Mast cell tumor in dogs

If your dog has a mast cell tumour, dendritic cell therapy is probably the right treatment option. When treating a mast cell tumour, it is important that you start treatment as soon as possible after diagnosis. The earlier the tumour is detected and the sooner treatment begins, the better the prognosis and life expectancy for your dog. General information about mast cell tumours in dogs can be found further down this page.

Unlike chemotherapy or other commonly used medications such as Masivet or Palladia, dendritic cell therapy does not treat the symptoms of a mast cell tumour, but the cause. Besides mast cell tumours, dendritic cell therapy can also be used for other types of tumours in dogs.

• General Information
• Breed Disposition
• Indications
• Diagnosis
• Quality of life and life expectancy
• Treatment
• Dendritic cell therapy
• Costs
• Tyrokinase inhibitors
• Case description

General Information

      Mast cells primarily serve your dog to fight inflammation and allergies. They are stimulated by irritation and activate various biological substances (e.g. histamine, serotonin, prostaglandin and proteolytic enzymes). So in terms of their function, mast cells are actually essential for your dog's survival. When overproduced, they can be life-threatening.

Mast cells are formed from precursor cells in the bone marrow and settle in many parts of the body. This means that they have an important physiological function, as they are involved in allergic, immunological and inflammatory reactions in the body from the sites where they settle.

Mast cell tumour or mast cell tumour (also called mastocytoma) is a collection of degenerate (neoplastic) mast cells of the skin or subcutis on the limbs, trunk and head. In rare cases, mast cell tumours of the internal organs are also found. About 25 percent of all skin tumours are mast cell tumours. Incidentally, these can occur in dogs of any age, although older dogs are usually more frequently affected.

Breed Disposition

Signs of a mast cell tumor in your dog

 Any lump of skin you feel on your dog could be a mast cell tumour. But it doesn't have to be. Contact your vet along with your dog if you notice any abnormalities. Suspicious areas range from nodular, doughy, hairless or hair-covered lumps to weeping and open sores. The tumour usually appears in the form of single skin nodules. Only in 11-14 percent of cases is it spread over several sites (multiple mast cell tumour) in or on the body.

The overproduction of mast cells causes various substances. These can have different effects on your dog's body and/or on individual parts of the body. Some of the possible symptoms are

• Local swellings
• Vomiting
• Shock symptoms
• Itching
• Bleeding tendencies
• Wound healing disorders
• Ulcers of the stomach and small intestine (more rarely)
• Loss of appetite
• Abdominal pain
• Changed behaviour

Diagnosis of mast cell tumor in dogs

Because the appearance of mast cell tumours is so varied, you should have an accurate diagnosis made. For example, fine needle aspiration may be considered. This involves taking cells from the affected areas using a fine needle. These are then examined under a microscope. However, this examination can only provide initial indications of the disease and should be supplemented by surgery if the diagnosis is positive. According to Klopfleisch, the possibility of differentiation in fine-needle biopsies has so far been limited by the limited number of cells to be examined, i.e. the small sample size.

Subsequently, the tumour should be removed in a surgical procedure, examined pathologically and subjected to a clear histopathological differentiation (grade I to III).

The course and prognosis of mast cell tumours in dogs

Overall, the histological classification (grading) of mast cell tumors follows a scheme of kiupel:

* In ten 400x microscope fields: ≥ 6 Mitosis figures or more than 2 multinuclear cells or more than 2 bizarre nuclei or anisokaryosis (different size of tumor cells) to a certain exten                                                      

** Should be combined with an additional treatment Possible: radiotherapy, chemotherapy and dendritic cell therapy.

It is important to know whether the tumour has already metastasised or not. Mast cell tumours grade II and III should also be further examined in the laboratory for malignancy. There is a classification into low and high malignant. High malignant tumors are more aggressive and require urgent further treatment, even if they are grade II at the initial assessment.

Mast cell tumours in dogs usually metastasise relatively late, so they initially remain only in the place where they occurred and do not spread to other organs. The higher the degree of mast cell tumour, i.e. the more aggressive the tumour, the higher the probability that the tumour will spread to other organs.

Mast cell tumours in dogs do not tend to infiltrate surrounding tissue, but they do displace the surrounding tissue. Invasive bone growth is extremely rare.

A current study shows interesting results for mast cell tumors that are classified as "low grade". According to the study 50 dogs with a low grade mast cell tumor were examined:

• In half of the dogs a safety distance of at least 20mm in healthy tissue could be maintained.
• Only in two of the 50 dogs did the mast cell tumor reappear within two years.
• Only in two dogs metastases were detected within two years after surgery.

Consequently, the prognosis is very positive for mast cell tumors that were classified as "low grade" and which could be removed with a sufficient safety margin in healthy tissue.

Source: Long-term outcomes of dogs undergoing surgical resection of mast cell tumors and soft tissue sarcomas: A prospective 2-year-long study.

