HEALTH AND NUTRITION
HEALTH ISSUES
PRIMARY CILIARY DYSKINESIA (PCD)
The Cocker Spaniel Club of Victoria Inc is committed to improving the quality of the breed, including eliminating any hereditary diseases. We support a genetic study for the development of a DNA test for Primary Ciliary Dyskinesia in Cocker Spaniels.
WHAT IS PRIMARY CILIARY DYSKINESIA?
Dog Primary Ciliary Dyskinesia (PCD) is an autosomal recessive inherited disorder that causes defects in cilia in the upper and lower respiratory tract. In simple terms, in the airway there are tiny hairs (cilia) that are constantly moving mucus. In normal airways, the cilia move the mucus up the respiratory tract to the back of the throat where the mucus with any foreign bodies is then swallowed and sent down the oesophagus into the stomach. In PCD sufferers, those cilia don’t function properly, so there is a far greater risk of foreign bodies, such as bacteria or dust ending up in the lungs and pneumonia developing. PCD sufferers can also have situ inversus, which is the condition where internal organs such as the heart are reversed and are in mirror positions to where they would normally be.
Clinical signs in dogs are predominately respiratory in nature, most commonly including chronic nasal discharge and recurrent lower respiratory tract infections commencing in the neonatal period.
An affected pup with a constant flow of chronic discharge
Symptoms of PCD include:
- Chronic mucoid nasal discharge
- Sneezing
- Coughing
- Exercise intolerance
- Respiratory distress
- Cyanosis (blue/purple discolouration of the tongue and gums)
- Deafness and/or loss of balance due to fluid build-up in the middle ear
- Infertility due to altered sperm motility.
Eventually, without the ability to protect their respiratory tract these puppies will suffer from chronic respiratory infections, (including pneumonia) and require ongoing/frequent antibiotic treatment. Adult dogs may have long term sinus infections that don’t resolve even with appropriate antibiotic use.
CARE AND MANAGEMENT
Pups that survive experience:
- Daily, life-long nasal discharge and chronic, often wet/productive cough
- Increased risk of acute symptoms due to the development of secondary infections
- Ongoing/frequent antibiotic treatment.
The prognosis for affected pups is guarded to poor. Life-expectancy will be significantly reduced due to the gradual loss of lung function and the potential for resistant/refractory infections (eg life-threatening pneumonia).
Care and management involve:
- Daily chest physiotherapy – coupage
- Daily exercise (which helps to shift mucus)
- Daily nasal saline sprays or daily saline nebulisation which may also help to humidify the airways and mobilise mucus
- Minimum exposure to inhaled irritants/allergens (eg dust, smoke, pollens, perfumes, aerosol sprays, incense) as these particles may get trapped in the mucus and trigger an inflammatory reaction
- Mucolytic medications (designed to reduce mucus build up)
- Periodical thoracic radiographs (every 6-12mths) to monitor for bronchiectasis (dilated airway) and pneumonia
- Bacterial culture of nasal swab +/- bronchoalveolar lavage (BAL, lung wash) samples with any worsening of symptoms
GENETICS
Dog Primary Ciliary Dyskinesia (PCD) is inherited as an autosomal recessive disorder, meaning that the affected pup must receive two copies of the mutated (abnormal) gene, one from each parent, to develop the disease, just like PRA. A dog carrying one copy of the mutated gene is heterozygous and will not show the PCD symptoms. When mating two carriers (heterozygotes) at conception each pup has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Currently there is no cure for PCD and the only way to avoid breeding affected pups is to breed dogs which are not carriers of the mutation. Defective genes for autosomal recessive disease can be passed for many generations without affected individuals occurring until two carriers are bred to one another. The only way to find out if there is a chance of getting an affected puppy is to do genetic testing. CURRENTLY THERE IS NO DNA TEST FOR PCD IN COCKER SPANIELS.
INCIDENCE AND FACTS OF PCD IN COCKER SPANIELS IN AUSTRALIA
PCD has been identified in more than 19 breeds, including Cocker Spaniels. Cases of PCD in Cocker Spaniels have been officially recorded in Australia from 2013 in different States and over different generations.
Two cases of Cocker Spaniels with PCD were published in the Australian Veterinary Journal in an article written by E Bell in 2016. One of the dogs mentioned in that study is now 8 and undergoes an extensive management regime to maintain her health and wellbeing. The other pup diagnosed was euthanised due to the severity of the disease.
