Animal breed lesson
Terminology
Breed Identification
Baying: Prolonged bark or howl of a hunting dog.
Retriever: Type of hunting dog used for recovering shot birds, often from water.
Crop: Cosmetic surgical procedure carried out on the ears of dogs of certain breeds.
Dock: Tail amputation procedure.
Tabby: Feline fur pattern that may be in stripes or spots.
Points: Refers to the color of an animal's nose (mask), ears, tail, and feet.
Dysplasia: Abnormal growth or development of an organ, tissue, or cell.
Undercoat: Fine hairs of an animal's coat that are usually shorter and more numerous than the coarse guard hairs.
Guard Hair: Coarse, stiff, and often longer and more prominent hairs in a coat with an undercoat.
Brindle: Coat pigmentation pattern where darker hairs form bands on a lighter background.
Merle: Coat color pigmentation pattern with dark, irregular blotches on a lighter background.
Ticking: Fur coat pattern characterized by guard hairs with darker tips mixed in.
Tortoiseshell: Feline fur with two colors (orange and black) producing a spotted or blotched pattern.
Calico: Cat with three colors of fur (black, orange, and white), typically female. Male calico cats often have a genotype of XXY.
Brachycephalic: Dogs with short, wide heads, such as bulldogs and pugs.
Brachygnathia: Medical term for flat-faced breeds like bulldogs and Persian cats.
Dolichocephalic: Dogs with narrow, long heads, such as greyhounds and collies.
Mesocephalic: Dogs with average width heads, such as Labrador Retrievers.
Dogs (Canine)
American Kennel Club (AKC): Classifies recognized breeds into several categories:
Sporting Group: Inherently active and alert, known for instincts in water and woods, and many still participate in hunting.
Requires regular, invigorating exercise.
Examples include:
Cocker Spaniel – prone to ear/skin problems.
English Springer Spaniel – prone to ear problems.
English Pointer.
German Short-Haired Pointer.
Golden Retriever.
Irish Setter.
Labrador Retriever.
Weimaraner.
Hound Group: Historically used for hunting with a common ancestral trait.
Capable of acute scent trail-following or stamina in chasing prey.
Notable for the unique sound called baying.
Examples include:
Afghan Hound.
Basenji – does not have a true bark, produces a yodel instead.
Basset Hound – prone to back problems.
Beagle – example of a tri-color.
Bloodhound.
Borzoi.
Dachshund – prone to back problems.
Greyhound – a sight hound that responds to visual cues.
Irish Wolfhound.
Rhodesian Ridgeback.
Saluki.
Whippet.
Working Group: Bred for guarding property, pulling sleds, and rescue operations.
Benefits from intelligence and quick learning, but size/strength can make them unsuitable for average families.
Requires proper training.
Examples include:
Akita.
Alaskan Malamute – prone to hip dysplasia.
Bernese Mountain Dog – high incidence of cancer, short lifespan.
Boxer – highest incidence of squamous cell carcinoma, often tail cropped.
Doberman Pinscher – often has ears and tail surgically cropped.
Giant Schnauzer.
Great Dane.
Great Pyrenees.
Mastiff.
Newfoundland – all black, known for rescuing drowning children.
Rottweiler.
Saint Bernard.
Samoyed.
Siberian Husky – prone to hip dysplasia, congenital retinal atrophy.
Standard Schnauzer.
Gastric Dilatation Volvulus (GDV): Condition also known as "bloat," primarily affecting large/giant breeds.
Etiology unclear; linked to eating one large meal and exercising right after.
Symptoms: pronounced abdominal distention and non-productive retching, a life-threatening emergency.
Terrier Group: Energetic, feisty dogs varying in size that require resolute owners.
Bred to hunt vermin, often display low tolerance for other animals.
Require special grooming called stripping.
Examples include:
Airedale Terrier.
American Staffordshire Terrier.
Bull Terrier.
Cairn Terrier – easier to train, males can be bossy.
Fox Terrier (Smooth & Wire) – strong-willed, tend to dig, may be aggressive towards dogs.
Jack Russell Terrier.
Miniature Schnauzer.
West Highland White Terrier (Westie) – prone to skin problems, originated from Cairn Terrier.
Toy Group: Ideal for apartment living, providing companionship on cold nights.
Small breeds are found in every group but are especially suited to the toy group.
Examples and their characteristics include:
Chihuahua – world's smallest breed.
