Tag: cancer

Lymphoma in Dogs

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A brown dog sitting down next to text that reads, ‘Understanding Lymphoma’.

Thanks to advances in veterinary medicine, nutrition and good daily care from owners like you, dogs are living longer than ever before. But unfortunately, pets can be diagnosed with cancer, especially as grey creeps into the fur around their faces.

One of the most common pet cancers is lymphoma in dogs. As you might know, cancer occurs when there is uncontrolled division (and proliferation) of abnormal cells. In the case of dog lymphoma, a group of cells in the immune system called lymphocytes go haywire and continue to multiply.

Lymphoma can affect dogs of any breed and any age, but it’s more frequently diagnosed in middle-aged and older dogs.

RISK FACTORS

No one is sure what, exactly, causes lymphoma in dogs.

Since certain breeds, such as golden retrievers, tend to be more affected than others, it’s possible there’s a genetic component to lymphoma in dogs.

SIGNS TO WATCH FOR

Because lymphocytes can travel anywhere in the body, dog lymphoma may be widespread, or it can be localized to particular organs, including the gastrointestinal (GI) tract, spleen, liver, bone marrow, skin, central nervous system or other organs. As a result, the signs can vary, depending on what part of the body is affected. Some pets may just show general signs that they don’t feel well, such as lethargy and loss of appetite.

For lymphoma in dogs, it’s common to have one or more firm, swollen lymph nodes that can be seen or felt in locations such as the neck and behind the knee. The lymph nodes can enlarge quickly and potentially press against other body parts, compromising function. Lymph nodes in the neck, for example, can compress the trachea, making it difficult for the dog to breathe.

LYMPHOMA DIAGNOSIS IN DOGS

The diagnosis is usually made by taking a sample of the malignant cells, either through a fine-needle aspirate or a biopsy of an affected organ. By analyzing a biopsy sample, a specialist can determine whether the cancer is low, intermediate or high grade, depending on how rapidly the cells appear to be dividing. High-grade lymphoma in dogs is typically considered more malignant, but in some cases may be more responsive to treatment.

Other tests may be recommended such as blood tests (including feline leukemia testing in cats) and a urinalysis, to assess the pet’s overall health.

Once a diagnosis is made, dog lymphoma is typically classified by the anatomic area affected, type of lymphocyte (T-cell or B-cell) and by stages, to determine the extent of the disease, potential treatments and prognosis and to monitor response to therapy. Other tests may be needed, including a bone marrow biopsy, X-rays and an ultrasound.

The stages range from I to V, with a single lymph node involvement in stage I to bone marrow or other organ involvement in stage V. Each stage also has a substage, depending on whether the animal is showing signs of illness. Dogs may progress from one stage to the next over time.

PROGNOSIS AND TREATMENT

The prognosis for pets with lymphoma depends on a number of factors including overall health, stage of the disease and type of tumor.

Your veterinarian or a veterinary oncologist (a cancer specialist) can outline treatments that can help your pet feel more comfortable and potentially put the cancer in remission, although this is usually temporary.

Because dog lymphoma is generally considered a systemic disease, some type of chemotherapy is usually recommended. Dogs typically tolerate chemotherapy fairly well, without as many side effects as humans. If the cancer is localized to a specific area, surgery or radiation therapy may be options. Your veterinarian can help you decide the right approach for you and your pet.

What Are The Early Signs of Cancer in Dogs?

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A close-up of a black and white dog sitting happily in a sunny green meadow under a blue sky with white clouds.

Hopefully, you’ll never be faced with a cancer diagnosis for your dog, but unfortunately, it is a relatively common situation for many pet parents. So we’re sharing pet cancer signs to help you recognize when something may be amiss with your dog’s health — especially as early detection and treatment gives your dog the best hope for remission or even a cure.

Can Dogs Get Cancer?

Yes, dogs can develop cancer, including bone cancer, skin cancer and lymphoma. While some of the diseases that affect humans are not an issue for our furry friends, unfortunately, cancer affects both. As with humans, some pets have a genetic predisposition, and we have to watch our senior dogs more closely, too. 

