VT121 Reproductive and Genetic disease LESSON

Terminology and Root Words

  • Cervic/o: narrowing, cervix
  • Colp/o: vagina
  • Episi/o: vulva
  • Galact/o or Lact/o: milk
  • Gravid/o: pregnancy
  • Mamm/o or Mast/o: mammary gland
  • Metr/o: uterus
  • Omphal/o: umbelicus
  • Orchid/o: testicle
  • Ovari/o: ovary
  • Phall/o or Priap/o: penis
  • Prostat/o: prostate
  • Salping/o: oviduct

Reproductive Terminology

  • Breech presentation:
    • Abnormal posterior-first position of fetus at birth
  • Ectopic pregnancy:
    • Implantation of the embryo at an abnormal site (outside of the uterus)
  • Paraphimosis:
    • Narrowing of the prepuce, swelling the glans and preventing retraction
  • Cesarean section (C-section):
    • Delivery of offspring through an incision in the abdominal and uterine walls
  • Pseudocyesis:
    • Pseudopregnancy; false pregnancy
  • Colostrum:
    • The first milk-like substance produced by the female after parturition; it is thick, yellow, and high in protein and antibodies

Diseases of the Female Reproductive System

Vaginitis

  • Puppy Vaginitis:

    • Common Clinical Signs: Vulvar discharge
    • Treatment: Antibiotics; usually resolves after first estrous cycle

  • Adult Vaginitis:

    • Causes: Anatomic abnormalities, bacterial infection, traumatic injuries, or chemical irritation, canine herpesvirus

Pseudopregnancy

  • An exaggeration of the normal hormonal changes that occur during the estrous cycle in the nonpregnant bitch.
  • Onset: Usually develops 6 to 12 weeks after estrus and may last 1 to 3 weeks.
  • Clinical signs include:
    • Weight gain
    • Mammary gland enlargement
    • Lactation
    • Mucoid vaginal discharge
    • May carry around stuffed toys and demonstrate increased mothering behavior
  • Treatment: Signs are usually self-limiting; Ovariohysterectomy

Eclampsia

  • Seen in heavily lactating females within 2 to 3 weeks after whelping.
  • Clinical Signs:
    • Nervousness
    • Salivation
    • Stiff gait
    • Ataxia
    • Seizures
  • Diagnosis: History and clinical signs
  • Treatment:
    • Treatment must be initiated soon after the first signs of problems occur
    • Slow intravenous (IV) administration of 10% or 20% calcium gluconate
    • Monitor the heart rate via a stethoscope or an electrocardiogram (ECG) for bradycardia or arrhythmias
    • Oral calcium supplements may be started after clinical signs regress
  • Prevention: Good prenatal nutrition and calcium supplementation.

Pyometra

  • Increasing levels of progesterone after ovulation result in hyperplasia and hypertrophy of the endometrial glands of the uterus.
  • Results in cystic endometrial hyperplasia with accumulation of fluid within the uterine lumen.
  • Symptoms:
    • Results in a decrease in myometrial contractions and predisposes the uterus to secondary bacterial infection (pyometra).
  • When it Occurs:
    • Occurs in middle-aged or older intact female dogs and cats within 60 days of their last estrous cycle.
  • Types:
    • Open pyometra – when the cervix is open
    • Closed pyometra – when the cervix is closed
  • Clinical Signs:
    • Vulvar discharge (open pyometra)
    • Abdominal enlargement
    • Vomiting
    • Lethargy
    • Polyuria (PU) or polydipsia (PD)
    • Dehydration
    • Azotemia
  • Diagnosis:
    • Radiology
    • Abdominal ultrasonography
    • Complete blood cell count (CBC): Leukocytosis, neutrophilia with a left shift, and dehydration +/- non-regenerative anemia
    • Serum chemistry may show increased alkaline phosphatase levels, increased serum protein level, increased blood urea nitrogen
    • Vaginal cytology reveals degenerative neutrophils, endometrial cells, and bacteria
  • Treatment:
    • Ovariohysterectomy – treatment of choice
    • Dehydration and azotemia must be corrected before surgery
    • Broad-spectrum antibiotics
    • If the animal is used for breeding, owners may elect medical treatment, which includes Prostaglandin F2α (Lutylase)
  • Prevention: Ovariohysterectomy

