Download Dealing with cancer in dogs: What this means to you and

Dealing with cancer in dogs: What this
means to you and your Westie
John Robertson VMD PhD
Center for Comparative
Oncology, Virginia Tech
Warning! This presentation
contains a few pictures of cats
and other critters
What’s this talk about?
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Tumors, neoplasms, cancer – what’s the difference?
How common is cancer in dogs?
How is cancer detected?
What causes cancer?
What do I do if my dog has a neoplasm?
Transitional cell carcinoma in Scottish breed terriers
Can the cancer epidemic in dogs be stopped?
Tumors, neoplasms, cancer
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Tumor – literally a swelling, but common
term for a neoplasm
Neoplasm – ‘new cells’; a mass of tissue
derived from normal tissue that grows
without normal regulation of growth
Cancer – ‘The Crab’; a malignant neoplasm
that grows by infiltration and which may
spread to distant sites
Multicentric melanoma – Arabian Horse
How is cancer detected?
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The owner is the first person to know if a neoplasm
is developing!
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Changes in normal routine (loss of appetite, for example)
(convulsions)
Detection of a growth (skin tumors are very common)
Persistent illness accompanied by discharges (vomiting,
diarrhea, blood in urine are examples)
Weight gain, weight loss (in a relatively short time)
How is cancer detected?
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The veterinarian
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Takes a careful history and does a thorough
examination
Recommends further tests (blood work,
radiographs, ultrasonography, surgical biopsy)
Communicates results to the owner
And as a team (owner, patient, veterinarian)
make a decision on what to do!
Companion animals in the US
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There are many companion animals in the
US
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Dogs – 60 million +
Cats – 90 million +
Horses – 10 million+
“Pocket pets” (hamsters, rats, mice, gerbils)
How common is cancer in dogs?
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Neoplastic disease is a (the) leading cause
of death in dogs
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45% of dogs reaching middle age (about 6-7
years) will either develop a tumor, suffer medical
complications as the result of a tumor, or die as
the result of neoplastic disease (Source: Small
Animal Clinical Oncology, Withrow and MacEwen,
3rd ed., 2005)
What causes neoplasms (1)?
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All neoplasms, whether benign or malignant
(cancer) are caused by mutation of critical
genes that control cell growth, maturation
and organization
Mutation is irreversible, cell-to-cell inherited
gene dysfunction
Exposure to certain viruses, excessive
radiation, and some chemicals can cause
mutation
What causes neoplasms (2)?
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There are many inherited factors which
increase the risk of developing neoplasms
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Mutated, inherited genes
Genes linked to phenotype
Patterns of metabolism
Sensitivity to environmental exposures
Male/female gender
Increasing age
Concurrent diseases (immunosuppression)
Breed predispositions in purebred dogs to
cancer
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Brachycephalic breeds (Boston Terriers, Boxers,
Bulldogs, Mastiffs) – primary brain tumors
Golden Retrievers – malignant lymphoma,
hemangiosarcoma
German Shepherds – hemangiosarcoma
Giant breeds – appendicular osteosarcoma
Scottish breed terriers – transitional cell carcinoma
of urinary bladder
Therapies for malignancies in
dogs
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Surgery is the primary modality for therapy
of all canine tumors
Chemotherapy is used to treat canine
malignant lymphoma (about 25% of cases
receive multiagent therapy)
Radiation therapy is effective for some
tumors
Combination therapy is common
Review of VMRCVM oncology
medical records 2004-2006
Results – Canine database
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718 dogs in database search
Top breeds in terms of incidence
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Mixed breed (198)(26% of total cases)
Labrador Retriever (78)(11%)
Golden Retriever (46)(6%)
Cocker Spaniel (24)(3%)
Boxer (22)(3%)
‘Other’(350)(49%)
Results – Age at presentation
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Canine (718 cases)
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0-3 yrs (46)(6%)
4-6 yrs (75)(10%)
7-10 yrs (345)(48%)
11-14 yrs (224)(32%)
15 yrs + (20)(3%)
Unknown (8)(1%)
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Feline (157 cases)
