Corneal ulcers are common causes of eye redness in dogs and cats. A corneal ulcer is an area of damage to the surface of the cornea, the clear structure at the front of the eye. These ulcers are painful but usually heal readily with treatment. Sometimes corneal ulcers develop complications that require surgery or other interventions.
 
Causes
Anything that scratches, hits, or irritates the surface of the eye can cause a corneal ulcer. Animals with low tear production are at increased risk for corneal ulcers because they have a low volume of tears to wash away irritants. These are some of the things that cause corneal ulcers:

• Trauma from a cat claw or object poking the eye
• Foreign object in the eye
• Hairs or eyelashes rubbing the cornea (for example, from rolled-in eyelids or skin folds around the eyes)
• Chemical irritation
• Eyelids that don’t adequately cover the cornea (common in brachycephalic, or short-faced, animals with shallow eye sockets and large eyelid openings)
• Immune system disorders that affect the tear film or cornea
• Abnormalities of corneal cells
• Infections
• Neurologic disorders affecting nerves of the eye or eyelids

 
Complications
Some animals have a defect of the corneal epithelium—the surface layer of corneal cells—that increases the risk of ulcers and keeps ulcers from healing. These slow-healing ulcers are called indolent ulcers. Corneal ulcers can become infected, threatening the animal’s vision. Deep corneal ulcers and wounds can penetrate all the way through the cornea and rupture the eye.
 
Eye medications that contain steroids (commonly used to treat conjunctivitis and other inflammatory eye conditions) prevent corneal ulcers from healing properly. Steroid-containing eye medications can also increase the risk of corneal infection.
 
Signs
The signs of eye discomfort are the same whether they are caused by a corneal ulcer or by another eye disorder. Typical signs are squinting, redness of the white part of the eye, and clear or cloudy eye drainage. The animal might rub the eye, and the cornea might look cloudy. Deep ulcers are sometimes visible without an ophthalmoscope and look like a dent or divot in the cornea. Superficial ulcers are usually not visible to the naked eye.
 
An animal with any of these signs should see a veterinarian right away. Although uncomplicated corneal ulcers are relatively minor, they are painful. Some of the conditions that cause the same signs are medical emergencies that require immediate treatment to save the eye.
 
Diagnosis
Corneal ulcers are diagnosed with fluorescein dye applied to the eye. This green dye shows areas where the normal corneal epithelium is disrupted or missing. The eye is also examined under magnification to assess the depth and size of the ulcer, detect complications, and find the cause.
 
Treatment
An uncomplicated ulcer is treated with eye medication to prevent infection and relieve pain. The animal might be fitted with a protective collar (the lampshade type) to prevent eye rubbing. The cause of the ulcer is also treated, if possible. The eye is rechecked with fluorescein dye after a few days to be sure the ulcer has fully healed.
 
Complicated ulcers are treated according to their cause and severity. Indolent ulcers are treated with a procedure to remove loose corneal epithelium. This procedure can often be performed in an awake animal with drops to numb the eye. Some indolent ulcers need a more extensive procedure with the animal under general anesthesia. Deep ulcers and wounds that might rupture the eye need surgical treatment by a veterinary ophthalmologist.
 
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An outbreak of a highly infectious cough has recently been affecting dogs in the Charlotte area. The disease spreads quickly wherever dogs gather: boarding kennels, dog day cares, dog parks, and so forth. Dogs with no symptoms can spread the infection to other dogs.
 
Most dogs have mild illness and recover at home, but some dogs develop pneumonia and need to be hospitalized. Dogs with pneumonia are at risk of dying.
 