Dystocia

  • Definition: Difficulty in delivery of fetuses through the birth canal
  • Causes:
    • Large fetuses (large puppy or kitten, fetal anasarca, or hydrocephalus), abnormal positioning (transverse presentation), narrowed birth canal, or uterine inertia (lack of coordinated contractions or exhaustion of the uterine musculature from prolonged contractions)
  • Clinical Signs:
    • A bitch or queen has been in labor longer than 4 hours without producing a fetus
    • Green vaginal discharge develops during parturition
    • More than 1 hour has elapsed between births
  • Diagnosis:
    • Physical examination with digital palpation of vagina
    • Radiography to evaluate fetal position, size, and number
    • Ultrasonography to evaluate fetal viability and distress
  • Treatment:
    • Manual manipulation: A fetus lodged in the vaginal canal can be manually dislodged through careful manipulation
    • Oxytocin
    • If medical treatment fails to correct the situation, a cesarean section is recommended

Inappropriate Maternal Behavior

  • Normal Behaviors: Nursing, retrieving, grooming, and protecting
  • Clinical Signs of Abnormal Behavior:
    • Mother is restless
    • Neonates are constantly crying
    • Mother is actively attacking and killing her young
  • Diagnosis: Observation
  • Treatment: Tranquilization – acepromazine, diazepam

Lactation Disorders

Mastitis

  • Description: A septic inflammation of the mammary gland – most common
  • Clinical Signs:
    • Mammary discomfort
    • Discolored milk
    • Fever
    • Reluctance to allow nursing
    • Abscessed glands
  • Treatment:
    • Broad spectrum antibiotics
    • Administer warm compresses; then milk the affected glands
    • Puppies and kittens should not be allowed to nurse from affected glands but can continue to use the non-infected teats

Diseases of the Male Reproductive System

Benign Prostatic Hyperplasia (BPH)

  • Definition: An aging change that occurs in intact male dogs as early as 2.5 years of age
  • Clinical Signs:
    • Most dogs exhibit no clinical signs
    • Tenesmus
    • Prostate palpates symmetrically (enlarged and non-painful)
  • Diagnosis: Physical examination – digital rectal examination
  • Treatment: Castration results in a 70% decrease in size of the gland within 7 to 14 days

Prostatitis

  • Definition: The prostate is predisposed to bacterial infection through the urinary system as well as direct infection of the gland itself
  • Clinical Signs:
    • Vary depending if acute or chronic:
    • Acute: Anorexia, fever, lethargy, stiff gait in the rear limbs, caudal abdominal pain
    • Chronic: May be asymptomatic; history of chronic, periodic urinary tract infections
  • Diagnosis:
    • Urinalysis: Urine shows blood, increased white blood cell (WBC) count, and the presence of bacteria
    • Physical examination – digital rectal examination
    • Urine culture and sensitivity
  • Treatment:
    • Antibiotics based on urine culture/sensitivity results
    • Castration may be beneficial

Prostatic Abscessation

  • Description: A serious form of bacterial prostatitis in which pockets of purulent exudate develop within the gland
  • Clinical Signs:
    • Tenesmus
    • Urethral discharge
    • Lethargy
    • Pain
    • Vomiting
    • Hematuria
    • Fever
    • Depression
  • Diagnosis:
    • History and physical examination
    • CBC and serum chemistries: Leukocytosis or normal WBC count; liver enzymes may be elevated; hypoglycemia; hypokalemia
    • Prostatic aspiration - hemorrhagic, purulent, septic
  • Treatment:
    • Surgical drainage - treatment of choice
    • Castration
    • Antibiotic therapy

Prostatic Neoplasia

  • Description: Uncommon in dogs but has been seen in cats; occurs in both intact and neutered males; are always malignant
  • Clinical Signs: Similar to other prostatic diseases
  • Treatment: Prognosis is poor

