What are Cataracts?
Cataracts are deep inside the eye, so it is hard to see the milky white opaqueness and some people believe when the outer eye is white and cloudy that it is a cataract. However, that type of situation is the cornea and may become milky or white for several reasons not related to cataracts. In some cases of genetic cataracts, the damage may be very small and not even cause any symptoms. These are usually found during a routine veterinary visit. Cataracts in an older horse are usually more serious and affect both eyes so the horse will need cataract surgery to regain vision.
Cataracts of the eye are a common cause of blindness in horses. In this condition, an opaque white coating covers the eyes, causing cloudy and blurry vision. In young horses, cataracts are a common genetic defect most often seen in Thoroughbred, Morgan, Rocky Mountain and Belgian horses. However, in older horses, cataracts usually affect both eyes and are caused by the swelling from repeated bouts of eye inflammation and irritation. This may be from eye infections or injuries of the eye. When horses are over 20 years old, the cataracts are considered to be senile cataracts. The cause of the senile type of cataracts are thought to be from the lack of antioxidants as the horse gets older caused by repeated eye inflammation.
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Symptoms of Cataracts in Horses
The signs that your horse may have cataracts include:
- Cloudiness or white opacity of the pupil
- Walking into things
- Shying back for no reason
- Inability to walk straight
Cataracts are separated into three categories, which are:
- Incipient (or early) cataracts only affect a small part of the lens and usually does not cause a reduction in sight
- Immature cataracts are more serious and create a deterioration in sight that progresses with age
- Mature cataracts involve the whole lens and cause blindness if not treated
Causes of Cataracts in Horses
- Congenital cataracts are genetic and affect mostly Thoroughbred, Morgan, and Belgian horses
- Senile cataracts are thought to be caused by repeated bouts of eye inflammation and affects older horses
- Nutritional deficiency and being exposed to certain toxins can cause cataracts in some cases
- Trauma or injury to the eye can cause cataracts
Diagnosis of Cataracts in Horses
Your equine veterinarian is the best equipped to diagnose cataracts in your horse. The veterinarian will do a comprehensive physical examination including height, weight, temperature, lameness check, body condition score, blood pressure, and breath sounds. Also, the veterinarian will check your horse’s vision and ability to maneuver while walking. Some vision tests such as blink reflex and pupillary light reflex will be done to be sure the retina is not detached.
Laboratory tests needed to rule out other eye diseases include a blood chemical analysis, complete blood count (CBC), blood gases, blood urea nitrogen (BUN), packed cell volume (PCV), and a glucose test. In addition, your veterinarian will need to get cranial x-rays and an ultrasound to look for abnormalities that may be causing the vision trouble. If necessary, a CT scan or MRI will be performed for a more detailed view.
Treatment of Cataracts in Horses
The only treatment for cataracts in horses is surgical removal of the cataracts. You will most likely be referred to a veterinary ophthalmologist for this procedure because this is their specialty. Cataract removal is a common surgery in horses and only takes a short time.
The ophthalmologist will need to do a vision examination to make sure your horse is a good candidate for this surgery because it is not usually successful in horses with inflammation, infection, or other problems.
If your horse has a condition, the veterinarian will prescribe medication to treat the problem before surgery can be done. For inflammation, the veterinarian will give corticosteroids and antibiotics for an infection.
The surgery to remove cataracts is called phacoemulsification. This is a relatively modern procedure that is done by using a small probe that creates high frequency waves. These ultrasonic waves actually shatter the cataract and turn it into a liquid so it can be vacuumed from the eye. The eye is then stitched up with small absorbable sutures that will be absorbed in the next 6 to 8 weeks.
The veterinary ophthalmologist will keep your horse in the hospital for about 7 to 10 days for observation and to monitor your pet’s intraocular pressure.
Recovery of Cataracts in Horses
You will have to spend a lot of time taking care of your horse after the surgery. The veterinarian will give you prescriptions for pain medication, corticosteroids, and antibiotics which you will have to administer 4 to 5 times a day. The medication will have to be continued for about three months. During the recuperation period, your horse must be kept in a darkened stall with little activity. Be sure to return for the follow up appointments and call the veterinarian if you have any questions or concerns.
Cataracts Questions and Advice from Veterinary Professionals
I've got a 2 1/2 year old filly she was bred by us so we own both parents and neither have eye sight issues and both have other foals and there is no issues with there eye sight.
A year ago her eyes became weepy almost like she had developed conjunctivitis I had the vet check her eyes and he was happy with them and just gave a dose of antibiotics. She's currently out on loan and yesterday the lady had the vet out as over the past couple of days she filly hasn't even been able to find her own food bowl. The vet claims they are genetic. Do they really come on that fast? Within a couple days for her to be completely blind amazes me. She has got scratches on her face they think she itches it in the brambles. The field owner also has a lot of barbed wire on the land. What would your personal opinion be on the cause?
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How can you diagnose if a cataract is heritable or if it is from trauma, Disease, etc
Can a veterinarian tell you if a cataract has been inherited. Is this something that is easy to tell (Trauma V's inherited)
Wondering whether to breed my mare who has a possible cataract, i don't want the possibility of passing it on. She is 11, has had no signs of impaired sight up to now (No spooking, jumps great meets her mark every time) i bought her 5 years ago
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