Pets and Asthma what do we know, what should we know and what should we advise? Chris Doyle Nurse Consultant Asthma & Allergy Alder Hey Children's NHS FT Sept 2010 Cats and Dogs In UK approx. 16 million cats & dogs 10 Million children 7% children are sensitised to cats 4% children are sensitised to dogs Sadeghnejad et al Thorax 2004 Cats and Dogs 60% of asthmatics show IgE to cat &/or dog allergen 1/3rd of asthmatics live with a pet cat &/or dog Sensitisation to cats is a major risk factor for asthma Individuals an become sensitised even if they have never lived with pets Early sensitisation is associated with more severe disease Sensitisation to pets is a risk factor for hospital admission with asthma 90 80 70 % 60 hopsital 50 admission 40 stable asthma 30 20 Control 10 0 cat dog mite Any allergen Murray et al Thorax 2006 Cat Allergen - Fel d 1 – Fel d 1 responsible for 90% of cat specific IgE – Allergenic activity present in dander, pelt & urine – Produced in sebaceous and salivary glands – Cats can produce 3-7 mcgs day – Fel d 1 higher in male cats – Castration of male cats lead to a 3-5 fold reduction in Fel d 1 Cat Allergen - Fel d 1 – Small, lightweight sticky allergen <5um diameter – After disturbance remains airborne long – Easily respirable – Easily transferable – Pet allergens found in huge concentrations in houses with pets – levels of pet allergen found in homes with no pets, public transport, hospital OPD‟s Homes with pets have >100 fold higher allergen levels on surfaces than homes with no pets Cat Allergen in Homes With and Without Cats Fel d 1 (µ g/g) 10000 1000 100 10 1 0.06 Mattress Bedroom Living room Uphd. carpet carpet furniture Homes with cats Homes without cats Custovic, Thorax 1998;53:602-607 Cat Allergen in Public Places Fel d 1 (µ g/g) 100 10 1 0.1 Carpets Seats Carpets Seats Carpet Seats Mattress Carpets Seats Public Cinema Hotel School Public Houses Transport Custovic et al Clin Exp Allergy 1996; 26: 1246-52 Cat Allergy - Sphinx Cat ($1000) All cats have dander – there is no safe breed! Cute? Not so cute ! Effect of Washing the Cat on Airborne Cat Allergen ) 90 ); or mg/100ml H2O ( 60 50 40 and 30 20 Fel d 1 ng/m3 ( 10 0 De Blay et al, Wash # 1 Wash # 2 Wash # 3 Wash # 4 ARRD 1991; 143: (Day 0) (Day 7) (Day 14) (Day 21) 1334-1339 What about washing the cat? Wash pet and pet bedding weekly DBPC trial of environmental control in the treatment of cat allergy – HEPA room air cleaner – Mattress & pillow covers – Cat exclusion from the bedroom Outcomes – Some reduction in airborne Fel d 1 – No difference between groups in any of the clinical outcomes Wood RA et al, Am J Respir Crit Care Med 1998; 158: 115-20 Effect of Removing Cat Wood RA et al, Am J Respir Crit Care Med 1998; 158: 115-20 What about mans best friend? Dog Allergen (Canis Familiaris) Allergenic activity in dander, pelt hair and saliva (not in urine) Major allergen Can f 1, produced in salivary glands 89-90% of dog allergic subjects have IgE to Can f 1 Cute…. but hypoallergenic? Are all dogs equal? – Varying degrees of Can f 1 amongst all dogs (1) – No totally non-allergic dogs – Some do cause fewer allergies – Smaller dogs produce less saliva – Shed less fur/dander – Some breeds require freq bathing/grooming – Washing dogs does cause a reduction in allergen levels – back to starting levels within 3 days (De Groot et al JACI 1991) Avoiding cat & dog allergens Reduce Gives airborne clinical allergen benefit Pet in situ: Wash pet ? Remove carpets ? HEPA ? Castration ? Removal of pet So we have established that…. Pets are common Sensitisation to pets is a risk factor for asthma Pet allergen is ubiquitous, easily transferable and easily respirable ‘Paws’ for thought……. Allowing