Genetic Diseases

Just as we are, dogs are plagued with a great number of inherited health problems. Some are prevalent in specific breeds: cancer in Bernese mountain dogs and golden retrievers; heart disease in boxers; bleeding disorders in Doberman pinschers; eye problems in pugs and Irish setters. Each year, veterinary science develops more genetic tests to provide greater information on these diseases.

Among small dogs, inherited maladies include the following:

  • Atopic dermatitis: This is an allergic skin condition seen in short-haired breeds and poodles.

  • Dental problems: These can include gingivitis, periodontal disease, and tooth loss, common in all small breeds, and malocclusion (over-bite or underbite), common in short-muzzled breeds like the Pekingese, shih tzu, and Lhasa apso.

  • Cleft palate: This condition is prevalent in short-nosed dogs including pugs, Boston terriers, and the shih tzu. It can sometimes be corrected by a skilled microsurgeon.

  • Diabetes mellitus: Like humans, overweight dogs are more at risk for this disease, which is caused by insufficient insulin production. It is a genetic problem for most small dog breeds.

  • Heart and circulatory diseases: These include mitral valve defect, pulmonic stenosis, and congestive heart failure. All are treatable through medication and surgery, but the smaller the dog, the more difficult the operation. Early diagnosis is key.

  • Elbow dysplasia: This degenerative disease of the elbow causes pain and lameness and is usually correctable by surgery.

  • Epilepsy (seizures): The dog's brain literally seizes up as nerve cells (neurons) react uncontrollably. Although hereditary, it can also be caused by brain injury. Seizures often become more severe and frequent as a dog ages and are sometimes controllable by medication.

  • Demodectic mange: The demodectic mange mite is present on most dogs but usually lies dormant. Dogs with this form of mange may have immune deficiencies, making them unable to keep the mites at bay. The localized form usually occurs in pups and is characterized by hair loss on the face, head, and forelegs. It is treatable with medicated shampoos, antibiotics, and immune-boosting supplements. A more serious generalized form spreads over the dog's body, causing hair loss and skin breakdown. Treatment can be prolonged, and the condition is not always curable. Small breeds with a tendency to develop this include the West Highland white terrier, Scottish terrier, Boston terrier, and pug.

  • Hypothyroidism: The thyroid glands regulate many body functions, stabilizing metabolic rate and affecting hair growth and energy levels. When this function is impaired, dogs become overweight and lazy, frequently showing hair loss as well. Although it is not curable, this condition is controllable through medication.

  • Degenerative disc disease: Disc problems are experienced more often by short-legged, long-backed small breeds like the dachshund and Lhasa apso. The condition develops when the disc is displaced from its normal position, protruding into the spinal canal. The resulting inflammation causes pain and partial paralysis. It can be precipitated by something as ordinary as jumping or twisting while the dog is at play. With rapid diagnosis and treatment, the odds of recovery improve. It is usually treated by anti-inflammatory drugs and surgery.

  • Patellar luxation: Common among several small breeds including the poodle, Chihuahua, and bichon frise, this is a condition in which the kneecap pops out and causes pain and difficulty in walking. Anti-inflammatory drugs are sometimes prescribed, but the condition is only repairable through surgery.

  • Legg-Calve-Perthes disease: This condition causes degeneration of the upper portion of a dog's thighbone, known as the femoral head. It usually starts in puppyhood, causing lameness with no apparent injury. Very common among small dogs, it may be completely or partially repaired through surgery.

  • If your small dog has tracheal problems, use a harness rather than a collar to put less pressure on the neck and throat. Make sure the groomer does not use a noose while your dog is on the table or in the tub, and bring your dog home as quickly as possible to cut down on the stress factor.

  • Tracheal collapse: When its cartilage weakens, the trachea begins to collapse, and the amount of air that can get through to the lungs is restricted. Heat, humidity, and excitement exacerbate the problem. A dog with this condition has trouble breathing and may cough or gag to try to clear its airway. The condition can usually be managed with medication and restricted activity. A surgical procedure using stents to widen the trachea is available, but this is risky and only done as a last resort. Small breeds at highest risk are Chihuahuas, Italian greyhounds, Pomeranians, Maltese, toy poodles, and Yorkshire terriers.

Eye Diseases

  • Keratitis, also known as dry eye, is caused by an impaired secretion of tears. Treatment involves the use of artificial tears, antibiotics, steroids, and flushing out the tear ducts.

  • Progressive retinal atrophy (PRA) involves the deterioration of the retina and eventual partial vision loss. Careful breeders prevent it in their line through Canine Eye Registration Foundation (CERF) vision screening prior to breeding dogs that have a high incidence of this malady. Schnauzers and Lhasa apsos are prone to this problem.

  • The opposite of PRA, epiphora causes excessive production of tears. It is caused by blocked nasalacrimal ducts, passages that usually allow the tears to drain inside the nasal cavity. These tears cause staining under the eyes, and the constant wetness often leads to infection. The ducts can be flushed and drops prescribed to relieve the condition. Short-muzzled dogs like the Pekingese and shih tzu are likely victims.

  • Glaucoma develops from the buildup of pressure in the vitreous fluids of the eyeball. It is caused by injury and old age as well as by heredity and leads to the loss of vision. The dog's eyeball will become enlarged, sometimes appearing cloudy. The pain and pressure of this condition can be relieved with drugs and occasionally through surgery.

  • Distichiasis is caused by a double row of eyelashes that irritate the cornea, causing inflammation and tearing. It can be corrected through surgery.

  • Another eyelash problem, trichiasis, occurs in small longhaired breeds with abnormally positioned lashes growing from the upper lid that need to be removed.

  • Cataracts occur when the lens of the eye becomes opaque and is sometimes an inherited condition. It causes loss of vision. Corrective surgery is far more difficult and not as successful in dogs as in humans. It is prevalent in pugs.

  • Entropion: This genetic fault exists in the skin surrounding the eyes of small dogs, often those with wrinkly faces. It involves the inversion of the eyelid itself and causes chronic irritation. The earlier it is diagnosed and surgically corrected, the better. The papillon, pug, Pekingese, and shih tzu all have a high incidence of this condition.

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