Doggone Diseases. The Top 5 Human Illnesses Your Pup Can Catch

Introduction

Zoonotic diseases are illnesses that can be passed between animals and humans. Some of the most common zoonotic diseases that dogs can get from humans include rabies, ringworm, salmonellosis, MRSA, influenza, intestinal worms, and fleas.

Dogs and humans have lived in close contact for thousands of years, so it’s inevitable that we pass diseases back and forth. Some zoonotic diseases like rabies can be very serious and even fatal, while others like ringworm result in more mild symptoms. Vaccinating dogs, practicing good hygiene, controlling parasites, and monitoring your dog’s health are important ways to reduce the risk of zoonotic disease transmission between pets and people.

In this article, we will provide an overview of some of the most common zoonotic diseases dogs can acquire from humans, including information on transmission, symptoms, diagnosis, treatment, and prevention.

Rabies

Rabies is a viral disease that affects the central nervous system and is transmitted through the bite or scratch of an infected animal. The rabies virus is found in the saliva and brain of affected mammals including dogs, bats, raccoons, skunks, and foxes. Rabies can be spread when an infected animal’s saliva comes into contact with a wound, eyes, nose, or mouth. The virus travels to the brain, causing progressive inflammation and ultimately death if left untreated.

a dog showing signs of rabies infection

Some signs of rabies in dogs include agitation, aggression, excessive drooling, difficulty swallowing, paralysis, and seizures. There is no cure for rabies once symptoms appear, but it can be prevented if treatment is administered shortly after exposure. The rabies vaccine is highly effective for both humans and animals. Treatment after potential exposure involves wound cleansing and a series of rabies vaccinations. Preventing rabies requires vaccination of domestic dogs, avoiding contact with wild animals, and safely handling pets.

Ringworm

Ringworm is a highly contagious fungal skin infection that dogs can get from contact with an infected animal or environment. The clinical name for ringworm is “dermatophytosis”. It is called ringworm because it can cause circular patches of hair loss on a dog’s skin. Despite the name, ringworm is not caused by a worm.

Ringworm fungi live in the dead layers of skin, hair, and nails. The fungi are called “dermatophytes” which means “plants that live on the skin” in Greek. There are three types of dermatophytes that commonly infect dogs: Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes. These fungal spores can survive for long periods in the environment (Fenner, 2013).

Dogs with weakened immune systems and puppies are more susceptible to ringworm. The spores enter through breaks in the skin and hair follicles. As the fungus multiples, it causes inflamed circular lesions with hair loss typically 1-3 inches in diameter. The edges of the lesions often appear red and scaly. Ringworm is highly contagious and can spread from dogs to humans through direct contact with the infected areas of the dog’s skin. Humans can also contract ringworm from contact with contaminated objects such as grooming tools, bedding, and furniture.

a dog with ringworm skin lesions

Ringworm is diagnosed through fungal culture, skin scrapings, UV light examination, and microscopic examination of hairs. Treatment involves thoroughly cleaning the environment and long term use of oral and topical anti-fungal medications such as miconazole, ketoconazole, itraconazole, and griseofulvin. All in-contact animals should also be treated. Ringworm can take 4-6 weeks of aggressive treatment to fully resolve (Miller Jr, Griffin, & Campbell, 2013).

Prevention involves maintaining a robust immune system through proper nutrition, hygiene, and limiting exposure to infected animals. Early detection and treatment is key to managing outbreaks. Any new pets should be quarantined and screened for ringworm.

Salmonellosis

Salmonellosis is a bacterial disease that can be transmitted between dogs and humans. Dogs most commonly get infected by ingesting contaminated food or water containing feces from an infected animal or human. The bacteria can also be spread through contact with contaminated surfaces. According to research, gastrointestinal issues are the most common clinical sign of salmonella infection in dogs and humans. However, many infected dogs and humans may not show any symptoms.

In dogs, symptoms of salmonellosis include vomiting, diarrhea (which may contain blood or mucus), fever, abdominal pain, lethargy, and anorexia. If the infection spreads to the bloodstream, dogs may develop life-threatening conditions like endocarditis, meningitis, pneumonia, and septic arthritis. Diagnosis involves culture of the bacteria from feces or other infected sites.

Treatment consists of oral or intravenous fluid therapy to prevent dehydration, antibiotics to control the bacterial infection, and supportive care like electrolytes, vitamins, and probiotics. Preventing salmonella involves practicing good hygiene like washing hands before and after handling pets, proper food handling and storage, keeping pets away from high risk items like raw food diets and feces, and prompt cleaning of contaminated surfaces [1]. Vaccination may also help reduce shedding and transmission.

a dog with salmonella infection

Leptospirosis

Leptospirosis is a bacterial disease that can affect dogs and humans. It is caused by spiral-shaped bacteria called Leptospira. The bacteria can infect any mammal, but dogs are particularly susceptible.

Causes:
Leptospirosis is spread through the urine of infected animals [1]. An uninfected dog can become infected by coming into contact with urine-contaminated soil, food, or water. The bacteria can enter the body through mucous membranes or abrasions on the skin.

Symptoms:
In dogs, symptoms may include fever, vomiting, diarrhea, loss of appetite, lethargy, muscle pain, and redness of the mucous membranes [2]. More severe cases can lead to kidney or liver failure. Some dogs may show no symptoms at all.

Treatment:
Mild cases may only require supportive care such as fluid therapy. Antibiotics like doxycycline are used for more severe infections. Hospitalization may be necessary in acute cases. Prompt treatment is important to prevent permanent organ damage.

Prevention:
Vaccination provides good protection against leptospirosis. Avoiding areas where infected wildlife may urinate can also lower risk. Promptly cleaning up dog urine and preventing them from drinking from puddles or streams are other preventive measures.

MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of staph bacteria that is resistant to some antibiotics including methicillin, oxacillin, penicillin and amoxicillin (Rutland et al., 2009). MRSA can spread between humans and dogs through direct contact with infected skin lesions, nasal secretions, or exposure to objects contaminated with MRSA bacteria.

a dog with a mrsa skin infection

Causes

Dogs can acquire MRSA through contact with infected humans, other dogs/pets, or environments where MRSA is present. Underlying conditions like wounds, broken skin, catheter use, and a weakened immune system can increase susceptibility (OSU, n.d.).

Symptoms

In dogs, MRSA most often causes skin infections which may appear as redness, swelling, pain, pustules, and abscesses on the skin. Dogs can also develop respiratory infections, urinary tract infections, and wound infections from MRSA bacteria (van Duijkeren et al., 2004).

Treatment

MRSA infections in dogs often require specialized antibiotic therapy as many common antibiotics are ineffective. Veterinarians may culture wound/skin samples to identify the most effective antibiotic option. Topical treatments, wound care, and keeping the infection contained are also important (OSU, n.d.).

Prevention

Preventing MRSA transmission between humans and dogs requires diligent hygiene and sanitization. Handwashing, covering wounds, and avoiding contact with infected skin are important. Cleaning a dog’s skin folds, nails, and environment can also help reduce bacterial spread and infection risk.

Influenza

Influenza viruses cause respiratory illness in dogs. There are two main strains that infect dogs: equine influenza virus H3N8 and avian influenza virus H3N2. Canine influenza is highly contagious between dogs and spreads through respiratory secretions like coughing, barking or sneezing. Influenza viruses can live on surfaces for 48 hours and exposure often happens at places where dogs congregate like shelters, boarding facilities, dog parks, groomers, daycare, competitions, and veterinary clinics. While it’s possible for humans to get infected with canine influenza viruses, there are no reported cases to date.

Symptoms of canine influenza include cough, runny nose, fever, lethargy, eye discharge and reduced appetite. Most dogs recover within 2-3 weeks but secondary infections can lead to more severe illness. Dogs at highest risk for complications include young puppies, seniors, pregnant dogs, and those with underlying health conditions.

Treatment focuses on supportive care such as rest, fluids, antibiotics for secondary infections, and medication to reduce fever. The only vaccine available for canine influenza in the US was developed for the H3N8 virus strain. While it may provide some cross-protection against H3N2, vaccination is not completely protective. Prevention includes avoiding direct contact with infected dogs, proper hygiene and disinfection, and vaccination when appropriate.

Worms

Dogs can get different types of worms that can infect humans, including roundworms, hookworms, tapeworms, and whipworms. Roundworms and hookworms are the most common intestinal worms passed from dogs to humans.

Roundworms are long, spaghetti-like worms that live in a dog’s intestines. A dog can get infected with roundworms by eating contaminated soil or stool, or from their mother’s milk. Roundworm eggs are shed in the dog’s feces and are transmittable to humans through accidental ingestion. Children are especially at risk when playing in contaminated areas. In humans, roundworm infection may cause vision loss, rashes, coughing, or abdominal pain (CDC).

Hookworms attach themselves to the intestinal wall of dogs and feed on their blood, causing anemia. Dogs get infected when hookworm larvae penetrate the skin. The larvae can also penetrate human skin from contaminated soil. Hookworm infection may result in a skin rash or respiratory problems in humans (CDC).

To prevent worm infections, pick up dog feces promptly and wash hands regularly. Puppies should be dewormed and kept away from areas potentially contaminated with stool. Ensure dogs are on monthly heartworm and intestinal parasite prevention medication prescribed by a veterinarian. If a human shows symptoms of a worm infection, see a doctor immediately.

Fleas

Fleas are a common external parasite that can infest both dogs and humans. Fleas feed on blood and can cause irritation, itching, infections and anemia in severe infestations. There are several ways dogs and humans can get fleas:

  • Coming into contact with an infested animal or environment. Fleas can jump from host to host.
  • Bringing an infested animal into the home.
  • Flea eggs surviving in carpets, bedding or outside areas even if the infested animal is treated.

In dogs, symptoms of flea infestation include scratching, licking and biting at the skin, hair loss and reddened skin. Fleas may also be visible running through the dog’s coat. In humans, flea bites cause small itchy red bumps on the skin. These are often found around the ankles and legs as fleas jump up from the floor.1

Treatment involves eliminating fleas on both the dog and in the home environment. On dogs, monthly spot-on or oral flea prevention treatments are highly effective. The environment must also be treated with sprays or powders containing insect growth regulators that kill eggs and prevent hatching. Thorough vacuuming and washing of bedding on hot cycles is also important.2,3

Prevention is key through consistent use of flea control products on pets and keeping the home and yard environments clean.

Conclusion

Dogs can contract a variety of diseases from humans or other animals. While some diseases produce mild symptoms, others can be very serious and even fatal. Key takeaways include:

  • Rabies, though preventable by vaccination, is almost always fatal once symptoms appear.
  • Ringworm is highly contagious but treatable.
  • Salmonellosis and leptospirosis can cause severe illness.
  • MRSA can be transmitted between dogs and humans.
  • Dogs are susceptible to strains of the flu virus.
  • Regular deworming and flea/tick prevention helps stop the spread of parasites.

Prevention through measures like vaccination, good hygiene, and parasite control is crucial to avoid disease transmission between species. Keeping a dog healthy involves diligence from pet owners as well as veterinary care. Stopping illness before it starts is vital for the wellbeing of our canine companions.

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