Other Cocker Spaniels have also been diagnosed since that report with 3 pups being diagnosed in 2022.
It is likely that PCD is more common in Cocker Spaniels than reported, because affected dogs may be misdiagnosed as having fadding puppy syndrome, aspiration pneumonia, or infectious causes of pneumonia or they may be euthanised at a a young age due to chronic respiratory infections without being diagnosed.
There are several other reported suspected cases of PCD in young Cocker Spaniels who presented with recurrent respiratory signs, however official diagnosis has not been carried out due to the expense and difficulty in diagnosis.
RESEARCH AND GENETIC TRIALING
Currently, there is no reasonable way to distinguish carriers from normal dogs because they look the same and do not have the disease. A DNA-based test would enable the identification of carriers so as not to breed a carrier to carrier and eliminate PCD from future breeding generations.
A genetic study into the development of a DNA test for PCD in Cocker Spaniels is being conducted by a project team through the University of Sydney and overseen by Professor Claire Wade BSc (Hons) PhD UNSW GCertEd UQ. Chair of Computational Biology and Animal Genetics Sub Dean International in consultation with Dr Lydia Hambrook BVSc (Hons), FANZCVS (Registered Specialist in Small Animal Medicine).
The purpose of this information is to raise awareness of the existence of PCD in the breed to our sister clubs, breeders and members and to invite those who may wish to do so, to participate in the trial.
There is a misunderstanding that there is already a DNA test for PCD specific to our breed. However this is NOT correct. A recent report provided by Professor Wade has found:
We have already checked the other variant test sites that are known to cause this condition in the dog. These include test sites in the genes NAT10, NME5, CCCDC39 and STK36. At all of the known test sites, the English Cocker Spaniels had the normal version of the gene as both copies. This means that these tests are NOT valid for Cocker Spaniels.
This means that other tests for PCD in other breeds that are available eg Old English Sheepdogs are not relevant and results will be inaccurate. There is currently NO DNA test for PCD for Cocker Spaniels, hence the genetic trial.
For further information on how to participate please see the contact details below:
Prof Claire Wade
School of Life and Environmental Sciences
University of Sydney
RMC Gunn B19-301
University of Sydney NSW 2006
Email: [email protected]
Dr Lydia Hambrook
Advanced Vetcare
26 Robertson St,
Kensington VIC 3031
(03) 9092 0400
Email: [email protected]
Attention to Lydia Hambrook
Participating in the trial is a simple as having a blood sample taken. All information pertaining to dogs, blood samples and pedigrees is totally CONFIDENTIAL and remains so with regard to any information that may be published in the findings of the trial.
With the development of a DNA test a simple swab sample will determine the status of dogs as being clear or carrier and hence enable breeders to eliminate this horrific disease from the breed as has been achieved with other known inherited diseases.
For further information about PCD you can also contact our PCD Liaison Officer
Meg Hardy
Email: [email protected]
Progressive Retinal Atrophy (PRA)
Familial Nephropathy (FN) or AHRN (Autosomal Hereditary Recessive Nephropathy)
Details about the disease
AON is an inherited neurological disorder characterised by a weakness in the hind limbs, eventually leading to weakness in the front limbs. Neurological signs of this condition seem to progress gradually over 3 to 4 years.
Clinical Signs
Clinical signs usually begin between 7 and a half to 9 years of age. These signs include weakening and unsteady hind limbs and uncoordinated movement. The weakness eventually progresses to include the front limbs. When all limbs are affected, there may also be difficulty in swallowing.
How is it inherited?
The disease is described as an autosomal recessive condition and is unique to Cocker Spaniels. This means that a dog must inherit two copies of an abnormal gene (one from its mother and one from its father) before its health is affected. A dog that inherits only one copy of the abnormal gene (from its mother or its father) will have no signs of the disease, but will be a carrier and may pass the gene on to any offspring.
Which laboratories test for this condition?
How to responsibly breed from your DNA tested dog
If, once your dog is DNA tested, you would like to find out what their DNA test results mean, or how to select the right mate to avoid producing affected puppies, then please read our breeding advice and information on the following link https://bit.ly/2oSbtnn.
Eye conditions such as cherry eye and entropion are also seen occasionally in cockers. Always check the pups for nice tight rims and clear eyes when assessing a litter.
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Please take your breeder's advice in regard to feeding your pup, and to avoid stomach upsets it is always best to continue the diet that the pup has been raised on prior to coming home with you. Any changes to the breeder's diet MUST be made gradually and carefully.
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