Cancer in Dogs: Symptoms and Therapy

Cancer is the leading cause of death in dogs. Read here how to recognize a tumor in your dog and which cancer therapies help to cure or contain the tumour.

When the vet diagnoses cancer, it usually comes as a huge shock to the dog owner. Cancer is still the leading cause of death in dogs. But diagnosed early enough, new therapies can significantly prolong the dog’s life and improve well-being.

Risk factors for canine cancer are:

  • hereditary predisposition
  • older age
  • infections
  • parasites
  • radiation exposure
  • chronic inflammation
  • poisons
  • overweight
  • lack of exercise

It is often not just a single cause that leads to the development of cancer, but a combination of different factors.

Typical signs of cancer in dogs

Most cancers in dogs affect the skin, but in principle any cell in the body can degenerate into a cancer cell. In cancer, the genetic make-up of the cells has changed. As a result of this mutation, the cancer cells no longer fulfill their original tasks and multiply uncontrollably. In these cases, a tumor develops.

Early detection increases the chances:

Solid skin tumors can be detected early by regularly palpating the dog’s entire body surface. Any nodules, sores, or other changes found during this examination should be monitored over the following days and weeks. If the changed skin areas do not heal after a few days or weeks, you should show them to a veterinarian.

Dog owners should always take the following abnormalities seriously, as they can be signs of cancer in the dog:

  • Swelling that doesn’t go away
  • wounds that heal poorly
  • pale gums, changes in the dog’s mouth
  • weight loss
  • sudden weight gain
  • little appetite
  • bleeding or discharge from body orifices
  • unpleasant smell
  • Difficulty swallowing and eating
  • Reluctance to move, lack of endurance
  • stiffness, lameness
  • shortness of breath
  • Problems with defecation and urination
  • behavioral changes

Malignant and benign tumors

Benign tumors tend to grow slowly. They usually form a solid capsule that separates the degenerated cells from healthy tissue. Due to this separation of healthy and diseased tissue, a benign tumor can usually – unfortunately not always – be surgically removed. Benign tumors do not develop secondary tumors (metastases). Even benign tumors can cause major problems in individual cases, for example if they restrict the dog’s mobility due to their growth or constrict vital organs.

Malignant tumors often grow into the healthy tissue with delicate extensions. The tiny extensions of the tumor tissue cannot be distinguished from healthy tissue with the naked eye. Therefore, there is a high risk that the surgeon will not remove all of the cancerous tissue and recurrence will occur. Secondary tumors (metastases) are a major problem with malignant tumors because they can spread the cancer throughout the organism.

The most common types of tumors in dogs

Dogs are particularly frequently affected by these types of tumors:

  • Skin tumors
  • Tumors of the digestive tract
  • Mammary tumors
  • Tumors of the urinary and genital apparatus
  • Tumors of the lymphatic and immune systems
  • Tumors of the endocrine glands
  • Tumors in the mouth/pharynx

Cancer therapies in dogs

Cancer therapy has made great strides in the last few decades. For incurable cancers, treatments are used to slow the growth of the cancer and reduce the patient’s pain and other symptoms, allowing the animal to regain zest for life.

In fact, veterinary medicine does not focus on prolonging the dog’s life, but rather on the patient’s quality of life: a dog with cancer should be able to enjoy life largely pain-free and like a dog. In many cases, the different therapies have to be combined.

1. Surgical removal of the cancerous growth

Removal of the cancerous tumor is the most important form of treatment for many types of tumours. If the tumor can be completely removed and no secondary tumors (metastases) have formed, the patient is cured. Unfortunately, an operation is not always possible (e.g. blood cancer, metastases).

However, some types of cancer cannot be operated on because an operation would be too dangerous (e.g. brain tumours, very large tumours) or because important parts of the body (e.g. nose) would have to be removed.

2. Chemotherapy

In veterinary medicine, fewer and milder side effects occur with chemotherapy than in humans. Chemotherapy is very often used in dogs with cancer to improve their quality of life. Minor side effects such as mild nausea can be managed with other medications.

An important goal of cancer research remains the development of more tolerable chemotherapeutic agents. Another current approach in cancer research is the development of vaccines against certain types of cancer. In the USA, a vaccine against a certain cancer of the oral mucosa (canine oral melanoma) is already in use to support conventional therapy.

3. Radiation therapy

High-energy rays such as gamma rays or X-rays damage the genetic material of the tumor cells, thus preventing them from multiplying and, in the best case, killing the cancer cells. Unfortunately, the radiation makes no difference between tumor cells and healthy cells. In order to protect healthy cells from radiation, more accurate devices and more precisely fitting shielding mechanisms have been developed in recent years. In addition, it has been recognized that healthy cells are spared if the radiation dose is fractionated, i.e. divided over several sessions.

Another method designed to protect healthy tissue is brachytherapy. Radioactive particles are usually enclosed in metal rods and implanted in the tumor. The advantage of this method is that the tumor cells are irradiated directly, while the healthy tissue hardly gets any radiation. However, not all tumors can be treated with brachytherapy.

4. Supporting measures

Accompanying measures play an important role for the well-being of the dog. The diet must be tailored to the needs of the dog, but above all it must taste good, because the dog should stay strong. Gastrointestinal therapy can sometimes help dogs that are nauseous. Effective pain relief is a must in painful processes and often promotes recovery after surgery.

Physiotherapeutic measures should be carried out by an expert. The animal physiotherapist should also show you simple massage techniques or exercises that you can do at home without causing any damage.

How much does cancer therapy cost?

Despite all the improvements in recent years, not every cancer is curable. And modern cancer therapy is not possible or sensible for every dog. In all animal cancer patients, one must carefully weigh the benefit of therapy against the burden it places on the animal.

But the burden on the pet owner must not be ignored either. Some cancer therapies can cost several thousand euros – not everyone can afford it. Others require a lot of time, for example if the nearest radiation clinic for dogs is far away.

Even if you decide against cancer therapy: the most important thing is the well-being of the animal. You can often maintain your quality of life for a while with painkillers – but if the animal starts to suffer, you have to face your responsibility and let the vet put it out of its suffering.

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