Cancer & non-cancerous tumors FAQs

 

Is cancer genetic?

Yes, but it isn’t necessarily inherited.  Cancer is the result of mutations in the DNA that cause cells to reproduce abnormally and in great numbers.  These mutations may be inherited but more often are due to environmental factors or an accumulation of DNA transcription errors.  These errors are the reason cancers often occur in older individuals.   Copying mistakes accumulate after many, many cell divisions.  The chromosomes themselves may get rearranged.  Depending on what those errors and rearrangements are and what genes they affect, the result can be cancer.

However, if any one cancer occurs in multiple members of the same family, especially if those dogs lived in different environments (i.e. different owners and households) one should be suspicious that some sort of genetic predisposition is at play.  We already know from the 2006-7 ASHGI cancer survey that we have two inherited cancers in Aussies:  Hemangiosarcoma and lymphoma.

Are all tumors cancerous?

No.  Some tumors are benign.  Two examples are lypoma, fatty tumors found under the skin usually in older dogs, and meningioma, a benign tumor of the brain.  However a benign tumor can be a health issue depending on what it is, whether it is enlarging, and where it is located.

Are there any environmental factors connected to cancer in Aussies?

The 2007 ASHGI cancer survey found no significant relationships found between environmental factors and cancer, though there was a slight correlation between urban and rural spraying programs and lymphoma.  Research on that cancer in humans has indicated that there may be a connection but at this point there is no conclusive evidence for dogs.

Do vaccines cause cancer?

There is no clear connection between any canine vaccine and any specific form of cancer.  If there were such a connection it is unlikely to be attributable to all vaccines or all cancers; the most likely scenario would be that a particular vaccine, or even a specific brand of that vaccine, might be associated with some specific type of cancer.  The 2007 ASHGI cancer survey found no correlation between vaccines and any of the cancers reported.

Are there vaccines that prevent cancer?

Cancer vaccines function differently than the more traditional vaccines we give our dogs and ourselves for infectious diseases.  Traditional vaccines are a preventative administered to healthy individuals.  They prompt the immune system to recognize the invading “bug” and go into attack mode if the vaccinated individual gets infected.  The vaccine makes sure bug gets killed off before it can do substantial damage.  The Human Papillomavirus (HPV) vaccine that prevents cervical cancer but it is actually a traditional vaccine targeting the HPV virus which causes the cancer.

True cancer vaccines, on the other hand, are given to patients already diagnosed with cancer.  They beef up the immune system’s ability to identify and therefore remove cancer cells.  They aren’t a preventative, like more traditional vaccines, but a “clean-up service,” that destroys any remaining cancer cells in cancer patients to minimize the risk of the disease returning in the future.  Cancer vaccines are a relatively new development in cancer treatment.  There is one currently (2013) available for canine melanoma and others are being researched.

Has cancer become more common in Aussies than it used to be?

Yes.  During a longevity study done in the late 1990s Cancer was found to be the breed’s primary cause of non-accidental death.  This isn’t surprising in elderly dogs but more recent generations were developing cancer at younger ages, often under 10.  Part of the increase may have been due the gradually rising level of inbreeding across the breed, but the 2007 ASHGI cancer survey found that two inherited cancers at that time accounted for nearly half of all cancers in the breed, probably as an unintended consequence of breeder selection.  Until that survey no one in the breed had any idea that any cancers might be inherited.

How common is cancer in Aussies?

The 2009-10 ASHGI health survey found that nearly 60% of deaths in the breed were due to cancer with 45% of deaths due to the inherited cancers, hemangiosarcoma and lymphoma.  16% of the dogs surveyed had cancer and seven out of ten of them died.

 How common are the inherited cancers in Aussies?

The 2009-10 ASHGI health survey found that 5% of the dogs surveyed had hemangiosarcoma and 2% had lymphoma.  These numbers are probably understated because they typically arise in later adulthood or old age and the youngest dogs in the survey were 4 years old so an unknown number will have developed these cancers later.

 What is hemangiosarcoma (HSA)?

HSA is a very aggressive cancer of vascular tissue (blood vessels.)  Because of this it can form almost anywhere but tumors most frequently initiate in the spleen, heart, and occasionally the skin.  Because it begins in a blood vessel it spreads readily, often to the lungs or liver.

How do I know if my dog has HSA?

