View Full Version : How cavalier research benefits other dogs and humans

18th July 2009, 11:19 AM
For those interested, this is the published abstract relating to the discovery of a gene for muscular dystrophy in cavaliers, referred to in a letter in a vet journal in the UK asking vets to help contribute to a better understanding on incidence.

As noted in the abstract, the gene has been identified in (only) three other breeds (all named) and in each breed, different genes are involved. This work is seen as important for understanding the affliction generally in dogs as well as humans. As with ongoing SM genome work, these are researchers hoping to benefit both dogs and human sufferers. By singling out a specific breed (the cavalier) for gene sequencing in this way, researchers believe humans may have a direct therapy benefit for a terrible, disabling disease that was not available from the results obtained from the other three breeds done. : -) I am certainly glad this work is being done on cavaliers -- as can be seen by the mix of US and UK researchers, as well as vet and human researchers (UC San Diego med school and the University College London Institute of Child Health -- I hope this reassures people that no one is targetting cavaliers to make them less appealing.

If people are concerned that too much research work is being done on cavalier health problems compared to other breeds, I encourage anyone to use one of the online scholarly publication databases and do some searches on various breeds. Cavaliers actually return quite a small number of studies, almost all done on 2 conditions, MVD and SM in the past 10-15 years (and in many of the MVD andother studies, cavaliers are simply part of a large sample). Other breeds can return many times as many published health-related papers. Fortunately for many of those breeds, the research work has resulted in direct therapies, genetic tests, and knowledge that has let breeders breed away from the problem. Hopefully cavaliers will benefit likewise from past and ongoing research funded by clubs, institutes and individuals. :-)

MUTATIONAL ANALYSIS OF DYSTROPHIN DEFICIENT MUSCULAR DYSTROPHY IN CAVALIER KING CHARLES SPANIELS. G. L. Walmsley1, V.Arechavala-Gomeza2, M. Fernandez-Fuente1,2, N. Nagel3, R. Stanley1, K. Chandler1, F. Muntoni2, G. D. Shelton4 and R.J. Piercy1,2 1. Department of Veterinary Clinical Sciences, Royal Veterinary College, London, UK; 2. Dubowitz Neuromuscular Centre, UCL Institute of Child Health London, UK; 3. Northdale Veterinary Practice, West Sussex, UK; 4.Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA.

Canine dystrophin-deficient muscular dystrophy, analogous to Duchenne muscular dystrophy of humans, is a severe inherited degenerative disorder of striated muscle. This debilitating and ultimately fatal condition results in a progressive destruction of skeletal and cardiac muscle due to mutations in the gene encoding dystrophin, a structural protein that links the contractile apparatus to the sarcolemma. The disorder is seen in several canine breeds but the genetic cause has only been reported in the Golden Retriever, German Short-haired Pointer and Rottweiler. Here we present the findings of clinical, histopathological and molecularcharacterisation of this condition in Cavalier King Charles Spaniels.A 10 month old male neutered client-owned Cavalier KingCharles Spaniel from the United Kingdom was presented witha chronic progressive history of lethargy, exercise intolerance and dysphagia. The dog was tetraparetic with poor skeletal muscle mass (body condition score = 2/9), reduced spinal reflexes, macroglossia and restricted jaw movement. Investigations documented a marked elevation in creatine kinase activity (33,695U/l; 61 394U/l) and electromyography revealed spontaneous activity indicative of a primary muscle disorder (complex repetitive discharges and pseudomyotonia). Dystrophin-deficient muscular dystrophy was diagnosed on the basis of skeletal muscle histopathology, immunohistochemistry and immunoblotting using monoclonal antibodies to the dystrophin rod and carboxy termini. Oligonucleotide primer pairs designed for RT-PCR to amplify overlapping regions of dystrophin cDNA identified, following sequencing, an exon deletion and a frame-shift not present in control cDNA, that is predicted to result in premature termination of the protein product. Sequencing the associated genomic DNA confirmed the causative (and novel) mutation. The ability of antisense oligonucleotide induced exon skipping to restore the reading frame was demonstrated in vitro in cultured myoblasts from the affected dog. Sequencing of amplified DNA from an additional Cavalier King Charles Spaniel with dystrophin-deficient muscular dystrophy from North America identified the same mutation. In conclusion, dystrophin deficient muscular dystrophy in the Cavalier King Charles Spaniel may provide an excellent model for Duchenne muscular dystrophy due to the potential application for trials of antisense oligonucleotide-mediated exon skipping one of the more promising research directions for genetic therapy in this fatal disorder.

