Introduction: This page is in two parts because it has been checked, added-to and republished as at January 2, 2022. The first part was written on January 2 and the second part was written about 13 years prior to that date. Rather than fully rework the article I have decided to do it in two parts. The earlier part is still valid and useful. Together they create a full picture.
Nasolacrimal duct blockage in cats
The effects of tear duct overflow are commonplace in the Persian and Himalayan cat breeds. You see staining from the corner of the eye down the sides of the nose as the fluids fail to drain through the nasolacrimal duct, which is fed by the lower and upper punctum and ducts. As you can see in the illustrations the nasolacrimal system consists of a series of three tubes which allows tears to drain into the nose and mouth.
The upper punctum is situated on the upper eyelid while the lower punctum is situated on the lower eyelid. They converge to form a larger nasolacrimal duct which extends to the nasal passages.
The nasolacrimal duct can become blocked. The tears backup and overflow down the face as described. This causes staining which needs to be cleaned by the human caregiver.
What causes the nasolacrimal duct system to become blocked? The cat may be born with a misshapen duct due to extreme breeding (Persian). VCA hospitals describe this as “a hereditary defect in the formation of the nasolacrimal duct”. It results in the lack of an opening where the duct meets the conjunctiva which is the pink tissue surrounding the eye.
If it’s not an inherited defect due to extreme breeding, it may be blocked because of what happened during the cat’s life such as inflammation after an infection or an obstruction caused by a tumour or perhaps a foreign body lodged within the duct itself.
The clinical signs are described as mainly cosmetic but cats may develop a skin infection below the eyes causing swelling, redness and itchiness.
Because the hair below the eyes becomes moist it becomes a medium for bacteria. A bacterial infection may develop which causes a nasty smell and a skin infection.
Veterinarians diagnose a lacrimal duct obstruction using a die called fluorescein. It glows under a black light which allows a veterinarian to see small amounts of dye. Several drops of it are placed in the eyes. The dye should travel down the nasolacrimal duct and become visible in the mouth and nose. If it isn’t visible in the nasal cavity within 5-10 minutes, the diagnosis is a duct obstruction.
At that point the veterinarian will examine the opening of the duct at the eyelids to ensure that it is functioning. He or she will do this with a magnifier. Mild obstructions can be flushed using a saline solution by inserting a thin tube into the opening.
RELATED: 7 causes of cat tear stains
A veterinarian might conduct x-rays and/or CT and MRI scans to check for tumours and other obstructions. The bacteria may be analysed for species and the required antibiotic.
Antibiotics will be used to treat inflammation due to bacterial infections. As mentioned, these can cause blockages. Sometimes surgery is indicated. This will enlarge the opening to the duct or remove tumours that are compressing the duct. There might be a foreign body which needs removing surgically.
If the cause is due to the malformation of the duct as a consequence of extreme selective breeding, there is no cure to my knowledge and it is beholden upon the cat caregiver to constantly wash the tear staining to preclude the possibility of skin irritation and bacterial infections in that area. Even when cleaned there will be a mark on the fur which has a negative impact on the appearance of the cat.
RELATED: Do cats shed tears?
Source of this section: Myself and VCA Hospitals.
The following section was written about 13 years ago
There are several topics that come to mind in respect of the clogged tear duct of a cat:
- What are the symptoms of a cat’s clogged tear duct
- Is it a clogged tear duct or a defective tear duct, meaning one that is not working properly because it is the wrong shape?
- Is the cat producing too many tears and if that is the case, why?
- Is a well-known product like Angel’s Eyes, which can be bought over the counter or online going to be the answer?
The symptoms are fairly well known and documented, namely tear duct overflow. The medical term is epiphora. Because the tears cannot drain through the duct, the tears flow down the face of the cat onto the fur below and dries there. This causes staining. This is because the damp conditions and the hair are a good environment for bacteria and yeast. Red yeast causes the staining that we see.
The staining extends downwards from the lower corner of the eye that is nearest the nose. This is the exact location of the opening through which tears from the eye pass into the tear duct. The tears would normally go down the duct into the nose. When we cry our nose runs as well. This is the reason.
