The Havanese Club of America, Inc.

Health

Introduction:

 

At this point in their evolution Havanese appear to be a very healthy breed with an average lifespan that remains relatively long. This can best be seen from the two major health surveys conducted by the Havanese Club of America [see our section on Health Surveys]. While the parent populations of these two surveys was a voluntary one- not selected in a formal or otherwise unbiased fashion - the surveys do span over 2000 dogs from both breeders and pet owners. There appears to be no single disease or malady that is prevalent in the breed at this time.

 Within small breeds as a whole however, there are clearly some health issues that are more commonly observed. The frequency and severity are often breed specific. For example, specific kinds of cardiac diseases are seen in a very large percentage of the Cavalier King Charles Spaniel population (and other forms in certain large breeds). Another example is liver disease which is frequently seen in Norfolk and Yorkshire Terriers, Shih-tzus and Maltese populations, but very very rarely in any large breeds. The various forms of cardiac and liver disease are believed to be genetic in origin. Depending on the nature of the genetic mutation, and its transmittance, it may be hard or impossible to breed away from with the tools we have at hand.

 In this section we address some of the diseases and health issues that are seen in smaller breed dogs. Not all are life threatening, but may impact the quality of life of your pet. At the end of each section we provide a set of references that may be useful.

 I. Liver Disease

 Blood carried to the liver arrives largely via the portal vein, which drains the intestines, stomach, pancreas, and spleen. This blood is rich in nutrients that have been extracted from food. Within the liver, the portal vein branches into smaller and smaller vessels allowing the blood to spread throughout the organ to the individual liver cells, whose functions are:

  • filtering out toxins in the blood

  • manufacturing or storing sugar for energy

  • processing drugs and other chemicals

  • making proteins

Portosystemic Vascular Anomalies (PSVA or “liver shunts”) and Hepatoportal Microvascular Dysplasia (MVD) are two common forms of liver disease. PSVA occurs when portal blood is diverted around the liver (shunted), while MVD occurs when blood is diverted from the microscopic vessels within the liver. These vessels can be underdeveloped or absent, positioned abnormally and/or throttled or there may be microscopic lesions on the liver. The result of either case is a liver that does not perform its normal functions efficiently. Clinical signs result because the dog cannot clear out toxins, add, remove or process drugs, and/or he lacks the building blocks for growth and repair. Clinical signs may also result from a buildup of toxins such as ammonia, which predispose the dog to cognitive impairment, urinary tract inflammation and infection.

Both PSVA and MVD are diseases of genetic origin. They are believed to be related and are seen almost exclusively in small-breeds such as Yorkshire terriers, Maltese, Cairn terriers, Tibetan spaniels, Shih-tzus, Havanese, and others. The two health surveys conducted by the HCA suggest that the incidence in Havanese is relatively small. 

The mode of inheritance is most consistent with “autosomal dominance with incomplete penetrance.” This means that it is not associated with the sex chromosomes, but simply determined by a single gene that one parent can pass to an offspring, the result having varying degrees of severity. Like many heritable diseases, breeding away is generally not effective, in part because of the difficulty to reliably detect/diagnose all carriers.

MVD and PSVA are often first detected in young dogs with no symptoms, by four to six months of age, but as early as six weeks- frequently during an otherwise routine examination where blood work indicates elevated liver enzymes. As indicated for example in Dr. Sharon Center’s article below, diagnosis is difficult and sometimes inconsistent in part because of the variation in severity that may exist. Often, the total serum bile acid (TSBA) test is done before and after eating, but it cannot distinguish between MVD and PSVA. A Protein-C test can be used to help distinguish between the two conditions. Other diagnostic tools are available including for example biopsies and 3D – CT imaging.

A more detailed description of liver disease and treatment can be found in the references below:

General Discussion: https://www.merckvetmanual.com/digestive-system/hepatic-disease-in-small-animals/portosystemic-vascular-malformations-in-small-animals

For more information on liver disease click on following links:

PSVA and MVD in Maltese http://www.americanmaltese.org/ama-health-information/portosystemic-vascular-anomalies-psva-and-microvascular-dysplasia-mvd

MVD: http://www.petmd.com/dog/conditions/genetic/c_dg_hepatoportal_microvascular_dysplasi 

Dr. Sharon Center: https://www.acvs.org/files/proceedings/2011/data/papers/096.pdf 

Dr. Karen Tobias: https://works.bepress.com/karen_tobias/21/

A useful article on diagnosis of Liver Disease from IDEXX:
 

II. Kidney Disease

 Residing in the upper abdominal cavity, the Kidneys are two bean-shaped organs of the urinary system. Their primary functions include:

  • Waste excretion: Filtering out toxins, excess salts, and urea, a nitrogen-based waste created by cell metabolism.

  • Balancing of water levels: through the chemical breakdown of urine, the kidneys react to changes in the body’s water level throughout the day, adjusting the level to leave water in the body instead of excreting it.

  • Regulating blood pressure: Kidneys need constant fluid pressure to filter the blood. When it drops too low, the kidneys increase the pressure by producing a blood vessel-constricting protein (angiotensin). This also signals the body to retain sodium and water.

  • Regulating red blood cell count: If the kidneys do not get enough oxygen, they excrete erythropoietin, a hormone that stimulates the bone marrow to produce more oxygen-carrying red blood cells.

  • Regulation of PH: The kidneys help balance the acids that are produced by cellular metabolization. Foods that are consumed can either increase or neutralize the acid in the body.

Congenital and developmental kidney diseases are those in which the kidney may be abnormal in appearance, function, or both. These diseases may result from inherited or genetic problems or disease processes that affect the development and growth of the kidney before or shortly after birth. Non-hereditary causes may include infectious agents, Canine herpes virus, response to medications, and dietary factors. Most dogs are diagnosed before five years of age.

 Nephrolithiasis is the condition in which clusters of crystals or stones -- known as nephroliths or “kidney stones” -- develop in the kidneys or urinary tract. There are a number of causes and risk factors that may contribute to their development; eg: the oversaturation of stone-forming materials in the dog's urine or increased levels of calcium in the urine and blood, and diets that produce high pH (alkaline) urine, and recurrent urinary tract infections. Some breeds of dogs appear to be particularly susceptible to one form of crystal or another (eg: calcium oxalate or urate nephroliths).

The two health surveys conducted by the HCA suggest that the incidence of diseases of the kidney and the development of kidney stones in Havanese is relatively small.

 For a more detailed description of congenital and developmental kidney diseases, kidney stones, and renal failure, see for example:

http://www.petmd.com/dog/conditions/urinary/c_dg_congenital_developmental_renal_diseases 

http://www.petmd.com/dog/conditions/urinary/c_dg_nephrolithiasis

http://www.petmd.com/dog/conditions/urinary/c_multi_renal_failure_chronic