Canine Melanoma Diagnosis in Dogs By Student Name Institute Name Course Name

Canine Melanoma Diagnosis in Dogs
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Introduction

Melanoma is a common form of cancer in dogs, and its medical diagnosis is a complicated
process. Dogs possessing this cancer may have one of two types of melanoma. There is a
malignant form and a benign form. Both of these forms can be related to stress, trauma, or
excessive licking in an area where cells start to multiply resulting in this disease. The malignant
form of melanoma is a metastatic disease meaning that it is rapid and aggressive, with essentially
no cure. This can be compared to the benign form that is less invasive and is usually restricted to
one area on the skin distinguishing challenges between the two types of melanomas. There is an
array of preliminary tests done in modern veterinarian medicine to detect malignant and benign
melanoma. These include fine needle aspirates, radiograph/ultrasound imaging, microscopic
imaging, and histopathologic analyzation. The problem with these methods is that they can
deliver conflicting results, making it hard to diagnose melanoma (Ballegeer, Hollinger & Kunst,
2013).
Canine melanoma is mostly considered as canine oral malignancy. Causes of this condition are
associated with local invasiveness or lung and metastasis to the lymph nodes representing
between 80% to 100%. Research conducted on this condition found a more favorable prognosis.
Histomorphology report showed 92% of tumors in canine melanocytic were diagnosed as
malignant while 59% of these tumors presented features of a malignant. Another study revealed
that only 5% (3/64) of dogs who were well-differentiated and had a heavily pigmented canine
melanomas died of tumor-related causes. A subsequent study that was cited revealed a one-year
survival rate for affected dogs and had results at the rate of 45.2% (19/42) for cases of canine
melanomas. According to the above data, it reveals that diagnosis of canine melanoma may
result to different data according to the method that was used to detect the condition calling for
the most accurate methods for diagnosing this condition (Brockley, Cooper, & Bennett, 2013).
The most diagnosed canine melanoma are accounting to 7% of all malignant tumors cases that
have been reported in dogs and about 160,000 cases malignant tumors reported worldwide each
year most frequently at (62%) among reported 1652 melanomas cases compared to the
aggressive median survival rate of 200 days. The most metastasizing tumors are Non-UV-
dependent canine melanoma malignancies with a post-surgery rate of 173 days of survival.
According to support evidence on this research, pre-clinical trial and medical monitoring appears
to be a reliable method for diagnosis canine melanoma and also in testing human cancers caused
by this infection as well as the disease in dogs (Campbell, Farmery, George, & Farrant, 2013).
To add to that, researchers from the Veterinary Medical Diagnostic Laboratory in Missouri
studied 338 different cases of canine melanoma. Though they found significant trends in Melan
A reactivity (a protein found on melanomas), the prognosis for canine melanomas is unrelated to
sex, the location of a tumor, amount of pigment, and microscopic appearance. Further evidence
shows that traditional veterinarian practices such as the ones discussed above are not effective
ways to diagnose melanoma. Histopathologic examination and fine needle aspirates performed
on tumors cannot be substituted with one another. They can deliver conflicting results, making it
hard to confidently diagnose melanoma (Gillard et al., 2014).
Statement of Purpose
Melanoma has been associated with most malignancies in the dog. Both mucosal and oral
melanoma is considered an extremely malignant tumor that is associated with a high degree of
high metastatic propensity and local invasiveness. Studies on this condition have revealed that
this condition is extremely prognostic. WHO states that the staging process for dogs associated
with canine melanoma depends on the size of the lymph node or tumor. Negative diagnosis of

the condition is associated with size, stage, evidence of metastasis, and histologic criteria
(Chapman, & Hostutler, 2013).
Melanoma is an aggressive tumor whose species may rise at the different anatomical site when it
affects dogs. Development of canine melanoma my subsequently cause infections to other
anatomical sites with different frequencies for every site that is affected.
As stated above, there is a big challenge and gap in the diagnosis of canine melanoma. The
variations in diagnosis are as a result of factors such as; inability to categorize melanoma as skin
cancer, the degree of skin pigmentation and other tumors are unpigmented. Melanomas viewed
microscopically may present features of other types of tumors thereby making a poor diagnosis
melanoma. A study conducted on Hovawart dog that was treated for melanoma malignant
showed a dog's spine had a haired tumor which had physical characteristics that resembled
benign tumor but the fact it was malignant. According to diagnosis done through ultrasound and
radiograph, the findings did not show any sign of melanoma making it impossible to diagnose for
cancer before the surgical procedure (Chow, Stent, & Milne, 2014).
This study aims to determine gaps and variations among different diagnostic methods for canine
melanoma. This study will focus on specific diagnosis methods such as; histopathologic
analyzation, microscopic imaging, radiograph ultrasound imaging, and fine needle aspirate.
CHAPTER 2
LITERATURE REVIEW

