Cat Saliva Vs. Human Saliva

Introduction

Cat and human saliva have some similarities but also many differences. This article provides an overview of the composition, pH levels, bacteria, allergies, diseases, healing properties, toxicity, and uses of cat saliva compared to human saliva. We will examine the key distinctions between the two and discuss why cat saliva can pose health risks for humans.

Composition

The composition of cat saliva is notably different from human saliva. Cat saliva contains about 65-78% water, while human saliva contains over 99% water (Harrison, 1974). In terms of minerals, cat saliva has higher concentrations of sodium, potassium, chloride, and iodine compared to humans. It also contains trace amounts of magnesium, copper, iron, manganese, and fluoride (Schenkels et al., 1995).

There are some key enzymes found in cat saliva that are not present in human saliva. Cats have amylase to help digest starches, but at a much lower concentration than in humans. However, cats have higher lysozyme levels to fight bacteria. They also produce lactoperoxidase, an enzyme not found in human saliva (Schenkels et al., 1995).

pH Level

The pH level of saliva refers to its acidity or alkalinity. Saliva has an optimal pH range of 6.2-7.6, with the average pH around neutral at 7 (Baliga, 2013). Human saliva tends to fall within this normal pH range.

Cat saliva has been found to be more alkaline than human saliva, with an average pH around 8-9 (Testing and Comparing the pH Levels of Canine, Feline, and Human Saliva, 2018). The higher pH means cat saliva is less acidic than human saliva.

One study measured canine saliva to have an average pH of 8.5, also making it more alkaline than human saliva (pH Levels of Saliva, 2002). Dogs tend to have more basic saliva compared to humans.

The pH level impacts the bacteria and overall environment in the mouth. More acidic saliva can erode tooth enamel, while more alkaline saliva provides better protection. The pH also affects enzymatic activities and microbial growth (Baliga, 2013).

Bacteria

Cats and dogs have many types of bacteria in their saliva that are harmless to them but can cause illness in humans. One of the most concerning is Capnocytophaga, which is found more prevalently in dog saliva but can also be present in cats.

According to the CDC, Capnocytophaga bacteria are common commensal organisms (normal flora) in the mouths of dogs and cats. These gram-negative bacteria live on the mucosal surface of animals but do not seem to cause disease in pets. However, in rare cases Capnocytophaga can be transmitted to humans through scratches, bites, or other close contact with dogs and cats. This can lead to systemic infection, especially in immunocompromised people.

Other bacteria that may be present in cat and dog saliva include Pasteurella, Streptococcus, Staphylococcus, and Neisseria species. These opportunistic pathogens can cause infections if introduced into the human body through a bite or scratch wound. Proper cleaning of wounds is important to prevent transmission.

Allergies

Cats produce a protein called Fel d 1 that is present in their skin, urine, and especially saliva. Fel d 1 is the primary allergen responsible for allergic reactions to cats in humans. Studies show that over 90% of people with cat allergies react to Fel d 1 [1]. When a cat grooms itself, the Fel d 1 particles from saliva are spread across its fur. These particles can then be transferred to fabrics, furniture, and even the air when the cat sheds its fur. For sensitized individuals, inhaling airborne Fel d 1 or having it come into contact with the skin can trigger an allergic response.

Common symptoms of cat allergies include sneezing, runny nose, watery eyes, wheezing, coughing, and skin rashes. In severe cases, exposure can trigger a potentially life-threatening anaphylactic reaction. Allergy tests like skin prick testing and blood tests can confirm Fel d 1 sensitization. Treatment focuses on avoiding exposure to cat allergens through various means like keeping cats out of bedrooms, using high-efficiency particulate air (HEPA) filters, washing hands after contact, and medications like antihistamines. Immunotherapy may help desensitize some individuals to cat allergens over time.

Diseases

Cat and human saliva can both transmit diseases between cats and humans, especially through bites and scratches. Some of the main diseases passed through saliva include:

Cryptosporidiosis – This intestinal infection is caused by the parasite Cryptosporidium and spreads through ingestion of contaminated feces. It can spread between cats and humans. According to the CDC, most human cases come from infected cattle but cats are also a source of infection [1].

