Disorders in Jack Russells
Definition of Disorders:
- Cataract: Lens opacity which obscures vision and may cause blindness.
- Congenital Cataract and Microphthalmia: Cataracts associated with a small eye
- Distichiasis: Abnormal location of eyelashes on the margin of the eyelid, causing
- Glaucoma: Increased pressure in the globe which can damage the eye causing
- 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 progress.
- 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 closer together.
- Hydrocephalus: Accumulation of fluid in the brain causing severe pressure and
degeneration of the brain.
- Myelodysplasia: Lack of development of the brain causing incoordination.
- Scotty Cramp: Muscle cramps triggered by excitement or exercise; you may see a
rabbit hopping gait.
- Trembling: Excessive shaking or trembling, particularly of the rear limbs.
- 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); dwarfism.
- 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
- 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 breeds.
- 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
- Undershot: Lower jaw extends beyond the upper jaw.
- Laryngeal Hypoplasia: Failure of development of the larynx (voice box) causing
- 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 reasonable provocation.
- 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 death.
- 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
- 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 fema~e chromosomes.
- 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.
Information courtesy of the Jack Russell Terrier Club of America
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