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As stated in the article Studying Genetic Causes of Disease in Purebred Dogs and Cats, "Purebreds are potentially at higher risk for diseases of genetic origin because individuals of the same breed are alike -not only in their external features and characteristics-, but also internally. The genetic makeup of animals affects temperament, internal anatomy and even response to infectious agents and toxins. As the animals of a particular breed become more similar, so will the genes that determine their susceptibility to disease." In general terms, the Havanese is a long lived (13-15 years) healthy breed. In fact, comparing it with other purebred dogs, the Havanese breed comes out pretty good. Nevertheless, as every other breed, they are prone to suffer from some genetic hereditary disorders. Moreover, we have to bear in mind the fact that this is a breed that was almost lost, and its process of recovery began with a very limited gene pool, in the USA and in Cuba alike. Therefore, it is extremely important that Havanese breeders make the best possible choices, and are aware of the consequences their actions will have upon the breed's future. Unfortunately, no breed of dog is totally free from inheritable genetic defects, but few breeds have the good fortune of having so many dedicated individuals and organizations caring for their well-being. Without a doubt, one of the reasons that attracted us to this amazing breed, and that made us consider the possibility of entering this vast and new universe of dog breeding, was the absolute dedication that we found in most Havanese breeders. But, how could you not want the best for them when they give us so much? Probably the most important step one can take is to be informed. It is imperative that as a responsible breeder one keeps abreast of all the new research that it's been done. It's also extremely important to support, in any way one can, all the initiatives being taken to solve the breed's health problems. One of the best ways to do so, is to test you Havanese, and to share your finding. Only then we will be part of the solution. We´ll go into some detail regarding the hereditary or juvenile cataracts, and the luxating patella. There are excellent sites that have more explanations on the other disorders that may affect a Havanese. You'll find links to their pages at the end of this section. You may also find some other good ones in the LINKS section. Please go to their sites to learn even more about these conditions, as well as of the other ones that may affect this breed.
The hereditary -sometimes called "juvenile" cataracts- are the most serious problem affecting the Havanese at the present time. This type of disorder affects some 125 breeds of dogs, so we are not alone. A cataract is the opacity of the lens of the eye and it is the most common cause of blindness in dogs. The lens is the spherical body behind the pupil that focuses light rays. It is situated toward the front of the eye behind the cornea and iris. It normally is highly transparent. The lens can become totally or partially opaque due to the cataract. The cataract blocks the light rays, thereby impairing vision. This cataracts are different from the non-hereditary cataracts affecting aged or senior dogs in that they may develop in dogs as young as 10-12 months of age. The research carried out by Dr. Kirk Gellat, VMD, of the University of Florida, indicates that juvenile cataracts may be carried by a recessive gene. In this is so, for one dog to inherit the disorder, both parents must be carriers of the gene. Unfortunately, at the moment, there is no DNA test available to find the carries of this gene. However, genetic research is being done to develop what one day will be a simple DNA test that will help us identify precisely the dogs and bitches that carry the recessive gene for cataracts. It is very important to test your Havanese annually. If the problem is diagnosed early, the chance of an effective treatment is a lot higher. In the US this tests are performed by Veterinary Ophthalmologists certified by the Canine Eye Research Foundation (CERF) and the pertinent CERF certificates are issued. Aware of this problem, a group of breeders formed the Havanese Eye Angel Research Team (HEART) that, up to recently, was working with Dr.Gellat to find and isolate the gene causing the problem. Also, in the last year, a possible connection between Chondrodysplasia or dwarfism (commonly called CD, and a characteristic of breeds like the Basset Hound and the Dachshund) and hereditary cataracts is being studied. CD is a range of disorders characterized by abnormal growth of cartilage and bone, typically resulting in skeletal dwarfism, with the limbs of an animal being disproportionately short and/or bowed.