The anatomy of people and cats is similar in many ways (that’s why cats are used sometimes in medical experiments). The picture, right, is of the tear duct of a human. The configuration is similar for a cat.
“Basically the tear ducts of the cat consist of a very tiny almost invisible opening on the inner aspect of the eyelid on the side the nose. These opening lead to the actual tear ducts which connect to the nose.” ( Scott Nimmo BVMS – new window)
Clogged tear duct of a cat – blocked or defective?
If the tear duct is defective, it is not clogged. I know of only one case where the tear duct of a cat is inherently defective through breeding and that is in the flat faced Persian cat and the Himalayan cat (a pointed Persian cat). Tear duct overflow in these cats is a medical condition brought about by irresponsible breeding. These cat breeds should not have been brought into existence. The doll face Persian does not suffer from the same condition because the face has a normal anatomy. Please see Cat Health Problems and Persian Health Problems.
If there is tear duct overflow in a cat other than a flat faced Persian it is probable that it is blocked. An operation under anaesthetic can be performed to clear it.
Clogged tear duct of a cat – too many tears?
Tear duct overflow might be due to the over production of tears that overburden the tear duct or partly due to over tearing and partly due to blockage. A vet will advise.
Over production of tears can be due to a number of causes – these are examples:
- Infections in the tear ducts (this would seem to be circuitous – a blockage may result in infection, which in turn exacerbates tearing).
- Allergies and irritation from cigarette smoke, dust, food allergies, water allergies, airborne allergies etc. (see feline allergies , hypoallergenic food , grain free cat food, feline eye disease .
- Hair from around the eyes.
- Eyelashes that grow into the eye.
Both over tearing and tear duct blockage would, it seems, need to be checked if there are signs of staining.
Clogged tear duct of a cat – Angel’s Eyes
As I understand it, Angel’s Eyes is a pet food supplement that comes in various flavours, the active ingredient of which is tylosin as tartrate (Angel’s Eyes description) and which is designed to “eliminate unsightly tear stains from the inside out”.
Tylosin is….an antibiotic used in veterinary medicine. Tylosin is used in veterinary medicine to treat bacterial infections in a wide range of species and has a high margin of safety.
A tartrate is a salt…As food additives, tartrates are used as antioxidants….Antioxidants are also widely used as ingredients in dietary supplements in the hope of maintaining health and preventing diseases such as cancer and coronary heart disease. Although initial studies suggested that antioxidant supplements might promote health, later large clinical trials did not detect any benefit and suggested instead that excess supplementation may be harmful. (Wikipedia)
The way the ingredient is described as “tylosin as tartrate” indicates that its presence is as both as a broad-spectrum antibiotic and a food supplement antioxidant. The Wikipedia author also says this about Tylosin:
…it has been used…as a way of reducing epiphora (tear staining) around the eyes of white-faced dogs. (Note: Angel’s eyes is also used on cats). It should be noted that no marketing authority exists for the use of tylosin as a tear stain remover and thus it is not legal to use it for such purposes- the exception being as a Prescription Only Medicine of last resort by vets under the Cascading Rule (UK) or the Extra Label rule (US).
Note: the manufacturers of Angel’s Eyes admit that the Food and Drug Administration have not evaluated their claims.
It has been said that broad spectrum antibiotics are not ideal. Ideally the causative agent of the infection (causing the tear duct blockage or as a result of the tear duct blockage) should be identified and a narrower and more targeted antibiotic used instead.
One contributor in a dog forum (I don’t know her or his qualifications) said that broad spectrum antibiotics can kill the good bacteria and the bad. This seems a sensible comment. On that basis it may be wise to seek advice as to how to offset that (e.g., probiotics). There are other issues attached to regularly giving an antibiotic over a long period (if that is the case with Angel’s eyes) such as immune system damage and liver damage, she says. Clearing or preventing the clogged ear duct of a cat or managing tear duct overflow with Angel’s Eyes carries some risk it seems.
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