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While most dog parents are clued in to the behaviors and moods of their four-legged babies, small ailments, such as vomiting and lethargy, can often be written off as inconsequential when in reality they are symptoms of potentially life-threatening diseases.

Learn about some of the most common hidden diseases that can prove fatal to your pup and how to spot them in the following gallery.

▲Parvovirus strikes swiftly and worsens dramatically. While dogs of any age can be affected, puppies under one year of age are most susceptible.

▲An affected dog often presents with vomiting, lethargy, and diarrhea.

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If your dog's diarrhea is particularly bloody or pungent, an immediate trip to the vet can rule out parvo or treat it before it becomes fatal.

▲This viral disease affects the respiratory, gastrointestinal, and central nervous system. It can be transferred through contact with infected dogs, contaminated water, or bodily fluids.

▲Early symptoms include sneezing, coughing, and leaking eyes.

▲This parasite can be picked up in wooded areas or open fields.

▲The parasitic worms make their home in the lungs where they lay eggs. Once hatched, the larvae can cause a host of respiratory and breathing problems.

▲If caught in time, a vet can prescribe an anti-parasitic medication to prevent more serious problems.

▲DCM is a genetic disease that affects the heart.

▲Affecting mostly older dogs and specific breeds, such as Great Danes, the disease disrupts the heart's size and function.

▲Lethargy, rapid breathing, and extreme weight loss are common early symptoms of the disease. While early diagnosis can improve chances of survival, the prognosis varies from dog to dog.

▲This growing bacterial disease is typically passed on through contact with contaminated water, particularly in woodland areas.

▲The infection is carried by animals, such as raccoons, and spreads through their urine.

▲Signs of a lepto infection include fever, shivering, excessive urination, and muscle stiffness.

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This highly contagious respiratory infection spreads rapidly in close and confined environments.

▲The infection is normally limited to an inflammation similar to bronchitis, with a loud and persistent cough that can be easily treated.

▲In severe cases, a dog may suffer from complications such as pneumonia, which can be fatal.

▲This well-known disease is transmitted through ticks.

▲While some dogs may not present with symptoms, others may experience inflammation of the joints and recurring lameness.

▲In serious cases, kidney failure and nervous system disruption can occur.

▲This life-threatening condition may appear as harmless bloating, but is indicative of a more serious underlying problem.

▲Commonly caused by old age, large chest size, and eating too quickly, GDV involves inflation of the stomach after air or fluid twisting cuts off blood supply.

▲This incredibly painful condition presents with symptoms including vomiting, labored breathing, and biting at the stomach. In some cases, an emergency surgery can save your dog's life.

▲This parasitic roundworm spreads through mosquito bites.

▲Symptoms increase in severity over time, starting with a decreased appetite and fatigue and advancing to a swollen abdomen and labored breathing.

▲Advanced stages bring about severe lung disease, blood vessel blockage, and eventually, cardiovascular collapse. Even if treated, the disease can cause lasting damage to the lungs, heart, and arteries.

▲This fungal infection primarily targets the lungs before spreading to other bodily tissues.

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Commonly found in acidic soil near bodies of water, the infection can cause blindness, lameness, seizures, coughing, enlarged lymph nodes, and respiratory problems.