As stated in the website of the Orthopedic Foundation for Animals (OFA), "The patella, or kneecap is located in the stifle joint in the 2 hind legs of dogs. In patellar luxation, the kneecap luxates, or pops out of place." Luxated patellas or "slipped stifles" are a common orthopedic problem in small dogs. A study of 542 affected individuals revealed that dogs classified as small (adult weight 9 kg (20 lbs) or less) were twelve times as likely to be affected as medium, large or giant breed dogs. In addition, females were 1.5 times as likely to be affected. Some researchers have suggested a recessive method of inheritance, and the higher incidence in females could possibly be related to X-linked factors or hormonal influences. Luxated patellas are a congenital (present at birth) condition. The actual luxation may not be present at birth, but the structural changes which lead to luxation are present. Most researchers believe luxated patellas to be heritable (inherited) as well, though the exact mode of inheritance is not known. The mission of OFA is to "identify those dogs that are phenotypically normal prior to use in a breeding program and to gather data on the genetic disease of patellar luxation." According to OFA, "the most opportune time to gather this data is at 6-8 weeks of age prior to the puppy's release to the new owner." Signs of luxation may appear as early as weaning or may go undetected until later in life. Signs include intermittent rear leg lameness, often shifting from one leg to the other, and an inability to fully extend the stifle. The leg may carried for variable periods of time. Early in the course of the disease, or in mildly affected animals, a hopping or skipping action occurs. This is due to the patella luxating while the dog is moving and by giving an extra hop or skip the dog extends its stifle and is often able to replace the patella until the next luxation, when the cycle repeats.
Patellar Luxation Grades According to OFA, a method of classifying the degree of luxation and bony deformity is useful for diagnosis, and can be applied to either medial or lateral luxations by reversing the medial-lateral directional references. The position of the patella can easily be palpated starting at the tibial tubercle and working proximal along the patellar ligament to the patella. Grade 1 The patella easily luxates manually at full extension of the stifle joint, but returns to the trochlea when released. No crepitation is apparent. The medial, or very occasionally, lateral deviation of the tibial crest (with lateral luxation of the patella) is only minimal, and there is very slight rotation of the tibia. Flexion and extension of the stifle is in a straight line with no abduction of the hock. Grade 2 There is frequent patellar luxation, which, in some cases, becomes more or less permanent. The limb is sometimes carried, although weight bearing routinely occurs with the stifle remaining slightly flexed. Especially under anesthesia it is often possible to reduce the luxation by manually turning the tibia laterally, but the patella reluxates with ease when manual tension of the joint is released. As much as 30 degrees of medial tibial torsion and a slight medial deviation of the tibial crest may exist. When the patella is resting medially the hock is slightly abducted. It the condition is bilateral, more weight is thrown onto the forelimbs. Many dogs falling in this grade live with the condition reasonably well for many years, but the constant luxation of the patella over the medial lip of the trochlea causes erosion of the articulating surface of the patella and also the proximal area of the medial lip. This results in crepitation becoming apparent when the patella is luxated manually. Grade 3 The patella is permanently luxated with torsion of the tibia and deviation of the tibial crest of between 30 degrees and 50 degrees from the cranial/caudal plane. Although the luxation is not intermittent, many animals use the limb with the stifle held in a semi flexed position. Flexion and extension of the joint causes abduction and adduction of the hock. The trochlea is very shallow or even flattened. Grade 4 The tibia is medially twisted and the tibial crest may show further deviation medially with the result that it lies 50 degrees to 90 degrees from the cranial/caudal plane. The patella is permanently luxated. The patella lies just above the medial condyle and a space can be palpated between the patellar ligament and the distal end of the femur. The trochlea is absent or even convex. The limb is carried, or the animal moves in a crouched position, with the limb partly flexed.
Diagnosis "Diagnosis is relatively simple for a veterinarian familiar with orthopedics. It involves palpation of the joint and manual luxation of the patella. X-rays may also be used to determine the degree of rotation. Motivated owners may be trained by veterinarians to palpate the stifles, but care must be exercised in order to avoid injuring the joint, or making an incorrect diagnosis. Diagnosis in severe cases may be possible at weaning, but in most cases the joints should be tight enough at 4 to 6 months to allow reliable palpation. Screening of puppies at this age will help prevent large expenditures training and showing dogs which later prove unsound. Screening of breeding stock and culling of affected individuals should, over time, reduce the incidence of the condition. Treatment involves surgical correction of the deformities. Many techniques are available depending on the severity of the condition. Satisfactory results are usually obtained if the joint degeneration has not progressed too far. Once the condition is repaired, most affected individuals make satisfactory pets." (From an article in written by Dr.Teri Dickinson, DVM, http://www.italiangreyhound.org/patella.html)
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Hereditary
Cataracts
