This week sees the second of 2, apparently conflicting publications, one saying that having domestic pets is good because it reduces the risks of allergy – the other warning that they pose an infection risk. The studies show how important it is to keep new research findings in perspective. Having pets in our home may be good because it helps us to become exposed to friendly microbes which regulate our immune system, but it’s equally important that that we practice good hygiene to ensure we are not exposed to harmful microbes they may also carry.
In the first study, of 1278 children in Sweden, it was found that, as the number of pets recorded as living with the child during its first year of life increased from zero 5 pets, subsequent development of allergic disease (asthma, allergic rhinoconjunctivitis, or eczema) in these children at age 7–9 years decreased. It is thought that exposure to microbes from the natural environment are important for regulating the immune system so that it does not overreact to allergens causing allergies, and that pets help to bring these organisms into the home.
In the second study, published today, researchers sampled 60 packs of raw meat products, intended for dogs, bought from retail stores. Raw meat-based diets have become popular for dogs in recent years, because it is seen as a ‘healthier’ and more ‘natural alternative’. Unlike commercial feeds, they are not heat treated or freeze dried to pasteurise their content. The products originated from Sweden, Norway, Finland, Germany or England.
Salmonella species were found in 4 (7%) of the 60 samples, while Campylobacter species were found in three samples. All 60 samples contained Enterobacteriaceae species, which are indicators of poor hygiene standards. Of the 60 samples 31 contained levels exceeding thresholds set by EU regulations of 5000 bacteria/g.
The authors conclude that pet owners who choose a raw food diet for their animals must be made aware of the risks and take full precautions while storing and handling the food. Bacteria in the juices from dog food can splash and spread to other foods and surfaces, and dogs can transfer potentially harmful bacteria by ‘kissing’ faces immediately after eating. Pets, fed with these foods can also shed these organisms in their faeces into their environment, so there is a risk to owners both in handling the food and coming into contact with the animal. Hand washing after handling animals and foods, before touching or eating food intended for family consumption is vital and it is important to keep and clean pet feeding utensils totally separate from family utensils.
The key to addressing this problem is targeted hygiene - targeting in our practices at the times (food hygiene, toilet hygiene, respiratory hygiene, caring for pets) and in the places (hands, hand contact usrfaces, food contact surfaces, cl;eaning cloths) that matter to protect against exposure to infectious microbes, whilst sustaining exspoure to our enviromental microbes
The research publications can be found at:
Hesselmar B, Hicke-Roberts A, Lundell AC,Adlerberth I, Rudin A, Saalman R, et al. (2018) Pet-keeping in early life reduces the risk of allergy in a dose-dependent fashion. PLoS ONE 13(12):e0208472. https://doi.org/10.1371/journal.pone.0208472
Josefin Hellgren, Lovisa Staaf Hästö, Camilla Wikström, Lise-Lotte Fernström, Ingrid Hansson. Occurrence of Salmonella, Campylobacter, Clostridium and Enterobacteriaceae in raw meat-based diets for dogs. Journal Vet Record 2019. doi 10.1136/vr.105199