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 four major health surveys conducted by the Havanese Club of America [see our section on Health Surveys]. While the parent populations of these surveys was a voluntary one- not selected in a formal or otherwise unbiased fashion - the surveys do span almost 3000 dogs from both breeders and pet owners. There appears to be no single life-threatening disease of clear genetic origin that is prevalent throughout 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). These appear at a young age and are attributed conclusively to a genetic origin. 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. Some forms of liver disease are also 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. And, as with any genetic pre-selection, one must be wary of its impact on other beneficial traits.

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:
 
 
For an excellent readable overview, see: 

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

 

III. Cardiac Disease

Background and Synopsis

The 2018-2019 Rainbow Bridge Survey found cardiovascular disease to be one of the two most prominent health issues contributing to early death in Havanese (see Figure 1).  No predominant underlying form of cardiac disease was identified in the individual survey responses - congestive heart failure being listed as the outcome in most cases. The mean age at death was 12.4 +/- 0.4 years, almost 3 years earlier than the natural lifespan exhibited in the survey population as a whole. And, while no statistical difference between male and female lifetimes was observed, the survey indicated that females were significantly more prone than males to die from a cardiovascular disease. 

While cardiovascular disease is a prominent contributor to Havanese mortality, the survey suggests it to be more the result of natural aging, rather than of congenital or genetic origin, with congestive heart failure being the most frequent final outcome. Dogs dying of congestive heart failure may still live quite long lives, as can be seen in Fig. 1.

Cardiac Health Chart 

Figure 1. The frequency of diagnosed and reported cardiovascular disease by age for 38 males and females from the Rainbow Bridge Survey.

Mitral Valve Disease

Mitral valve disease (MVD) is the most common heart disease in all breeds of dogs, accounting for more than 70% of all canine cardiovascular disease. The disease manifests as a slow but progressive condition in which the mitral valve thickens, resulting in an imperfect seal between the chambers of the heart.  The risk of MVD increases with age and is most common in small to medium sized dogs, developing typically after about six years of age.  Often symptoms are not recognized by owners and the disease goes undetected until the dog reaches about nine years of age or older.

The first step in the diagnosis of MVD is hearing a murmur during a cardiac examination (cardiac auscultation).  As dogs age, the mitral valve naturally tends to degenerate, so many older dogs will have some form of mitral valve disease.  Evidence from the most susceptible canine breeds indicate a strong inherited component to the disease, with a polygenic mode of inheritance. The level of exercise, the degree of obesity, and diet are usually not attributed to causing MVD in these breeds.

MVD has four major stages:

  • Stage A: Patients at risk, no symptoms (for example, Cavalier King Charles Spaniels where MVD appears as early as 5 years in ~50% of dogs, and has a genetic, heritable basis).
  • Stage B1: Heart murmur heard by your veterinarian, but no heart enlargement detected on echocardiogram.
  • Stage B2: Heart murmur heard by your veterinarian and heart enlargement detected on echocardiogram.
  • Stage C: Symptoms of congestive heart failure (CHF) present (exhibits difficulty breathing).
  • Stage D: Refractory congestive heart failure (receiving maximum doses of medications but symptoms are still present).

The American College of Veterinary Internal Medicine (ACVIM) recommends echocardiograms be performed whenever murmurs are heard to accurately identify the cause.

Dogs with MVD may not exhibit any noticeable symptoms for a long time.  Once a murmur is even detected, it typically takes several years for there to be sufficient damage to the heart that owners begin to notice a cough caused by the enlarged heart pushing on the airways or by congestion in the lungs themselves.  

An increase in the resting breathing rate is also an indicator of worsening heart disease.  Most dogs have a respiratory rate at home that is less than 30 breaths per minute.  If the respiratory rate starts to increase above what is normal for that dog, specifically, if it exceeds about 40 breaths per minute, this may be a sign that heart failure is starting to develop.

Other Cardiovascular Conditions

There are several other common cardiovascular conditions identified in dogs:

Dilated Cardiomyopathy (DCM) is a disease of the heart muscle which causes the heart to enlarge and become thin walled, resulting in progressive heart failure.  This disease is a common inherited disease with breed specific DNA variants.

Pulmonic Stenosis (PS) is an abnormality of the pulmonary valve that limits blood flow to the lungs; left untreated dogs tend to die before five years of age.

Ventricular Arrhythmias have DNA mutations which are breed specific. These are abnormal heartbeats that begin in the lower heart chambers (causing the heart to beat too fast) and can cause sudden death, often between 12 and 24 months of age.

Sub-valvular Aortic Stenosis (SAS) is a heart defect characterized by a fibrous ridge below the aortic valve resulting in an average lifespan of about 19 months.  SAS has genetic mutations which are breed specific.

Atrial Fibrillation (AF) is a common heart rhythm abnormality affecting all breeds of dogs usually coexisting with heart failure.

Tricuspid Valve Dysplasia (TVD) is a developmental anomaly of the tricuspid valve of the heart.  TVD has breed specific genetic predispositions.