Priapism and Paraphimosis

  • Priapism:
    • Persistent abnormal erection of the penis, accompanied by pain and tenderness. Occurs occasionally in dogs.
    • Etiology: Excessive parasympathetic stimulation or possible impairment of venous drainage from the penis may result in priapism.
  • Paraphimosis:
    • Inability of the dog to retract the penis into the preputial sheath.
  • Treatment of Acute Cases:
    • Sedation
    • Removal of any causative agents
    • Immersing the tissue into a cold hypertonic glucose solution to reduce swelling
    • Gentle cleaning of the penile tissue

Neoplasia of the Genital System and Mammary Glands

Tumors of the Testicles

  • Statistics: Approximately 5% to 15% of all tumors seen in male dogs are testicular tumors.
  • Risk Factors: Cryptorchid dogs and those with inguinal hernias are at greatest risk for testicular tumors.
  • Common Age: Usually seen in older, intact male dogs (9–12 years of age).
  • Clinical Signs:
    • Non-painful testicular enlargement may be seen
    • Feminization occurs in approximately 25% to 50% of dogs with Sertoli cell tumors; characterized by bilateral non-pruritic alopecia, hyperpigmentation in the inguinal region, gynecomastia, non-regenerative anemia, and thrombocytopenia.
    • Enlarged lymph nodes may be seen in some animals (10%–20%).
  • Treatment: Castration - treatment of choice

Penile, Preputial, and Scrotal Tumors

  • Most Common Tumor: The transmissible venereal tumor (TVT) occurring only in dogs.
  • Epidemiology: Most commonly seen in temperate climates in areas with large free-roaming dog populations.
  • Transmission: Spread during sexual contact; can be transmitted through licking and sniffing.
  • Clinical Signs:
    • Found on sexually intact male dogs
    • Tumors on the penis, prepuce, or scrotum appear as cauliflower-like masses at the base of the penis or lining of the prepuce; also seen on vulva in females, face, and rectum.
  • Diagnosis:
    • Cytology: Impression smears show large, round-to-oval cells with abundant pale cytoplasm containing many vacuoles; nuclei contain frequent mitotic figures and visible nucleoli.
  • Treatment:
    • TVTs are immunogenic and may spontaneously regress with adequate tumor stimulation
    • Surgical removal is also an option

Tumors of the Female Genital Tract

  • Types: Include ovarian tumors, uterine and cervical tumors, vaginal and vulval neoplasia, and tumors of the mammary glands.
  • Vaginal and Vulvar Tumors: The most common tumors of the female genital tract in dogs.
  • Clinical Signs:
    • A pedunculated mass protruding from the vulva
    • Perineal swelling
    • Vaginal discharge
    • Dysuria or constipation
  • Diagnosis: Clinical signs
  • Treatment: Surgical removal with ovariohysterectomy prevents recurrence.

Tumors of the Mammary Gland

  • Commonality: The most common tumor of female dogs
  • Spaying Statistics: The risk for mammary tumor is 0.5% for bitches spayed before their first estrus, 8% for those spayed after one estrous cycle, and 26% for bitches spayed after two or more cycles.
  • Nature of Tumors: Approximately 50% of canine mammary tumors are benign; in cats, only 10% to 20% are benign.
  • Clinical Signs:
    • A firm nodule is palpable in the mammary chain or gland
    • Lymph nodes in the region may be enlarged
  • Diagnosis: Physical examination, CBC, serum chemistries, and thoracic radiographs, which should be evaluated before surgery
  • Treatment: Surgical removal

