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Cancer Care in Pets
(Veterinary Oncology)
Orna Kristal, DVM
Dip. American College of Vet Internal Medicine (oncology)
Chavat Daat, Beit Berl
Veterinary Specialty Training
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Requirements: DVM degree and internship
Began in the US
Today in Europe as well
3 yrs of working under supervision of
specialists in different fields
Tumor biology studies
Publication, presentations
Specialty examination
Specialty in Veterinary Medicine
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Large Animals (horses, ruminants)
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Internal medicine, Surgery, reproduction
Small Animals
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Internal Medicine, oncology, cardiology, neurology
Surgery
Imaging
Emergency medicine
Ophthalmology, Dermatology, anesthesia
Exotic animals (birds, reptiles, ferrets, rodents)
Pathology – clinical and histopathology
Cancer in dogs and cats
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No accurate incidence rates (IR)
Dorn et al. 1968 – new cancer cases a yr in 2
counties in CA
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Dogs – 382/100,000
Cats – 156/100,000
IR today probably much higher
Estimated lifetime risk of cancer
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Dogs – 50%
Cats – 30%
Comparative aspects
Humans
Dogs
Cats
Breast/prostate
Breast*
Lymphoid
Lung
Skin
(non-melanoma)
Sarcoma
Skin
(non-melanoma)
Breast*
Colorectal
Testicular (intact) Sarcoma
Lymphoid, oral
tumors
Genetic factors
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Golden Retriever
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Boxer
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Histiocytic Sarcoma
Scottish Terriers
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Lymphoma (T-cell)
Bernese Mountain Dogs
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1 in 5 – Hemangiosarcoma
1 in 8 - Lymphoma
Transitional Cell Carcinoma
Sharpei
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High grade Mast Cell Tumors
Hormonal factors
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Ovariohysterectomy
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Before 2.5 yrs of age in dogs and 1 yr in
cats is protective of mammary tumors
Castration
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Reduces risk of testicular cancer
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Esp. in cryptorchids
Increases risk of prostate cancer (still
uncommon)
Environmental factors - Dogs
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Exposure may be higher in indoor pets
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Exposure to passive smoke
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Insecticides in shampoos or dips  risk of
TCC, esp. if obese
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 risk for lung cancer – short and medium length
nose (weak)
 risk for nasal cancer – long-nosed breeds
But not spot-ons like Frontline or Advantage
Herbicides and insecticides on lawns  risk of
TCC in Scottish terriers
Environmental factors - Cats
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Oral Squamous Cell CA (SCC)
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 risk with:
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High intake of canned food (RR – 3.6) and
canned tuna fish (RR – 4.7)
Flea collar use (RR – 5.3)
 risk with flea shampoo use
Lymphoma
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 risk with exposure to passive smoking
Why treat pets with cancer?
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Cancer is perceived by many to be a serious and
often fatal disease
Treatment in people is commonly associated with
side effects leading to poor QOL
Therefore treating pets with similar treatment is
perceived as cruel and selfish
This perception represents total misunderstanding of
the treatment of cancer in animals
The main goal of treating animals with cancer is to
extend a good quality of life for the patient (and
family) for as long as possible.
What is QOL in animals?
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Life without pain & daily normal
activity
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Happy when owners come home, plays
Wants to eat and drink
Has control of eliminations
Quality is more important than quantity
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Life without QOL means prolonging unnecessary
suffering of the animal
How do we maintain QOL?
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We try to prevent treatment’s side effects
Before treatment is begun risk vs. benefit is
considered
Often animals treated for cancer live longer
and better than animals treated for other
chronic disease (i.e - diabetes, chronic renal
or heart disease)
Maintaining QOL
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If the animal develops significant
treatment toxicity
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We can lower drug dosages
Use other drugs
Consider stopping treatment
Treatment can be with a curative intent
or palliative
Know when to quit
Treatment modalities
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Treatment options depend on
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Tumor type
Location in body
Tumor stage (TNM)
Comorbidities
Treatment modalities
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Surgery
Radiation therapy (not in Israel)
Chemotherapy
Small molecule
inhibitors (TKI’s)
Cancer Vaccines
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Melanoma
Multimodality Tx
Symptomatic Tx
Choosing the treatment
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Owners ultimately choose the treatment
after hearing
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Different options
Prognosis for each option
Possible side effects
Cost
Should they choose not to treat, they
are making an educated decision
Common signs of cancer in small
animals
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Abnormal swellings that persist or continue to grow
Sores that do not heal
Weight loss
Loss of appetite
Bleeding or discharge from an opening
‫סימנים שכיחים של סרטן בחיות קטנות‬
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Offensive odor
Loss of energy, tire easily
Persistent lameness
Difficulty breathing, chewing, urinating, defecating
Aural SCC
Baaci
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7 yr old spayed female Golden Retriever
Baaci
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Presented with enlarged lymph nodes, fever, unwell
and diagnosed with lymphoma on cytology
Baaci
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With no treatment median survival is 4-6
weeks and QOL is poor most of this time.
With CHOP based chemotherapy median
survival is extended to 12 months and about
25% are alive @ 2 yrs.
Drug dosages is lower than in humans. Only
20% develop grade 3-4 toxicity.
Baaci’s owner chose to treat with chemo.
Baaci
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Achieved complete remission
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Treatment continued for one yr
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One episode of vomiting & diarrhea requiring
supportive care.
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Still alive and happy today > 4 yrs from
diagnosis.
Chaos
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4 yr old female Great Dane
Diagnosed with osteosarcoma (OSA)
Osteosarcoma
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Many similarities to human OSA
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Affects large to giant breed dogs
Metaphyses of long bones most affected
Most stage negative at presentation
90% are high grade
Common hematogenous lung metastases
Two main differences
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10 times more prevalent in dogs
Mean age
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Dog – 7rs
human – 14 yrs
Osteosarcoma
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Dogs
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Are an outbred species
Have innate immune system
Their cancer progresses more rapidly
Combined with similarities in tumor behavior
they can serve as an excellent model for
research of this disease
Dr. Steve Withrow - pioneer in the field
Clinical trials in dogs serve a dual purpose
Chaos
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Had forequarter amputation
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To control primary tumor and relieve pain
Post-operatively entered into a clinical trial
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5 treatments with doxorubicin
Followed by the oral trial drug vs. placebo
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No side effects at all
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Enjoyed an excellent QOL for 18 months after treatment
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Median survival with amputation and chemo is 10 months
Slim, 7 yr old male Whippet
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Presented with unilateral nose bleed from the
left nostril (Sept 2008)
CT and biopsy – left nasal adenocarcinoma
Slim
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Treated with Radiation
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12 X 4 Gy, 3 days a week
Tumor shrunk by 30%, was stable for 2 yrs then
started growing very slowly
Receives low dose prednisone permanently for nasal
congestion
Canine Mast Cell Tumors
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Common skin cancer
Can be benign to malignant
May swell up and shrink due to surges of
histamine release
Mast cell tumors
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Fairly easy to diagnose by cytology
Biologic behavior highly correlated with
histologic grade
Treatment depends on tumor grade and stage
Targeted therapy for canine MCT
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33% of MCT express mutation in c-kit
Toceranib Phosphate
(Palladia™)
Masitinib Mesylate
(Masivet®)
KIT
PDGFRβ
VEGFR2
Flt3
KIT
PDGFR
FGFR3
FAK (focal adhesion
kinase)
In summary
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The main goal in treating animals with cancer
is good QOL for as long as possible
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Every case should be evaluated individually
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Owners should be given all options
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The decision is theirs to make after weighing
risk vs. benefit and cost