These are some of the signs of mild illness:

• Cough (any type: soft, moist, dry, or hacking like a goose honk or a hairball being hacked up)
• Sneezing
• Runny nose
• Runny eyes

 
Call your veterinarian if your dog has any of the following signs:

• Mild signs that last longer than a few days

• Cough becoming more frequent, more pronounced, or more productive (moist)
• Cough affecting ability to sleep
• Decreased energy
• Decreased appetite

 
Take your dog to an emergency clinic right away if your dog has signs of trouble breathing:

• Continuous rapid breathing or panting
• Exaggerated chest movements while breathing
• Using muscles of the abdomen while breathing
• Holding head with neck extended forward or chin lifted up
• Puffing out the cheeks while breathing
• Purple or blue gums or tongue (in a dog whose gums and tongue are normally pink)
• Collapse

 
Causes
Many viruses and bacteria cause canine infectious respiratory disease complex (CIRDC), sometimes called kennel cough. Dogs are often infected with more than 1 agent at the same time.
 
These are some of the agents that cause CIRDC:

• Viruses: canine distemper virus, canine parainfluenza virus, canine adenovirus type 2, canine herpesvirus type 1, canine respiratory coronavirus, canine influenza virus (H3N2 and H3N8 subtypes)
• Bacteria: Bordetella bronchiseptica, Mycoplasma species, Streptococcus equi subsp zooepidemicus

 
Core vaccines (standard for all dogs) give protection against some but not all of the viral agents. Noncore vaccines (optional lifestyle vaccines) are available for canine influenza virus and Bordetella. Vaccines don’t completely prevent CIRDC, but fully vaccinated dogs tend to have shorter and less severe illness. Vaccines also help limit spread of the disease.
 
Transmission and Risk Factors
The infectious agents spread through respiratory droplets and secretions. Some of the agents stay in the environment and continue to infect dogs for weeks. Dogs are infected by direct contact with an infected dog, by inhaling respiratory droplets, or by licking contaminated objects like bowls, bedding, toys, floors, walls, or people’s hands or clothes.
 
Because CIRDC can spread silently (by dogs with no symptoms) and some of the agents persist in the environment for a long time, outbreaks can be hard to control.
 
Any dog that has contact with other dogs or spends time in areas where dogs gather can be infected. Most dogs develop only mild illness and recover within a couple of weeks. Puppies, senior dogs, and dogs with impaired immune function are at higher risk of pneumonia.
 
Some of the agents that cause CIRDC can also infect cats. The only CIRDC agent known to infect humans is Bordetella, but transmission to people is very rare. Canine influenza is not contagious to people.
 
Diagnosis and Treatment
The decision to pursue diagnostic tests depends on the individual dog. Dogs with mild illness need physical examination but often don’t undergo other tests if they have symptoms that suggest CIRDC, have been around other dogs (especially in an area with an outbreak of respiratory disease), and are feeling well otherwise. Additional diagnostic tests can include chest radiographs, bloodwork, tests for specific infectious agents, and tests to rule out other causes of coughing.
 
Treatment can range from just resting at home to being hospitalized for intensive care, depending on the severity of illness. Antibiotics don’t kill viruses, but because CIRDC often involves a combination of organisms, dogs suspected to have a viral respiratory disease (like influenza) might receive an antibiotic as a precaution against bacterial infection.
 
Prevention
These are some tips to help keep your dog safe from infectious respiratory disease:

• Keep your dog’s vaccinations current and talk to your veterinarian about noncore vaccines (canine influenza and Bordetella).
• Keep your dog away from water bowls, toys, and other objects that have been used by dogs that don’t live in your household.
• If your dog has any signs of respiratory disease, keep your dog at home: no day care, dog parks, trips to the pet store, group training, etc.
• During an outbreak, keep your dog home and away from non-household dogs, even if none of the dogs seem sick.
• Plan ahead for holiday travel during an outbreak. Instead of taking your dog to a boarding kennel, you might need to take your dog with you or find someone (friend, family member, pet sitter) to take care of your dog at home.
• Don’t put a mask on your dog.

 
For more information

• Canine infectious respiratory disease complex (AVMA): https://www.avma.org/resources-tools/pet-owners/petcare/canine-infectious-respiratory-disease-complex-kennel-cough
• Canine influenza: pet owners’ guide (AVMA): https://www.avma.org/resources/pet-owners/petcare/canine-influenza-pet-owners-guide

 
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