Like humans, early diagnosis increases the chances that treatment outcomes will be good. Prevention is also important — like using pet sunscreen when your dog is outside. If you have doubts about the health status of your dog, prompt veterinary evaluation means the team can get the cancer diagnosed early and start helping your dog’s immune system fight as soon as possible.

Symptoms of Cancer in Dogs

Pet owners have a general sense of what’s normal for their animals. Noticing changes such as pain, discomfort, difficulty eating, persistent bad breath, abnormal bleeding, changes in bathroom habits or persistent sores can help with early recognition and lead to a definitive diagnosis.

Is There a Cancer Lump on My Dog?

Not every unusual lump you feel on your dog is cancer, but you should still have them examined by your veterinarian, and you should check for lumps regularly. Run your fingers over your dog’s skin at least once a month so you can identify any skin lumps or bumps that are growing or changing. Female dogs that have not been spayed are at greater risk for mammary cancer, so be sure to check for any unusual growths on their chests and bellies.

The lymphatic system is another area you can monitor with your fingers. The lymph nodes that are the easiest to find are just under the jaw, right below the ear and behind the knees. Normally, the lymph nodes feel like a small, pliable blip between your fingers. But if you feel enlarged lymph nodes, anything firmer or bigger than usual, talk to your veterinarian.

Cysts vs. Tumors in Dogs

Not all lumps indicate cancer! Your dog’s lump might be a cyst: a sac filled with fluid, air or other material. Tumors are abnormal growths of tissue. Your veterinarian can examine the cells to determine whether they are benign or malignant. Benign tumors may not require treatment, but some can become malignant tumors, and the tumor location may mean the dog’s quality of life will be improved by treating it. Cancer care could be in the form of surgery, chemotherapy or radiation.

Other Warning Signs of Cancer in Dogs

Of course, the signs of cancer vary depending on the organs or body parts affected, such as the skin, lungs, blood or bones. These signs can also signal other conditions, so don’t panic. Just see your veterinarian if you find any of the following:

  • Unexplained weight loss: If your dog starts looking thinner than usual, has a reduced appetite, and you haven’t started a new diet or exercise routine, it’s time for a checkup.
  • Chronic cough or difficulty breathing: Tumors that occur in or around the lungs can cause respiratory problems.
  • Lameness or limb swelling: If you run your hands along both of your dog’s front or rear legs at the same time, it’s easy to compare the affected limb with the other side and spot areas with unusual swellings along the bones. If your dog starts limping or is hesitant to bear weight on a limb, talk to your veterinarian.
  • Stinky breath or difficulty chewing: These can certainly be signs of periodontal disease, but dogs can get oral tumors, as well. If your dog will allow it, take a peek at the gums and under the tongue, checking for unusual growths.
  • Chronic vomiting or diarrhea: Not surprisingly, cancers of the digestive tract can lead to loose stools, upset stomachs and, in some cases, trouble with defecation. If the problem persists, or your dog starts losing weight, make an appointment.
  • Circling or seizures: A dog with a potential brain tumor may experience a sudden onset of seizures, especially in the older years, or may pace in circles over and over again. If you notice a change in your dog’s behavior, contact your vet.
  • Abdominal distension: Dogs might have swollen bellies from overindulging in the treat jar, but it can also be a sign of enlarged internal organs such as the liver.
  • Lethargy or weakness: Any time your dog seems less active than usual, lags behind on walks or just doesn’t want to interact with the family as much, there’s a good chance something’s not right. Again, behavioral changes have many possible causes, so check them out before they become worrisome.

When in doubt, see your veterinarian. It may be nothing. But if it’s something more serious, you want to catch it in the early stages.

Can Dogs Smell Cancer? Exploring Cancer-Sniffing Canines

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An extreme close-up of a dog’s nose and nostrils, showing the unique skin texture.

When it comes to their sense of smell, a dog’s sniffing ability operates on a whole other level compared to ours. They can sniff out hidden treats, and there are even trained bed-bug sniffing dogs! But could a dog’s nose be so good that it could sniff out cancerous cells? 

