Lymphoma Cancer in Dogs
What are lymphomas?
Lymphoma is a diverse group of cancers that originate in lymphocytes - a type of white blood cell in the immune system.
The commonly affected sites are lymph nodes, spleen and bone marrow, but lymphoma can occur in almost any tissue in
the body where there is lymph tissue such as the gastrointestinal tract, eyes, central nervous system, bone, testes,
bladder, heart, and nasal cavity. Lymphomas typically affect middle-aged dogs (6-9 years old), and certain breeds such as
boxers, bull mastiffs, basset hounds, Saint Bernards, Scottish terriers, Airedales, and bulldogs appear to be at higher risk.

Lymphoma can be classified into several categories:
  • Multicentric lymphoma
  • Mediastinal lymphoma
  • Alimentary/intestinal lymphoma
  • Cutaneous (skin) lymphoma
  • Extranodal lymphoma

How common is lymphoma in dogs?
Lymphoma is one of the most common cancers in the dog. It accounts for approximately 7%-24% of all dog cancers and
83% of all hematopoietic (blood cell) cancers. The annual incidence is estimated at 1.5 cases per 100,000 dogs younger
than 1 year and 84 cases per 100,000  dogs 10-11 years old. Multicentric lymphoma (affecting many lymph nodes in the
body) is the most common type of lymphoma in the dog and accounts for approximately 80% of all lymphoma cases.

What are the symptoms of lymphoma in dogs?
The symptoms are variable and will depend on the cancer's location and how advanced it is. Commonly observed findings
are painless swollen lymph nodes, enlarged spleen and bone marrow involvement. The dogs may also show nonspecific
signs such as lack of appetite, weight loss, vomiting, diarrhea, shortness of breath, increased thirst, increased urination
and fever.

Dogs with gastrointestinal lymphoma can experience vomiting, diarrhea, weight loss, and lack of nutrient absorption. Dogs
with lymphoma in their chest cavity can have edema (swelling) of their neck, head or front limbs. Dogs with skin lymphoma
will show tumors that appear as nodules, plaques, ulcers or dermatitis (inflammation of the skin). Dogs with lymphoma in
their central nervous can experience seizures, paralysis, and partial loss of movement. Dogs with eye lymphoma show
infiltration and thickening of the iris, eye inflammation, blood in the eye, presence of puss, or glaucoma.

How is the diagnosis made?
Pets with suspected lymphoma will have a variety of tests done to confirm the diagnosis, including physical exam, blood
tests, urinalysis,
imaging studies and biopsy. In many cases, fine-needle aspirates of the affected area is sufficient to
confirm lymphoma but biopsy remains as the gold standard for any cancer diagnosis. After confirming the diagnosis, it is
important to evaluate how advanced the disease in order to plan an appropriate treatment. More than 80% of dogs show
signs of advanced disease by the time of diagnosis so it is important to evaluate whether the bone marrow is involved (by
bone marrow aspirate or biopsy) and whether the disease has
metastasized (spread) to other organs (by imaging
techniques such as ultrasound, X-rays, CT scan or MRI).

Does cancer cause pain in pets?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.

To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer with
advanced cancer. Pets with cancer lose weight partly because of lack of appetite and partly because of cancer-induced
altered metabolism. Some of the causes for decreased appetite are related to the cancer itself (for example, tumors may
physically interfere with food chewing, swallowing, and digestion process) and some may be related to the side effects of
cancer treatment (for example, some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause
mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

What are the treatment options for dogs with lymphoma?
Multicentric lymphomas
The treatment strategy for a dog with lymphoma will depend on the subtype, how advanced the cancer is and the overall
health of the pet.
Chemotherapy remains as the treatment of choice, and combining several different chemotherapeutic
drugs has shown greater benefit compared to single drugs. The most effective chemotherapeutic drugs currently in use
include the combination of doxorubicin, L-asparaginase, polyethylene glycol-L-asparaginase, vincristine,
cyclophosphamide, and/or prednisone.

