Periodic Ocular Inflammation in Horses: Cause, Symptoms, Diagnosis, Treatment

General information about periodic ocular inflammation

Equine recurrent uveitis, also known as periodic ocular inflammation or commonly known as moon blindness, is a disease that has been documented since the Middle Ages. This eye disease manifests itself through recurring inflammation of the skin of the eye, either in one or both eyes. The disease is characterized by periodic attacks of increasing intensity. As a result, damage to the eyes occurs continuously, which can ultimately lead to complete blindness of the horse if no countermeasures are taken in time.

Currently, approximately 10-12% of horses worldwide are affected by periodic ocular inflammation. Horses with specific color genes, such as Appaloosas, Cremellos, and tiger piebalds, seem to be particularly susceptible. The exact cause of this condition is not fully understood, but leptospires are suspected as possible bacterial triggers. Other potential factors, including immunodeficiency and genetic predisposition, are also being explored.

The progressive nature of periodontitis makes early diagnosis and targeted interventions essential to minimize irreversible damage. The knowledge gained about this disease is of great importance to sensitize both horse owners and veterinarians to the challenges and necessary measures in dealing with periodic ocular inflammation.

Causes of periodic ocular inflammation in horses

The causes of periodic ocular inflammation vary considerably depending on the region. In North America and the UK, it is predominantly thought to be an autoimmune disease, while in Germany the prevailing opinion is that it is caused by infection with leptospires. Leptospires are bacteria that are mainly transmitted by rats and mice.

Almost every horse comes into contact with leptospires in the course of its life, but only a few horses actually get these pathogens into their eyes. Even after infection, it can take months or even years for the symptoms of periodic ocular inflammation to appear.

In addition, a genetic link indicates a possible role in the development of periodic ocular inflammation. In particular, horses with tiger pinto patterns such as Appaloosas and Knabstruppers tend to develop this eye disease. The disease also occurs to a greater extent in cremellos, pintoes and blacks.

Symptoms of periodic ocular inflammation

Identifying the symptoms is crucial for early diagnosis and effective treatment of periodic ocular inflammation.

• Redness of the eyes

A clear sign of the disease is the reddening of the eyes, which indicates inflammation of the conjunctiva. This can range from a slight reddening to more intense discoloration.

• Tear flow

Excessive lacrimation is another characteristic symptom. This can lead to adhesions of the eyelashes and affect the horse's well-being.

• Light sensitivity

Horses with periodic ocular inflammation are often sensitive to bright light. This manifests itself in increased blinking and attempts to protect the eye from direct light.

• Rubbing and squinting your eyes

Increased rubbing or blinking of the eyes indicates discomfort and pain. This symptom requires an immediate veterinary examination.

You can also see how periodic ocular inflammation can be recognized and treated in the following video on the ClipMyHorse.TV Academy:
Trigger warning: The following video contains explicit footage from the operating theatre!

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Diagnosis and veterinary examinations

The diagnosis of periodic ocular inflammation requires a thorough veterinary examination and specific diagnostic tests. To diagnose the disease, the veterinarian inquires about the horse's medical history (anamnesis) and performs an examination of the inner eye. At the first manifestation, only inflammation of the inner eye can be detected. The term ERU(equine recurrent uveitis) can only be used if the inflammation recurs. In practice, however, it is assumed that it is a case of uveitis as long as the opposite is not proven.

In addition to the medical history, a thorough examination of the eye is required for the clinical diagnosis. In order to detect an infection with leptospires, the vet takes aqueous humor samples from the horse under sedation and local anesthesia in the clinic, which are then tested for antibodies or antigens in the laboratory. Alternatively, a rapid test can be carried out by the vet directly in the stable (snap lepto). As part of a doctoral thesis, the reliability of the rapid test was compared with established testing methods. The result showed that the rapid test is sometimes more reliable than other methods.

Treatment for periodic ocular inflammation

If the recognition stage of equine periodontitis is identified early, anti-inflammatory ointments or drops, often containing cortisone, or antibiotics in the case of bacterial infection will be prescribed. Prompt intervention at this stage can help to mitigate the progression of the disease and minimize irreversible damage.

In the advanced stage of periodontitis, when the inflammation is already well advanced, muscle paralyzing and pupil dilating drugs are used. These drugs aim to reduce pain and prevent the eyes from sticking together, which is particularly important to improve the horse's well-being.

In addition to these measures, corticosteroids, either administered intravenously or injected directly into the conjunctiva during particularly severe flare-ups, can also be used to combat inflammation. A catheter can also be used to facilitate eye irrigation and the administration of medication.

Modern technologies also offer the possibility of placing an implant with virus-inhibiting active ingredients in the horse's eye. These implants release the required amount of active ingredient over a longer period of time, which can reduce the need for drops or ointments.

For severe cases, vitrectomy is available as a surgical measure. During this operation, the vitreous body in the horse's eye is cut up and removed, eliminating inflammation and opacities. This can lead to a considerable improvement in vision.

In cases where a horse is already blind, it may be necessary to remove the painful eye under general anesthesia. This not only relieves the pain, but also allows the horse to regain its zest for life.