Daniel et al. found a further indication of factors that influence the course and prognosis of canine mast cell tumours, and investigated the collagen content of mast cell tumours in addition to the factors mentioned above.

The extracellular matrix of the mast cell tissue has the largest proportion of the dermis, i.e. the middle part of the skin. It consists of fibrous proteins, including collagens, elastin and laminin, which provide strength and elasticity, and proteoglycans, such as dermatan sulphate and hyaluronan, typically consist of several glycosaminoglycan chains (formed from repeating disaccharide units) branching from a linear protein core. Extracellular proteoglycans are large, highly hydrated molecules that help to cushion the cells in the matrix. The integrity of the extracellular matrix (ECM) can play a protective role against tumor progression and favors cell proliferation, angiogenesis, invasion and metastasis when altered. The hypothesis is the researcher was that the amount of collagen and elastin found in mast cell tumors can predict their aggressiveness and survival rate.

And so, in fact, significantly less collagen was found in high grade tumors in the samples studied than in low malignant samples. The investigation of the collagen content could therefore be a further characteristic for the classification of the malignancy of mast cell tumours.

Quality of life and life expectancy

Your dog has a particularly favourable prognosis for recovery if the tumour has been completely surgically removed in grade I and II. With grade III, the tumour has already metastasised and the recurrence rate, i.e. the probability of recurrence, is relatively high, so that the prognosis is correspondingly cautious.
Generally speaking, the higher the grade of the mast cell tumour, the shorter the life expectancy and the worse the patient's prognosis. In later stages, the tumour can also spread to other organs, i.e. form metastases. These reduce life expectancy and worsen the prognosis for your dog. It is therefore important to act quickly.

Treatment of mast cell tumors in dogs

Mast cell tumours should be removed by surgery if possible. Complete removal (complete resection) improves the prognosis and reduces the risk of recurrence.

Radiation therapy is sometimes recommended after surgical removal of the tumour or in the case of changes that cannot be addressed by surgery. Please note that radiation therapy in animals is only carried out under anaesthetic in specialised centres.

Many dog owners are also increasingly turning to immunotherapy - such as dendritic cell therapy.
Information on nutrition in the case of a mast cell tumour in dogs can be found here:/hunde/ernaehrung/mastzelltumor

Treatment of mast cell tumors in dogs with dendritic cell therapy

Dr. Thomas Grammel is a partner for dog owners to discuss and coordinate treatment for dogs suffering from mast cell tumours. Regardless of the severity, intensity and aggressiveness of your dog's mast cell tumour, you can enable your dog to be treated with dendritic cell therapy with the least possible effort and improve the prognosis. For this purpose, a blood sample will be taken from your dog by your vet. We collect the blood sample from your vet, culture the dendritic cells and send them back to your vet for use. This procedure is carried out three times at intervals of four weeks.
Our treatment method is particularly gentle and aims to "revive" the immune system of your four-legged friend. In this way, the quality of life can be improved and life expectancy increased - through the body's own cells..

Costs

The cost of treating the tumour will surtenly vary. If surgery is performed at the beginning to remove as much of the tumour mass as possible, the most important thing is to make sure that the operation is well supervised and carried out.

If other treatment options such as chemotherapy are used, additional costs will be due. Depending on the illness, size and weight of your dog, they have varying costs, some of which are due monthly. Basically, you always have to realise how important a good health insurance is to help with the costs.
You are welcome to ask us about the costs of dendritic cell therapy for your patient. There are no additional costs for medication, for example, to suppress the side effects of the therapy - because these are practically non-existent with our gentle immunotherapy. The only side effects that occur are usually an elevated temperature and slight exhaustion. However, these are positive. They show that your dog's immune system is responding to the treatment.

Tyrokinase inhibitors

This class of drugs (c-kit inhibitors) act on a genetic change (mutation) found in mast cell tumours. Masivet® (masitinib) and Palladia® (toceranib) are active ingredients that are approved for this purpose. Patient owners have reported relatively many side effects.

 Case description - Mast cell tumor of the leg

We have recorded the case of our patient Chenny with a mast cell tumor and present it as a case study: /hunde/fallbeispiel/mastzelltumor/chenny

Sources:

Milovancev M et al.: Long-term outcomes of dogs undergoing surgical resection of mast cell tumors and soft tissue sarcomas: A prospective 2-year-long study. Vet Surg. 2019 May 2. doi: 10.1111/vsu.13225

Klopfleisch, R: Kanine Mastzelltumoren – Ist die Gradbestimmung in der Zytologie möglich?, (2018) Der Prakt. Tierarzt 99 11/2018,1142-1160

Kiupel M et al.: Proposal of a 2-tier histologic grading system for canine cutaneous mast cell tumors to more accurately predict biological behavior. (2011) Vet Pathol 48:147-155

Daniel J et al (2019): Intratumoral collagen index predicts mortality andsurvival in canine cutaneous mast cell tumours. Vet Dermatol2019; 30: 162–e48.DOI: 10.1111/vde.12726