National Canine Lymphoma Awareness Day is observed each year on November 7 to help draw attention to the prevalence of this deadly disease and the advances being made in treating it. Highly regarded dog agility trainer Terry Simons founded an organization called CLEAR (Canine Lymphoma Education Awareness and Research) and National Canine Lymphoma Awareness Day in honor of his dog Reveille, who died from the disease.
Today, the increased awareness of canine lymphoma and ongoing research efforts promoted and supported by these types of organizations and events are leading to a better understanding of the disease and how best to treat it.
What is Canine Lymphoma?
Lymphoma is a type of cancer that is common both in dogs and in people. Lymphoma is one of the most common canine cancers, accounting for 7 to 24 percent of all canine tumors and 85 percent of all blood-based tumors. In dogs, lymphoma actually refers to a group of approximately 30 different cancers that originate in the lymphocytes – a type of white blood cell that helps fight infection and is found throughout the body but especially in organs that support the functioning of the immune system such as the spleen, bone marrow, and lymph nodes. Consequently, lymphoma tends to target those areas, although it can affect any organ in the body.
The four main types of lymphoma found in dogs are extranodal lymphoma, mediastinal lymphoma, alimentary lymphoma, and multicentric lymphoma. Multicentric lymphoma is the most common form, at approximately 80 percent of all lymphoma cases. Each type of lymphoma has its own characteristics including how aggressive the disease is and the expected survival rate. Lymphoma typically progresses very rapidly, and the average survival rate for untreated dogs after a diagnosis is only four to six weeks.
Canine Lymphoma Causes
The cause of canine lymphoma is unknown, and experts believe that there are likely many genetic and environmental factors that play a role. Exposure to chemicals or toxic substances like herbicides is one area that is being explored. Exposure to radiation or electromagnetic fields may be another factor.
Several factors have been identified as predisposing a dog to developing lymphoma. The disease is more common in dogs that are six years of age or older, but can even strike in younger dogs. There appears to be an increased incidence of canine lymphoma in certain breeds including:
- Golden Retrievers
- Chow Chows
- Scottish Terriers
- Saint Bernards
- Basset Hounds
- Bull Mastiffs
- Airedale Terriers
- English Bulldogs
- German Shepherds
A dog’s sex does not seem to be a factor in developing canine lymphoma, although there are reports that spayed females may have a better prognosis. Research into the genetic and chromosomal factors that affect a dog’s likelihood of developing cancer is ongoing.
Canine Lymphoma Symptoms
The symptoms of canine lymphoma vary widely based on the type. With multicentric lymphoma, the first sign of the disease is swelling of the lymph nodes. This swelling tends to be most noticeable to pet owners in the dog’s neck, chest and behind the knees. Often there is no other sign of illness initially. If the cancer is not treated, dogs with canine lymphoma tend to develop fever, lethargy, weakness, dehydration and weight loss as the disease progresses.
Dogs with alimentary lymphoma will typically display vomiting, diarrhea, abdominal pain, and weight loss. Those with the mediastinal form of the disease develop lesions in the chest cavity that cause shortness of breath and coughing. They may also have swelling of the front legs or the face and increased thirst resulting in increased urination. The symptoms of extranodal lymphoma are different depending on the organ affected and can include blindness, kidney failure, seizures, bone fracture, and respiratory distress.
Diagnosing Canine Lymphoma
Early detection and treatment are both important to ensure a successful outcome. If canine lymphoma is suspected, your veterinarian will ask you about your dog’s health history, including any symptoms you have seen. The more detail you are able to provide, the more effective your veterinarian can be in diagnosing this disease.
Your dog will also undergo a full physical exam as well as lab tests to determine blood cell counts and to look for other biochemical indicators of disease. Fluid from the lymph node is often collected and analyzed to more accurately assess the type of lymphoma. X-rays, ultrasound exams, and other forms of diagnostic imaging may also be performed. Ultimately, your veterinarian will be able to determine whether cancer is present, and if so, what type and which organs or systems are affected.
Traditional Treatment for Canine Lymphoma
Although lymphoma is not curable, it is one of the most successfully treated cancers and most dogs will respond to treatment. The traditional treatment for canine lymphoma has been chemotherapy – generic human drugs that have been around for decades and adapted for use in the veterinary setting. The specific therapy used varies based on the type of lymphoma. For example, multicentric lymphoma has historically been treated with a multiple chemotherapy drug regimen known as the University of Madison-Wisconsin protocol (UW-CHOP), whereas cutaneous lymphoma is typically treated with a drug called lomustine.
Dogs tend to respond well to chemotherapy and typically tolerate it better than humans do. Most canine lymphoma patients treated with chemo don’t lose their hair (although there are some breed exceptions), however, the side effects can include vomiting, diarrhea, lethargy and decreased appetite. Some chemotherapy drugs can also have heart or liver side effects. In some cases, additional canine lymphoma procedures are prescribed, such as surgery and/or radiation therapy.
Advanced Treatment for Canine Lymphoma
One of the most promising new advances in the fight against canine cancer is TANOVEA®-CA1 – the first FDA conditionally approved drug for the treatment of lymphoma in dogs. The drug can be used to treat dogs both naïve to and no longer responding to prior chemotherapy, and has demonstrated a 77 percent overall response and a 45 percent complete response rate, supporting a reasonable expectation of efficacy.
TANOVEA-CA1 is designed to target and kill canine lymphoma cells. It is administered every three weeks by a veterinarian in a 30-minute intravenous infusion that is convenient for pet owners – with a full course of treatment consisting of only five treatment visits (relative to 12-16 visits for traditional CHOP chemotherapy regimens). Data from clinical studies shows it to be generally well-tolerated. The most common side effects of TANOVEA-CA1 include decreased white blood cell count, diarrhea, vomiting, decreased or loss of appetite, weight loss, decreased activity level and skin problems. It should be noted that more serious and potentially fatal complications have occurred in dogs treated with TANOVEA-CA1, so it is important to speak with your veterinarian when making a treatment decision.
TANOVEA-CA1 is now available to licensed veterinarians, making it a promising new option for families looking to treat their dog’s lymphoma.
Focused on a Cure for Canine Lymphoma
Today, novel dog cancer treatments — with TANOVEA-CA1 leading the way — have the potential to put canine lymphoma into remission, with the goal of giving pets and their owners more quality time together. However, in the majority of cases, this disease will eventually return. But with the advances that have been made to date and ongoing research, there is hope that one day a cure for lymphoma – and ultimately cancer – will be found. Until then, TANOVEA-CA1 represents an important new option which may help dogs enjoy more walks, games of fetch and being a beloved member of the family.