Introduction
Diagnosis of canine melanoma in dogs can be challenging because of the variety of histological
appearances of canine melanocytic neoplasms. This chapter aims at discussing the literature
review on major methodological flow or gaps in research for canine melanoma diagnosis. This
chapter will also review other literature on inconsistencies in theories and findings related to
canine melanoma diagnosis as well as establishing important areas that can be useful for future
studies.
Histopathologic analyzation
Melanomas comprise about 6% of tumors in the skin in heavily pigmented dogs but commonly
in neoplasm of the canine oral cavity. There is a description of the histologic classification of
melanomas as malignant and benign. According to findings from other researchers, cutaneous
melanomas are benign while the majority of canine melanomas are behaviorally malignant.
Other researches found that behavior of canine melanoma is not correlated with a histologic
appearance at the rate of 10 to 40% of histologically benign oral compared to canine cutaneous
melanoma. This makes therapeutic protocols that focus on the histologic appearance of
melanoma to be inappropriate.
Similarly, single parameter flow cytometry can detect changes associated with malignancy,
provide quantitative measurements of DNA and increase proliferation rate (Paoloni et al., 2015).
Cytometry has also been used in some cases to demonstrate small numbers of malignant cells
among targeted species, even after determining histologic diagnosis was equivocal (Ottnod et al.,
2013). Individual cells are used to determine the DNA of the specifies through measuring DNA
specific dye and fluorescence emitted after stoichiometric nucleotide. This technique has been
used in the diagnosis of canine melanoma in dogs through a retrospective analysis of formalin
fixed in the cytometric analysis. This method of diagnosis is used to determine behavioral
characteristics of canine melanoma to evaluate the flow of cytometry within the species (Rossi et
al., 2015).
Correct histopathological analyzation helps in predicting the biological behaviors of melanomas.
According to another study that was conducted to determine the effectiveness of
histopathological analyzation, eight of behaviors that were detected were associated with benign
melanoma while fourteen behaviors were associated with histologically benign as well as having
more histological criteria or malignancy. This study helps to understand how histopathological
analysis can be used to determine the presence of canine melanoma in dogs. It also establishes its
unique technique of determining this malignant thus proving the importance of histopathological

analyzation (Shafiee et al., 2013).
Radiograph and Ultrasound Imaging
According to a study on a 6-year-old male boxer dog which was referred at Western College of
Veterinary Medicine, the dog had a history of unilateral nasal discharge through its right nostril,
and blindness over two days and progressive lethargy. On palpation, no pain was detected at
retropulsion of the eyes. The submandibular lymph nodes were also observed to be in normal in
size and texture. According to examination, there was a bilateral absence of menace response as
well as poor direct consensual pupillary light reflexes and bilateral mydriasis. According to this
study, nasal cavity was observed to be destroyed and extended into the cranium. Imaging report
found a focal round the spleen. There was also expanding and infiltrating the submucosa which
was destroying the nasal bone and ulcerating the nasal mucosa causing a poorly demarcated and
densely cellular neoplastic mass which composed of cells arranged that were in an interlacing
bundles. Radiograph imaging also revealed polygonal to spindloid with distinct cell borders
which contained eosinophilic cytoplasm that is mostly associated with dark brown melanin
pigment (Oblak, Boston, Woods, & Nykamp, 2015). Radiograph report also showed oval to
spindloid that was associated with stippled chromatin that had at least one or three distinct
nucleoli. Areas of necrosis and nasal bone invasion were observed. Neoplastic cells were seen
effacing the brain and infiltrating. According to the study, there was no evidence of metastasis
within any other organs examined including the spleen and draining lymph nodes. According to
evidence of canine melanoma diagnosis, malignant melanoma was confirmed by
immunohistochemistry hence resulting in a positive melan A (Cabon et al., 2016).
The study was evident that melanocytes were not present in nasal mucosa; hence malignant
canine cases were high among dogs. The clinical presentation of this tumor showed the
development of neurological signs that had a larger mass around the canine area of nasal origin
on the dog subjected to the study. There are insufficient studies to confirm melanocytes from the
dogs hence limiting clinical presentation of these cases as well as the existence of canine
melanoma within nasal mucosa in the dog (Iida et al., 2013).
Fine needle aspirate
A fine needle aspirate is not a biopsy, but it's a diagnosis technique where a sample of the mass is
taken by the use of a skinny little needle. On the use of this technique, the vet disinfects the
surface of the site to be aspirated, often after clipping the hair, to prevent infection. Next, a
needle is introduced into the area of interest, and the plunger is drawn back, creating a vacuum

