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The Feline Leukemia Virus (FeLV) and the Feline Immunodeficiency Virus (FIV) play an underlying role as the etiologic agent for the genetic mutations found in Feline Lymphoblasts, the viral factor must be weighed into account. Cats present in basically one of three different clinical stages of disease: the truly ill, the symptomatic and the unaffected. There is less optimism and less response for the very sick cats. We see more success for the sick but stable cases, and good to great responses for the asymptomatic cats.
Young cats may develop a large tumor in the chest cavity in front of the heart (Anterior Mediastinal Mass, AMM). These poor cats will die quickly without rapid diagnosis and treatment. The veterinarian can examine the fluid aspirated from the chest cavity or the mass itself. If lymphoblasts are found, the diagnoses can be made. If even one lymphoblast is found in this fluid, the cat can be treated for lymphoma immediately and given the chance to live.
Anything short of this quick action creates delay. Many cats with this condition deteriorate quickly and the family is forced to elect euthanasia. It is a shock to the owners because these young cats were healthy just days before! Since they have over an 80% response rate, there should be little hesitation to give chemotherapy to cats with AMM.
Most of our current cases of feline lymphoma are presented as intestinal or mesenteric (membrane supporting organ/body) forms. The typical history of weight loss, soft stool, diarrhea or vomiting should alert clinicians to suggest a work up to rule out lymphoma. Cats with ropey intestines, palpable mesenteric nodes, or obstructions are highly suspect for G.I. lymphoma.
Cats that have the diagnosis of inflammatory bowel disease (IBD) are at greater risk of developing intestinal lymphoma. IBD is considered a precancerous lesion and lymphoma may be near at hand. The tricky part is knowing when to abandon the treatment for IBD and go to the more intense chemotherapy needed for lymphoma.
A fine needle aspiration (FNA) cytology is highly recommended by Dr.Villalobos. A 1-1?2 inch 27 gauge needle is used to aspirate any structure in the abdomen. Ultrasound guided FNA of mesenteric nodes and thickened bowel loops is another way to get a non-surgical diagnosis. The next method that bypasses the stress of surgery is with endoscopy (a fiber optic instrument used to exam hollow organs).
Despite the fact that the wound may be below the mucosa for this technique, enough cases are definitively diagnosed this way with little stress on the cat. Laparoscopy (performance of a minor abdominal surgery using a laparoscope) is becoming more available in private practices. Cats that are weak and thin would be best served if the diagnosis could be made via laparoscopy without open abdominal surgery. Finally, exploratory surgery is elected as the only sure method to harvest multiple organ tissue and full thickness intestinal samples.
Some cats will present an enlarged kidney or hepatomegaly. Ultrasound and FNA can quickly establish the diagnosis for immediate treatment.
These cats can respond to aggressive immediate treatment if they are supported with fluid therapy and nutritional support with hand feeding or esophageal feeding tubes. It is possible to rescue cats from near fatal conditions induced by lymphoma and to restore their well-being.
If the cat is FeLV and FIV negative, they have a better prognosis. One of these viruses may be hidden in the cat in a dormant form and is most likely the cause of the lymphoma. In viral negative cats, the survival can be expected to last for one to several years. Many of our cases are enjoying 2 to 5 +years remissions. Some have even discontinued the chemotherapy treatments.
Dr. Villalobos recommends the Wisconsin based protocol for cats in these cases. Administer of Vincristine at O.O25mg / kg i.v. along with 400 i.u. / kg of L-asparaginase S.Q. are often given on the first day. As a pre-treatment for the L-asparaginase, we give Dexamethazone 0.1ml to 1 ml i.v. prior to the Vincristine injection using the higher dose depending on the magnitude of the cat’s tumor burden.
Prednisone at 5mg B.I.D. forever is dispensed along with two tablets of 25mg Cytoxan to be used orally on day #8 and #9. We instruct the owner to return on day #15 for Adriamycin at 1mg / kg i.v. We also administer Dexamethazone as above as a pre-treatment. We instruct the client to return in one more week for Vincristine as above on day #21, repeat the Cytoxan day #28 and #29, and then the second Adriamycin as above on day # 32. Thereafter, we use a 10-day interval between treatments.
The cat returns for Vincristine every 21 days for 6 months. Ten days after the Vincristine, the owner is to rotate the Cytoxan with oral Chlorambucil giving one 2mg tablet B.I.D. or one tablet two days in a row only.
We place the entire chemotherapy regimen onto a calendar for the client to use as a guide. This calendar is important and we ask the family to keep notes on how the cat is doing on the calendar. After one year the interval between treatments may be extended to two weeks.
For those clients who cannot return every 3 weeks, the schedule may be adjusted to using the Chlorambucil 10 days after the Vincristine and the Cytoxan 20 days after with a return at 30-day intervals for i.v. Vincristine. Further adjustments may be made to accommodate the caregivers.
In response to client wishes, Dr.Villalobos has developed a stay at home protocol that is called the “LU-C-LO-V” protocol, which incorporates lomustine at 50mg / M2 after the Chlorambucil and Cytoxan. This protocol is now being introduced to long-term cases and although it seems to help keep cats in remission and at home, results are not compiled for reference.
A CBC test must be done on all cats to monitor signs of Leukopenia, Anemia, Thromocytopenia just prior to Chemotherapy treatment. They also need detailed medical support for ongoing clinical symptoms and simultaneous disease conditions.
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Pawspice, Hermosa Beach 562-493-5025
Animal Oncology, Woodland Hills 818-712-0060