Congestive Heart Failure (CHF) is a condition which causes difficulty breathing because of fluid accumulation in the lungs.  MVD and DCM are common causes of CHF.

Myxomatous mitral valve degeneration (MMVD) leads to structural heart changes and CHF; genetic mutations appear to be polygenetic.  In Cavaliers for example diagnosis prior to five years of age is considered early onset and considered to be "highly heritable."

Cardiac Tamponade refers to compression of the heart caused by fluid collecting in the sac surrounding the heart. It prevents the ventricles from expanding properly.

Cardiomegaly refers to an enlarged heart, which is usually a sign of another condition, such as a heart valve problem or other heart disease.  

Treatment

At the present time there is no cure for heart disease but therapies do exist that can delay the progression of the disease.  Dogs exhibiting CHF from moderate to severe valvular insufficiency or dilated cardiomyopathy will often be started on the drug pimobendan when actual chamber enlargement is first detected. Studies show that for these dogs, the pimobendan regimen can delay the development of congestive heart failure by about 15 months on average.  

Recommendations for Havanese: 

Cardiac disease appears to show up mid- to late-life in Havanese.  An annual auscultation by a Board Certified Veterinary Cardiologist beginning around 5 years of age will increase the likelihood of early detection and treatment that can slow the progression of disease.  If a murmur is detected, typically the cardiologist will follow with an echocardiogram for a more precise diagnosis. This may be repeated at a later time to track the progression of the disease and to adjust the treatment.

While the field of canine genetics is still very new, the AKC Canine Health Foundation has several research grants studying the genetics of heart disease.  

Miscellaneous References and Resources

Chronic Mitral Valve Insufficiency in Dogs:  Recent Advances in Diagnosis and Treatment. Sang-II Suh, Dong-Hyun Han, Seung-Gon Lee, Yong-Wei Hung, Ran Choi and Changbaig Hyun; Published in: Canine Medicine - Recent Topics and Advanced Research, 2016, Chapter 5.

Degenerative Mitral Disease, Small Animal Hospital, College of Veterinary Medicine, University of Florida;  

See: https://smallanimal.vethospital.ufl.edu/clinical-services/cardiology/degenerative-mitral-valve-disease/

Identifying Congenital Heart Disease, Veterinary Practice News. Kim Campbell Thornton;

See: https://www.veterinarypracticenews.com/identifying-congenital-heart-disease/

Catch Heart Disease in Dogs Early, Veterinary Medicine at Illinois. Hannah Beers;

See: https://vetmed.illinois.edu/pet_column/heart-disease-in-dogs/

Canine Heart Failure - Early Diagnosis, Prompt Treatment. Mark A. Oyama.

Univ. of Penna. Departmental Papers (Vet). May 2011.

Holter Monitoring in Clinically Healthy Cavalier King Charles Spaniels, Wire-Haired Dachshunds, and Cairn Terriers.  C.E. Rasmussen, S. Vesterholm, T.P. Ludvigsen, J. Häggström, H.D. Pedersen, S.G. Moesgaard, L.H. Olsen. J.Vet.Int.Med. May 2011; 25(3):460–468.

Mitral Valve Disease and the Cavalier King Charles Spaniel;      

See: https://cavalierhealth.org/mitral_valve_disease.htm

Myxomatous Mitral Valve Disease in Dogs: Does Size Matter?  Heidi G. Parker and Paul Kilroy-Glynn. J.Vet.Card. March 2012; 14(1): 19–29.

Heart Rate, Heart Rate Variability, and Arrhythmias in Dogs with Myxomatous Mitral Valve Disease. C.E. Rasmussen, T. Falk, N.E. Zois, S.G. Moesgaard, J. Häggström, H.D. Pedersen, B. Åblad, H.Y. Nilsen, L.H. Olsen.  J.Vet.Int.Med. Jan/Feb 2012;26(1):76-84.

Historical Review, Epidemiology and Natural History of Degenerative Mitral Valve Disease. Michele Borgarelli, James W. Figure 1Buchanan. J.Vet.Card. March 2012; 14:93-101.

Genome-wide Analysis of Mitral Valve Disease in Cavalier King Charles Spaniels. Anne T. French, Rob Ogden, Cathlene Eland, Gibran Hemani, Ricardo Pong-Wong, Brendan Corcoran, Kim M. Summers. Vet J; July 2012;193(1):283-286. 

Whole Genome Sequencing to Explore Genetic Risk Factors in Canine Myxomatous Mitral Valve Disease. Melanie Hezzell, Marsha Wallace, Jenny Wilshaw, Stephen Hare, Nicholas Timpson, Adrian Boswood, Lucy Davison. 2020 ACVIM Forum. June 2020. J.Vet.Intern. Med. Doi: 10.1111/jvim.15903. 

Management of Incidentally Detected Heart Murmurs in Dogs and Cats. Etienne Cote, DVM etal.  J.Vet.Card., March 2015; 17:245-26.

 

American Kennel Club Canine Health Foundation Educational Resources;  

See: https://www.akcchf.org/educational-resources/