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0-3 yrs (12)(8%)
4-6 yrs (20)(13%)
7-10 yrs (36)(23%)
11-14 yrs (66)(42%)
15 yrs + (15)(10%)
Unknown (8)(5%)
Results – Category of diagnosis
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Canine (718 cases)
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Benign (313 cases)
Malignant (343 cases)
Metastatic (62 cases)
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Feline (157 cases)
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Benign (57 cases)
Malignant (73 cases)
Metastatic (27 cases)
Results - Outcomes
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Canine (718 cases)
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Surgery (532)(74%)
Surgery/euth (64)
Euthanasia (64)
Chemotherapy (28)
Surgery/chemo (3)
Chemo/euth (22)
Chemo/surgery (3)
No Rx (2)
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Feline (157 cases)
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Surgery (105)(67%)
Surgery/euth (18)
Euthanasia (21)
Chemotherapy (2)
Surgery/chemo (1)
Chemo/euth (8)
Surg/chemo/euth (2)
Results – Cost breakdown
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Canine
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$0-499 (145 cases)
$500-999 (209 cases)
$1000 – 1499 (167 cases)
$1500-$1999 (103 cases)
$2000+ (94 cases)
($9784 – primary brain
tumor)
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Feline
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$0-499 (46 cases)
$500-999 (55 cases)
$1000 – 1499 (29 cases)
$1500-$1999 (22 cases)
$2000+ (5 cases)
“Here, gentlemen, a dog teaches us a lesson in
humanity”
(Napolean Bonaparte)
Why study dogs?
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Dogs are the only species of animal, besides man, in
which there is a high incidence of spontaneous
primary brain tumors (as just one example)
Dogs share the human environment and “lifestyle”
Dogs are of sizes approximating humans, display
cognitive functions and learning, and are long-lived
in comparison to other species
Dogs with tumors, and their owners, suffer and need
workable therapies
Transitional cell carcinoma (TCC)
Transitional cell carcinoma (TCC)
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A malignancy of the urinary bladder and
kidney that is more common in Scottish
breed terriers (Scottish Terriers, West
Highland White Terriers) than other breeds of
dog
Signs: loss of housebreaking, frequent
attempts to urinate, blood in urine and/or foul
smell, vocalization, inconsistent urination,
abdominal pain, palpable mass (+/-)
TCC facts
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TCC represents 1.2-2.0% of all canine
cancers
The incidence of TCC increased 600%
between 1975-1995 in dogs
TCC risk
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Mixed breed dogs – risk of 1.0x (baseline)
Scottish Terriers – 18.0 x (more than mixed
breed dogs)
Shetland Sheepdogs – 4.5 x
Wire-haired terriers – 3.2 x
West Highland White Terriers – 3.0 x
Urinary bladder TCC
CT study of TCC in urinary bladder
TCC and lawn chemicals?
“Herbicide exposure and the risk of
transitional cell carcinoma of the urinary
bladder in Scottish Terriers,” Glickman, LT,
Raghavan, M, Knapp, DW, Bonney, PL,
Dawson, MH, Journ Amer Vet Med Assoc
24:1290-1297, 2004
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TCC and lawn chemicals?
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Studied 83 Scotties with TCC and 83
Scotties without TCC but with other medical
conditions
Retrospective analysis of medical record and
exposure data
(1991 – 2,4 dichlorophenoxyacetic acid
[2,4,D] – lymphoma in dogs and people)
2,4 D (dichlorophenoxyacetic acid)
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Decreases synthesis of RNase – helps clean
up damaged genome
Uncouples oxidative phosphorylation –
critical for cell metabolism
Increases hepatic peroxysome synthesis –
transformation of drugs and chemicals
Odds ratios of development of TCC in
Scottish Terriers
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Herbicides and insecticides - 7.19
Phenoxyherbicides – 4.42
Herbicides – 3.62
Non-phenoxyherbicides – 3.49
Insecticides – 1.62
Affected (mutated) genes in Scotties not yet
known
How do we stop the cancer epidemic in
our dogs?
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Understand risk factors ( breeds, age) (Breed
Genetics Study)
Understand clinical signs
Early detection (CKA, gene array, proteomics) (Need
Westie Tissue and Serum Bank)
Early intervention
Research to find out the why (genetics, genomics,
triggers)
John Robertson VMD PhD
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Director of the Center
for Comparative
Oncology (CeCO)
Professor of Pathology,
VA-MD Regional
College of Veterinary
Medicine (VMRCVM)
Co-author of Westie
Health E-Book
The Center for Comparative Oncology