Pre-Vet Exam 1

Domestic dog family

Canidae family (40 million years ago) - 14 genera, 34 species

First Canidae member

Prohesperocyon wilsoni

First dog fossil’s can

Canidae subfamilies

Eocene era

Hesperocyoninae

Borophaginae

Caninae

Hesperocyoniae (39.7 - 15 Mya)

endemic to North America

Comprises total of 10 recognized genera / 26 species

earliest and most primitive branch of the canidae

Borophaginae (34 - 2 Mya)

earliest and most primitive animal was a small fox-sized animal

most western North America

small omnivores and powerful bear-sized carnivores

Caninae (34 - 0 Mya)

Only living subfamily

lineage that led to present - day canids

Canidae members

coyotes, wolves, jackals, fozes, maned wolves, african wild dogs, bush dogs, dholes, racoon dogs,

Domestic dog original classification & updated term

Canis familiaris / Canis familiarus domesticus - Carolus Linnaeus

Canis lupus familiaris (gray wolf subspecies) - Smithsonian / ASM

Reasons for taxonomic reclassification of domestic dogs

Behavior, vocalizations, morphology, molecular biology

Dogs and wolves - genetic information

mtDNA sequence is less than 0.2% different

mtDNA of grey wolf and coyote is about 4% different

When did dog domestication first occur

30,000 years ago (Upper Paleolithic - earliest remains of organized human settlements)

Paleolithic dog resemblance

Siberian huskies in appearance

Shepherd dogs in size

How did domestication occur

1) hunters killed a female wolf and brought home pups

2) founder group of less fearful wolves pulled to encampments to scavenge kills

gradually, natural selection and genetic drift from human activity

Natural selection

changes in allele (gene forms) frequencies of a population

Genetic drift

random changes in the allele frequencies in a gene pool - usually smaller populations

Prehistoric uses for dogs

Tacking, game hunting / transport, fur / meat, pets, ritual connotation

Definitive evidence

5000 years ago - artwork by ancient Egyptians

Saluki (persian greyhound)

one of the oldest known breeds of domesticated dog, used for hunting

bred for the desert, used by the Bedouin tribes

careful breeding for long legs, stamina, good eyesight

don’t kill prey, hold it for master

flexible spine, long stride, larger heart

Pekingese

2000-3000 years ago

first recorded dog to be kept in China (imperial court)

“lion dog” - earliest breeds with written standards for what it should / shouldn’t look like - led to health problems (eye/back/breathing)

arrive in London Court of Queen Victoria post-raid (1860)

Papillon

150-400 years ago, dog liked by 15th century Europeans

Industrial Revolution and dog breeds

created an upsurge in the middle class, people had more time and money

pre-this, there were only around 40 types of dogs, after this number exploded (to around 400 dogs!)

Why are there so many dog breeds and not as many cattle breeds despite similar levels of extensive breeding

Tandem repeats in dogs are more prevalent than in any other species - variation

Why are there increased rates of cancer in dogs

Longer lifespan with improved veterinary care combined with genetic predisposition

Factors impacting cancer incidence

Breed (goldens / boxers), age (very young / very old), gender (male dogs), environment (urban areas)

Metastasis

uncontrolled growth, then spread and establishment of cancer cells to distant areas

reason for the majority of cancer deaths, big obstacle in curative therapy

spread via lymphatics, vascular channels, or directly

Modern Neoplasia

Common, diagnose first, treatable

more common in specific breeds - mountain dogs, boxers, schnauzers, poodles, rotties, irish wolfhounds, cocker spaniels, dobermans, pommies, mewfies, gsd, saint bernards, great danes, greyhounds, basset hounds, golden retrievers

Oncological work-up

History

physical exam on mass, nodes, mouth, palpation, auscultation - determine if separate exams needed

staging

Why is staging necessary

identifies diagnosis / extent of disease, comorbidities

provides prognosis

Stage one

one lymph node / region

Stage 2

multiple regions

Stage 3

generalized disease (multiple organ systems)

