The Most Common Severe Dog Diseases

Common Severe Dog Diseases

One of your main jobs as a pet owner is to keep an eye on your dog and help them seek treatment for diseases. Since your dog can’t use words to explain that they’re in pain, it’s important that you’re familiar with common dog diseases so you can watch for symptoms and help your pup if they seem to be suffering from a particular disease.

Most Common Severe Dog Diseases

Dog diseases range from severe to relatively harmless, though all dog diseases can cause serious health problems or death if left untreated permanently. Let’s start by looking at common severe dog diseases to watch for. Next week, we’ll pick up with some milder dog diseases you also want to keep an eye out for.


Rabies is probably the most well-known dog disease out there. It is usually passed through saliva from an infected animal. Common symptoms of rabies include:

  • Seizures
  • Behavioral changes
  • Sudden aggressiveness toward humans, animals, or other objects
  • Fever
  • Hypersensitivity
  • Paralysis
  • Foaming at the mouth
  • Weakness

Rabies is one of the few diseases for which there is no known cure. If your dog gets rabies and has never been vaccinated, the disease is fatal. To prevent your dog’s death, be sure to get them vaccinated as soon as possible. Some states even require this vaccination by law.


Parvovirus is a disease that commonly affects puppies and young dogs. It is a viral disease that attacks your dog’s cells, especially those in the intestinal tract and white blood cells. Parvovirus is generally spread through infected dog poop. Common symptoms include:

Parvovirus is incredibly contagious. It is not always fatal but it can cause lifelong heart issues. Treatment for parvovirus consists of a hospital stay with intravenous fluids and medications to boost your dog’s immune system and keep them alive to fight the disease. 

To prevent parvovirus, your best bet is to vaccinate your pup as soon as possible. You can also keep them away from other dog poop and be sure to clean thoroughly if you know an infected dog has been in your home or yard.


Distemper is usually spread through secretions from the nose, though it can also be airborne or contracted through the placenta. This disease begins in the lymphatic tissue of the respiratory tract and then spreads throughout the body. 

There are two stages to distemper, each with different symptoms. The first stage includes symptoms such as:

  • Watery, pus-like eye discharge
  • Loss of appetite
  • Nasal discharge
  • Fever
  • Lethargy
  • Coughing
  • Vomiting
  • Diarrhea
  • Brain and spinal cord inflammation
  • Difficulty breathing or pneumonia

The second stage of canine distemper affects the central nervous system and includes neurological symptoms such as:

  • Head tilt and circling
  • Seizures
  • Paralysis
  • Muscle twitching
  • Convulsions
  • Death

To prevent distemper, you must vaccinate your dog as soon as possible. If they are infected, you will need to take them to the hospital for immune support and symptom treatment, though there is no treatment or cure for distemper.


Hepatitis, or adenovirus, is usually spread through dog poop, dog urine, eye discharge, or saliva. Hepatitis is a viral infection and usually comes with symptoms such as:

  • Depression and lethargy
  • Loss of appetite
  • Fever
  • Eye opacity (cloudiness)
  • Cough
  • Eye or nasal discharge

Some young puppies may suffer from severe abdominal pain, diarrhea, vomiting, and edema. While hepatitis has no specific treatment, dogs may be hospitalized so they can get immune system support and help to manage symptoms. To prevent hepatitis, be sure to vaccinate your puppy as soon as you can.


Leptospirosis is a bacterial infection spread through water, soil, or contact with an infected animal. Leptospirosis ranges from mild to fatal, depending on the severity of the strain and your dog’s immune system. Common symptoms include:

  • Fever
  • Shivering
  • Muscle tenderness
  • Lethargy
  • Vomiting and diarrhea
  • Loss of appetite
  • Increased thirst 
  • Dehydration
  • Jaundice
  • Eye inflammation

Leptospirosis can also lead to liver failure, kidney failure, severe lung disease, and bleeding disorders. This disease is usually treated with antibiotics and can usually be cured with proper swift treatment. However, it often leads to long-term kidney or liver damage. 

Your best method of prevention is to vaccinate your dog, especially if your area is known for leptospirosis infections.


Cancer in dogs is not much different from cancer in humans. Common in older dogs, cancer causes cells to grow uncontrollably, invade tissue, and spread throughout the body. Common cancer symptoms include:

  • Lumps or swelling
  • Persistent sores
  • Bad breath
  • Lethargy
  • Abnormal discharge of any kind
  • Rapid weight loss
  • Black and tarry poop
  • Lameness
  • Loss of appetite
  • Difficulty breathing, urinating, or pooping

Cancer carries a wide range of symptoms and may or may not be curable. Sometimes, you can use chemotherapy, radiation, and other treatments to help your dog, but sometimes there is no way to cure cancer once it has entered your dog’s body. In such cases, pain relief is one of the main treatment options.

Preventing cancer is also difficult. Spaying or neutering your dog early can prevent breast or testicular cancer, but other cancers are not specifically preventable. Feeding your dog a healthy diet and giving them plenty of exercise can keep them healthy for longer, though it may not help prevent cancer.


Heartworm is spread through infected mosquitoes. It is a parasitic worm that travels through the dog’s bloodstream and lives in the heart and pulmonary arteries. Heartworm harms the heart, lungs, organs, and vital arteries of infected dogs. The main symptoms include:

  • Labored breathing
  • Coughing
  • Vomiting
  • Listlessness and fatigue after mild exercise
  • Weight loss

Some dogs exhibit no symptoms until late in the disease, so prevention is key for heartworm. In general, your vet will prescribe a pill or a topical medication that you will administer to your dog monthly. It is advisable to start heartworm medication when you first get your puppy and continue treatment all year as long as they live. 

Thankfully, if you do find out that your dog has heartworm, there is treatment available. Your dog will likely need to go to the hospital for drug injections to fight and kill the heartworms. This treatment has a high success rate.

Keeping Your Dog Healthy

This is a list of all the most severe dog diseases you’ll find as you raise your dog in this world. If you need more information on any of these diseases or are worried that your dog has one, be sure to talk to your vet as soon as possible. 

In the meantime, you can keep your dog healthy with a few practical tips:

  • Keep your dog up-to-date on vaccinations.
  • Take your dog out for regular exercise.
  • Provide your dog with a healthy, balanced diet.
  • Keep your dog’s yard clean and only visit safe, disease-free places, if possible.

If you need help picking up your dog’s poop to keep their play area safe and as germ-free as possible, be sure to reach out to us! Our team at Idaho Poop Scoop would be happy to help. Check out our services and let us help you scoop your dog’s poop today!