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Early symptoms of malignancy in the appearance of melanoma in dogs.


Melanocytic tumors develop from melanocytes, constituting the basal layer of the epidermis or of the epithelium of the mucous membrane of the mouth, and produce specific polypeptide melanin. Typical for melanoma is the accumulation of melanin in tumor cells, although there are so-called amelanotic melanomas [1, 2].

Melanoma is a quite frequently diagnosed pathology in dogs and, according to the literature, ranges from 2 to 9% of all malignant tumors in these animals [3].

Melanoma occurs in 5-9% cases of skin tumors in dogs [4, 5] and, in this case, often has a less aggressive clinical course [6]. The majority of melanomas on mucous membrane of oral cavity of dogs are highly malignant [7, 8].

In a study conducted in fifties of XX century by Gorlin et al, it was shown that melanoma is a primary malignant tumor of the oral cavity in dogs [9]. Later these results were confirmed by other studies [10, 11].

The melanoma is diagnosed in 30-40% of the cases, cytological and morphological analysis of tumors of the mucosa of the oral cavity, and, in these cases, is almost always malignant [12,13].

Mucosal melanoma of the oral cavity most commonly occurs in dogs older than 10 years [14, 15].

According to foreign literature, the pathology is more common in small breeds, especially Cocker Spaniels, Poodles, and Scotch Terriers, Dachshunds, and dogs of other breeds with strong pigmentation of the mucous membrane of the mouth and skin. Some discrepancy of data on breed predisposition of dogs to the occurrence of melanoma can be attributed to the severity of the population of each breed in the country where the study was conducted [16].


The studies were performed from 2013 to 2016 at the Department of Epizootology, Parasitology and the LFI West of Kazakhstan Agrarian-Technical University; and clinical studies were conducted in veterinary clinics in the city of Uralsk. The objects of the study were dogs with melanoma of the skin. To study the symptoms of the malignancy of melanomas, we examined the data of 247 ill primary dogs with melanoma of the skin. The combination and frequency of occurrence of clinical symptoms at start of the treatment for these dogs is presented in Table 3.

Results and Discussion

For the period from 2013 to 2016 in the veterinary clinics, JSC "Talap" and PE "Vinnikova," 643 dogs with suspected melanoma and melanocytoma were examined.

Among them, melanoma of the skin was discovered in 247 dogs (21.8% of the total number of examined dogs) and melanocytoma in 164 dogs (10% of the total number of examined dogs). The total number of cases of melanoma and melanocytoma amounted to 411 dogs. The dogs have been subjected to full examination, including hematological, cytological, and histological examination. We identified and confirmed 247 pathological cases with malignant neoplasms and 22 cases of benign.

Thus, 60.09% of all tumors amounted to malignant neoplasms and 39.9% were benign.

Outpatient examination of dogs is available in most examination superficial tumor localizations.

Thus, the dogs are most commonly affected by neoplasms of the oral cavity (30.9), followed by the lips (18.6%), head area (16.5%), eye (3.8%), torso (8.7%), and lower limbs (21.7%). See Table 1.

Melanoma and melanocytoma in dogs diagnosed in different age groups (Table 2).

In dogs the tumor was identified at the age of:

0-3 years-23 cases (5.6% of all dogs with tumors), including 0 malignant (0% of patients in this age group) and 23 benign (100%);

3-6 years-68 cases (16.5%), 41 of them malignant (60.3%) and 27 benign (39.7%);

6-9 years-196 cases (47.6%), 121 of them malignant (61.7%) and 75 benign (38.2%);

9-12 years-86 cases (21%) 62 of them malignant (72%) and 24 benign (27%);

12 years and older-38 cases (9.2%) 23 of them malignant (65%) and 15 benign (35%).

Thus, in the first place are the dogs in the age of 6-9 years that most often develop melanoma and melanocytoma. Second are the dogs in the age group of 9-12 years. The average age of the dogs with tumors is approximately 9.4 years. In the adult dogs (12 years and older), the incidence of malignancies outnumber benign tumors. In the youngest age group (0-3 years), malignant neoplasm was not detected.

Noteworthy is the fact that, at the beginning of treatment, 105 (60%) of 247 dogs already had ulceration of the epidermis above the tumor, or bleeding from its surface. This fact indicates late diagnosis. It should be emphasized that Table 3 displays relatively late symptoms that accompany the primary tumor, since they had already taken place before the surgical treatment of the patients. There is no doubt that at the beginning of the disease, that is, before the first call to the vet, symptoms of primary melanomas of the skin in dogs had to be somewhat different. For the efficiency of early clinical diagnosis of the primary tumor, the early symptoms of malignancy of melanocytic nevi must be identified and their prognostic significance must be evaluated.