If multi-drug therapy cannot be used, single drug doxorubicin or prednisone can be offered as an alternative. For
doxorubicin, complete response is expected to be observed in 50-75% of dogs, with a median survival time of 6-8 months.
For prednisone, the response lasts 1-2 months but if pet owners decide to try
chemotherapy after the prednisone, they
should be aware that the chemotherapy will be most likely be ineffective. Therefore, the earlier the pet owner chooses a
more aggressive multi-drug therapy, the better the chance of favorable outcome. In the rare cases where only one location
is affected by the cancer, it may be possible to treat it with
surgery or radiation therapy rather than chemotherapy. The role
of radiation therapy for treating lymphoma in dogs is currently under investigation.

Non-multicentric lymphomas
There is not much information available for the treatment of non-multicentric lymphomas in dogs. If the cancer is localized
to a single site, surgery and/or radiation therapy are recommended and where the disease is present in multiple locations
of the body, chemotherapy is the treatment of choice.

Bone Marrow Transplantation as a New Treatment Option for Dogs with Lymphoma
Canine bone marrow transplantation for lymphoma is the replacement of irradiated bone marrow with normal stem cells
after chemotherapy is concluded. It allows veterinary oncologists to treat lymphoma with the most aggressive
chemotherapy possible. They can administer a dose of total body irradiation high enough to kill lymphoma cells that may
be resistant to chemotherapy or residing in locations in the body where chemotherapy cannot reach. To learn more about
this new treatment option, please visit the
Bone Marrow Transplant for Dogs section.

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

How much does chemotherapy cost to treat lymphoma in dogs?
The cost of chemotherapy will differ from a clinic to clinic but according to Purdue University School of Veterinary Medicine,
the cost of the UW-25 protocol (a current standard of care at Purdue) is approximately $4000-$5000, depending mostly on
the size of the dog. The cost is somewhat less for smaller dogs since they receive smaller amounts of chemotherapy drugs.
The cost of chemotherapy does not have to be paid all at once, but is paid on a per-visit basis over the course of 25 weeks.
There are several other chemotherapy protocols that are available for treating canine lymphoma, some of which are less
expensive and require less frequent visits.

Are there any clinical trials investigating new treatments for dogs with lymphoma?
There are several available clinical trials investigating new treatments for lymphoma in dogs. To learn more about these
trials, please visit the
Clinical Trials for Lymphoma in Dogs section.

Additionally, there are several clinical trials available for cats and dogs with any tumor type for which your pet may qualify.
To learn more these trials (which are partially or fully funded by the institutions), please visit the
Dog Clinical Trials (any
tumor type) or Cat Clinical Trials (any tumor type) section.  

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

What is the prognosis for dogs with lymphoma?
The prognosis for dogs with lymphoma will depend on the lymphoma subtype, location of the disease, how advanced it is
and the overall health. Generally speaking, the earlier the diagnosis is made, the better. Without treatment, most dogs will
die of the disease in 4-6 weeks. Fortunately, a high percentage of dogs have a good response to chemotherapy without
major side effects. Dogs that respond to chemotherapy and achieve complete remission (absence of disease) usually
remain free of symptoms and return to a very good quality of life. About 25% of dogs are long term survivors (longer than 2
years) and some are cured.

Read about other pet owner's experiences with lymphoma:
www.bullmastiff.blog.com - a story of Yoshi, a 7-year old male bullmastiff, diagnosed with lymphoma in 2010.

Additional online resources about lymphoma in pets:
Frequently asked questions about lymphoma in dogs (from Purdue University)
www.caninecancerawareness.org/html/CanineCancerLymphoma.html
www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/10500.htm
www.veterinarypartner.com/Content.plx?P=A&A=575
www.marvistavet.com/html/canine_lymphoma.html
www.vetmed.wsu.edu/clientED/lsa.asp
www.vrcc.com/library/disease_k9_lymphoma.shtml
www.lymphomainfo.net/lymphoma/animal.html
www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2005&PID=10916&O=Generic
www.vetspecialists.co.uk/06_Animal_Welfare/Oncology_Facts/Canine_Lymphoma.html
www.dogcancer.net/lymph.html

Sources:
  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 10/5/2014
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