The majority of owners surveyed over the years believed that cancer was the main mortality problem for their pets. The scientific reality also confirms the suspicion: 45% of dogs that had lived to be ten years old or more died of cancer. Of the total study, 25% of animals died from this cause.
causes of cancer
Cancer usually originates from a single cell in the body that undergoes a series of genetic changes or mutations. Many environmental agents are capable of causing these changes:
- Viruses (ex: Feline Leukemia virus)
- Chemical agents (herbicides, pesticides…)
- Radiation (ultraviolet light)
- Ionizing radiation (X-rays)
- Certain hormones.
The effects of many of these agents accumulate throughout the life of the animal, and this may be the explanation why most cancers appear in middle-aged or older animals.
Risk factor’s
Among the main risk factors in our dogs we have:
- Age: it is the most important risk factor.
- Breed: there are certain breeds with a greater predisposition to cancer: Boxer, German Shepherd, Scottish Terrier, Golden Retriever…
- Sex: certain tumors affect one sex more than the other (eg: mammary tumors in females)
- Animal size: some bone tumors are more frequent in dogs over 20 kg.
- Pre- existing conditions: Cryptorchid testicles are more likely to be cancerous than testicles physiologically lodged in the scrotum.
signs of cancer
The “Veterinary Cancer Society ” developed a list of the ten most frequent signs for owners to educate themselves in the early management of cancer:
- Abnormal swellings (lumps, nodules, scars…) that remain over time or continue to grow.
- Ulcers that do not heal.
- Weightloss.
- loss of appetite
- Bleeding or discharge from any body orifice.
- Bad smell.
- Difficulty eating or swallowing.
- Hesitation before exercise or lack of resistance to it.
- Persistent limp or stiffness.
- Difficulty breathing, urinating, or having a bowel movement.
Cancer diagnostic methods
Almost all diagnostic means can offer information to approach the suspicion or confirmation of cancer:
- Complete blood count (blood test).
- Biochemical profiles (blood tests).
- Urinalysis (urine analysis).
- Aspirations and biopsies (direct sampling of the altered tissue or organ).
- Diagnostic imaging:
- Bone scan.
- Ultrasound.
- Magnetic resonance.
- Endoscopy: direct visualization of alterations inside the animal.
- Bone marrow study.
- Others.
Tumors: prognosis and survival rate in dogs
| Types of tumors and locations | Survival rate and prognosis |
| The most frequent tumors are those of the skin and subcutaneous tissue, accounting for a third of all canine tumors. The most frequent are mastocytomas (21%), perianal adenomas (18%) and lipomas (8.6%). Between 20 and 30% of these tumors are malignant. |
Dogs with well-differentiated mast cell tumors have a long survival period, but dogs with undifferentiated mast cells do not. The prognosis is good in the case of lipomas and perianal adenomas. |
| Oral cancer accounts for 6% of canine cancers; among the most frequent are squamous cell carcinomas (20-30%) and malignant melanomas (30-40%) | Malignant melanomas have a poor prognosis due to their rapid metastasis. |
| Breast tumors are very common in female dogs; more than half are malignant. | Up to 95% of malignant mammary tumors recur and/or cause the death of the animal within 2 years. |
| Osteosarcomas are the main neoplastic processes that affect the skeleton. They typically appear in large and giant breed dogs, although they can appear in any breed; More than 90% of these tumors appear in dogs over 20 kg. | The prognosis is poor; Treatments, including amputation, only manage to delay the death of the animal for a short period. |
cancer treatment
The goal of cancer treatment is to achieve a cure or, at a minimum, remission.
- Surgery: it is generally used in localized or regional neoplasms. It is the most widely used treatment for cancer.
There are preventive surgeries (ovarihysterectomy, castration in males…) that help avoid the presentation of many tumors.
Surgery is more likely to achieve a cure than any other treatment. - Chemotherapy: it is the only treatment modality that extends to the entire body of the animal; its resolution capacity varies according to the type of tumor, the state of the animal…
- Radiotherapy: this technique is applied to local or regional tumors; Its use is usually not possible as there are no centers that provide this treatment.