Genetic Diseases

Overview of Genetics

  • Definition: Genes provide the blueprint for life and define the characteristics of lifeforms. An abnormal or defective gene can lead to disease.
  • Importance of Genetics: Allows prediction and control of the spread of defective genes through informed breeding.
1. Von Willebrand’s Disease (vWD)
  • Description: Most common bleeding disorder in dogs.
  • Key Component: Von Willebrand’s Factor (vWF) – important in clotting blood. A decrease in vWF concentration or activity causes inability to clot blood, leading to hemorrhage.
  • Breed Disposition: Dobermans, German Shepherds, Poodles, Golden Retrievers, Shelties.
  • Inheritance Pattern: Autosomal dominant trait with incomplete inheritance.
  • Clinical Signs:
    • Easy bruising in susceptible breeds
    • Prolonged bleeding during estrus
    • Prolonged bleeding from venipuncture
  • Diagnosis:
    • Buccal mucosal bleeding time (BMBT)
    • vWF (von Willebrand’s Factor) level
  • Treatment:
    • If severe hemorrhage, may need fresh frozen plasma or whole fresh blood transfusion and/or DDAVP to increase vWF levels.
  • Prevention: Dogs with this disease should not be used for breeding.
2. Polycystic Kidney Disease (PCKD)
  • Description: Small, fluid-filled sacs develop in the kidney, resulting in kidney failure.
  • Breed Predilection: Mostly Persians, also Himalayans and British Shorthairs.
  • Inheritance Pattern: Autosomal dominant trait.
  • Diagnosis:
    • Genetic testing
    • Abdominal Ultrasound
  • Treatment: Treat for kidney failure
3. Progressive Retinal Atrophy (PRA)
  • Description: Retina degenerates and causes impaired vision, often leading to blindness.
  • Breed Predilection: Toy Poodles, Miniature Poodles, Golden Retrievers, Irish Setters, Cocker Spaniels, Miniature Schnauzers, Collies, Samoyed, Gordon Setters, and Norwegian Elkhounds.
  • Inheritance Pattern: Autosomal recessive trait.
  • Clinical Signs:
    • Defective night vision
    • Slowly progressive loss of day vision
    • Cataract formation
  • Diagnosis: Examination by ophthalmologist
  • Treatment: None
4. Patent Ductus Arteriosus (PDA)
  • Description: Congenital heart disease in juvenile dogs.
  • Inheritance Pattern: Polygenic trait.
  • Pathophysiology: Ductus arteriosus is a normal fetal blood vessel that allows blood to bypass the lungs; normally closes at birth. In PDA, it fails to close → shunts blood from left to right.
  • Breed Predilection: Chihuahuas, Collies, Maltese, Poodles, Pomeranians, English Springers, Keeshonds, Bichons Frises, and Shetland Sheepdogs; females > males.
  • Clinical Signs: Loud heart murmur
  • Diagnosis:
    • Thoracic radiography
    • Electrocardiography (ECG)
    • Echocardiography
  • Treatment: Surgery
5. Canine Hip Dysplasia
  • Common Disease: A complex disease involving the canine hip.
  • Contributing Factors: Genetics, environmental/dietary factors, disparity between muscle mass and the developing skeletal system.
  • Pathophysiology: Failure of the femoral head to press correctly into the developing acetabular cup, resulting in damage to the dorsal rim.
  • Clinical Signs:
    • Difficulty in rising and stiffness diminishing as the animal warms up on exercise
    • Pain elicited on palpation of the dorsal pelvic area or hip joint
    • In older dogs, lameness, waddling gait, and atrophy of the thigh muscles may be seen.
  • Diagnosis: Pelvic radiographs, Orthopedic Foundation for Animals (OFA) Certification, Penn Hip Method
  • Treatment:
    • Conservative treatment
    • Moderate exercise
    • Weight control
    • Anti-inflammatory medications
    • Nutriceuticals
    • Surgery: Femoral head ostectomy (FHO), Total hip replacement, Triple pelvic osteotomy

Punnett Squares

  • Definition: A grid used to predict the genotypes and phenotypes of offspring.
  • Terminology:
    • Genotype: The specific gene combination for a particular trait
    • Phenotype: The actual physical appearance resulting from the genotype
    • Alleles: Variants of the same gene determining a trait (one from the father, one from the mother)
    • Homozygous: Both alleles are identical
    • Heterozygous: Both alleles are different
  • Dominance:
    • Dominant: Trait expressed when at least one copy of the allele is present (designated with a capital letter)
    • Recessive: Both alleles must be present for the trait to be expressed (designated with a lowercase letter)

Example of Simple (Autosomal) Dominance

  • Example Gene: Dense pigment gene (A) in black cats
    • A = Dark hair coat pigmentation (black)
    • a = dilute hair coat pigmentation (blue)
  • Punnett Square Example: Crossing a heterozygous Black mother (Aa) with a heterozygous Black father (Aa).
    • Put the alleles for the mother over the columns and for the father at the beginning of the rows.
  • Results: Depending on the combinations in the Punnett square, the resulting offspring genotypes and phenotypes can be predicted.