11 Deadly Dog Diseases

11 Most Deadly Dog Diseases by Mortality Rates

When adopting a dog, you will likely come across some health problems. However, they are most often easily treated and the condition is usually mild. Conditions that have a severe impact can cause injuries or permanent damage. Potential dog owners should be aware of the potentially deadly diseases that can strike their pet. By maintaining a strong immune system, the risk of contracting one of these diseases will be greatly reduced.

While some deadly dog diseases are inherited or incurable, your dog could avoid others by knowing what signs and symptoms to watch for and how to treat them. Knowing what those deadly dog conditions are can save your dog’s life.

Here are the eleven most deadly dog diseases that you should know about

1. Rabies

Rabies is one of the most infamous deadly dog diseases, which everybody has heard about. It’s a virus that’s always fatal and if humans are bitten or scratched by a rabid dog, they could also get infected.

Symptoms may not show themselves before 8 weeks pass, and this virus usually takes 2-8 weeks to develop fully.

That’s why rabies is so deadly in dogs – there is no way to diagnose it before the symptoms appear, and by then it’s too late.

No test can diagnose rabies in live animals. The most accurate way to diagnose it is to wait for the animal’s death and take brain tissue samples.


Rabies infection can cause extreme behavioral changes such as apprehension, restlessness and aggression. You should be aware of the signs because your dog may start biting, licking, and chewing parts of their body. Fever is another characteristic sign.

As the virus progresses and the dog’s condition worsens, it may become extremely sensitive to light, sound, and touch.

When a virus or bacterial infection reaches the brain, the animal starts foaming from its mouth. In most cases, paralysis of the jaw and throat muscles occur here. As a result, the infected animal may experience disorientation, weakness, seizures and death.


The good news is that rabies is a preventable disease. While there is no cure for it, if you keep your dog up to date with their vaccination, you won’t have to worry.

This means that, despite the availability of treatment, rabies is still causing tens of thousands of deaths around the world. This is especially prevalent in developing countries like Asia and Africa.

However, this has been reported in all US states except for Hawaii. But cats are reportedly more common than dogs.

2. Canine Distemper

This is another vaccine-preventable but otherwise very deadly dog disease. It is a contagious viral illness, a relative of the measles virus that affects humans.

Unvaccinated puppies and older dogs are particularly susceptible to this illness. Canine distemper is transferred by direct contact and airborne exposure, which makes it very contagious.


Canine distemper virus (CDV) typically starts by attacking the tonsils and lymph nodes. The infection moves on to attack the respiratory, gastrointestinal, urogenatic and nervous systems in that order.

CDV symptoms come as two stages. In the first stage, dogs usually suffer from fever, watery eyes, nasal discharge and appetite loss.

Some other symptoms you may notice include coughing, vomiting, diarrhea, anorexia, and lethargy.

Your dog may also get a condition called hyperkeratosis of the nose and paw pads which causes their feet to swell and harden.

As the disease progresses to the second stage, some dogs may start to experience neurological problems, such as head tilting, muscle twitching, paralysis, seizures and convulsions.

It’s important to be aware that the distemper mortality rate is around 50% — but the consequences are worse for animals infected with this disease. The damage can be so severe that some animals may not survive it.


The canine distemper virus is incurable and doctors focus on managing and relieving the dog’s symptoms.

Additional treatments may include intravenous fluids for diarrhea or anorexia, antibiotics if a secondary bacterial infection is present, and potassium bromide or phenobarbital to control the dogs seizures and convulsions.

Since there is no cure available for this virus, prevention is essential. Give your dog the necessary vaccines coverage to keep them safe and avoid contact with infected dogs.

Beware that if you are socializing with an unvaccinated puppy or adult unvaccinated dog, they may be putting you at risk of contracting serious causes of diseases.

3. Fungal Infections

Fungal infections in dogs are usually not serious but can occasionally be quite serious or fatal. They usually cause mild symptoms.

Fungal infections affecting just the skin are easy to treat, but if they spread to the lungs, liver, or brain then treatment can be harder.

These three infectious diseases are most likely to be fatal for dogs: histoplasmosis (a fungal infection), blastomycosis, valley fever, and cryptococcosis.

