Conjunctivitis in dogs, especially long standing cases, is generally
due to allergic conditions. In cats most cases of conjunctivitis
are due to infections from Feline Herpes Virus and Chlamydia. In
humans most cases of conjunctivitis are due to infections that will
readily respond to antibiotics.
Signs of Conjunctivitis:
Ocular discharge - this can vary from watery to mucky discharge
Ocular irritation - the patient may rub at the eye
diagnosis can be made on clinical signs. Other diagnostic tests
that may be considered include conjunctival cytology. In rare cases
bacterial culture and biopsy may be required.
cats a swab may be taken for PCR testing for Feline Herpes Virus
Management in Dogs
Wipe the eyes clear of any mucky discharge
If the dog has other signs of allergy such as eczema, dermatitis
or ear problems, it may be worthwhile doing allergy testing. This
is generally done in conjunction with your local veterinarian.
* Most dogs with chronic conjunctivitis will require long term treatment.
Unlike in humans, long-term cortisone drops will not cause cataracts
or glaucoma. The only potential complication is if something else
happens to the eye, the cortisone drops can make an ulcer or an
infection worse. So stop the drops if the eye is suddenly more closed,
watery, mucky, blue or red.
Most chronic cases of conjunctivitis in dogs can only be controlled
rather than cured.
Most cases of conjunctivitis in cats are secondary to infections
such as Feline Herpes Virus or Chlamydia. It is important to keep
the eyes as clean as possible of any discharge. Chlamydia can in
rare cases infect humans so it is important to wash your hands after
cleaning the catís eyes.
Cats with conjunctivitis will generally require a 3 week course
of antibiotic tablets. We have found that double the recommended
dose is required at twice daily to eradicate Chlamydia. Other cats
can act as carriers, so it is important to treat all cats in the
Most feline conjunctivitis cases settle well after the prolonged
antibiotic course. In some cases it may be necessary to use anti-inflammatory
medications to resolve an underlying reaction. Cats can occasionally
get unusual reactions such as eosinophilic keratoconjunctivitis.
These can be difficult to treat.
Complications from Conjunctivitis
Eye (keratoconjunctivitis sicca): This is a deficiency of the
tears which normally bathe the cornea and conjunctiva. Dry eye can
either cause or can be the result of conjunctivitis. It is important
to regularly check the tear readings in both eyes. Thick mucky discharge
with a dry look to the eyes is characteristic of dry eye. The normal
tear reading for a dog is >15mm, for a cat >10mm wetting in a minute.
This is where the eyelid rolls onto the eyeball. It is seen most
commonly in large breed dogs such as Rottweilers. In most cases
eyelid surgery is required even if the primary conjunctivitis is
scarring: In some severe cases of conjunctivitis, the inflammation
can spread onto the cornea causing reaction in the cornea Ė keratitis.
In most cases the conjunctivitis treatment will reduce the corneal