Giardiasis – Caused by the parasite Giardia, this diarrheal illness spreads through ingestion of contaminated feces and can pass between cats and humans. Giardia is one of the most common intestinal parasites in cats [2].

Toxoplasmosis – This parasitic disease is caused by Toxoplasma gondii and spreads through contact with infected feces. Cats are the definitive host for T. gondii. The CDC estimates over 40 million Americans carry the parasite with most infections occurring through eating undercooked meat or ingesting contaminated soil [3].

Capnocytophaga – This bacteria naturally occurs in cat and dog saliva. In rare cases it can infect humans through bites or scratches, causing sepsis, meningitis and other severe illnesses, sometimes leading to limb amputation or death. People with weaker immune systems are at higher risk [4].

Healing Properties

Cat saliva has some healing and antimicrobial properties that can benefit both cats and humans. When cats lick wounds on their own bodies or other cats, they are instinctively trying to clean and disinfect the wound. Cat saliva contains proteins like lysozyme that have antibacterial effects and can kill microbes that cause infection in wounds (1). These antibacterial enzymes like lysozyme break down bacterial cell walls.

One protein called calprotectin is found in cat saliva and has antifungal and antibacterial properties. Cat saliva also contains growth factors that promote wound healing (2). The antimicrobial substances in cat saliva can help disinfect cuts or wounds if a cat licks it. However, too much licking can cause further irritation and damage, so cat owners still need to clean out wounds properly.

Toxicity

Cat saliva contains bacteria and other organisms that can be toxic or harmful to other species. According to Musehealth (source), cat saliva contains organisms like Pasteurella, Capnocytophaga, and Bartonella which can cause infections or even sepsis if they enter the bloodstream of humans or other animals through bites or scratches. The bacteria Pastuerella multocida, found in over 50% of healthy cats, is especially dangerous as it can cause fever, abscesses, respiratory infections, and joint infections in humans. Similarly, Capnocytophaga can cause fever, vomiting, diarrhea and septic shock.

Quora (source) notes that cat saliva can be toxic to birds, reptiles, and rodents due to the presence of bacteria. Even a small scratch or bite from a cat can be lethal to these small animals. Cats also carry Feline calicivirus which is highly contagious between cats.

So while cat saliva is not poisonous, the bacteria present in it can definitely be harmful or even fatal to humans, birds, reptiles and other animals. Proper treatment of bites/scratches and good hygiene is important to prevent infections when handling cats.

Uses

Both cat and human saliva serve important functions. Cat saliva contains enzymes and proteins that help cats groom and clean themselves. The antibacterial properties in cat saliva allow cats to disinfect wounds from grooming and keep their fur clean 1. Cat saliva also helps cats digest their food. The enzymes in cat saliva start breaking down food as they chew. This allows cats to extract nutrients efficiently from their meat-heavy diets 2.

Human saliva plays a similar role in digestion by helping to break down starches and fats in food. It also helps maintain oral health by washing away food debris and bacteria. Additionally, human saliva contains compounds that aid wound healing both orally and on the skin. Research shows human saliva can stimulate new cell growth and blood vessel formation when applied to skin or mouth wounds 3. So while cat and human saliva have some differences, they share common functions in grooming, digestion, and healing capacities.

Conclusion

In summary, cat and human saliva share some similarities but also have important differences. Both contain enzymes like amylase to help break down starches and mucins which lubricate the mouth. However, cat saliva has a more alkaline pH around 8.5 compared to human saliva which is neutral or slightly acidic. It also contains more bacteria overall, with species that are harmful to humans but don’t affect cats. While human saliva promotes healing of wounds, cat saliva can introduce infection. Neither cat nor human saliva is highly toxic, but diseases can sometimes transmit between cats and humans via saliva contact. Overall, cat saliva is best avoided due to the bacteria and infection risks. Proper hygiene like handwashing is recommended after interacting with cats.

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