We carried out the analysis of anamnestic and clinical data of newly diagnosed dogs with skin melanoma. They were examined and treated. All of them had a melanoma developed on the background of long-existing pigment spots. Table 4 presents the early clinical symptoms (from the point of view of owners of dogs) of malignancy of long-existing pigment spots and their prognostic significance. As can be seen from the table, the most frequent symptoms of malignancy of pigmented spots were horizontal growth, vertical growth, and bleeding of the surface of the pigment spots.

Study of prognosis in patients with primary cutaneous melanoma allowed us to evaluate the prognostic significance of clinical symptoms of malignancy of pigmented skin spots. This gave us the basis to submit a list of these symptoms in the order of their predictive "weighting." Perhaps the following sequence of clinical symptoms to some extent is arbitrary and may not always be the case in each patient with primary skin melanoma. However, from our point of view, such an increase in clinical symptoms is a reflection of pathogenetic changes in the nevus-melanoma, that is, clinical manifestation stages of tumor progression.

On the basis of our observations and literature data, we compiled a table consisting of the groups that are in the risk of primary cutaneous melanoma. It lists the types of dogs that most likely have the appearance of melanoma of the skin (Table 5).


Obviously, the first of the following symptoms below correspond to the initial stages of transformation spots in melanoma. On the contrary, the presence of the last clinical symptom in this list suggests that the patient has a melanoma with deep invasion of the skin and poor prognosis of the disease.

1. The disappearance of the skin pattern on the surface of the pigment spots.

2. The appearance of shiny, glossy surface spots.

3. The appearance of asymmetry or imperfection in the shape (festinate) edges of the spots, that is, the change in its shape.

4. Horizontal growth of pigment spots.

5. The emergence of a subjective feeling of itching or burning sensation in the area pigment spots.

6. Peeling of the surface spots with the formation of a dry "crust."

7. The absence or loss of hair on the surface of pigment spots.

8. Partial (irregular) or complete color change pigment spots melanoma (the emergence of the so-called related sites depigmentation).

9. The appearance of small nodules of a point on the surface of the pigment spots--melanoma.

10. Vertical growth of pigment spots--melanoma above the surrounding tissues.

11. A change in texture age spots--melanoma-defined palpation, its softening.

12. Ulceration of the epidermis over the pigment spot of melanoma.

13. The phenomenon of inflammation in the area of pigment spots--melanoma and its surrounding tissues.

14. The oozing of the surface spots of melanoma.

15. Bleeding spots of melanoma.

16. Child appearance of pigmented or pink entities (satellites) in the skin pigment around the spots of melanoma.


[1.] Buzaid AC, Ross MI, Balch CM, Soong S, McCarthy WH, et al. (1997) Critical analysis of the current American Joint Committee on Cancer staging system for cutaneous melanoma and proposal of a new staging system. J Clin Oncol 15: 1039-1051.

[2.] Head KW (1976) Tumours of the upper alimentary tract. Bull World Health Organ 53: 145-166.

[3.] Rinborg U, Andersson R, Eldh J, Glaumann B, Hafstrom L, et al. (1996) Resection margins of 2 versus 5 cm for cutaneous malignant melanoma with a tumor thickness of 0.8 to 2.0 mm. Cancer (Philad.) 77: 1809-1814.

[4.] Cohen D, Brodey RS, Chen SM (1964) Epidemiologic aspects of oral and pharyngeal neoplasms in the dogs. Am J Vet Res 25: 1776-1779.

[5.] MacEwen EG, Patnaik AK, Harvey HJ, Hayes AA, Matus R (1986) Canine oral melanoma: Comparison of surgeiy versus surgeiy plus Corynebacterium parvum. Cancer Invest 4: 397-402.

[6.] Ramos-Vara JA, Beissenherz ME, Miller MA, Johnson GC, Pace LW, et al. (2000) Retrospective study of 338 canine oral melanomas with clinical, histologic, and immunochemical review of 129 cases. Vet Pathol 17: 597-608.

[7.] Goldschmidt MH (1985) Benign and malignant melanocytic neoplasms of domestic animals. Am J Dermatopathol 7: 203-212.

[8.] Bostock DE (1979) Prognosis after surgical excision of canine melanomas. Vet Pathol 16: 32-40.

[9.] Gorlin RJ, Clark JJ, Chaudry AP (1958) The oral pathology of domesticated animals. Oral Surg 11: 500-535.

[10.] Chenier S, Dore M (1999) Oral malignant melanoma with osteoid formation in a dog. Vet Pathol 36: 74-76.

[11.] Clark WH, Elder DE, Van Horn M (1986) The biologic form of malignant melanoma. Hum. Pathol 17: 443-450.

