Do cats and / or dogs have saliva that has antibacterial or antiseptic properties?
Are these any more effective at preventing infection than the saliva of humans or any other animal (is cat or dog saliva more special than any other animals saliva)?
The claim is that dog/cat saliva is an effective antibacterial / antiseptic agent:
Dog Saliva:
At least one study on sciencedirect.com suggests that canine saliva is "bactericidal against Escherichia coli and Streptococcus canis but only slightly".
An article on ABC's 20/20 reports that a dog's mouth is not cleaner than a human's mouth and the rapid healing of wounds observed in dogs is due to the constant licking removing dead tissue and stimulating circulation.
The US Center for Disease Control (CDC) lists a variety of infections that can be passed from dogs to humans, including: Campylobacter, Dipylidium, Giardia, Leptospira, Rabies, and Ringworm.
Finally, a project submitted to the 2010 California State Science Fair comparing the antibacterial properties of dog saliva with Neosporin concludes that:
Dog saliva may perhaps help slow the growth of bacteria for a little while, but it also may be adding its own bacteria when applied.
Cat Saliva:
FamilyDoctor.org explains that "Cat-scratch disease is an infection caused by a type of bacteria [...] called Bartonella henselae and can be passed from a cat to a human" through scratches, bites, or even by rubbing your eyes after petting a cat that has the bacteria on its fur.
A research paper available from The Journal of Antimicrobial Chemotherapy (jac.oxfordjournals.org) finds that...
P. multocida and other Pasteurella species are Gram-negative coccobacilli found in the oral cavity of many animals. Bites, scratches or licking of open wounds by cats or dogs may result in cellulitis within hours to a few days.
Finally, an article titled "Osteomyelitis Associated With Cat-Scratch Disease" from PediatricsConsultantLive.com concludes with this helpful tip:
In addition, caregivers should advise patients with open wounds to avoid contact with domestic animals.
Conclusion:
While dog saliva has been shown to be bactericidal against Escherichia coli and Streptococcus canis, it is only slightly so again two specific bacteria. No research was found supporting the hypothesis that cat saliva has any similar qualities. There is much more evidence that suggests that dog and cat saliva applied to an open wound can transmit more bacteria than it will kill. My advice: wash your hands thoroughly with soap after playing with your pets.
Cat bites are toxic and usually fatal to rabbits and other small animals due the potency of the bacteria in a cat’s saliva. Victims of cat bites must be treated with appropriate antibiotics as soon as possible. I think this speaks against antiseptic properties.
In 1922 Fleming discovered an antiseptic compound capable of killing and dissolving certain bacteria ( * ) which he called "lysozyme” ( * * )
Many animals have this protein: cat, human, dogs, it can even be found in the eggs ( * * * ). All mammals do.
This protein is widely distributed in the animal body, but is found in high concentration in saliva, blood, tears and duodenal (from the small intestine) secretions.
Epstein and Chain' of Oxford University (dunno the date) have confirmed the antiseptic effect of lysozyme by identifying the lysozyme-susceptible substrate in bacterial cells.
The antibacterial properties of saliva where studied later on dogs. It showed that the maternal grooming and in licking of wounds after birth helps prevent the infection of the wounds, but that not all types of bacteria are affected (Hart BL, Powell KL)
However the lysozyme can not dissolve the bacterial compounds completely if it is alone. The acidulation of the saliva after swallowing (in the stomach) improves the antiseptic effect of the lysozyme. Another enzyme, the Trypsin which is a protease (it cuts proteins) is capable of dissolving different parts of the bacterial cell. Complete lysis, however, is affected by a combined action of these two enzymes.
Saliva can prevent the infection but it can not cure anything: British bacteriologists have shown that its bactericide effect depends A LOT on the composition of the cell wall of the bacteria.
( * ) such as Escherichia coli, Staphylococcus aureus, Bacillus anthracis, and Candida albicans. The GRAM+ bacteria are the most affected due to the structure of their cell wall. Follow this link if you do not know what the GRAM test is: http://en.wikipedia.org/wiki/Gram_staining
( * * ) The “lys” part of the word comes from the ancient Greek: λύσις (lusis) which means “dissolve”. The other mart of the word “zyme” is the end of “enzyme”.
( * * * )As an example: A COMPARISON OF LYSOZYME PREPARATIONS FROM EGGWHITE,CAT AND HUMAN SALIVA. By E. A. H. ROBERTS,' B. G. MAEGRAITH,2 and H. W. FLOREY. From the Sir William Dunn School of Pathology, Oxford.