Staging tests

bloodwork, U/A (urine culture), rads (u/s), aspiration cytology, biopsy (golden standard - punch, wedge, surgical), CT / MRI, bone scan

Chemotherapy

chemical reagents which have a specific and toxic effect on neoplastic cells

attacks specific parts of cell cycle - DNA/RNA/Protein synthesis, mitosis

works best with tumors with high growth fraction vs. growth rate

balance of toxicity and antitumor

maintain plasma concentrations over time

tumors will develop resistance - combination / multimodal options

Chemo formula

high growth fraction (proportion of actively dividing cells) v. growth rate (increase in tumor size)

Antimetabolites

class of chemo drug - analogues of compounds used in biosynthesis - stops the cell cycle

Alkylating agents

class of chemo drug - cause interstrand DNA binding; not cell cycle specific

Radiation

ionizing radiation to control / kill malignant cells

cure (definitive, adjunct) and palliation (pain, neuro signs)

some tumors are more sensitive to this treatment

targets DNA

RT Sensitivity

Hematopoetic > epithelial > mesenchymal

Radiation - Highly sensitive tumors

seminoma, lymphoma, perianal, TVT

Radiation - Sensitive tumors

nasal, pituitary, mast cell

Radiation - Moderately sensitive tumors

soft tissue sarcomas, some mammary gland

Radiation - Resistant tumors

Oral cavity, primary bone

Alternative cancer treatment

Amputation, diet change, supplementation, empirical treatment, palliative treatment

Lymphoma

common, unknown etiology (genetics, toxins, retrovirus)

B & T cells (better and terrible)

Anywhere! - look for lymphadenopathy, weight loss, dyspnea, v/d, mass

Diagnose - CBC, Chem, Rads, ECG, aspirates, biopsy, u/s

Lymphoma Staging

1 = single node

2 = multiple nodes (one side)

3 = generalized lymph node development

4 = 1 - 3 and liver and/or spleen

5 = 1-4 with bone marrow

substages - a = no signs of systemic illness, b = opposite

Lymphoma survival

2 months to 3 years depending on stage, hypercalcemia, strength of chemo protocol

Multiple Myeloma

Plasma cell tumor that’s systemic (terminally differentiating b cell dzs)

Bone marrow infiltration of neoplastic plasma cells, bence jones proteinuria, monoclonal gammopathy, lytic bone lesions (2/4)

chemo (melphalan, pred); radiation

Multiple myeloma survival

18 months, worse if extensive systemic dzs

Chronic lymphocytic leukemia

older, usually female

mature lymphocytes infiltrate the bone marrow, usually associated with lymphocytosis

mortality usually from infection

chemo

Acute lymphoblastic leukemia

younger animals (labs)

immature lymphoblasts infiltrate the bone marrow

± lymphocytosis

anemia / thrombocytopenia common

mortality due to inflection or anemia

short survival time (21 days)

Mammary tumors

very common, 42% of tumors in females

1:1, malignant:benign

OHE prior to 1st estrus = 0.5%

OHE after 1 = 8%

can be epithelial, mesenchymal, mast cell, or mixed

should be approached as if malignant

treatment = surgery

can have implant / seeding metastasis during surgery (be careful)

rad/chem not proven extremely effective

Mast cell tumors

common, in skin (trunk, limbs) - older bostons, boxers, bulldogs

can have visceral masses, mets to spleen, liver, kidney

dermal - usually small, well defined

subq larger, gelatinous

grade based on number, demarcations, spread (LN involvement)

diagnose via FNA, biopsy, abdominal rads, U/S

active tumors (heparin, histamine, enzymes, can have complications)