18th July 2009, 11:52 AM
I just can't understand why this Article has caused Ruffled Feathers .
As Karlin has Posted,this Gene has been identified in 3 other Breeds ,that in each Breed though,different Genes are involved

That Cavaliers were being picked on,as some are suggesting,is surely being Blinkered.

If some Cavaliers have this Type of Musculor Dystrophy Gene ,and will help in in Future Research for Humans and Dogs, that surely is all to the good.


18th July 2009, 05:22 PM
Well I tend to think that DNA research helps both humans and dogs, this even if in some the hereditary disease might involve different genes or even if involving variations of the same genes. I don't see that Cavaliers are being picked on as dogs of quite a number of breeds are involved in various DNA Projects around the world. Like this as one example in the LUPA Project, and on the front page of their website the following is mentioned at this address.

Dogs are more than mans best friends; they can help us unravelling the genetic of diseases such as cancer, epilepsy, cardiovascular troubles or inflammatory disorders as diabetes or thyroid unbalance. Living in the same environment human and dogs are often suffering from the same complex diseases but the genetic complexity is lower in dogs. During 4 years (2008-2011) twenty veterinary schools from 12 countries spread across Europe will work together to collect 10,000 DNA samples from purebred dogs healthy or affected by similar diseases as human.

The analysis of the genome of affected dogs compared to healthy ones of the same breed will lead to the identification of genes implied in the mechanisms of these diseases. This project will first generate genetic markers for dog diseases and help to reduce the high level of inherited canine disease in purebred dogs. Then identification of the genes implied in disease development will allow to understand the mechanisms and pathways of the pathology. Human medicine will ultimately benefit from these results.That's why the LUPA project has been named after the female wolf that fed the twin founders of Rome to reflect the benefits human will obtain from dog genetics.

19th July 2009, 12:28 PM
I don't want to be pessimistic about this,Eddy, but will some Cavalier Breeders ,when the SM Gene/Genes are discovered ,find out if their Breeding Stock have the SM Gene.

Why I wonder about this is, I think I have mentioned it before ,that I was told on the Phone by a Cavalier Breeder ,that they and some other Cavalier Breeders ,would not be taking part in the Cavalier EBV Scheme.

The question has to be being asked, has there got to be Mandatory Health Testing for the SM and MVD Problems in Cavaliers.

That would help, if some Cavalier Breeders don't follow the UK CKCS CLUB Breeding Guidelines ,and are Breeding from Cavaliers under the age of 2,6 years.

For the Cavalier MVD Problem , The Cardiologist said at the recent CKCS CLUB AGM, that the Cavalier Heart Problem is no better than it was years ago.That the Cavalier Breeding Guidelines were being ignored by some if not many Cavalier Breeders, so is Mandatory Health Testing the answer ,to be giving our Cavalier Breed the chance of Healthier ,Longer Lives.


19th July 2009, 02:55 PM
Have the people you've spoken to Bet actually indicated why they weren't planning on making use of the EBV scheme?
Do you think it's because they feel that their years of experience of breeding should not be superceded by a computer?
At the end of the day,the veterinary profession can provide access to medical technology at a low cost and make it as convenient as possible for breeders, (and to be fair,the mumber of cavaliers being scanned is rapidly gathering pace as shown by the popularity of club organised scanning days.) but if breeders won't avail of it then it's disappointing .Also the heart testing is widely available at shows across the UK so more and more people are availing of this service so making testing mandatory may generate more ill will than it's worth in terms of gathering data and you still have to face the problem of having breeders interpreting how best to make use of the test results.
What it will take is not regulation,but hard irrefutable scientific evidence proving the severity of the problems with SM.It appears that different neurologists are seeing pretty much the same levels of syrinxs no matter which centre carries out the testing so the sooner this is conveyed officially and with statistical data to back it up,only then will the claims that the Syringomyelia situation is a scam and the incidence is low can be blown out of the water.
Is there any move to identify the approx 10% of cavaliers who do not have CM? Surely if as one prominent neurologist claims that the situation is almost irretrievable then it's vital that the these dogs are not lost to the genepool for future generations.

