate horses with clinical signs.
  • Vaccination depending on the country.

Equine viral arteritis vaccine

Vaccination is prohibited in Spain. However, the countries where it is possible to vaccinate have at their disposal two types of vaccines to control this disease, specifically:

  • Modified live virus vaccine: safe and effective for males, empty mares and foals. However, it should not be put in pregnant mares in their last two months of gestation and in foals less than 6 weeks old, unless there is a high risk of infection. It protects against EVA for between 1 and 3 years, but does not prevent reinfections or replication of the virus. However, the elimination of the virus through the nasopharyngeal route is significantly lower than in horses that have not been vaccinated..
  • Dead virus vaccine: safe in pregnant mares, but does not induce as strong an immunity as the previous one, requiring two or more doses to achieve a good neutralizing antibody response.

It is advisable to vaccinate foals between 6 and 12 months of age before they are at risk of being infected by the virus.

This article is merely informative, at AnimalWised.com we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

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