treat with radiation, chemo, antihistamines

Mast Cell Tumors - survival

relative to grading and treatments

grade 1 - up to 1500 days

Soft Tissue sarcomas

15% of skin tumors

came from mesenchymal (connective) tissue

fibro, nerve sheath, hemangiopeicytomas, vaccine-assocaited

poor margins, recur if conservative surgical removal

Osteosarcoma

most common primary bone tumor

middle aged / very young dogs

large breeds (limbs); smaller dogs (axial skeleton)

rarely see mets at diagnosis, but can cause death within a year

treatment = amputation, radiation, chemo - longer survival with all 3

Hemangiosarcoma

Older dogs, GSDs

from vascular endothelium, then mets

spleen most common site, R atria, skin, kidney, need u/s and rads

sometimes accidentally found - may collapse and recover due to hemoabdomen - ruptured spleen

treat with spleenectomy, chemo

Transitional Cell Carcinoma

most common bladder cancer

older female dogs

mimics cystitis, so diagnosed after lower UTI signs and conservative treat doesn’t work

U/S for diagnosis - avoid cystocentesis (can transplant tumors)

50% will have mets at presentation

treat with chemo, radiation

Lipomas

Benign tumor from adipose tissue

old, obese females in their trunk / proximal limbs

dobies, labs, schnauzers, mixed breeds

soft, predunculated, discrete nodular masses that are freely moveable

should be monitored for enlargement / mobility interference

excision is usually curative

Trichoepithelioma

Benign tissue - cystic hair follicle neoplasm

can have malignant forms - not common

late to middle aged bassets, mastiffs, setters, poodles, springers, goldens

trunk and head

palpably encapsulated custic nodules in skin and subq

watch for self trauma

excision is curative, but animals that develop this are prone to develop additional lesions at other sites (bassets)

chylothorax

accumulation of chyle within the thoracic cavity

• chyle milky

dog / kennel club

organization for canine affairs that concerns itself with the breeding, showing, and promotion of more than one breed of dog

The Kennel Club (1873)

First dog club, formed in England; Crufts Dog Conformation Show

Kennel club responsibilities

Maintains breed standards

Records dog pedigrees

issues rules for conformation dog shows and trials / accreditation of judges

Basically a purebred registry

3 oldest and most recognized purebred dog clubs in North America

AKC (American Kennel Club)

CKC (Canadian Kennel Club)

UKC (United Kennel Club)

Why were new clubs formed in 2000?

New requirement imposed by the AKC that required paternal DNA testing, as well as costs and kennel inspections

American Kennel Club

founded 1884

largest purebred dog registry in the world - only for dogs in the US

5000 licensed / member clubs & affiliated orgs

World Canine Organization

AKC is not part of it, unlike most other country’s kennel clubs

80 countries

AKC Dog Registration

dog’s parents must be registered with the club as the same breed

Litter must be registered

Special registry research

How to register a dog in the AKC without registered parents

Purebred Alternative Listing Program / Indefinite Listing Privilege

AKC program that provides purebred dogs who may not have been eligible for registration a change to register “alternatively” (usually for animals where the status of the parents are unknown)

• can participate in AKC companion and performance activities, but not conformation

Conformation

externally visible details of a dog’s structure and appearance, as defined in detail by each dog breed’s written breed standard

Groups recognized by the AKC

Sporting

Hound

Working

Terrier

Toy

Non-sporting

Herding

Miscellaneous

Sporting group characteristics

Naturally active and alert

bred to help hunters in the field by finding, flushing, and/or retrieving game (mostly birds)

great water / woods instincts

Golden Retreivers

sporting dogs

Feathered, medium length cream to golden colored coat

Outer coat = water-repellent; undercoat = dense

Black nose, brown eyes with dark rims, ears medium sized and pendant

70-75 lbs; 23-24 inches at withers

Gentle, loyal, active family dogs

Golden retrievers - medical issues

Hip dysplasia

Congenital eye defects

Needs exercise to avoid… yk,..