Yes, some dogs do have special cancer-sniffing abilities — but usually it’s only if they’ve been trained. However, there are some cases of average dogs who have shown cancer detection abilities without being trained.  

Can Dogs Sense Cancer?

The first published evidence of a cancer-sniffing dog appeared in 1989 in the medical journal Lancet. Two physicians wrote a letter about a dog who became obsessed with a mole on his person’s leg. The mixed-breed dog constantly sniffed at the mole and eventually tried to bite it off. Although his owner wasn’t particularly concerned about the mole, her dog’s persistence convinced her to have it checked out. The mole was indeed a malignant melanoma (skin cancer). 

Since that time, dogs in special training programs have been able to detect cancer in human tissue, blood, urine and breath samples, enabling them to identify skin, bladder, prostate, colorectal, breast and lung cancers, in addition to ovarian cancer. 

The trained dogs can’t differentiate breast cancer from prostate cancer (or any other type of cancer), but the dogs can detect the scent of volatile organic compounds given off by the malignant (cancerous) cells in the human body. Only a doctor can diagnose a disease, but these highly trained cancer-detection dogs are able to contribute to valuable cancer research studies.

Can Untrained Dogs Smell Cancer?

There’s typically no need to tense up every time your dog runs their snout over your skin; dogs that can detect cancer generally only do so after intensive training. If your dog is licking your skin or focusing on a particular part of your body, it’s more likely that you spilled some food or there’s another substance there that smells or tastes interesting to your dog. However, there are rare, personal accounts of untrained dogs’ behaviors that convinced their owners to consult their doctor and confirm a diagnosis.

Can Dogs Detect Cancer by Licking?

No, dogs that have been trained to detect cancer do so by sniffing not licking. Dogs have around fifty times as many scent receptors as humans, or about 300,000 of them. And unlike people, dogs have a second scent organ located on the bottom of the nasal passage called the vomeronasal or Jacobson’s organ, to aid in detecting even more scents. This powerful olfactory system enables them to detect scents like the volatile organic compounds given off by the cancer cells. 

However, in anecdotal stories of dogs alerting their owners to signs of potential cancers or tumors, they may have done so by licking, sniffing or nipping at a certain spot on their owner’s body.

How Do Dogs Act When They Smell Cancer?

In untrained dogs, there have been reports of dogs persistently licking, sniffing or nipping at cancerous skin lesions. Others have reported the dog sniffing or pawing at the area where the cancer was later found. 

In trained cancer detection dogs, how the dog acts depends on what they’ve been trained to detect. In general, trainers start by exposing the dog to blood samples or tissue samples from cancer patients. If the dog can alert to the correct sample, they are rewarded with praise and a treat or toy. Through positive reinforcement, the dog is rewarded each time they differentiate the cancer sample odors from other scents.

Can Dogs Tell When You’re Sick?

Your dog knows what you usually smell like, and when you’re sick your smell changes due to changes in your body chemistry and hormones. Some dogs may pick up on this change in smell and realize that something isn’t right. They may also notice that your routine has changed, and now you’re lying on the couch or in bed all day instead of going to work. Some dogs can also read human emotions and may notice that you’re not your usually happy self. 

If your dog comes over to comfort you when you’re sick, there can be a couple of different reasons for this. They may be trying to make you feel better, or they may feel worried about the change in your behavior and routine and need comforting themselves. Your instinct is, of course, to snuggle with your canine companion, and this positive reinforcement means that the next time you’re sick, they’ll want to snuggle with you again. But a little snuggle therapy is good for everyone.

What Is the Future for Cancer Medical Detection Dogs?

Currently, dogs are only trained to detect cancer in medical samples, not in people. These canine scent detection training centers collaborate with other cancer research scientists who are working to isolate the exact chemicals the dogs identify. Since the accuracy of the dogs can vary depending on a number of factors, including breed, level of training and handler bias, the hope is to eventually create an electronic sensor that can essentially replace the dogs.

But for now, these trained dogs are applying their noses to help researchers get one step closer to early detection of many human cancers. Amazing, isn’t it?