19th July 2009, 08:02 PM
No the person that I spoke with gave no reason for saying why they would'nt be using the EBV Scheme.

I do think the UK Cavalier Club seems to be split at the moment.

As I have mentioned also before ,when the feuding was going on about the MVD Cavalier Problem around 20 years ago,the bitter feelings that have now surfaced is not like what it was at the time. Every body was at least polite to each other ,now there is a vindictiveness, and viciousness around.

Some Cavalier Breeders seem to think that the SM and MVD trouble in Cavaliers should not be being mentioned. Just take what happened this past week about the mention of a Type of Muscular Dystrophy Gene that some Cavaliers have ,and the Researchers have said that this Gene could maybe help Humans suffering from this condition.

I have been given much abuse for daring to mention that prospective Cavalier Puppy Buyers should ask to see a Certificate from the Cavalier Breeder showing that their Cavalier Breeding Stock is Health Tested.

I was told I needed to get Professional help ,because I had asked this question!!!

So at the moment my regard for some Cavalier Breeders is zero.

19th July 2009, 08:04 PM
Just noticed I had'nt given my name to my Previous Post.

Bet (Hargreaves)

19th July 2009, 09:33 PM
In Australia where I am I did see our Kennel Club trying to start in January 2008 mandatory DNA testing system for breeds where DNA testing was available. Soon as breeders heard of this so many complained that the mandatory requirement was dropped and the word voluntary replaced the word mandatory. But then some Breed Clubs did introduce mandatory testing as a requirement for registration, this even for Elbow and Hip Dysplasia where DNA testing is not available but xray testing with scoreing was available plus they also did this in regards to eye health testing.

Time passed then our Government decided to step in and pass Animal Welfare Legislation under the Prevention of Cruelty to Animals Act, this for some hereditary diseases where DNA testing has been available. In the initial stages of this some breeders did not think this was possible and would not happen, but later on when they heard it being introduced in Parliament as Legislation they then very actively fought it but with no success. Keep in mind its Government Acts and LAW and it can apply to ANYONE WHO BREEDS DOGS including commercial puppy farmers and even backyard breeders, also as the Act already exists it would be easy for the Government to later amend and add in more DNA testings after they have been made available to anyone to use. Interestingly Im tending to see some initial activity in the UK which just might later progress to something similar over your way.

Anyway back to my part of the world. Say if a pet owner goes to their veterinarian with a dog that is affected by disease and has been confirmed by DNA testing to be one of the Tabled Heritable Defects under the Act, then that pet owner can complain to the authorities that administer the Act where the breeder could be investigated and may be summoned to appear in court and if found guilty then it is a criminal offence.

After the Legislation was passed the Government Minister for Animal Welfare assembled a working group of specialists where they devised breeding guidelines which they called "Code of Practice for the Responsible Breeding of Animals with Heritable Defects that cause Disease". When the draft of this had been done they passed it to our Kennel Club and they in turn passed it to Breed Clubs, so that they had opportunity to comment and suggest amendments to that draft. That draft is now finished and I think later this year we may see the printed version in the waiting rooms of veterinary practices this after the Government printer has printed them, and if you want to see a copy of this online as a PDF document then click on this link address.
http://www.dpi.vic.gov.au/dpi/nrenfa.nsf/LinkView/D6995A0C78FF4AD3CA2575D8002239F918CDE14E012AB3A0CA 2573FA000E0AC8/$file/Code%20of%20Practice%20for%20the%20Responsible%20B reeding%20of%20Animals%20with%20Heritable%20Defect s%20that%20cause%20Disease.pdf

Regarding the above our Kennel Club then notified their members and Breed Clubs and has arranged Seminars, and below is a recent notification and which is even online at this address.

Dogs Victoria
S E M I N A R - Attention All Clubs/Breeders Code of Practice

The Code of Practice for the Responsible Breeding of Animals with Heritable Defects that cause Disease was gazetted on 18 June 2009 and is now in effect. This code was made under Section 7 of the Prevention of Cruelty to Animals Act. Copies of the code are available from the DOGS Victoria office, or can be downloaded from

The code specifically lists five diseases/defects, and sets standards for breeding practices to eradicate or manage these diseases.
They are:
* Von Willebrands disease (vWD)
* Progressive Retinal Atrophy (PRA)
* Neuronal Ceroid Lipofuscinosis (NCL)
* Hereditary Cataract (HC)
* Collie Eye Anomaly (CEA)

We are fortunate to have a representative from the Bureau of Animal Welfare (DPI) attending the seminars to explain the COP and how we can best work with it.

