Disorders in Jack Russells: A Brief Definition
- Cataract: Lens opacity which obscures vision and may cause
- Congenital Cataract and Microphthalmia: Cataracts associated
with a small eye globe.
- Distichiasis: Abnormal location of eyelashes on the margin of
the eyelid, causing irritation.
- Glaucoma: Increased pressure in the globe which can damage the
eye causing blindness.
- Glaucoma (pigmentary): Glaucoma in which a dark pigment is also
present in the globe and which apparently blocks
the drainage angle.
- Lens Luxation: Dislocation of the lens from its normal site
behind the cornea (partial or complete).
- Persistent Pupillary membranes: Failure of blood vessels in the
anterior chamber to regress normally; there may be
impaired vision or blindness.
- Progressive Retinal Atrophy: Degeneration of the retinal vision
cells which progresses to blindness.
- Trichiasis: Abnormal placement of the eyelashes on the eyelid.
- Cerebellar Ataxia: Degeneration of the cortex of the
cerebellum leading to a staggering gait; it may or may not
- Congenital Myasthenia Gravis: Severe muscle weakness may cause
megaesophagus, fatigue and collapse due to a
failure of neuromuscular transmission of nerve impulses.
- Bilateral Deafness: Inability to hear; i.e., completely deaf,
both ears affected.
- Unilateral Deafness: Partial deafness; one ear affected.
- Epilepsy: Seizures commonly called fits; they recur generally
- Hydrocephalus: Accumulation of fluid in the brain causing
severe pressure and degeneration of the brain.
- Myelodysplasia: Lack of development of the brain causing
- Scotty Cramp: Muscle cramps triggered by excitement or
exercise; you may see a rabbit hopping gait.
- Trembling: Excessive shaking or trembling, particularly of the
- Wobbler Syndrome: Abnormality of the neck vertebrae causing
rear leg ataxia which may progress to paralysis.
b. Ceroid-Lipofuscinosis (ATP subunit C storage): Causes night blindness, confusion, unpredictable aggressiveness, and ataxia late in the course of the disease.
c. Ceroid-Lipofuscinosis: Causes visual impairment, confusion, erratic temperaments, and apparent loss of memory for previously learned tasks.
d. Congenital Vestibular Disease: Causes loss of balance/incoordination, dog appears to try to keep from falling.
HARD TISSUE DISEASES
- Achondroplasia (Appendicular): Lack of normal development of
the skeleton, particularly of the appendages (limbs);
- Cleft Lip/Cleft Palate: A fissure in the roof of the mouth and
upper lip, may be present together or separately.
- Hemivertebra: Abnormal formation of the body of the vertebra,
can cause posterior ataxia and paralysis. It causes the
twisted tail in the screw tailed breeds.
- Legg-Perthes: Aseptic necrosis of the head and neck of the
femur, causes rear leg lameness.
- Overshot: Upper jaw extends beyond the lower jaw.
- Patellar Luxation: Poor development of structures holding
patella (knee cap) in place, usually medial (inward) in small
- Premature Closure of the Ulna: Ulna stops growing sooner than
radius, causes wrists to turn in and front feet to turn out.
- Radial Agenesis: Radius stops growing sooner than the ulna
causing bowed front legs.
- Undershot: Lower jaw extends beyond the upper jaw.
- Laryngeal Hypoplasia: Failure of development of the larynx
(voice box) causing breathing difficulties.
- Tracheal Collapse: Improper formation of cartilaginous rings
of the trachea causing mild to severe breathing problems.
- Tracheal Hypoplasia: A small trachea due to improper
development causes mild to severe breathing difficulties.
- Oligodontia: Absence of most if not all teeth.
- Pyloric Stenosis: Abnormally small opening between the stomach
and the duodenum, prevents food from passing and
causes sharp projectile vomiting.
- Aggressiveness (Excessive): Excessively assertive or forceful
with other dogs or people, may attack or bite without
- Von Willebrand's Disease: Reduced factor VIII in the blood
resulting in a prolonged bleeding time; may be mild,
moderate, or severe and can cause death.
- Cardiomyopathy: Abnormality of heart muscle may cause edema of
the lung, weakness at exercise and sudden death.
- Patent Ductus Arteriosus: Failure of the fetal vessel between
the aorta and pulmonary artery to close around the time of
birth, causes heart murmurs, exercise weakness, and may cause
- Inguinal Hernia: Outpouching of skin in the area of the
inguinal ring which may contain viscera; a scrotal hernia is a
type of inguinal hernia.
- Umbilical Hernia: Outpouching of skin over belly button; may
contain abdominal viscera, and regress spontaneously.
- Diabetes Mellitus: Excessive sugar in the blood and urine due
to a lack of insulin.
- Growth Hormone Deficiency: Lack of production of or inability
to use growth hormone causes dwarfism.
- Hypothyroidism: Destruction of the thyroid gland due to an
attack from the animal's own immune system causes rough,
scaly skin; hair loss; weight gain.
- Cryptorchidism: Absence of testicles due to retention in the
abdomen or inguinal region, may be one or both sided or
may slide in and out of the scrotum.
- Hermaphrodite: Presence of gonadal tissue for both sexes due
to the presence of a full compliment of both male and
- Short or "High" Toes. This is a developmental condition where
the outside toes, usually on one or both front feet,
do not grow to normal length, giving the appearance of being a
"short" or "high" toe that does not touch the ground
when full the terrier is full grown.
- Absence of premolars (one or more). Terrier is missing one or more pre-molars; does not have full denture.