It is important to emphasize that horses can cope surprisingly well with partial or total blindness. After a short acclimatization phase, most horses are able to orient themselves well and lead a full life. All these measures are, of course, carried out under sterile conditions in specialized equine clinics.

We accompanied a day in the operating room during a periodic ocular inflammation.
‍Trigger warning: The following video contains explicit footage from the operating room!

Preventive measures

Preventive measures are very important to avoid periodic eye inflammation.

• Genetic selection

Breeders should take care to avoid horses with known genetic susceptibility in order to minimize the inheritance of risk factors.

• Care and hygiene

Regular eye care and hygiene can reduce the risk of infection and promote the horse's well-being.

• Environmental protection

Creating an environment that is free from irritants is crucial. This can include the use of UV protection, dust-free bedding and other preventative measures.

Case studies and success stories

The presentation of specific case studies and success stories illustrates the positive results that can be achieved through appropriate treatment and care. Specific cases of horses that have been successfully treated offer insights into different treatment approaches and show that a good quality of life is possible despite this disease. Personal experiences of horse owners provide a practical insight into the challenges and successes of overcoming periodic ocular inflammation.

Tips for horse owners when dealing with periodic ocular inflammation

Horse owners play a crucial role in the management and care of horses with periodic ocular inflammation.

• Early detection of symptoms

Attention to early signs enables faster intervention and improves the chances of successful treatment.

• Cooperation with a veterinarian

Close cooperation with an experienced veterinarian is crucial for an accurate diagnosis and an individual treatment plan.

• Care and management at home

Proper eye care, management of environmental factors and adherence to prescribed treatment plans will help to promote the well-being of the horse.

Conclusion on periodic ocular inflammation

In conclusion, it is crucial to understand the complexity of this disease and at the same time raise awareness of the importance of comprehensive care and prevention.

Knowledge of periodic ocular inflammation and its many causes, from genetic factors to environmental influences and infections, lays the foundation for targeted treatment and prevention. Horse owners, vets and breeders can improve the quality of life of affected animals by recognizing the symptoms early and working closely together.

The constant development in veterinary medicine opens up new perspectives for the treatment of periodic ocular inflammation. Research approaches could lead to innovative therapeutic options that enable even more targeted and effective treatment. Collaboration between veterinarians, breeders and researchers is crucial to achieve progress in the treatment and prevention of this disease.

Horse owners play a central role in dealing with periodic ocular inflammation. Implementing preventative measures such as genetic selection, regular grooming and environmentally friendly management can not only help to minimize the risk but also improve the quality of life of horses.

The tips outlined in the article provide specific guidance for horse owners. Early recognition of symptoms, close cooperation with a vet and careful care and management at home are key elements in maintaining the animal's quality of life.

It is not only a medical challenge, but also an ethical obligation to ensure that horses affected by this disease receive the best possible care. Ongoing research and collaboration between all parties involved provide a promising basis for optimized care of horses with periodontal ocular inflammation in the future.

FAQ's periodic eye inflammation

Frequently asked questions about periodic ocular inflammation in horses:

Is periodic ocular inflammation in horses contagious?

Periodic ocular inflammation is usually not contagious and is not transmitted from horse to horse. It is often an individual reaction to genetic factors, environmental conditions or infections.

How does periodic ocular inflammation develop in horses?

The exact causes can be varied, including genetic predisposition, environmental factors such as dust or allergens, and bacterial or viral infections.

How do you recognize periodic ocular inflammation in horses?

Typical symptoms are reddening of the eyes, increased tearing, sensitivity to light and increased rubbing or blinking. A vet can confirm the diagnosis through specific examinations.

Where does periodic ocular inflammation in horses come from?

Periodic ocular inflammation can be genetic or triggered by environmental factors such as dust, pollen or infections. An individual examination is often necessary to determine the exact cause.

Is it bad if a horse is blind in one eye?

One-sided blindness can affect a horse's quality of life, but many horses adapt surprisingly well and can live well with their impairment.

What does a cloudy eye mean in a horse?

A cloudy eye can indicate various eye problems, including cataracts, corneal injuries or eye inflammation. An accurate diagnosis by a vet is essential.

Can you ride a horse with conjunctivitis?

Riding a horse with active conjunctivitis is strongly discouraged as this can exacerbate the situation and cause pain to the horse. Appropriate treatment and rest are necessary.

What causes moon blindness in a horse?

Moon blindness often refers to uveitis, a painful inflammation of internal eye structures. There can be many causes, frominfections to autoimmune diseases.

Can a horse live with moon blindness?

With appropriate veterinary care and management, a horse with moon blindness can often have a good quality of life, although the condition can be chronic.

How often should a horse be given atropine?

The frequency of use of atropine depends on the specific treatment and should be determined by the veterinarian.

How long do atropine drops work in horses?

The duration of action of atropine drops varies, but they should normally be used as directed by the vet.

How long does the effect of atropine last in horses?

The duration of the atropine effect may vary depending on the individual reaction and should be monitored by the veterinarian.