Harmonia, a 60-pound middle-aged dog, has had her share of mishaps and ailments over the years, but over all has been a happy, healthy dog. Then this spring, she developed a bad case of conjunctivitis — a long word that just means “inflammation of the mucous membranes lining the inside of the eyelids.” It is a description, but not an explanation of the cause. Seasonal pollen can be fierce on the Vineyard, so in otherwise healthy dogs with red eyes and ocular discharge, I’m usually thinking allergic or contact irritant conjunctivitis. But I like to be thorough. I did the standard tests indicated for a dog with conjunctivitis. First I measured Harmonia’s tear production. This is done by tucking a small calibrated piece of blotting paper into the corner of her eye and timing how much fluid diffuses down the strip over 60 seconds. Harmonia’s eyes were not producing enough tears. This is called keratoconjunctivitis sicca, another fancy name that is a description, not an explanation. Kerato means “related to the cornea,” the transparent front layer of the eyeball. If you were paying attention, you know what conjunctivitis means. Sicca means dry. So we have a lovely ten-syllable term, abbreviated KCS, that simply means “dry eye.”
The most common cause of KCS is local, immune-mediated disease in which, for some unknown reason, the dog’s immune system targets and damages the tear-producing tissue in the eye. KCS can also occur with diseases like diabetes, hypothyroidism, or distemper, and as a side effect of certain drugs. Treatment usually involves topical application of cyclosporine, a medication that stimulates tear production, which I prescribed for Harmonia. “This can take a few months to reach full effectiveness,” I told her owner, “but should help.”
But Harmonia’s case was more complicated. Her owner reported the dog had seemed lethargic recently. Were her eyes causing more discomfort than from just KCS? I put a drop of fluorescein dye into each eye to highlight any damage to the normally waterproof corneal surface. In regular light, Harmonia’s corneas did not seem to be retaining any dye. I turned off the lights and grabbed my Woods Lamp, a device that emits longwave ultraviolet light to detect fluorescence not visible otherwise. (We old hippies remember psychedelic “black light” posters in the ’60s that glowed when exposed to UV light.) Harmonia did, indeed, have bilateral corneal ulcers, probably secondary to her KCS. Without adequate tears, the corneas become dry and more susceptible to damage. I prescribed antibiotic ointment, and scheduled a series of rechecks.
Harmonia’s ulcers healed quickly, but her eyes were not responding adequately to the cyclosporine in terms of tear production. We increased the frequency of application. Then we increased the strength of the drops. Then we added artificial tears to be used in between cyclosporine applications. Still no improvement. We decided to try tacrolimus, an immunosuppressant recommended for dogs with KCS that does not respond to cyclosporine. It is not commercially available in the U.S. as an ophthalmic preparation, so we ordered it from a compounding pharmacy.
But Harmonia’s case was more complicated. Her owner reported periodic vomiting and continued bouts of poor appetite and lethargy. When she arrived for her two-month recheck, the first thing we immediately noticed was she had lost quite a bit of weight. We popped her up on my table and I began my exam. Uh-oh. Oh no. This was one of those moments when a veterinarian’s heart sinks. Harmonia had generalized lymphadenopathy. This means that many of her lymph nodes were enlarged. When this happens, it is usually due to one of two possibilities: massive infection or cancer. Harmonia had no fever and no other symptoms suggesting infection. After a long discussion with her owner, we submitted blood work and an aspirate of one of the enlarged nodes to the diagnostic laboratory. The blood tests revealed abnormalities suggestive of lymphoid cancer, lymphocytic leukemia, or what is called the “leukemic phase” of lymphoma. The lymph node aspirate was also “suggestive of lymphoma.”
Lymphocytes are white blood cells that normally help the body fight infection. There are several types of lymphocyte-related cancer in dogs. Lymphoma, also called lymphosarcoma (LSA), primarily presents as tumors in the lymph nodes. Early symptoms may be just lymphadenopathy, or may include lethargy and poor appetite. Although definitive diagnosis can sometimes be made with an aspirate, often an actual biopsy is needed so the pathologist can exame the architecture and cell distribution of the tissue. Blood work can look completely normal or show a variety of abnormalities, depending on the stage and location of the cancer. In Harmonia’s case, abnormal lymphocytes present in the blood were suggestive of, though not definitive for, a particular stage of LSA.
Another possible diagnosis here is acute lymphoblastic leukemia, in which the cancerous lymphocytes are in the bone marrow and blood. Signs can include weight loss, lethargy, vomiting, diarrhea, and decreased appetite. Enlarged lymph nodes are not common, but may occur. Most dogs have marked abnormalities in their complete blood count. The final possible diagnosis is chronic lymphocytic leukemia, also a cancer of the bone marrow, but one that tends to have a slower progression and may have a longer survival time. But none of these diseases were good news. If we wanted Harmonia’s exact diagnosis and a definitive treatment plan, we would need additional biopsies, and a test called flow cytometry to confirm and determine what cell lines are involved.
Any owner faced with these possibilities will have difficult decisions to make. Do more tests? Consult an oncologist? Consider chemotherapy? Will the benefits of treatment outweigh the side effects? Each family must explore these things with their veterinarian, taking into consideration their pet’s temperament, the prognosis, the financial aspects, and then do what is right for them. Was Harmonia’s presenting sign of KCS somehow related to her cancer? I just don’t know, but for now, we are doing what we can to make her as comfortable as possible for as long as we can.