Followed by
Breeding Programs - Where do we begin?

A Power Point presentation giving some examples and suggestions of ways to formulate appropriate breeding programs for individual breeders and breed clubs, especially with reference to the Code of Practice Diseases.

If your breed suffers from any of the above diseases, you need to attend one of these seminars. You are welcome to send any questions you may have in relation to the COP together with your RSVP.

* Thursday 12 November 2009 - KCC Park
* Thursday 19 November 2009- Bulla Exhibition Centre
Time: 7.30pm - 9.30pm
Cost: Free to members

RSVP your attendance to Heather at DOGS Victoria on:
9788 2501 or office@dogsvictoria.org.au including the names and DOGS Victoria membership numbers of each person attending.

Presentations by PLAC (Protection Legislation Advisory Committee) and CHC (Canine Health Committee)

20th July 2009, 07:19 PM
Thanks for the information on the Australian approach to some of these issues! Some very interesting reading there. :thmbsup: I know some of this is being considered by some of the welfare advisory groups to government in the UK.

22nd July 2009, 06:23 PM
I just came across this recent research that maybe of benefit to dogs and humans, and the following from this address.

Submitted December 30, 2008; Revised April 15, 2009; Accepted April 15, 2009

Calcium Reuptake Related Genes as a Cardiac Biomarker in Dogs with Chronic Mitral Valvular Insufficiency
J.-S. Lee 1 , S.-I. Pak 2 , and C. Hyun 1

1 Section of Small Animal Internal Medicine, School of Veterinary Medicine and Institute of Veterinary Medicine, Kangwon National University, Chuncheon 201-100, South Korea; and 2 Section of Veterinary Clinical Pathology and Epidemiology, School of Veterinary Medicine and Institute of Veterinary Medicine, Kangwon National University, Chuncheon 201-100, South Korea.
Corresponding author: Professor Changbaig Hyun, Section of Small Animal Internal Medicine, School of Veterinary Medicine and Institute of Veterinary Medicine, Kangwon National University, Chuncheon 201-100, South Korea; e-mail: hyun5188@kangwon.ac.kr

Background: Gene expression linked to sarcoplasmic reticulum calcium reuptake (SRCR) is altered in humans and animals with heart failure.

Hypothesis: The expression of SRCR genes in peripheral blood cells have the potential to be cardiac biomarkers of heart failure in dogs with chronic mitral valvular insufficiency (CMVI).

Animals: Client-owned 15 healthy control dogs and 23 small breed dogs with CMVI classified by severity, based on the classification system determined by the international small animal cardiac heart council.

Methods: Prospective, controlled, observational study. The expression levels of SRCR genes (SERCA2α, PLN, and HAX-1) were evaluated in peripheral blood of dogs at different stages of CMVI via real-time reverse transcription polymerase chain reaction.

Results: The mRNA expression levels of PLN and HAX-1, but not SERCA2α were significantly (P= .08), reduced in dogs with moderate to severe CMVI. The fold change in PLN expression compared with control were 0.38 0.07 (in group II) and 0.20 0.10 (in group III), while HAX-1 expression were 0.37 0.06 (group II) and 0.41 0.12 (group III). The expressions of PLN and HAX-1 were significantly reduced in groups II and III (P < .05) but not in group I (P > .05). The reduced PLN and HAX-1 expressions were highly correlated with the severity of heart failure (P < .001), vertebral heart score (P < .05), and left atrium to aortic root ratio (P < .05).

Conclusions and Clinical Importance: PLN and HAX-1 can be potential biomarkers for heart failure caused by CMVI.

23rd July 2009, 09:14 AM
Eddy ,

Thanks for Post, but I'm a wee bit lost, will this Research help in finding the MVD Gene.


23rd July 2009, 02:37 PM
Thanks for Post, but I'm a wee bit lost, will this Research help in finding the MVD Gene.

The Research Abstract mentioned expression of the SRCR GENES (SERCA2α, PLN, and HAX-1) and this in relation to Mitral Valvular Insufficiency. Bet one could call Mitral Valve Disease (MVD) by some other names which could include Chronic Mitral Valvular Insufficiency Disease. Also note the word GENES in the Abstract.

