All you need to know about your dog’s cataract
Dogs grow older in a similar fashion to humans. They lose muscle tone, their joints stiffen, and they often don’t see as well as they once did. Eyesight, in fact, can become a major concern as a dog enters its senior years. Cataracts can appear in different forms and all types of dogs, regardless of breed or size, are susceptible to getting them.
As with people, cataracts are a common malady as a dog ages. But what exactly are cataracts, what do they do to an eye and how can pet parents treat them?
What is the cataract disease?
A cataract affects an eye’s lens, which, like a camera, focuses on an object so we can see it. When the normally transparent lens becomes clouded by opacity, it is considered a cataract.
“The word cataract literally means ‘to break down,’” petmd reports. “This breakdown refers to the disruption of the normal arrangement of the lens fibers or its capsule. This disruption results in the loss of transparency and the resultant reduction in vision.”
In its initial stages, a cataract affects a very small part of the lens, which is located behind the iris (or colored part of the eye). Called an “incipient cataract,” the small opacity does not generally affect a dog’s vision. Because it is so mild, it may be difficult for pet parents to tell if their dogs have something wrong with their eyes.
If, however, the opacity grows and covers more of the lens, called an “immature cataract,” then it begins to interfere with a dog’s vision. If the cataract progresses and covers the entire lens, called a “mature cataract,” the dog essentially loses the ability to see.
“The clouding is caused when some of the protein which makes up the lens begins to clump together and interferes with vision,” states MedicalCenter.osu.edu. If left untreated, the disease can progress further with some cataracts turning into a “hypermature cataract.” How long a cataract takes to develop into the hypermature stage varies from several months to years, depending on the dog. “Hypermature cataracts usually are reduced in size due to loss of water and proteins from the lens. This causes the lens to shrivel and the lens capsule to wrinkle—similar to a grape turning into a raisin,” reports AnimalEyeCare.net.
Once the cataracts reach the later stages, dogs’ eyes appear cloudy or hazy, which can alert parents to take their dogs to the veterinarian.
But cloudy eyes may lead to some confusion, as they do not necessarily mean that a dog has cataracts. Many times, when dogs begin to exhibit signs of cloudy eyes they actually have what is called nuclear sclerosis, a more common condition than cataracts. Beginning around the age of 6, dogs’ lenses begin to harden, giving their eyes a grayish hue. As dogs continue to age, the gray or cloudy appearance continues to darken. It’s a normal sign of aging and doesn’t typically interfere too much with their vision.
Nuclear sclerosis affects both eyes at the same time; cataracts, on the other hand, often appear in only one eye at a time. Over time, cataracts may appear in both eyes but usually begin in one or the other.
Because the signs of cataracts can closely resemble other conditions, it’s best to let a veterinarian examine your dog to determine the actual cause of her cloudy eyes. There are several signs that a dog may have cataracts, so monitoring a dog’s behavior and physical changes can help a pet parent decide when to visit the vet.
- Eyes appear cloudy in shades of white, blue or gray within the eye
- Experiencing trouble with depth perception
- Newly skittish
- Redness or irritation around eyes (this might also be due to allergies)
- Hesitancy or discomfort in unfamiliar surroundings
- Misjudging distance
- Not recognizing people
- Unsure footing
- Additional signs of blindness or vision impairment
How and why do cataracts Form?
Cataracts in dogs can develop for several reasons, but generally develop the same way.
“The normal lens is maintained in a dehydrated state. It consists of 66 percent water and 33 percent protein,” reports PetEducation. “There is a complicated so dium water pump system in the lens that keeps this water/protein balance in check. When the bio mechanical system in the lens is damaged, this pump system begins to fail and extra water moves into the lens. In addition, the percentage of insoluble protein increases. These changes result in the loss of transparency and cataract formation.”
Depending on the dog, cataracts can take several weeks or even months to develop and they can appear in dogs of any breed. Furthermore, there are several reasons a dog can develop cataracts.
