chemotherapy in dogs is one of the veterinary treatments that it is possible to resort to when we receive the terrible diagnosis of cancer. In general, this type of disease, which is increasingly common in animals, usually appears in older dogs, although the action process is usually the same if it occurs in younger dogs.
In this article on our site we are going to explain what chemotherapy consists of in older and younger dogs, how it works, what they are its most common side effects, as well as the precautions required for its administration. Together with our veterinarian, we will have to assess the advantages and disadvantages of its use, taking into account the characteristics of the cancer and the conditions of our dog.
What is chemotherapy in dogs?
When our dog is diagnosed with cancer, the first option for treatment is usually surgery. But, after the intervention, it may be indicated to start chemotherapy with the aim of preventing recurrences or delaying possible metastases On other occasions, chemotherapy is used before surgery to shrink the tumor.
Finally, in those inoperable tumors or in cases of metastasis, chemotherapy is prescribed as palliative These dogs, untreated, They have a life expectancy of weeks. With chemotherapy they can reach a year or exceed it. Keep in mind that a year in the life of a dog is more than for us.
How does chemotherapy work in dogs?
The drugs used for chemotherapy will act mainly on cells that are dividing. As cancer consists of uncontrolled cell growth, chemotherapy will attack and eliminate tumor cells The problem is that this attack is not selective, that is, these drugs they will act on the tumor but also on he althy cells, especially from the intestine and bone marrow because they are the ones that divide the most. These effects of chemotherapy in dogs are responsible for adverse reactions, as we will see.
Dog Chemotherapy Protocols
In general, chemotherapy is prescribed at the maximum tolerated dose (MTD) and the effect will depend on the dose administered. Sessions are usually established on a regular basis, every 1-3 weeks, depending on tissue recovery. Veterinarians follow standardized doses that are studied to be well tolerated by most dogs.
Except in some types of cancer, such as transmissible venereal cancer, where a single drug is effective, in most cases a combination of drugs is recommendedIn this way, the chemotherapy treatment is adapted to the characteristics of the cancer and the dog in order to achieve the best results.
Metronomic chemotherapy in dogs
Still experimentally, what is known as metronomic chemotherapy has begun to be used. It is intended to inhibit the formation of blood vessels that develop tumors to achieve a good supply of nutrients, which they invest in continuing to grow. This type of chemotherapy has an approximate cheaper price, since it is carried out with lower-cost drugs and, moreover, at home. Contrary to maximum tolerated dose chemotherapy, metronomic chemotherapy is based on a low dose administered continuously by oral, intravenous, intracavitary or intratumoral route.
Currently, we are also working with targeted chemotherapy capable of selecting its action on specific tissues, thus minimizing side effects, and with electrochemotherapy, using electrical impulses.
Chemotherapy Side Effects in Dogs
As we have said, chemotherapy can affect he althy cells, especially those located in the intestine and bone marrow. Adverse effects, therefore, are usually related to these areas. Thus, we can find gastrointestinal disorders, anorexia, vomiting, diarrhea, decrease in the number of leukocytes, which makes the dog more prone to infections, decrease in platelet levels or fever. The color of the urine can vary.
In addition, depending on the medications used, symptoms due to them may be seen, such as cystitis, cardiac disorders, dermatitis and even local necrosis if the product comes out of the vein and allergic reactions. The appearance of these side effects is influenced by the fact that the dog belongs to breeds with a genetic mutation that makes it difficult for them to metabolize certain drugs, that they suffer from other diseases or that they are taking other medications.
The most serious effect is the decrease in leukocytes To combat it, this and other disorders, we can use drugs, even administered by preventative way. If the dog shows no appetite we can offer him his favorite food. Diarrhea usually subsides without treatment. The possibility of urinating more frequently decreases the contact of the drug with the bladder and reduces the occurrence of cystitis. It should be known that all these side effects are mild and well controlled with drugs.
Combination of drugs for chemotherapy in dogs
We have already seen that it is usual to combine several drugs to formulate a specific chemotherapy for our dog's cancer. Thus, the veterinarian will be able to choose between different options and will opt for those drugs that have shown efficacy, separately, against that type of cancer. In addition, all of them must have different mechanisms of action, to complement each other and, of course, they cannot present overlapping toxicities.
What is a chemotherapy session like in dogs?
A typical session will take place at the veterinary clinic. The first step is to take a blood test to assess the general condition of the dog. Drugs must be prepared with precautions, due to their toxicity, so touching or inhaling them must be avoided. In addition, in intravenous chemotherapy the professionals will ensure that the line is perfectly placed in the vein, preferably in a front leg, to avoid the adverse effects of contact of the product out of it. The leg is protected with gauze and bandages from possible leaks.
During the administration of chemotherapy, which is done slowly, in about 15-30 minutes, it is important to control, at all times that the road works properly. The dog must be calm, sedated if it is not possible to keep it still, with a professional, veterinarian or ATV, controlling it at all times. When the medication is finished, continue for a few more minutes with fluid therapy to clean the line and leave no drug residue. The animal can return home and lead a normal life.
Care during and after chemotherapy in dogs
Before starting chemotherapy, the vet may prescribe some drugs to try to avoid side effects. If the session takes place in the clinic, the professionals will be in charge of taking all precautions and care. If we are the ones who have to treat the dog with oral chemotherapy at home, it is important that we always wear gloves, never break the pills and, of course, follow all the instructions given by the vet. Pregnant women cannot handle these drugs.
After chemotherapy, in addition to control the temperature, the symptoms and administer the prescribed drugs, if applicable, we must wear gloves if we are going to come into contact with dog feces or urine during the next 48 hours. Chemotherapy drugs are eliminated from the body in 2-3 days, but in minimal amounts, so with basic hygienic standards, we are not at risk.
