Lymphoma in animals
Lymphoma (lymphosarcoma) in animals is a type of cancer defined by a proliferation of malignant lymphocytes within solid organs such as the lymph nodes, bone marrow, liver and spleen.
[3] Breeds that are commonly affected include Boxer, Scottish Terrier, Basset Hound, Airedale Terrier, Chow Chow, German Shepherd, Poodle, St. Bernard, Bulldog, Beagle, Rottweiler[1] and Golden Retriever.
The four location types are multicentric, mediastinal, gastrointestinal, and extranodal (involving the kidney, central nervous system, skin, heart, or eye).
Multicentric lymphoma, the most common type (by greater than 80 percent),[5] is found in the lymph nodes, with or without involvement in the liver, spleen, or bone marrow.
Gastrointestinal lymphoma occurs as either a solitary tumor or diffuse invasion of the stomach or intestines, with or without involvement in the surrounding lymph nodes, liver or spleen.
Lymphoma is the most common cancerous cause of hypercalcemia (high blood calcium levels) in dogs.
Mediastinal lymphoma can cause fluid to collect around the lungs, leading to coughing and difficulty breathing.
[10] Gastrointestinal lymphoma causes vomiting, diarrhea, and melena (digested blood in the stool).
The epitheliotropic form typically appears as itchy inflammation of the skin progressing to nodules and plaques.
The non-epitheliotropic form can have a wide variety of appearances, from a single lump to large areas of bruised, ulcerated, hairless skin.
[8] The epitheliotropic form must be differentiated from similar appearing conditions such as pemphigus vulgaris, bullous pemphigoid, mycosis fungoides, and lupus erythematosus.
[13] Polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR) identifies circulating tumour cells based on unique genetic sequences.
Due to the high risk of recurrence and ensuing problems, close monitoring of dogs undergoing chemotherapy is important.
Some of the blood tests used in diagnosing lymphoma also offer greater objectivity and provide an earlier warning of an animal coming out of remission.
[15] Complete cure is rare with lymphoma and treatment tends to be palliative, but long remission times are possible with chemotherapy.
In most cases, appropriate treatment protocols cause few side effects, but white blood cell counts must be monitored.
Allogeneic and autologous stem cell transplantations (as is commonly done in humans) have recently been shown to be a possible treatment option for dogs.
Current cure rates using stem cell therapy in dogs approximates that achieved in humans, 40-50%.
When cost is a factor, prednisone used alone can improve the symptoms dramatically, but it does not significantly affect the survival rate.
Whereas dogs often appear healthy initially except for swollen lymph nodes, cats will often be physically ill.
The most common sites for alimentary (gastrointestinal) lymphoma are, in decreasing frequency, the small intestine, the stomach, the junction of the ileum, cecum, and colon.
It is important to differentiate the alimentary form of lymphoma from inflammatory bowel disease because the signs are so similar in cats.
[31] One approach to differentiate inflammatory bowel disease is to test the infiltrating lymphocytes for their monoclonal origin in lymphomas.
[22] Gastrointestinal lymphoma has also commonly been treated with a combination of prednisolone and high dose pulse chlorambucil with success.
Multicentric lymphoma has a better response to treatment than the gastrointestinal form, but infection with FeLV worsens the prognosis.
Other side effects include low white blood cell count, vomiting, loss of appetite, diarrhea, or fatigue.
[33] The most commonly affected tissues are the lymph nodes, spleen, liver, intestine, mediastinum, bone marrow, lung, and kidney.
[35] Symptoms seen are the same as in young ferrets, plus splenomegaly, abdominal masses, and peripheral lymph node enlargement.