One of the most common causes of cataracts in dogs is simple heredity, which is something that can affect pedigree dogs as well as mixed breeds. Cataracts caused by genetics can appear in a dog of any age, so your veterinarian will probably ask about the dog’s age and note the breed. Some breeds prone to cataracts include Afghan Hounds, Akitas, Beagles, Bearded Collies, Bichon Frises, Boston Terriers, Chow Chows, Cocker Spaniels, German Shepherd Dogs, Golden Retrievers, Labrador Retrievers, Miniature Schnauzers, Old English Sheepdogs, Pointers, Rottweilers, Shiba Inus, Siberian Huskies, Staffordshire Bull Terriers, Standard Poodles, Springer Spaniels and West Highland White Terriers.
Because the lens requires some glucose, when the concentration gets too high cataracts can develop rapidly and often in both eyes. Dogs are susceptible even when taking insulin.
Seventy-five percent of diabetic dogs develop blinding cataracts, often within the first year, according to AnimalEyeCare.net. Diabetic dogs showing symptoms of cataracts should see a veterinarian immediately.
Caused by, say, an accident or a puncture wound, these types of cataracts affect the injured eye as opposed to both. When the lens ruptures from a thorn or cat’s claw, for example, the contents leak through the hole and cause a cataract and a “severe immune-mediated reactive uveitis,” reports AnimalEyeCare.net. It is not always immediately apparent that a dog is developing a cataract in response to an injury until it is too late to save the eye. For complete safety, dogs should receive immediate medical attention for any eye trauma.
Dogs are sometimes born with cataracts, but that doesn’t necessarily mean that the cause is heredity. “There may have been a problem in the development of the lens or of the blood vessel that surrounds the lens as it develops during the pregnancy,” says doctors.
- In Relation to Other Diseases
Occasionally, a lens can get “sick” due to another ocular disease or, less commonly, a drug reaction. Some examples of “toxic” cataracts include retinal degeneration, especially progressive retinal atrophy (PRA), uveitis or glaucoma.
- Old Age
The type of cataracts associated with age typically progress slowly and tend to be small, though still require treatment.
The good news is that cataracts are typically easy to treat, though currently the only way to remove cataracts is through surgery. They cannot be reversed. The surgical procedure calls for removal of the original lens and then an artificial lens is placed into the lens capsule.
In rare cases, a veterinarian may determine that she cannot insert a replacement lens. If this is the case, the damaged lens will still come out. The dog’s vision will still improve over what she could see before, but there will still be some blurriness. Prior to surgery, a veterinary ophthalmologist will need to determine if the dog and its eyes are healthy enough for the operation.
“To understand the importance of evaluating the rest of the eye and especially the retina prior to surgery, consider this analogy: A cataract is like a physical barrier to light, similar to a cover over the lens of a camera. This barrier can be physically removed by surgery. In contrast, the retina is like the film in the camera, and the rest of the eye is the camera itself. If the camera or the retina is not working properly, then removing the lens cover (cataract) will not improve the animal’s vision. The rest of the camera must be working well and the film must be good before removing the barrier over the lens [for the surgery to] be worthwhile”
Ask your vet!
The vet will likely run blood tests to help determine a dog’s candidacy for surgery. Other tests may include urine analysis or, sometimes, chest X-rays or EKGs.
Other conditions, such as diabetes, must also be taken into account. “Diabetic dogs are excellent candidates for cataracts surgery, but their diabetes and any cataract-associated inflammation must be well-controlled before surgery”.
Fortunately, the success rate of cataract surgery is high, with 85 to 95 percent of patients regaining most of their sight. Once a cataract has been removed and a replacement lens inserted into the eye, the cataract will not grow back.
After a dog comes home, she’ll have to wear an Elizabethan collar to prevent scratching or rubbing her eyes. A very nice idea is to grind its nails so they are not sharp and prone to cause eye injuries.(check this article for best practices on how to trim or grind your dog’s nails. Pet parents will need to discourage intensive activity such as playing, barking and running, and encourage a quiet, calm atmosphere for the first couple weeks.
Pet parents will also need to strictly follow the veterinarian’s instructions when it comes to medications (antibiotics and anti-inflammatory) and drops. The vet will need to re-examine the dog several times within the first few weeks and then eventually annually.
Complying with the doctor’s instructions will greatly improve a dog’s chances for a successful recovery.