Is it because they have so much in common that cats and dogs' are Man's best friend? Science proves that our pets are like us when it comes to illness, sharing the same cancers and often the same treatments!
Explanations and advice from Doctor Mélissa Pottier, veterinary at Oncovet (59650, Villeneuve d’Ascq), one of the only centres for Veterinary Oncology in France.
When a pet arrives, has the cancer already been detected?
MP : Regularly, the usual veterinary has already completed the first steps of diagnosis: for example, a small cutaneous tumor, small lumps that can be seen from the exterior that have caused the pet parent to bring their pet for a consultation.
Often in these kinds of cases, the veterinary has already removed a part of the cancer, sent it for analysis and refers the patient to us with the results of the histological analysis and cancer diagnosis. Sometimes, worries pet parents come directly to us for a full check up because they pet is losing weight, is not very well, listless…
What treatments are there for cancer in cats and dogs?
MP : There are quite a few, the most frequent of which is surgery. When possible, it is the ideal treatment because the less tumor remains afterwards, the more efficiently the following treatments will be. The analysis can allow verification of the nature of the tumor, its grade, its aggressiveness...
Then, if necessary, there are other kinds of follow up treatment such as chemotherapy, which often worries pet parent but, in reality, chemotherapy is much better withstood by pets than by humans.
It is not the same dose, the aim is not the same, and we're aiming to increase life by three or four years, not thirty or forty: animals' life expectancy is much lower than humans'. And above, we are trying to get the best possible result so that they can lice comfortably!
There is also radiotherapy treatment, which targets more localised areas. Chemotherapy is a general treatment to prevent or treat metastasis. But radiotherapy is a locoregional treatment of a tumor to avoid local relapses. Often, the treatments are used in conjunction with surgery.
So surgery, chemo and radiotherapy are the main treatments?
MP : Yes. Afterwards, there are other types of radiotherapy, which is a bit more complex, such as curietheraphy... but usually it comes under the category of radiotherapy.
Why would one treatment be chosen over another?
MP : Once again, it would be in accordance with the type of tumor and the previous assessments undertaken: if the cancer has already metastisized, if it's spread out, if we can or can't operate... there are tumors that are very radiosensitive or others that aren't very chemosensitive. Some react very well and others less.
However, as soon as we can operate, we must do it because there will be less tumerous cells and therefore the secondary treatments will be more effective. Sometimes the diagnosis doesn't allow this, because the tumor is too difficult to reach, too spread out, or situated on an organ that is impossible to remove. This is why there are different options for treatment.
There are also the different constraints of the pet parents (financial, availability, distance). The limits are very individual. Our role is to propose the best therapeutic strategy: the best for the tumor, the best for the dog or cat. Afterwards, the choice is up to the pet parent.
How long do the treatments last?
MP : This varies a lot! There are cancers for which we operate, some radiotherapy sessions and then nothing more than some follow-up. The follow-up takes a long time: we see the pets often over two years to check that the cancer is in remission, that everything is fine with the part of the pet operated on.
Sometimes, treatments last 1 month and that's it. But for Lymphoma, for example, follow-up is necessary often for life. We know that we can never really get rid of the tumors completely, that though the dog may do well, we'll need chemotherapy in case of reoccurrence.
What happens before, during and after a treatment?
MP : The 'during' is more complicated because there is a lot of to-ing and fro-ing. For example, with chemotherapy, the pet needs to stay hospitalised for the night... afterwards, there isn't much to do at home other than give them little pills and usually, that goes well.
Are there side-effects?
MP : With radiotherapy, there isn't much . There are no residual rays as they are there only during the treatments. With conventional chemotherapy, we keep the pets with us for 24 hours in order to collect urine, for example. Information is then given to the pet parents for the return home so that there is no danger.
The same goes for metronomic chemo (with pills to give to the pet at home): if the pet vomits or relieves themselves, it's necessary to clean whilst wearing gloves and clean with bleach…
We try to prevent certain side-effects before they occur. In chemo, with dogs as well as cats, digestive issues can develop in the days after a session (often just being a smaller appetite). If the pet is sensitive, we treat them with an anti-diarrhetic or an anti-vomit at the same time as the chemotherapy and the time afterwards, there are no problems.
So these are the same effects are there are in humans!
MP : Yes, except there are no psychological effects. Pets can feel stress when they are brought here: they are in a territory that is not their own, and there is a night of hospitalisation. In 90% of cases, it goes well and the dogs get used to the new environment very quickly, and once they go home, all is forgotten!
There is no fear of illness. It's often harder for the pet parents than for the pet! And if a dog or cat is very stressed here, we try to adapt, either seeing them less often or treating them under sedation, but it's very rare.
Are there any pet types that can't do certain treatments?
MP : There are some dog breeds for whom there are genetic mutations that disallow certain kinds of chemotherapy. This is quite rare but we know this in advance. When they arrive and we see that they have cancer, we undertake the genetic test.
Border Collies and Australian Shepherds for example: either the test comes back positive and we change protocol, or the test is negative and it's not a problem. Other than this, the specificities of cats are well known: some can't withstand certain kinds of treatments.
Do the treatments have any risks for the pet?
MP : This depends a little on the treatments. We never say that there is 'zero' risk because that doesn't exist, but usually, the treatments have a risk-positive balance.
How much do these treatments cost?
MP : It depends on the choice of treatments and their intensity. At first, as soon as we have the results of the analysis, we know that we should advise a certain type of treatment, and we present a quote to the pet parent with different options going from an optimal treatment to a palliative treatment.
According to what is the most envisageable option for the pet parent, we adapt. For tumors where there is only one type of treatment necessary, the cost is of course lower than two-step treatment, which happens from time to time. It's try that the cost can reach thousands of euros over several months when necessary! We are aware that it's not very easy.
Have clinical trials already been tested and approved?
MP : They have, and sometimes have already been approved for humans but just require accreditation for dogs. And it is necessary to have cats and dogs already suffering from cancer in order to confirm these treatments so as not to use 'experiment animals'. These studies are very rigorously monitored. It may seem like a bad option but in fact, it is a chance for pets to experience cutting-edge treatments.
To conclude, this bears thinking about when adopting a puppy. Insurance companies often cancer treatments, and therefore the pet parents is more calm, which is understandable.