Heartworm
When your puppy is around 12-to-16 weeks, talk to your vet about starting her on a heartworm preventive. Though there is no vaccine for this condition, it is preventable with regular medication. The name is descriptive — these worms lodge in the right side of the heart and the pulmonary arteries (that send blood to the lungs), though they can travel through the rest of the body and sometimes invade the liver and kidneys. The worms can grow to 14 inches long (ick!) and, if clumped together, block and injure organs. A new infection often causes no symptoms, though dogs in later stages of the disease may cough, become lethargic, lose their appetite or have difficulty breathing. Infected dogs may tire after mild exercise. Unlike most of the conditions listed here, which are passed by urine, feces, and other body fluids, heartworms are transmitted by mosquitoes. Therefore, diagnosis is made via a blood test and not a fecal exam. The FDA has more information about heartworm.

Kennel Cough
Also known as infectious tracheobronchitis, kennel cough results from inflammation of the upper airways. It can be caused by bacterial, viral, or other infections, such as Bordetella and canine parainfluenza, and often involves multiple infections simultaneously. Usually, the disease is mild, causing bouts of harsh, dry coughing; sometimes it’s severe enough to spur retching and gagging, along with a loss of appetite. In rare cases, it can be deadly. It is easily spread between dogs kept close together, which is why it passes quickly through kennels. Antibiotics are usually not necessary, except in severe, chronic cases. Cough suppressants can make a dog more comfortable.

Leptospirosis
Unlike most diseases on this list, Leptospirosis is caused by bacteria, and some dogs may show no symptoms at all. Leptospirosis can be found worldwide in soil and water. It is a zoonotic disease, meaning that it can be spread from animals to people. When symptoms do appear, they can include fever, vomiting, abdominal pain, diarrhea, loss of appetite, severe weakness and lethargy, stiffness, jaundice, muscle pain, infertility, kidney failure (with or without liver failure). Antibiotics are effective, and the sooner they are given, the better.

Lyme Disease
Unlike the famous “bull’s-eye” rash that people exposed to Lyme disease often spot, no such telltale symptom occurs in dogs. Lyme disease (or borreliosis) is an infectious, tick-borne disease caused by a type of bacteria called a spirochete. Transmitted via ticks, an infected dog often starts limping, his lymph nodes swell, his temperature rises, and he stops eating. The disease can affect his heart, kidney, and joints, among other things, or lead to neurological disorders if left untreated. If diagnosed quickly, a course of antibiotics is extremely helpful, though relapses can occur months or even years later.

Parvovirus
Parvo is a highly contagious virus that affects all dogs, but unvaccinated dogs and puppies less than four months of age are at the most risk to contract it. The virus attacks the gastrointestinal system and creates a loss of appetite, vomiting, fever, and often severe, bloody diarrhea. Extreme dehydration can come on rapidly and kill a dog within 48-to-72 hours, so prompt veterinary attention is crucial. There is no cure, so keeping the dog hydrated and controlling the secondary symptoms can keep him going until his immune system beats the illness.

Rabies
Rabies is a viral disease of mammals that invades the central nervous system, causing headache, anxiety, hallucinations, excessive drooling, fear of water, paralysis, and death. It is most often transmitted through the bite of a rabid animal. Treatment within hours of infection is essential, otherwise, death is highly likely. Most states require a rabies vaccination. Check with your vet about rabies vaccination laws in your area.

Of course, your veterinarian should weigh in and can always provide more information and guidance if needed on necessary and optional vaccinations.