2 CUTE HAVANESE GENETIC TESTING

​2 Cute Havanese has always wanted the best assurances available for a healthy puppy. Our goal is to have healthy puppies and parents, void of any avoidable troubles that can plague the Havanese and just dogs in general.

With this in mind it is important to remember that some problems do not present themselves until later in life.  Like  old dogs getting cataracts, it is not a genetic issue, but a fact of aging.
​
Other issues fall into gray zones and beg the question of whether or not the answer is genetics or Mother Nature, i.e. a fluke or a bad parental genetic combination. 

ORIGINALLY WRITTEN 04.02.2020

Common Conditions
Tests are continuing to be developed as time passes but the choice of which test presented is strongly driven by profitability - not necessarily desirability, commonality  or necessity, especially when it pertains to a specific breed issue. We are not automatically  notified when a new test becomes available but we check in as we order our normal tests. 

Specialized or Specific Test as Breed Recommended/OFA Tests:  

1. Eyes (General)
2. Ears (Deafness)
3. Hips (Dysplasia)
4. Patella’s (Luxation)
5. Heart (Arrhythmia) This test is optional but we do it for all our adult dogs.

    
From UC Davis – Note some of these tests became available as of Dec. 2017

1.   Genetic Testing
2.   Canine Diversity
3.   DNA
4.   Havanese Panel:  CDDY/CDPA/CMR1/vWDType 1

 
Testing  
We learned almost immediately that canine testing can be a mine field. For example, we first learned years ago that one of our dogs had a freckle on his eyeball!  We were distraught.  If a dog has any of what we called ‘flaws’ in our book, it automatically meant the questions about breeding suitability.  It was quite stressful as we were and are still very attached. 

So, there was a great gnashing of teeth, angst, and hand wrenching about the eyeball freckle.  Let us tell you right now that veterinarian speak is not necessarily clear. We whittled our brains away pouring over various articles in an attempt to find some sort of clarity until we found a specialized vet that could explain freckle’s existence. What we were told after many a long night with even longer conversations, was that it meant nothing genetically and did not hamper the function of the eye.  In other words that ridiculous freckle was just a dot on the eye and that the eye is ok.
 
What we learned to ask:

1. What is it?
2. Is it a fluke or hereditary?
3. Will it/how does it impact the dog’s quality of life?
4. What is the prognosis?
5. Options?

 
Chondrodysplasia
The most difficult test to date we have had to decipher is the CDDY/CDPA.  You would think results would be clear but it’s complicated. For UC Davis the CDPA test came on line about Dec. 2017. CDPA was earlier known as just CD for chondrodysplasia. As Havanese breeders this meant straight legs versus bowed or deformed in some manner. The early tests included wetting the dog to examine if the dog’s legs were straight. This is true today and straight legs is still something to be examined in a puppy and its parents for good health. Chondrodysplasia is defined as “abnormal cartilage and bone growth mostly resulting in shortened legs”. 

​The FGF4 or Fibroblast Growth Factor 4 retrogene was recently discovered in 2009 and is “involved many biological processes including bone development.” With Havanese it depends  on which chromosome this retrogene is found that can determine many things.  It can also cause a lot of confusion. Retrogene FGF4 insertion into chromosome 18 is termed FGF4-18. It explains CDPA resulting in short legs in about 40 dog breeds and in particular about 16 of them as “breed defining” (includes Havanese) and it is term ‘favorable’ in these breeds. The short leggedness is “caused by a different mutation other than the undesired dwarfism causing genetic disorder found in some breeds such as the Norwegian Elkhound” (J. Bouirmane). 
 
Chondrodystrophy
CDDY or Chondrodystrophy was discovered about 2017.  It has FGF4 inserted on dog  chromosome 12 and includes short leggedness but the difference between CDDY & CDPA,  besides chromosomes, is that CDDY may make “dogs susceptible to Hansen’s type I  intervertebral disc disease or (IVDD).” – UC Davis -VGL Breeding two dogs with CDDY together should be avoided, if present.
 
According to UC Davis, “breeders can benefit from test results to implement breeding strategies to reduce incidence of CDDY, while retaining the short-legged phenotype conferred by CDPA.”
 
What we learned for the road:
Suffice to say, since the ‘Freckle Lesson’ we have learned a lot.  We still do not have our DMV but we love our veterinarians, they are amazing.  We have learned about finding terrific veterinarians, ask better questions. How to research in order to educate ourselves on pertinent subjects we experience and dive in to do due diligence to understand new issues.   It has led to interesting discussions with our veterinarians, head scratching and learning curves with hours of study and some heart break along the way with good stuff, too.  It has also added a seasoning we needed when dealing with these tests.

A good example of this is within the past two years, there has been a shift in the canine medical community recognizing the damage done jumping off and onto furniture, etc., during a Havanese puppy’s first year.  Jumping can result in the same patella injuries previously credited to genetics. So today we caution new puppy owners to limit​  this activity or get stairs or both. 

References:
​Batcher, Kevin, et al. “Phenotypic Effects of FGF4 Retrogenes on Intervertebral Disc Disease in Dogs.” MDPI, Multidisciplinary Digital Publishing Institute, 7 June 2019, https://www.mdpi.com/2073-4425/10/6/435/htm. 

“Havanese Health Panel.” Havanese Health Panel | Veterinary Genetics Laboratory, https://vgl.ucdavis.edu/panel/havanese-health-panel. 
​
“Chondrodystrophy (CDDY and IVDD Risk) and Chondrodysplasia (CDPA).” Chondrodystrophy (CDDY and IVDD Risk) and Chondrodysplasia (CDPA) | Veterinary Genetics Laboratory, https://vgl.ucdavis.edu/test/cddy-cdpa.