Chinese Crested – nearly hairless; breeding challenges; prone to teeth/toenail issues.
Maltese – good natured, does not shed with a long luxurious coat.
Papillon – French for "Butterfly"; excellent in obedience.
Pekingese – long-haired, closely related to Pugs.
Pomeranian.
Toy Poodle – very smart and trainable.
Pug – prone to respiratory problems; rarely aggressive.
Shih Tzu – social, playful; looks similar to Lhasa Apso.
Yorkshire Terrier – energetic and trainable; prone to gingivitis/collapsed trachea.
Non-Sporting Group: Varied collection of breeds in terms of size, coat, and personality.
Examples include:
Bichon Frise – prone to gingivitis but not color-linked genetic issues.
Boston Terrier – often needs Caesarean sections.
Bulldog – susceptible to teeth and/or jaw problems; elongated soft palates.
Chinese Shar-pei – prone to skin-fold dermatitis and aggressive tendencies.
Chow Chow – prone to GDV, hip and elbow dysplasia.
Dalmatian – well-rounded dog that can serve multiple purposes; predisposed to urate stones.
Keeshond – excellent watchdog and companion.
Lhasa Apso – meaning "hairy, barking dog" in Tibetan.
Miniature and Standard Poodles – Standard Poodles prone to GDV.
Shiba Inu – most popular indigenous dog of Japan.
Herding Group: Created in 1983, initially part of the Working Group; specialize in controlling movements of other animals.
Example breeds include:
Australian Cattle Dog (Heeler) – needs early socialization.
Australian Shepherd – smart, play-driven, prone to hip dysplasia; excellent service dogs.
Border Collie – needs constant stimulation, or may become destructive.
Collie – both rough and smooth variants, rough-coated needs daily grooming.
German Shepherd – prone to hip dysplasia, arthritis; excellent service/police dogs.
Komondor – large breed with unique corded coat.
Bearded Collie (Highland Collie).
Old English Sheepdog.
Shetland Sheepdog (Shelti) – resembles a small collie.
Welsh Corgi (Cardigan & Pembroke) – energetic, bred low to avoid kicks from cows.
Dogs Colors
Brindle: Solid color with thin striping (e.g., Mastiff, Great Dane).
Tri-color: Three separate colors with distinct borders (e.g., Collie, Shetland Sheepdog).
Merle: Blended colors producing a splotchy look (e.g., Australian Shepherd).
Cats (Feline)
Breeds: Examples and characteristics:
Persian: Known as Longhairs in Europe; features including brachycephalic nature leading to breathing issues.
Domestic Shorthair.
Domestic Longhair.
Scottish Fold: Notably has folded ears, but not all have this trait.
Siamese: Extremely vocal and demanding, several color varieties (seal-point, blue point, lilac, chocolate, red, tabby, cream, tortie).
Manx: Genetically has a cropped tail, dominant trait must be bred with non-Manx to prevent stillbirths; prone to congenital spinal problems.
Maine Coon: Large, heavy-boned cats, typically 15 lbs or more.
Burmese: Recognized only in sable (dark brown) to chocolate color with a shorter head than the Siamese.
Himalayan: Resembles color-pointed Persians.
Abyssinian: Known for hyperactivity and unique coat with bands of different colors.
Russian Blue: Features a double coat for warmth.
Somali: Red, bred from the mutant Abyssinian longhairs.
Rex: Understood to have a wavy hair coat, delicate appearance.
Turkish Angora: Remarkable for its well-plumed tail and easier grooming compared to Persian with no undercoat.
Cat Colors: Description of color patterns:
Calico: Almost always female; tri-colored with white, black, and orange/red patches.
Tortoiseshell: Almost always female; distinctive splotches of orange and black blending.
Tabby: Variants including silver, blue, red, brown, mackerel (thin stripes), patched tabby (red or cream mixed).
Color points: Refers to coloration patterns on noses, faces, ears, paws, and tails; includes seal, flame, blue varieties.
White cats with blue eyes: Predisposed to deafness.
Genetics
Heredity: The passing of physical or mental characteristics genetically from one generation to another.
DNA:
Contained within the nucleus of each cell, defining the characteristics of every organism.
Each sequence is established at conception when sperm and ovum combine into a zygote.
Gregor Mendel
Known as the "father of modern genetics."
His experiments on pea plants revealed inheritance patterns that became the foundation of modern genetics.
