Genetics: Miscellaneous

deaf_test_resultsGenetic Disorders - Miscellaneous

THYROID DEFICIENCY - Hypothyroidism, a low thyroid is a common cause of skin and hair problems. Some dogs with low thyroid will show no symptoms at all or only a few symptom, while others show numerous symptoms. Possible symptoms include dry brittle hair, thinning coat and hair loss, dry flaky skin, cool skin, skin infections, weight gain with low food consumption, lethargy and fatigue, irregular heat cycles, infertility, inconsistent bowel movements, heat and cold sensitivity and excessive skin pigmentation. A blood test is the only way to determine a thyroid deficiency. Thyroid replacement therapy is very effective; treatment, once started must continue for life.

ALLERGY - This condition is a disorder of the immune system leading to hypersensitivity to assorted environmental allergens. The primary sign in most dogs is itching. This symptom can exhibit many forms, licking or chewing of the feet, and groin area; chewing tail, excessive rubbing and scratching the face, ears, and chest; and rubbing body along furniture or any thing else to scratch the itchy area. Dogs with allergies can also display reversed sneezing, coat discolouration, crusty, reddened weepy eyes, skin irritations, skin blisters, and hair thinning and hair loss. The most common environmental allergens are dander, pollens, dust and moulds. These can be seasonal and be much worse at certain times of year. Other allergies or intolerances can occur in response to food or chemical and artificial additives and preservatives. Food allergies can show up as the itching above but may also produce vomiting, gas, and loose and frequent stools. Ideally, avoiding the irritating substance is the best means of treatment. This can be achieved in some cases (particularly food), but in most cases of environmental allergens, this is not possible or practical. There are a number of medical treatments including specialty shampoos, herbal preparations, steroids and antihistamines.

SKIN DISORDERS - Problems of the skin are among the most troublesome and difficult to diagnose and treat. Among these is a perplexing condition called SEBACEOUS ADENITIS . In SA, the skin's sebaceous glands which normally produce fatty secretions to help prevent drying of the skin, become inflamed and are eventually destroyed. Clinical signs vary with severity. In long-coated breeds like the Havanese, the condition develops as dry, scaly, flaky skin and silvery dandruff along with patches of hair loss. More severely affected Havanese will have extensive hair loss and a moth eaten look. They may also have areas of thickened skin ("hyperkeratosis") accompanied by a rancid, musty odour and secondary skin infections. Sebaceous adenitis is primarily a cosmetic disorder as it affects the appearance of the dog rather than general health. SA affected dogs can be otherwise healthy and happy but are distressing to look at and unpleasant to smell and touch which make it a frustrating condition to cope with. SA cannot be cured. Symptomatic treatments are long term and can be extensive, time consuming and expensive. SA is best diagnosed by the examination of skin biopsies.

SHORT HAIRED GENE - A Havanese which inherits two copies of this recessive gene will appear as a short coated Havanese. The coat is smooth on the face and legs with longer fringes on the ears, body and tail. In appearance, it is very different from a typical long haired Havanese. This gene appears to have been a spontaneous genetic mutation several generations ago. The trait is genetic. Dogs with only one copy of the gene will be long haired though they still carry a copy of the short haired gene which can then be passed along to offspring. Coat differences within a litter can usually be discerned at about 6-8 weeks of age. A short hair is a serious deviation from the breed standard and should never be bred.

DEAFNESS - In recent years, deafness has been identified in Havanese. It is a heritable disorder but one with a complex mode of inheritance. It has not yet been determined if this may be color linked as it is in other breeds. A number of Havanese may be carrying these genes. You cannot check hearing yourself. Most people with unilaterally affected dogs are completely unaware that there is any problem until a bilaterally deaf puppy is produced. There is a test available to check hearing. It is the BAER test. It is a very simple test and can be done at anytime after a puppy is about 6 weeks old. Unlike CERF, the BAER test does not need to be repeated yearly. It is a one time test. It is a wise precaution to test breeding stock and test the pups if possible. Also very important not to breed the unilaterally deaf dogs. BAER testing clinics can be difficult to locate though are generally available at veterinary colleges. A single test may be expensive but prices are usually substantially lower if done at a hearing clinic. Some veterinarians recommend sedating the dogs to preform the test. In Havanese, sedation is generally unnecessary. At this time, there appears to be very few bilaterally affected dogs, but this number may  rise as untested unilaterals are bred and produce bilaterally affected offspring.

Review - At first glance all this appears alarming and certainly there is cause for concern but at the same time one must not lose sight of the fact that ALL breeds have heritable disorders and that some are more serious and widespread than others. The conditions mentioned here have all been diagnosed in Havanese and all have a hereditary component. Some are widespread like the cataracts while others like Legg Perthes are much more limited in their occurrence.

This information was presented to inform about both upsides and downsides of owning a Havanese and to stress the importance of researching a breed thoroughly before choosing to add a Havanese or any dog to your family. Please choose a breeder with care to ensure that you are getting a quality puppy from a reputable ethical breeder who tests their breeding stock for heritable disorders. Though these cannot be eliminated completely, careful breeding practices help to minimize problems. Do not choose a puppy on impulse.