Any research information about the heart and the diseases associated with it might be of help in finding the genes for heart diseases including Mitral Valve Disease.

By the way, the Abstract mentions "23 small breed dogs with CMVI classified by severity" and I wonder if they were Cavaliers.

24th July 2009, 03:35 PM
Think this is quite exciting

<H2>Cardiac Research at Colorado State University Shows Diseased Heart Valves in Dogs Produce Serotonin

FORT COLLINS - A significant part of the question of what causes mitral valve disease in dogs, giving scientists and medical experts clues into new possible ways to treat or prevent the disease, may have been solved by a Colorado State University veterinarian. The discovery refutes the current believe that mitral valve disease, the top heart disease in dogs, is inevitable as a part of aging in pets.
Dr. Chris Orton, a cardiac surgeon at Colorado State's Veterinary Teaching Hospital, has been investigating the role of serotonin in heart valve disease in dogs. It has been known for some time that drugs that enhance serotonin production in humans -- such as appetite suppressants, migraine medications and antidepressants -- cause drug-induced heart valve disease. It turns out that naturally occurring heart valve disease, known as degenerative myxomatous heart valve disease, is virtually identical in dogs and humans. Dr. Orton's group has discovered that cells in diseased heart valves of both dogs and humans produce serotonin locally, and this may be driving the disease process.
"Serotonin is made in the brain and in cells in the gut. We previously thought that those were the only places it was made before it is circulated in the blood," Orton said. "But we found the local creation of serotonin in diseased heart valves. We think that drug-induced and naturally occurring heart valve disease share the same mechanism for creating the disease - the production of serotonin. The valve is making serotonin, which causes its own disease. Serotonin is directly linked to pathologic changes in the valve, which cause the malfunction of the mitral valve."
Orton's group is working to discover what triggers the enzyme in the valve that makes serotonin, and he would like to launch a clinical trial on dogs to look at the impact of a drug that inhibits the enzyme that produces serotonin in the heart.
Mitral valve disease impacts the mitral valve, one of two valves on the left side of the heart. In degenerative valve disease, the valve becomes deformed and begins to leak. Serotonin is made in the gut by an enzyme called TPH1, Serotonin then goes into the blood stream where it is picked up by platelets which are involved in blood clotting. Orton's group has shown that TPH1 is present in high levels in abnormal mitral valves from both dogs and humans.
"Like all diseases, mitral valve disease is mediated by cells," Orton said. "If we can understand the mechanism in cells that triggers the disease, we can slow, treat or prevent the disease process in new ways."
Mitral valve disease, also often called mitral valve prolapse in humans, tends to impact smaller breed dogs and usually develops when they are middle aged or older. Chihuahua, King Charles spaniels, and other toy and small breeds of dog tend to develop the disease more often than other breeds. Of the dogs that develop heart disease, 40 percent develop mitral valve disease, and the disease is the eventual cause of about 70 percent of all heart failure in dogs.
Orton heads up Project CARE at Colorado State. The project focuses on researching the causes of and development of new treatments for mitral valve disease in dogs. The project is supported through grass roots funding. To learn more about the program or to support the research, visit http://csuvets.colostate.edu/heartcenter/research/mvd/index.shtml.

http://www.news.colostate.edu/Release/4712 (http://www.news.colostate.edu/Release/4712)

24th July 2009, 03:59 PM
That is quite exciting.

Cavaliers have heart valve disease that is hereditary which has been passed on to them by genes from their parents, and the genes cause the diseased heart valves which then produce Serotonin and this in turn drives or contributes to the diseased heart valves becoming worse.

However this research may lead to specific drugs being developed to limit the production of Serotonin within the diseased heart valves. This could be of great value in relation to treatment of MVD and where such specific drugs would have to be taken for the rest of their lives and that I think could be quite expensive over many years. BUT note that specific drugs will NOT address the actual cause which is faulty genes producing diseased heart valves which are being passed on through the generations and still will be.

I think we really should focus on finding the genes so that we can breed dogs that do not have heart valve disease that is hereditary, then we will have dogs that do NOT produce Serotonin at the heart valves that these researchers are talking about.

