Health Issues Glossary

compiled by Health Committee Members
Cathe Harvey, Debbie Meador,
Carl Handy, Suzanne Macre, & Maigan Harvey-Pinder

Addison’s Disease

Addison’s Disease is a disorder of the adrenal glands, where the glands produce insufficient adrenal hormones. The condition may result from damage to the glands through infection, cancer, or drugs. Pituitary gland disease may also cause adrenal insufficiency, as well as unknown causes.

Insufficient adrenal hormones can upset the body’s conservation of salt, reducing circulating blood volume, impairing heart and kidney function, damaging the heart muscle, and may cause faulty sugar and fat metabolism. Decreased tolerance of stress is the primary characteristic of Addison’s disease and affected pets often present in a shock-like state of collapse called an Addisonian crisis.

Extensive blood and adrenal function tests are necessary to properly diagnose and plan treatment for Addison’s disease. Due to frequent laboratory tests, medication and fluid therapy, the initial treatment for Addison’s disease is made in a veterinary hospital. This condition can be effectively treated at home and lifetime treatment is usually necessary.


Arthritis is defined as inflammation which may occur in any joint. Symptoms may include painful or stiff joints, swelling, a grating sensation during joint movement, as well as fever and redness over the affected joint. Arthritis can occur in several joints at one time (polyarthritis), and can be associated with internal diseases. Aging, infection, injury, blood diseases, inherited conditions, cancer, and allergic or immune-mediated disease can be causes of arthritis. X-rays and lab tests are required to determine the type and extent of the disease.

Arthritis cannot be cured however therapy can be designed to minimize the discomfort and delay or prevent the progression of the disease.


Cataracts are any abnormal cloudiness (opacity) of the eye lens or the capsule that contains the lens. The cloudiness may range from a pinhead spot to total loss of transparency. The lens lies directly behind the iris and pupil, and accounts for 20% of the light-bending action which forms an image on the retina.

Cataracts may be caused by body chemistry changes or defects, injuries to the eye as well as may be inherited. The rate of cataract development ranges from a few days to years. Development is defined in stages: incipient or very early stage, immature or where vision is diminished by the lens is not completely opaque, mature where vision is lost and opacity is complete, intumescent where the lens is swollen and vision depends on the degree of cloudiness, and hypermature where the cataract liquefies and some vision may return.

Surgery to remove the lens and sometimes the insertion of artificial lenses after cataract removal will return function vision to the pet. Occasionally psychological or health related problems will render a pet ill suited for cataract surgery.

Cataracts should not be confused with lenticular sclerosis, which is a natural graying of the lens occurring in pets which are or are nearing about 9 years of age. This graying results from older lens fibers being forced forward by new fibers, crowding the center of the lens. Reasonable vision is retained and no corrective action is required.

Cushing’s Disease

Cushing’s disease, also known as hyperadrenalism, is a disorder of the adrenal glands in which excessive adrenal hormones are produced. Possible causes of this condition include abnormal pituitary gland function, cortisone therapy, tumors of or unexplained overactivity of the adrenal gland. Due to hyperadrenalism being a slowly progressing disease, the early signs are often overlooked. These signs include reduced activity, increased drinking and urination, increased appetite, and enlargement of the abdomen. These symptoms will intensify as the disease progresses, and further symptoms of increased weight gain, heavy panting, and losing hair evenly on both sides of the pet’s body.

Lab tests and x-rays are necessary to diagnose Cushing’s. There is no cure for this disease and controlling it may require surgical and medical treatment. Treatment must be monitored as medical therapy may cause underproduction of adrenal hormones (Addison’s disease).

Diabetes Mellitus

Diabetes mellitus is a disease caused by a deficiency of insulin, a hormone produced by the pancreas necessary for body tissues to use blood sugar. Without insulin, sugar remains in the blood and eventually passes into the urine. This causes increased urine production and thirst. Hunger increases because the body cannot use the sugar in the blood. As the disease progresses, chemicals called ketones accumulate, resulting in vomiting and dehydration. Eventually coma and death occur in untreated animals.

Although not curable, with proper insulin administration and urine sugar testing, the disease can be controlled at home.

Elbow Dysplasia

Elbow dysplasia results when there is abnormal development of one of the bones of the upper foreleg (ulna). As this bone grows a small area of the bone fails to join with the rest of the bone, causing unstable elbow joint and lameness that is aggravated by exercise. This may also cause arthritis of the elbow to develop later in the pet’s life. Treatment involves the surgical removal of the ununited fragment and post-operative strict exercise restriction.

Elbow dysplasia occurs in young dogs and may affect on or both front legs. Due to it’s inheritable nature, affected animals should not be bred.


Nerve cells in the brain function by transmission of electrical impulses. Epilepsy is a sudden, excessive discharge of electrical energy in groups of brain cells which causes seizures or convulsions. The cause of this spontaneous discharge is unknown, but in many causes the condition is hereditary in dogs.

This disease usually appears between 6 months and 5 years of age. Almost all breeds have been affected, as have mixed breeds. There is no known cure for Epilepsy, however treatment controls the condition by decreasing the frequency, duration, and severity of the seizures.

