PRIMARY CILIARY DYSKINESIA
Welcome to Ellie's Page
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A responsible breeder is not one that never produces a problem, but one that deals with a problem when it does occur.
In December 2021, I unknowingly bred a litter that produced 3 puppies with a disease that I had never ever heard of and that there is NO DNA test for. That disease I have since found out is Primary Ciliary Dyskinesia (PCD). PCD has been identified in more than 19 breeds, including Cocker Spaniels. Cocker Spaniels affected with PCD have been diagnosed in Australia since 2013.
The purpose of Ellie's Page is to raise awareness of this disease in our breed. A research team is currently conducting a genetic trial to develop a DNA test for PCD so that like other herediatry diseases, we can eliminate PCD in our breed.
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.
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Even in their first few weeks of life, Ellie and her two litter sisters displayed respiratory symptoms that required antibiotics.
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
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Ellie requires daily saline or antibiotic nebulisation
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 two carriers (heterozygotes) are mated, 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 available for PCD in Cocker Spaniels.
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 trial is supported by the Cocker Spaniel Club of Victoria Inc and the Canine Research Foundation.
I wish to firstly thank, the owner's of the two other puppies that I bred with PCD for their understanding and for the love, management and care that they give to Luna and Crumpet.
I also wish to personally thank some very special friends who have supported and helped me raise awareness of this disease in our breed.
Through ongoing specialist care and managment Ellie and her sisters are currently doing well.
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