Conjunctivitis, also called pink eye, very regularly affects cats and can be triggered by numerous causes. It isn’t a single disease, but rather a symptom. Although all cat breeds and all ages can be affected, young cats in particular suffer from cat colds, whilst older cats often have allergic conjunctivitis. Consequently, conjunctivitis with cats can also be accompanied by other symptoms, which influences treatment and prognosis.
Conjunctivitis in cats 
Written by Franziska G., Veterinarian
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Table of contents
How does conjunctivitis emerge with cats?
The onset of conjunctivitis with cats is varied, therefore it makes sense to split the causes into infectious and non-infectious events for better comprehension.
Infectious causes
Conjunctivitis with young cats is often a sign of the cat cold complex. This is a globally occurring infectious illness triggered by numerous bacterial and viral pathogens. However, the feline herpesvirus 1 (FHV-1) and bacterium Chlamydophila play a particularly significant role. Both infectious agents are transmitted via droplet infection, e.g. through contact with contaminated nasal discharge. Typically, households with multiple cats such as an animal shelter or even cat exhibitions carry a particular high risk of spreading pathogens due to the large amount of cats. Along with typical conjunctivitis, this respiratory disease is often accompanied by other symptoms like sneezing, fever or lack of appetite.
Non-infectious causes
This category includes in particular allergic reactions and inflammations triggered by foreign bodies. Allergies are equally frequent with cats and often lead to further hypersensitivity reactions like itching, respiratory complaints or other skin irritations, as well as conjunctivitis. Parasites (e.g. fleas), household dust or certain medications are particularly frequently diagnosed allergens with cats. However, foreign bodies often cause irritation of the eyes along with allergic reactions, which leads to inflammation of the conjunctiva as a consequence. Examples of this are particles from the environment or hairs.
What are the symptoms of conjunctivitis?
Conjunctivitis in cats can be recognised by certain signs. These include:
- Reddening of the eyes (conjunctival infection)
- Swelling of the conjunctiva and squinting of the eyelids
- Lacrimal discharge (e.g. watery or purulent)
- A foreign body sensation
- Depending on the primary disease, additional symptoms like sneezing and coughing or other skin irritations can emerge.
What are the diagnosis options?
Conjunctivitis in cats doesn’t always have to triggered by a serious disease. If other symptoms emerge though or it doesn’t heal on its own within a few days, a vet should be consulted without further ado.
The vet follows a certain examination routine:
At the start of the visit, the vet carries out a thorough interview with the owner (medical history). The aim of this is to collect important information on possible illnesses. In addition, the cat’s vaccination status, other signs of illnesses or contact with other sick animals are very useful for eliminating differential diagnoses.
After the anamnesis, there is always a general clinical examination to determine the cat’s general state of health. This is very important, because further diagnosis depends on the cat’s current condition. The most important parameters are the cat’s general condition, heart and respiratory rate as well as the state of the mucous membranes and the rectal internal body temperature.
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If the results of the general clinical examination don’t show any strong deviation from the vital parameters, the special examination can commence. The eye is examined more closely in order to rule out the presence of a foreign body. If the cat is uncooperative, a local or general anaesthetic may be necessary in cases of suspicion. In contrast, infectious primary diseases can be quickly detected by a swab. In order to locate the bacteria and viruses involved, the swab is examined microscopically and also with the PCR method (polymerase chain reaction). However, very few veterinary practices have the diagnostic capabilities for the PCE method, so samples are often sent to special laboratories. The vet treating your cat then generally finds out the result a few days later. In order to find out the cause of an allergy, a time-consuming elimination diet, skin test (intradermal test) or blood test can be performed.
How is conjunctivitis treated?
Treatment of conjunctivitis in cats is divided into special treatment, which tackles the root cause, and symptomatic treatment, which is meant to decrease symptoms and other side effects:
Special treatment:
- Bacterial infection: antibiotics in the form of eye cream and possibly administered systematically
- Viral infection: if necessary antiviral medication
- Foreign bodies: these may perhaps have to be removed manually (in some cases under anaesthesia)
- Anti-allergy measures: anti-histamines, cortisone, desensitisation
Symptomatic treatment:
- Cortisone (eye creams or systematic): cortisone has an anti-inflammatory and anti-allergy effect, though can damage the eyes if used incorrectly (e.g. corneal ulcer)
- Fluid therapy and electrolytes can improve your cat’s condition if suffering from a circulation disorder
- Allergy: avoid contact with allergens
What is the prognosis?
The prognosis of conjunctivitis depends on the cause of the illness and generally doesn’t lead to severe eye damage. However, if the inflammation spreads to the surrounding tissue and damages the inner eye structure, the risk of blindness increases.
How can I prevent conjunctivitis with my cat?
Infectious diseases like the cat cold complex can be avoided with the following preventive measures:
- Avoid contact with sick animals
- Vaccines against feline herpesvirus 1 (FHV-1), Chlamydophila felis and other causes of the cat cold complex are available. The basic immunisation is given after 8, 12 and 16 weeks of age and depending on the vaccine, a booster should be carried out by a vet every year until the age of 3.
It’s difficult to avoid the entry of foreign bodies. However, allergic reactions can be reduced thanks to certain precautionary measures.
The following tips are recommended:
- Remove allergens from the cat’s surroundings if possible
- Effective flea prevention: e.g. flea collar or spot-ons
At the Justus-Liebig-University of Giessen I was extensively trained as a veterinarian and was able to gain experience in various fields such as small animal, large animal and exotic animal medicine as well as pharmacology, pathology and food hygiene. Since then, I have been working not only as a veterinary author, but also on my scientifically driven dissertation. My goal is to better protect animals from pathogenic bacterial organisms in the future. Besides my veterinary knowledge, I also share my own experiences as a happy dog owner and can thus understand and enlighten fears and problems as well as other important questions about animal health.
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