which draws cells into the hub of the needle. These cells are then used to make a slide for the vet
or a pathologist to look at for a diagnosis. The technique is effective because it takes about 2
minutes to do, and your dog gets to go home without sedation, anesthesia, or hospital stay. This
is a good technique to diagnose canine melanoma growth in dogs (Cordner, Sharkey, Armstrong,
& McAteer, 2015).
Fine-needle aspiration cytology (FNAC) is routinely used for staging canine malignant tumors in
the lymph nodes (LNs), but are few studies to prove the efficiency of this technique. The study
conducted to evaluate specificity and sensitivity of this technique (FNAC) as well as non-
diagnostic (FNAC) of melanoma malignancy revealed that specificity and sensitivity of FNAC
were determined with the association of lymph nodes in diagnosis process when using
histopathology standard diagnosis method. The study assessed and determined the presence of
nondiagnostic FNAC that were associated with its prevalence through the use of histopathology
(Martini et al., 2015). The findings of this study revealed that sensitivity of FNAC was 100% for
other round cell tumors, 100% for carcinomas, 75% for mast cell tumors, 67% for sarcomas and
63% for melanomas. The specificity variation was between 96% and 83%. Findings on
nondiagnostic FNAC revealed that 25% of the sample was nonenlarged hence being difficult to
access while 20% of the sample was metastatic on histopathology. Assessment of this study
concluded that there was 24% of prevalence of metastases. It was also revealed that lymph node
evaluation could not be substituted with FNAC which makes histopathologic evaluation and
assessment on canine melanoma to remain ideal. Consequently, there is a need for more studies
to be conducted for assessment of appropriate diagnosis method for canine melanoma to avoid
limiting assessment to a single lymph node (Wall, Cook, & Cook, 2015).
Microscopic Imaging of Canine Melanoma In Dogs.
Melanoma is a malignant that develop in dogs from melanocytes. Since dogs live or stay near
humans, they get affected by similar environmental factors similar to this that causes chronic
diseases and cancer (Lévy, Niżański, Von Heimendahl, & Mimouni, 2014). The domestic dog
(Canis familiaris) have more naturally inherited chronic diseases compared to other species.
Diagnosis of canine melanoma in dogs is supported because they are high susceptibility to
melanomas, and cancers including other behavioral similarities (Simpson, Bastian, Michael, &
Smedley, 2014).
According to a retrospective study of neoplasms that was conducted on domestic animals
particularly by the School of Veterinary Medicine of Sao Paulo, of 1813 cases of neoplasms that
were discovered in dogs, 58 of the cases were melanocytic neoplasms which represented 3% of
the total species that was involved in the study (Labelle & Labelle, 2013). Another retrospective
study that was conducted among 2154 neoplasms were diagnosed the same university; there
were 186 cases of melanocytic neoplasm which were observed from the dogs. The study also
revealed that common affected type of dogs were male dogs of age 8 to 11 with black hair coats
(Campagne et al., 2013).
In a different study that was conducted to determine the presence of canine melanoma in dogs,
this malignance was found among the majority of dogs that were studied on accounting to 14%
to 45% of canine melanoma (Nishiya et al., 2016). This condition was subjected as the most
common cancer affecting dogs today than any other domestic animals hence requiring more
technological advancements in its diagnosis.
Malignant melanoma diagnosis can be conducted at any portion of the oral cavity, but the most
common site is gingival mucosa (Pierezan, Mansell, Ambrus, & Hoffmann, 2014). Microscopial

imaging revealed that the most common area that was affected by this condition was the
mandibular labial mucosa at 53%. Imaging report also showed that other sites that other
anatomical sites affected by this condition were the tongue, but it was a rare observation. The
most breeds of dogs at high risks of being affected by canine oral malignant melanoma were
dogs with pigmented oral mucosa and small breeds of dogs (Teixeira et al., 2014).
Other scientific studies revealed that most dogs that were affected with canine melanoma were of
ages between 10.5 to 12years of age, but an average age for canine melanoma condition in dogs
was 11.4years, but male dogs were more susceptible to the condition compared to female dogs.
In a microscopic imaging study that was done among 70 dogs with canine melanoma, 11.4% of
the dogs had mandibular lymph node while 1.4 had lung metastasis as other organs affected by
the malignant. Canines with melanomas were also observed with metastasis when
lymphadenomegaly was confirmed to be present resulting to median survival time for dogs with
untreated melanoma (Tuohy, Selmic, Worley, Ehrhart, & Withrow, 2014).
Conclusion
In conclusion, canine melanomas is a very aggressive tumor affecting a large number of dogs.
There is a wide scientific effort in finding the best technological methods of detecting canine
melanomas in dogs and address gaps in other researches on this malignancy. Consequently, there
is a need for more studies to be conducted for assessment of appropriate diagnosis method for
canine melanoma to avoid limiting assessment to a single lymph node. Lastly, the study also
proved existence of gaps in research about diagnosis of canine melanoma in dogs. This was
evident in explanation above since every method has its own findig on possible diagnosis
methods of this condition hence need for an extensive research to find the most appropriate
diagnostic method for this condition in dogs.

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