Valley Fever

Valley fever is a dust-borne infection contracted by dogs, mostly present in dry regions of the southwestern US and the valleys of Southern California. It’s not contagious and can be found in parts of Texas and Arizona.

Epidemic like Valley Fever in dogs often occurs when there’s heavy rainfall after a period of drought. This causes dust storms that spread throughout the area and causes respiratory problems with other parts of one’s body.

Symptoms vary depending on the severity of the infection and the organs that are affected. Signs include loss of appetite, cough, apathy, fever, enlarged joints, and diarrhea. Ulcers may appear on a dog’s skin as well.

Treatment involves the prescription of antifungal medication and will usually last from six months to a year.


Cryptococcosis is a fungus that can be found in soil worldwide. It may also be found in bird manure, particularly pigeon droppings. This disease typically affects the dog’s respiratory tract, eyes, skin and central nervous system.

Typical symptoms of cryptococcosis in dogs include inflammation and bleeding in the eyes.

Other common symptoms are mostly related to the central nervous system and include eye-tiles, poor coordination, and seizures.

If your dog is suffering from a nasal fungus, you might want to consult with a vet & get the treatment started. Typically, this will consist of various antifungal drugs that will need to be taken for several months’ time.


According to the CDC, histoplasmosis in dogs is a non-contagious infection caused by Histoplasma found in soil worldwide. It can be found in the US primarily in the Midwest and southern regions, particularly in river valleys.

Dogs typically contract infections through their lymph nodes and lungs, but the gut can also become infected.

The symptoms are nonspecific because they involve different organs. The most obvious signs are digestive ones like diarrhea and weight loss.

Coughing and difficulty breathing are also common. Other symptoms include fever, anemia, digestive ulcers, enlarged lymph nodes, skin sores and various eye conditions.

Treating disseminated histoplasmosis in dogs can be complicated. The main thing is to give antibiotics, but other things such as good nutrition and lots of water helps, too.


Blastomycosis is a fungal disease that can affect dogs. It’s caused by the Blastomyces fungus that thrives in wet, acidic soils and rott this such as rotting wood or other decaying vegetation. In North America, it’s most prevalent in river basins and along the St. Lawrence Seaway and the Great Lakes.

This usually leads to the infection of the lungs, but in some cases it may be transmitted through the skin. Common symptoms include difficulty breathing, fever, weight loss and apathy. Other symptoms may include the dog’s lymph nodes swelling.

Eye problems, such as light sensitivity, glaucoma, or blindness can occur if your infection spreads to that area. Dogs who have these types of eye infections often have draining skin nodules.

Treatment for blastomycosis typically involves taking antifungal medications and breathing treatments, and dogs with respiratory problems may need supplemental oxygen.

4. Leptospirosis

Leptospirosis is a zoonotic infection that can be passed between animals and humans. It takes different strains of bacteria to cause it, one of which is transmitted via your dog.

Leptospirosis is a bacterial disease that can be contracted in a number of ways. Direct contact with other infected animals, or ingestion of contaminated meat or feces, or from contact with animal urine are all routes to contraction for this deadly disease.


Leptospirosis infection has a lot of different and slight symptoms, which may range in level of intensity. Some dogs might show no symptoms at all.

The majority of canine leptospirosis signs are fever, increased thirst, urination, lethargy, sore muscles and stiffness in joints, loss of appetite, diarrhea, vomiting and jaundice.

Severe leptospirosis cases can sometimes lead to swelling & bleeding disorders in the legs, lung disease, fluid in the chest or abdomen, and kidney failure.

Studies show that leptospirosis is deadly to dogs in nearly 50% of cases.


Since this is a bacterial disease, a veterinarian can give antibiotics to help with recovery. However, it is important to start the treatment as quickly as possible in order to increase the chance of a full recovery.

Veterinarians can protect their dogs from leptospirosis with vaccines that last 12-months or longer.

Vaccines can protect against this dog disease to a degree, but it is impossible to be completely safe. The best way to protect your pet is by keeping a core vaccine up-to-date year round.