24th July 2009, 04:28 PM
There may be more than one cause to MVD but even finding one possible is achievement. From there one searches for the gene causing the serotonin to flow and if there is excess in certain breeds looking at their genes. If no excess, than studying sensitivity predisposition of those breeds to serotonin and the genes causing the predisposition. Piling on meds is only a bandaid and a poor one at that. Cures are found in eradicating the cause and with all the brilliant scientists working at this there will be an answer. Until the answer, and after the answer, careful breeding will still be paramount.

24th July 2009, 06:30 PM
The more you read of this new Research Report ,the more there is food for thought.

Take the mention of Platelets,it is a fact that some Cavaliers have large Platelets, and they have to be counted manually.

A team of Researchers at Auburn University mentioned that they could have found a Possible Link between Oversized Platelets and MVD in Cavaliers.

Other Researchers also mention Serum Serotonin Concentration is elevated in CKCS,this was carried out at the University of Pennsylvania.

The team said that initial Research was showing that CKCS have higher levels of Serotonin than other Breeds which are Predisposed to to MVD ,that because of the results ,it is suggested that 5-HT ,may play a role in the development of Dengerative MVD in small Breeds and in particular CKCS ,that further studies involving the relationship between 5-HT ,DMVD,Breed and Platelet Number ,morphology ,and function are warrented.

Dr Orton 's Group said that they think that drug -induced and naturally occurring Heart Valve Disease share the same mechanism for creating the Disease, the Production of Serotonion

More mention of Platelets,in DMVD,the Heart Valve becomes deformed and begins to leak

Serotonion,is made in the Gut by an Enzyme called TPHI,Serotonion then goes into the Blood Stream where it is picked up by Platelets

Whether some Cavaliers with Larger Platelets have a part to play in this ,I don't know.

Has any-body else any thoughts about this. ?


24th July 2009, 07:28 PM
BUT note that specific drugs will NOT address the actual cause which is faulty genes producing diseased heart valves which are being passed on through the generations and still will be.

I think we really should focus on finding the genes so that we can breed dogs that do not have heart valve disease that is hereditary, then we will have dogs that do NOT produce Serotonin at the heart valves that these researchers are talking about.

Well precisely. That is why I laughed when one breeder posted this article across several lists, implying this discovery was somehow a vindication of how breeders breed (which at this time, for most, whether club or BYB or puppymill, seems to include either ignoring the MVD protocol entirely or only using the bits that seem useful and always owning several dogs that need to be the exceptions to the rule). I must say her posts only confirmed how some breeder's thought processes are so self-serving that they can invent and believe the most twisted logic.

However, the positive side is that this was such a perfect example of why individual breeders cannot be trusted to self-regulate that it, along with so many other discussions and individual posts and email exchanges, has been submitted to the formal groups considering whether legislation is needed to oversee dog breeding practice. :thmbsup:

Public lists and boards are extremely helpful in producing this type of commentary directly from certain breeders themselves, which often stands in stark contrast to the formal submissions the breeders, breed clubs and national kennel clubs make to such bodies. The internet is so very useful! :)

25th July 2009, 09:35 AM
I am sorry if I gave the impression that the answer to the MVD Problem in our Breed is the Research findings about Serotonin,

Unfortunately I was one of those Kids, whose two words were

BUT WHY !!!! Drove my Mum Mad !

I never thought for a minute thought that some Cavalier Breeders would use the information as an excuse for not Health Checking their Cavaliers for MVD .

Just thought that if Serotonion had a part to play in the MVD Problem then the Cavaliers could maybe benefit,I think that those Cavaliers being involved with the effects of Sertonion must some-how be Genetically Susceptible to how Sertonion is there.

I have got so much stick from a good number of Cavalier Breeders for saying for years , don't Breed from a Cavalier who has a Heart Problem .

I have written to the 2 Committees with my views about this ,that will Mandatory Health Testing be the answer to the serious Health Problems SM and MVD afflicting the Cavalier Breed to-day. Got word back ,my views had been noted.

Is Serotonion another part of the Jig Saw in the fight against MVD in Cavaliers,who knows but it may even be involved in Genetically Susceptible Cavaliers with Vaccinations. ?

It's a fact that Platelets drop because of the Parvo Part in the Combined Vaccine, Platelets have been mentioned in the Serotonion Research, and some Cavaliers are known to have Large Platelets, all this are just my thoughts, BUT NO EXCUSE for Cavalier Breeders not be Health Testing for MVD in their Breeding Stock.