Recognising & treating Dog cataracts!
Cataract in pooches can develop rapidly, so it is most important to treat this problem as early as possible; otherwise the effects on your pooch’s vision can be very detrimental and eventually lead to complete blindness. Here’s how to take care of your dog’s vision.
Dr Brejesh Singh
What is cataract?
Your pooch’s eye has a clear lens inside that is used for focusing just like a camera lens. Cataract is one of the most common types of eye condition, which occurs in both people as well as pooches. The word cataract is a Latin term meaning ‘break down’. This disease occurs when the lens in the eye becomes cloudy which causes the pooch’s vision to decrease. The cloudiness of the eye can initially take the form of a small white spot, which then spreads out over the lens of eye. The symptoms might appear in just one eye or in both the eyes at once. As this ocular disease develops, it will be more noticeable, spreading further across the lens of the eye and you will see the lens getting cloudier and more opaque. One of the commonest causes of cataract in pooches is diabetes; all pooches with diabetes will ultimately develop cataracts and will eventually go bind if left untreated.
How does cataract form?
Despite the fact that there are several different forms and causes of cataracts, they all develop in a similar fashion. The normal lens is maintained in a dehydrated state. It consists of 66 percent water and 33 percent protein. There is a complicated sodium water pump system in the lens that keeps this water/protein balance in check. When this biomechanical system in the lens is damaged, this pump system begins to fail and extra water moves into the lens, leading to swelling and rupture of lens fibers and development of cataract. Too much water is retained in the lens of the pooch’s eye and the amount of protein increases.
Types of cataract
When cataracts develop, it is significant to know how old your pooch is. It will make it easier to diagnose what type of cataract your pet has.
Congenital cataract: These are cataracts that are present at birth and usually occur in both eyes. This type of cataract is often very dense, white (like boiled egg white), and usually progresses slowly. Infections or toxins may cause the formation of these cataracts in unborn puppies. Primary congenital cataracts such as those found in Miniature Schnauzers are, however, inherited.
Juvenile cataract: This cataract develops usually between the 1st and 8th years of life. If causes such as diabetes mellitus, trauma, intoxication or radiation are unlikely or can well be excluded, it is possible that the cataract is hereditary.
Radiation cataract: It is due to exposure to infrared, ultraviolet, microwave or x-ray radiation and radioactive materials can induce cataract.
Alimentary/intoxication cataract: Substance such as naphthalene, dinitrophenol and possibly some substance in food can cause cataract and sometimes this type of cataract is reversible.
Senile (Late Onset) cataract: This is a local cloudiness of the lens that mostly develops in pooches over six years of age. They occur much less frequently in pooches than in humans. Nuclear sclerosis, which is not considered to be a medical problem, is often confused with cataract at this age.
Traumatic cataract: It can develop as a result of a deep stab wound by a thorn, splinter or cat claw. If the capsule heals quickly, the damage can remain limited to a local, non-progressive cataract. These types of cataracts usually occur only in one eye and can be treated successfully with surgical removal.
Inherited cataract: A recessive hereditary defect is the most frequent cause of cataract in pooches. Inherited cataract in the pooches may occur independently or in association with other ocular disease. If a pooch is diagnosed with inherited cataracts, the pooch should obviously not be used for breeding because of the likelihood of perpetuating the disease in the offspring.
Which pooches are prone to cataract?
Though pooches of all ages and breeds can develop cataract, they are more commonly found in Cocker Spaniels, Poodles, Miniature Schnauzers,
Terriers and Golden Retrievers. Pooches with diabetes are also especially prone.
How is cataract diagnosed?
If you observe cloudiness in one or both of the pooch’s eyes, contact your veterinarian immediately. The veterinarian will ask for a thorough history of your pooch’s health, including the onset and nature of the symptoms, and possible incidents that might have precipitated the problem. He will then perform a complete physical examination, focusing on the eyes and ocular region, to determine the severity of the problem.
Routine diagnostic tests, such as complete blood count, biochemistry profile and urinalysis may be conducted. However, the results of these tests are usually non-specific unless another concurrent disease like diabetes mellitus or hypocalcaemia is at the root of the problem. Ocular ultrasounds or electroretinography (which measures the electrical responses of cells present in the retina) are two forms of advanced diagnostic exams which also help determine the severity of the issue and may confirm whether surgery is necessary to correct a cataract.
How can cataract be treated?
If your pooch develops cataracts, the treatment is the same as in humans, that is, to surgically remove the eye’s lens. This type of surgery is frequently done in pets and has approximately 95 percent success rate. There are some dogs who are not good candidates for cataract surgery and include those dogs who have uncontrolled diabetes, are aggressive or are in poor health. Mature cataracts are more difficult to manage during surgery than less advanced cataracts.
Surgery to remove cataracts is done under general anaesthesia. A small incision is made a in the eye, and most often a procedure called phacoemulsification, which is the same technique used on human cataracts, is employed to break down the cataract and remove the cloudy lens. The lens is removed from the lens capsule, and in most patients the lens can be replaced with an implant which is permanent and can restore almost normal vision in your pet.
However, sometimes the lens capsule is loose-fitting or can’t be fragmented completely by emulsification. When this happens, the lens and lens capsule are removed, and in this situation there’s no way to do a lens replacement. Pets with this issue can still see after their surgery. They just won’t see as well as those who have received a replacement lens.
Animals with the whole lens removed will also end up being far-sighted (hypermetropia), which means objects close to them will be blurry. These patients will adjust over time and usually wind up with good functional vision.
How to prevent cataract in pooches?
Studies have shown that taking extra amount of vitamin C can reduce the risk of developing cataracts. The eye has a greater concentration of vitamin C than any other organ in the body. Humans don’t produce vitamin C in their body; however, pooches do, so canine supplements often don’t include it. Make sure you examine the ingredients in your pooch’s supplement to ensure it is included, if your pooch needs it. A diet rich in antioxidants also helps to prevent cataract formation. A pooch with cataract should also get vitamin A, C and E along with zinc in its diet. Lutein, a yellow carotinoid pigment, is valuable in prevention as well as treatment of cataracts. Kale and carrots are excellent sources of lutein. Adding bright coloured fruits and vegetables to your pooch’s diets will also help in preventing cataract along with other diseases such as cancer. In addition to dietary support, some eye drops containing N-acetyl carnosine (NAC) can help in reducing or eliminating cataracts.
(Dr Brejesh Singh is Assistant Professors at Department of Veterinary Medicine, Veterinary College, Rewa, MP ; Dr. K.K.Mishra is a Associate professor in the Department of Veterinary Medicine, Veterinary College, Rewa, MP)