What are the most common infectious diseases veterinarians treat in dogs?

Dogs, like all animals, are susceptible to a variety of infectious diseases. These diseases can be caused by bacteria, viruses, parasites, or fungi and can range from mild to life-threatening. As a veterinarian, I frequently diagnose and treat several common infectious diseases in dogs. Below, I will outline the most prevalent ones, their causes, symptoms, treatment options, and prevention strategies.

1. Canine Parvovirus (Parvo)
Canine parvovirus is a highly contagious viral disease that primarily affects puppies and unvaccinated dogs. It attacks the gastrointestinal system, leading to severe vomiting, diarrhea (often bloody), lethargy, and dehydration. Parvo is spread through direct contact with an infected dog or contaminated feces, environments, or objects.

Treatment involves aggressive supportive care, including intravenous fluids to combat dehydration, anti-nausea medications, and antibiotics to prevent secondary bacterial infections. Hospitalization is often required. Prevention is key, and vaccination is highly effective. Puppies should receive a series of parvovirus vaccines starting at 6-8 weeks of age, with boosters given every 3-4 weeks until they are 16 weeks old.

2. Canine Distemper
Canine distemper is another serious viral disease that affects the respiratory, gastrointestinal, and nervous systems. Symptoms include fever, nasal discharge, coughing, lethargy, vomiting, diarrhea, and, in advanced cases, seizures or paralysis. Distemper is spread through airborne exposure or direct contact with infected bodily fluids.

There is no specific cure for distemper, so treatment focuses on supportive care, such as fluids, antibiotics for secondary infections, and anticonvulsants for seizures. Vaccination is the best prevention, and puppies should receive a series of distemper vaccines starting at 6-8 weeks of age.

3. Kennel Cough (Infectious Tracheobronchitis)
Kennel cough is a highly contagious respiratory disease caused by a combination of bacteria (Bordetella bronchiseptica) and viruses (such as canine parainfluenza virus). It is characterized by a persistent, dry, hacking cough, often described as a "honking" sound. Dogs in close quarters, such as boarding facilities or shelters, are at higher risk.

Treatment typically includes rest, cough suppressants, and sometimes antibiotics if a bacterial infection is present. Vaccines are available for both Bordetella and parainfluenza, and these are recommended for dogs that frequent boarding facilities, dog parks, or grooming salons.

4. Leptospirosis
Leptospirosis is a bacterial infection that can affect both dogs and humans. It is spread through contact with contaminated water, soil, or urine from infected animals. Symptoms include fever, muscle pain, vomiting, diarrhea, jaundice, and kidney or liver failure.

Treatment involves antibiotics, such as doxycycline, and supportive care for organ damage. Vaccination is available and is particularly important for dogs in areas where leptospirosis is prevalent or for those with outdoor lifestyles.

5. Lyme Disease
Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted through tick bites. Symptoms include lameness, joint swelling, fever, and lethargy. In severe cases, it can lead to kidney damage.

Treatment involves antibiotics, such as doxycycline, and pain management for joint discomfort. Prevention includes regular tick control measures, such as topical treatments or oral medications, and vaccination in endemic areas.

6. Canine Influenza (Dog Flu)
Canine influenza is a viral respiratory infection caused by two strains, H3N8 and H3N2. Symptoms resemble kennel cough and include coughing, sneezing, nasal discharge, and fever. Severe cases can lead to pneumonia.

Treatment is supportive, including fluids, rest, and sometimes antibiotics for secondary infections. Vaccines are available for both strains and are recommended for dogs at high risk, such as those in boarding facilities or dog shows.

7. Heartworm Disease
Heartworm disease is caused by the parasite Dirofilaria immitis, transmitted through mosquito bites. It affects the heart and lungs, leading to coughing, exercise intolerance, and, in severe cases, heart failure.

Treatment is complex and involves a series of injections to kill the adult worms, along with strict rest to prevent complications. Prevention is critical and includes monthly heartworm preventatives, such as oral medications or topical treatments.

In conclusion, infectious diseases in dogs can be serious, but many are preventable through vaccination, regular veterinary care, and good hygiene practices. If you suspect your dog has an infectious disease, seek veterinary care promptly to ensure the best outcome. Regular check-ups and preventive measures are essential for keeping your dog healthy and reducing the risk of these common illnesses.