Labrador retrievers

sporting dog

Longer than tall

Short, hard, water-resistant double coat

Colors = black, yellow, or chocolate

Broad head, wide muzzle

Ears medium and pendant

65-80 pounds, 22-24 inches at withers

Loving, patient, intelligent, loves water, not aggro
prone to hip dysplasia and progressive retinal atrophy

Irish setter

sporting dog

Silky, feathered red coat

longer than taller

long, chiseled head

long muzzle that ends in dark black or brown nose, teeth meet in scissors/level bite

70 lbs, 27 at withers

high energy, loyal, gets along

Irish setter medical issues

Bloat, cancers (osteosarcoma), epilepsy, hip/elbow dysplasia

Hound group characteristics

Ancient ones used for hunting

seek and follow prey by either sight or scent

bred to track game in the field

Beagle

Hound

short, easy to care for coat

straight muzzle, wide drop ears

hazel / brown eyes, straight tails

tricolor or red/white

18-30 lbs, 13 - 15 inches

friendly but sensitive, good guard dogs (howling) but not good guard dogs

Beagle medical issues

Deafness, epilepsy, hip dysplasia, hypothyroidism, patellar luxation

Daschshund

Hound

low to ground body, robust muscular development

elastic skin

intelligent / alert

smooth / short coat, long coat, or wire coat

playful, hard to train, loyal

Standard dacshund

16-32 pounds

Miniature dachshund

11 pounds and under at 12 months of age and older

Dachshund medical issues

Spinal problems (intervertebral disk disease); risk of injury worsened by obesity- places greater strain on vertebrae

Irish wolfhound

Hound

Large, muscular build - tallest of the dogs

endurance runner

grey, brindle, red, black, white, fawn

120 lbs minimum; 32 inch minimum

family dog, will still chase fleeing prey

firm, but gentle, leadership

Irish Wolfhound medical issues

like most large breeds, they have a relatively short lifespan, dilated cardiomyopathy and bone cancer are the leading cause of death

• like all deep-chested dogs, gastric torsion is common

Working group characteristics

Bred to work with people (pulling sleds, guarding, policing, water rescue)

Cane Corso

Working dog - roman warfare!

sturdy, strong skeleton; muscular but moves with ease

weight prop to height; 25-27.5 inches

easy to obedience train, sus, quiet but will bark at unsure, need exervcise

Cane corso medical issues

Canine hip dysplasia common - usually inherited

Rottweiler

Working

black with clearly defined rust markings

massive and heavier males than females (110-132 lbs, 24-27 inches)

Medium pendant / triangular / wide / high ears

calm, confident, devoted, family protection, alert

Rottweiler medical issues

relatively healthy, but like other large breeds, hip dysplasia is common

Siberian Husky

Working dog - medium sized

agile runners, compact / well furred body with erect ears and brush tail

21-32.5 inches, 45-60 pounds

howl instead of bark, consistent training with positive reinforcement

Siberian husky medical issues

Mainly genetic, like seizures and eye defects, including corneal dystrophy, canine glaucoma, juvenile cataracts, progressive retinal atrophy

Terrier group characteristics

feisty, energetic

bred to follow prey

have little tolerance for other animals (including dogs)

bred to hunt and kill vermin

wiry coats that require special grooming - stripping

Miniature schnauzer

Terrier

whiskers and double coat - hard, wiry outer coat / close, soft undercoat

salt and pepper, black / silver / solid black

14-18 pounds, 14 - 18 inches

alert, friendly, intelligent, easy to train, territorial (bark over bite)

Miniature schnauzer medical issues

Relatively healthy- unless high fat levels, which lead to hyperlipidemia, pancreatitis, diabetes, bladder stones, eye problems

Manchester terrier

Terrier

small, black, short coated with mahogany markings and taper tail

wedge-shaped, long, clean head with a keen, alert expression

Toy - <12 lbs; standard - 12-22 pounds

not aggressive nor shy, observant

Manchester terrier medical issues

von Willebrand’s disease - inherited bleeding disorder

hypothyroidism, patellar luxation, eye problems like glaucoma and cataracts