Seizures occur in three distinct phases and rarely last more than 5 minutes. The first phase (aura) is the period before a seizure where the pet may seem overly anxious, and will last less than a minute. The second phase is the actual seizure, which may range from a mild muscle spasm to a severe convulsion accompanied by urination and defecation. Loss of consciousness may or may not occur. The final phase occurs immediately after the seizure, when confusion, weakness, and rapid breathing can be seen. Status epilepticus is when one seizure immediately follows another. This condition can be fatal therefore status epilepticus is a medical emergency and requires immediate medical assistance.

Nationwide Database of Epileptic Pets:
Each seizure study that we embark upon typically requires many hours of recruitment, advertising and telephone/email contacts to locate the specific breeds or characteristics that we need for a particular study. To help minimize the time and costs associated with this process, we are developing a Nationwide Database of Epileptic Pets to streamline the recruitment process.

NC State College of Veterinary Medicine
Companion Animal Epilepsy Research
4700 Hillsborough Street
Raleigh, NC 27606


Glaucoma is a disease in which pressure within the eyeball increases to dangerous levels, and is one of the most common causes of blindness in dogs and cats. Normal pressure within the eye depends on a balance between the production and the escape of internal eye fluid (aqueous humor). Internal eye pressure may rise to dangerous levels is this fluid flow is blocked. The pressure can permanently destroy the retina as well as injure other structures of the eye. If glaucoma persists over a long period of time, the eyeball may become enlarged.

Glaucoma may be caused in several ways - a birth defect which blocks the drainage passage (possibly inherited), injuries to the eye, tumors, inflammatory conditions, blockage of the pupil, and lens disorders. Reduction of the pressure and relieving the pain can be a complex treatment which may require hospitalization. Eye pressure should be monitored to ascertain the pet’s response to treatment. Often medication alone will not control the condition over time and other procedures may be necessary to reduce pain and save vision.

Hip Dysplasia

Hip dysplasia, or HD, is a potentially crippling condition where abnormal formation results in an unstable hip joint, causing arthritis and hip degeneration as the dog ages. There is no certain cause for HD but it is believed to develop because the skeleton grew faster than the supporting muscles. This imbalanced growth can be influenced by heredity and diet, and there may be other unknown factors which may influence the development of and severity of HD.

Symptoms may occur and will vary due to the degree of affectedness. HD usually affects both hips however it occasionally affects only one side. 𠇋unny-hopping” while running, hind leg lameness, reluctance to jump or climb stairs, and a staggering gait are all common signs of HD. Treatment depends on the severity of the disease and can range from supplemental joint therapy to surgical treatment.

Dogs with HD should not be bred.


Hypothyroidism is caused by abnormal functioning of thyroid hormone resulting in inadequate production of hormones of the thyroid. The condition rarely occurs in animals under two years of age and is most likely to be seen in middle-aged or older pets. Symptoms include all or a random combination of the following: hair loss, slow hair growth, recurrent skin infection, dry coat and skin, premature graying of the muzzle, dark pigment in the skin, increased sleep, reduced stamina, and reduced tolerance to cold. Females may experience irregular heat cycles as well as reduced fertility. Males may have a shrinkage of the testes and do not show interested in females.

Blood tests are necessary to diagnose the condition and monitor the treatment. There is not a cure for this condition, but lifetime drug therapy is necessary to control it.

Patellar Luxation

Patellar luxation is defined as the dislocation of the kneecap, allowing the kneecap to move toward the inside, or outside of the leg, as well as moving on both directions. Patellar luxation may be present at birth or may be the result of an injury. This disease can vary in severity and duration of the luxation, although it usually is found in milder forms in small breeds. Severe cases will cause more intense pain and limping.

Treatment can range from 1-2 weeks rest to surgical reconstruction of the knee joint. Over weight dogs will also require weight reduction. Affected pets should not be bred due to this disease’s possible inheritable nature.

Persistent Pupillary Membranes

Persistent papillary members, or PPM’s, are remnants of the papillary membrane that covered the pupil during fetal development. This membrane normally disappears shortly before birth to reveal the pupil. In a newborn it can be possible to see small strands of PPM after the eyelids open, although these normally disappear within a few weeks.

Occasionally some strands persist. They can extend across the pupil, may also connect the iris to the inner surface of the cornea, or extend and attach to the front of the lens. The points of attachment appear as small white areas on the cornea or lens. Little problem is cause to the pet’s vision unless too many exist.

PPM may occur in some breeds more often than in others, however PPM in Basenji has been determined to be inherited.

Progressive Retinal Atrophy

Progressive retinal atrophy, or PRA, is a slowly progressive eye disease where the retina slowly wastes away. It causes no discomfort but will result in permanent blindness. PRA has been determined in some breeds to be inherited from both parents and develops after birth. It occurs in all breeds of dogs and cats, can appear earlier in some breeds as well as taking several years to complete blindness in others. The retina contains light-sensitive rods and cones that change light into energy for transmitting messages to the brain, and can be likened to that of film in a camera.

The first noticeable symptom usually is the pet’s inability to see in dim light. Due to the slowing progressive nature of PRA most pets adapt well to the gradual loss of sight. There is no effective treatment available and blindness will eventually result. Prevention can be obtained through selective breeding of animals with normal eyes.