[12.] Montayeva NS, Kushaliyev KZ, Shalmenov M, Gusmanov MG, Sadenov MM (2015) Haematological, biochemical and immunomorphologic changes in dogs with melanoma and melanocytoma. Biosci Biotechnol Res Asia 12: 321-326.

[13.] Gross TL, Ihrke PJ, Walder EJ (1992) Melanocitic tumors. In Veterinary Dermatology, ed. Gross TL, Ihrke PJ and Walder EJ. Mosby year Book, St. Louis, MO, 451-464.

[14.] Bostock DE (1979) Prognosis after surgical excision of canine melanomas. Vet Pathol 16: 32-40.

[15.] Bolon B, Calderwood Mays MB, Halls BJ (1990) Characteristic of canine melanomas and comparison of histology and DNA ploidy to their biologic effect. Vet Pathol 27: 96-102.

[16.] Kuznetsova LA, et al. (2009) Comparative characteristics of methods of treatment of melanoma in dogs. Russ Vet J. Small domestic and wild animals. 4: 28-33.

Nurgul Sarsenbekovna Montayeva (1) *, Kaisar Zhalitovich Kushaliyev (1), Zeljko Grabarevic (2)

(1) West Kazakhstan Agrarian-Technical University, Zhangir Khan Street, 51, Uralsk 090009, Kazakhstan (2) University of Zagreb, Heinzelova 55, Zagreb 1000, Croatia

* Corresponding author: Montayeva NS, West Kazakhstan Agrarian-Technical University, Zhangir Khan Street, 51, Uralsk 090009, Kazakhstan.

Received: Jan 9, 2016; Accepted: Feb 9, 2016; Published: Mar 4, 2016
Table 1: The incidence of dogs with melanoma and melanocytoma

                                   The number

The tumour localization   Common   Malignant   Benign

The oral cavity            127        82         45
Lips                        75        45         30
The head area               68        35         33
Eyes                        16        11         5
Corpus                      36        23         13
Lower extremities           89        51         38
All dogs with tumors       411        247       164

Table 2: Distribution of the incidence of melanoma and
melanocytoma in dogs depending on age

                                     The number
The tumour localization
and the age of the animal   Common   Malignant   Benign

0-3 years                     23         0         23
3-6 years                     68        41         27
6-9 years                    196        121        75
9-12 years                    86        62         24
12 years and older            38        23         15
All dogs with tumors         411        247       164

Table 3: Clinical symptoms that accompany a primary skin melanoma
in dogs at the start of treatment

                                     The number of sick dogs

Clinical symptoms                    The absolute number    %

Itching in the region of the tumor           22            8.9

The bleeding surface of the tumor            73            29.6

Ulceration of the epidermis over             32             13
the tumor

Discoloration of the tumor,                  12            4.8
including depigmentation

Infiltrative or purulent                      7            2.8
inflammation in the surrounding

Uniform throughout the growth of             13            5.3
the tumor

The emergence of child nodules in             6            2.4
the skin around the tumor

The emergence of small exophytic             16            6.4
nodules on the surface of the

The absence of symptoms                      11            4.5

A complex of symptoms, including             55            22.3
ulceration of the epidermis and

Total                                        247           100

Table 4: First clinical signs (the earliest from the point of view
of the owners of dogs) of malignancy of pigment spots and their
prognostic significance

                                            The number of sick

Clinical symptoms                           The absolute number

Horizontal growth                                   52

Vertical growth of pigment spots                    31

Bleeding                                            12

Peeling of the surface                               7

Discoloration age spots                              6

Itching                                              5

Asymptomatic                                         4

Ulceration of the surface                            3

Oozing surfaces                                      2

Inflammation in the area of pigment spots            2

The appearance of satellites in the                  1
surrounding skin of the pigmentation

A change in texture age spots                        1

The appearance of asymmetry (festinately)            1
edges of the spots

Total                                               127

Table 5: Groups of melanoma risk

#                      Dogs                      Type of prevention

1   Dogs that have contact with various               Primary
    chemical carcinogens and ionizing
    radiation Dogs with the pigmentation of
    the organism (dog breed: Cocker Spaniel,
    Poodle, Scottish Terrier,

2   Dachshund and other dog breeds with strong        Primary
    pigmentation of the mucous membrane of the
    mouth and skin

3   Dogs with a genetically determined or             Primary
    acquired immunodeficiency

4   Dogs taking hormonal drugs for a long             Primary
    time. Dogs which spots are constantly
    exposed to

5   trauma, as well as dogs with once                Secondary
    traumatized nevi skin
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Title Annotation:Research Article
Author:Montayeva, Nurgul Sarsenbekovna; Kushaliyev, Kaisar Zhalitovich; Grabarevic, Zeljko
Publication:Biology and Medicine
Article Type:Report
Date:Jan 1, 2016
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