cats in bedroom in 1st yr. of life prevents development of childhood asthma (Orbele et al 2003) Early exposure to cats increases risk of developing asthma in adolescence and adult life (Wahn et al 1997) Dog owners are at reduced risk for allergic sensitisation (Simpson 2006) Pet keeping neither favors nor protects from allergic disease in childhood (Apelberg et al 2001) Frequently asked questions during Asthma & Allergy clinics Question 1 How can I stop my child becoming allergic to pets? Answer – Don‟t Know – Can become sensitised even if you don‟t live with pets – No evidence supporting hypoallergenic breeds Question 2 We have 2 cats and 1 dog. My 7 year old daughter is sensitised to both and my Dr. tells me she is on is on „Step 3 of the BTS guidelines‟. How can I improve her asthma control? Answer – Get rid of the pets – Allergen levels will fall faster if you get rid of the carpets Question 3 I love my 3 pet cats and my 2 schitzu dogs and would rather get rid of the children, what can I do? Pet Allergen Avoidance with Pet in situ Three studies have addressed pet allergen control measures in pet-sensitised pet owners. – Two showed small improvements in asthma related outcomes but one did not – Cochrane - no beneficial effect of pet allergen control measures for allergic asthma in children and adults Francis 2003,van der Heide 1999, Wood 1998, Kilburn 2003 Practical Advice If child sensitised - best remove offending pet ! Can take months or yrs to allergen levels Keep pets out of living areas & bedrooms, off beds! Remove carpets - replace with vinyl/wooden flooring Use a vacuum cleaner with a HEPA filter Fit allergen-impermeable bedding covers Wash pet and pet bedding weekly All pets have dander - no safe breed Question 4 – Can getting a dog prevent our children from developing allergies? – If so which type of Dog? Answer – Don‟t Know – Don‟t Know Case Study 1- Kathryn – 14 yrs Referred to Resp Clinic May ‟08 Diagnosed age 3 yrs. usually well controlled Increasing asthma symptoms past 12 months Daily cough, worse at night, worse with URTI‟s, frequently wheezy, now has exercise limitation and now missing lots of school 4 A&E visits in past 18 months 5 courses of prednisolone – always help No eczema Now has “hay fever all year” Case Study 1- Kathryn – 14 yrs DHx Becotide 200 BD & Salamol 50 BD Salbutamol – “using lots” FHx No Asthma/No Allergies 10yr old sibling with Type I Diabetes SHx No Smokers No Damp 18 mo. old dog. O/E Slight wheezy LFT FEV1 78% Nasal passages inflamed CXR Normal Changed to Seretide 50/25 2 puffs BD AMP & inhaler technique checked IgE Case Study 1- Kathryn – 14 yrs 4 month review IgE 350 >100 to Dog (neg to all else) Very symptomatic, no great improvement, still missing school GP had recently increased Seretide to 125/25 2 puffs BD Bi lateral wheeze FEV1 68% Mum refused to consider removal of dog but would no longer allow it upstairs 10 mgs Cetirizine daily Case Study 1- Kathryn – 16yrs 2 yrs. on 4-6 monthly review Still symptomatic Frequent exacerbations Added in Montelukast (Step 3 of BTS Guidelines) FEV1 at last visit 66% „Strained relationships within family‟ Dog still in home Kathryn waiting to leave home In Summary – Sensitisation to pets is a risk factor for asthma – Can become sensitised even if you have never lived with pets – Patients who are sensitised and exposed have more severe asthma – Pet sensitised, pet exposed asthmatics with symptoms should part with their pets! Many thanks to Dr Angela Simpson University of Manchester University Hospital of South Manchester NHS Foundation Trust “OK, where‟s that nurse that works in the allergy clinic”? Any Questions?
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