If you find a dark or purplish lump on your dog’s skin, it may be an HSA tumor.  You might also find a soft mass under the skin or a hard mass with an associated ulcer on the skin surface.  However, most cases are internal.  Dog’s whose cancer starts in the spleen or heart may be lethargic, anorexic, lose weight, fluid in the abdomen, or difficulty breathing.  If your dog has tumors you can see or feel, or any of the internal symptoms for more than a day or two get your dog to the vet for an exam.   Sometimes a weakened blood vessel will rupture causing an internal bleed which can be catastrophic.  If the dog is over 4 years and suffers sudden collapse this may be a sign of HSA.  A veterinarian will examine the dog, do blood tests, or tumor biopsy.  If the abdomen is distended he may withdraw some of the fluid for exam.  Short of direct identification of a tumor and biopsy, diagnosis is made by exam and ruling out other possible causes of the symptoms.

 What does having HSA mean for my dog?

Unfortunately, prognosis for this cancer is very poor.  Most dogs only survive weeks to a few months after diagnosis.  Sometimes the first indication you have that your dog is sick is a sudden catastrophic collapse.  If any Aussie over 4 years dies suddenly from no apparent cause may have died from HSA; if at all possible a necropsy should be done to verify whether or not HSA was the cause. The skin form, if caught early enough, may be cured by tumor removal.  It is also the easiest type to treat with the longest survival time.

 Is HSA common in Aussies?

The 2009-10 ASHGI health survey found that 5% of the dogs surveyed had hemangiosarcoma.

 Is HSA inherited in Aussies?

Yes.  Specific gene(s) have not yet been identified but they probably are risk factors – not a guarantee the dog will develop cancer but something that significantly increases the likelihood the dog will do so.

 What does HSA mean for my breeding program?

Affected dogs are unlikely to be well enough or live long enough to breed, but if semen is stored from males who had HSA it should be discarded because this disease is virtually always lethal.  First step kin of affected dogs (parents, full and half siblings, and offspring) should be bred only to mates with pedigrees as clear of HSA as possible and who have no affected close relatives.

 What is lymphoma?

Lymphoma, sometimes called lymphosarcoma, is a cancer of the white blood cells.  It most frequently arises in the lymph nodes, spleen, or bone marrow.  It can also start in the gastric system, skin, or thymus gland.

How do I know my dog has lymphoma?

The most common sign is an enlarged lymph node below the jaw or behind the stifle (knee.)  Affected dogs often are lethargic, anorexic, lose weight, or have swelling of the legs or face.  Occasionally they will drink and urinate frequently or have difficulty breathing, irritated patches on the skin or mouth, vomiting, or dark foul-smelling diarrhea.

The best way to diagnose lymphoma is with a biopsy; in some cases this can be done with a needle rather than surgery.  Other testing could include blood tests, x-rays, abdominal sonogram, or bone marrow tap.

What does having lymphoma mean for my dog?

Prognosis varies and is somewhat dependent on what form of lymphoma the dog has.  Some will respond better to chemotherapy though most dogs will relapse after a period of remission.  With additional chemotherapy a second remission is usually possible, though of shorter duration than the first.  Most dogs will eventually die of the disease.

 How common is lymphoma in Aussies?

The 2009-10 ASHGI health survey found that 2% of the dogs surveyed had lymphoma.

 Is lymphoma inherited in Aussies?

Yes.  Specific gene(s) have not yet been identified but they probably are risk factors – not a guarantee the dog will develop cancer but something that significantly increases the likelihood the dog will do so.

 What does lymphoma mean for my breeding program?

Affected dogs should not be bred and  if semen is stored it should be discarded because this disease is almost always fatal.  First step kin of affected dogs (parents, full and half siblings, and offspring) should be bred only to mates with pedigrees as clear of lymphoma as possible and who have no affected close relatives.

What is a lypoma?

Lypomas are fatty deposits, sometimes described as tumors, which form just under the skin.  They are fairly common in older dogs, regardless of breed but may be found in younger dogs as well. 

 How do I know if my dog has a lypoma?

Lypomas are rounded, soft, lumps under the skin.  If you put gentle pressure on them they will move.  They do not cause pain or discomfort.  Lypomas can arise anywhere but most commonly are on the torso or legs.  Some dogs will have more than one.  While lypomas are benign it is always wise to have your vet inspect any lump you notice on your dog.

 What does it mean for my dog if it has a lypoma?

Lypomas rarely require any kind of treatment or surgical intervention.  They generally don’t grow or change, but monitor them regularly and if you notice something bring it to your vet’s attention.

 How common is lypomas in Aussies? 

Unknown.  Very few were reported in the health survey ASHGI conducted in 2009-10, however since they are benign people may not have felt them to be of enough concern to mention.

 Is lypoma inherited in Aussies?

Unlikely.

 What do lypomas mean for my breeding program?

Lypoma is not a breeding concern.

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