Genes
Definition: Segments of DNA containing specific nucleotide sequences; serve as templates for producing RNA molecules, which subsequently serve as templates for proteins.
Gene Function: Each gene codes for a specific protein.
Genes at Work Example
Melanin Synthesis: Black pigment is created from the amino acid tyrosine, requiring four protein enzymes, each coded by separate genes.
Any defect in these genes can lead to conditions such as albinism.
Chromosomes
Contain organized DNA.
Somatic Cells: Diploid, contain two sets of genes (one from each parent).
Gamete Cells: Haploid, contain one chromosome of each type (sperm or ovum).
Zygote: Receives one set of haploid chromosomes from each parent; contains total DNA organized among several chromosomes.
Canine Karyotype
Total chromosomes: 23 pairs (46 total).
Autosomes: 22 pairs.
Sex Chromosomes: 1 pair.
Genetic Traits
Dominant vs. Recessive Traits:
Dominant Conditions: Expressed with at least one allele copy; both males and females equally pass it to offspring.
Suppresses other alleles’ expression, often designated with a capital letter (e.g., BB or Bb).
Recessive Conditions: Only expressed with two allele copies; designated with a lowercase letter (e.g., bb).
Gene Expression
Genotype: Genetic makeup of an animal for a trait, not visible outwardly; represented by a pair of letters (e.g., Bb).
Phenotype: Observable physical traits resulting from genotype (e.g., brown eyes).
Punnett Squares: Tools used to predict offspring genotypes and phenotypes through a grid format.
Terminology Related to Genetics
Punnett Square: A grid used to predict offspring genetics.
Genotype: Specific gene combinations.
Phenotype: Physical appearance based on genotype.
Alleles: Variants for the same gene; inherited from each parent.
Homozygous: Identical alleles.
Heterozygous: Different alleles.
Simple (Autosomal) Dominance
Expressed completely by a single presence in genotype.
Example: Dense pigment gene in black cats (A).
A = Dark hair coat pigmentation (black).
a = Dilute hair coat pigmentation (blue).
Example of Genetic Cross
Heterozygous black mother (Aa) crossed with heterozygous black father (Aa).
Use of Punnett square yields results for genotypes and phenotypes.
Inheritance Patterns
Simple Dominance: One allele dominates.
Incomplete Dominance: Offspring has a blended phenotype between parents.
Co-Dominance: Both alleles presented; distinct blended phenotype.
Sex-linked Traits
Definition: Genes related to sex chromosomes (X, Y).
X-linked genes impact males more due to singular X presence; females need two recessive alleles for expression.
Hemophilia example in dogs as X-linked recessive disorder.
Example Genetics Cross for Hemophilia
Carrier mother (XDXd) crossed with normal father (XDY).
Affected animals rarely survive; carriers may breed and continue the gene.
Sex-linked and Co-dominant Traits Example
Orange and black coat colors in cats linked to X chromosome; calico females (XO XB) require two X chromosomes.
Lethal Genes
Genes that cause death before birth (e.g., Manx cats).
Homozygous genotype: TT (normal tail length).
Heterozygous genotype: Tt (short tail length phenotype).
Homozygous recessive genotype: tt (lethal phenotype).
Mutated Genes
Definition: Change in genetic material (DNA).
Causes:
Spontaneous Mutations: Example is the Mexican hairless dog (autosomal dominant trait).
Radiation Exposure: Mutations from radiation exposure to germ cells.
Chemical/Toxin Exposure: Chemicals causing structural DNA changes during fetal development.
Gene Interactions
Polygenic Inheritance: Traits created through multiple interacting genes (e.g., coat color in mice).
Example: Specific genes affecting pigmentation determined by a hierarchical action.
Epistasis: Involves one gene’s expression depending on one or more modifier genes.
Environmental Interaction: Certain gene expressions require specific environmental conditions (e.g., Siamese cat coat color sensitive to temperature conditions).
Animal Breeding
Inbreeding: Breeding within related animals to ensure inherited traits; promotes homozygosity but can also highlight weaknesses.
Outcrossing: Introducing unrelated parents into the gene pool, fostering heterozygosity.
Hybrid Vigor: Positive offspring traits from diverse genetic backgrounds.
Line-breeding: Involves closely-related animals while maintaining overall diversity.
In all cases of pure breeds, the interplay of inbreeding and line breeding can shape the genetics of breeds significantly over generations.