5. Heartworm Disease

This is another serious dog disease which can lead to death if left untreated. However, it is preventable with the correct medications for heartworm prevention.

Though heartworm disease is largely prevalent in humid climates, this vector born disease has been reported in all US states.

This parasitic disease mostly affects a dog’s heart and surrounding blood vessels, although it can also infest the lungs and other circulatory system areas. Due to its longevity (up to 5 years), the worms may cause many serious health complications.


The progression of canine heartworm disease is divided into four classes, based on the severity and symptoms exhibited.

  • The first class is often asymptomatic, which means that dogs usually don’t show any disease signs.

  • Class II symptoms include cough and fatigue after a moderate level of physical exercise.

  • Dogs with Class III heartworm disease can experience weight loss or muscle loss, greasy or dry hair, difficulty breathing and increased abdominal fluid accumulation.

  • Class IV heartworm disease is the most serious stage in which dogs develop a life-threatening condition known as caval syndrome.

Caval syndrome, a condition in which there are too many heartworms in a dog’s heart.

The worms block the flow of blood into the animal’s heart. At this stage, the disease is considered fatal and untreatable. Treatment instead focuses on providing comfort for the animal.


Treating heartworm in dogs requires medication that kill the circulating worms. Most often, that entails three injections spread over one month. Hospitalization is required during the administration of these injections or even beyond that if necessary.

Some medications like doxycycline or prednisone can be given to your dog in order to decrease their chance of reacting badly when the worms die.

Some dogs may also receive pain medication, diuretics as needed for lung fluid, and various heart medications. These may be needed even after heartworm disease is treated.

If your dog suffers from caval syndrome, surgery is the last option to explore. It’s a difficult procedure for them and most of them don’t survive it on top of that, but you should consult with your vet about it.

Caval syndrome on its own has been found to be one of the most deadly dog diseases. Studies show that mortality rates can be quite high in dogs and cats.

6. Lyme Disease

This disease is a tick-borne illness that can be fatal if not treated, although this is not such a common occurrence.

It takes as little as 36-48 hours for Lyme’s disease to spread from dog to dog through tick attachment. It also exists all over the world, with exception of Antarctica.

A licensed physician can prevent the disease with a vaccination.


The most common symptom of Lyme disease in dogs is lameness in their limbs. Stiffness in joints and loss of appetite can also occur, and lethargy, fever, and enlarged lymph nodes. Kidney failure is the most serious symptom of Lyme disease, but only happens if left untreated for a long time.


The processes for most dogs are similar – treatment with Amoxicillin or Doxycycline will usually lead to a full recovery after four weeks. It is important to vaccinate your dog against Lyme disease and make sure they don’t come into contact with ticks.

You should also check your dog for ticks often, if he/she spends a lot of time outdoors.

7. Parvovirus

You might also know canine Parvovirus (CPV), or Parvo, as the disease that attacks dogs’ intestines and hearts. It can be hard to cure and is very contagious.

Since Parvo vaccines are a part of the core vaccinations given to dogs, unvaccinated puppies and dogs in shelters or kennels have a higher risk of contracting it. In most cases, Parvo is spread through contaminated feces

Parvo is a contagious and resilient virus, and while some dogs have died from it, mortality rates have been estimated to be as high as 20%.


Parvovirus in dogs mainly causes symptoms of weight loss, vomiting, diarrhea, lethargy, and depression. Dogs with Parvo have a poor appetite. Other symptoms are less common but include dehydration and weakness.


If your dog has symptoms of Parvo, it is important to get immediate veterinary attention. Immediate care will significantly improve the prognosis of the disease.

Your dog is likely to get hospitalized where it will receive supportive care. One eye on any signs of secondary infections, your vet will keep an eye out.

8. Bloat

Gastric dilatation-volvulus (GDV), commonly known as canine bloat, is a serious health condition in which a dog’s stomach twists and fills with gas.

It is unclear why some dogs get bloat, but larger or giant breeds are more susceptible to it. Also the chances of a bloat occurring in a dog increases if it is male.

It is believed that eating too much food or too fast can contribute to this condition, although it is not yet clear what specific types of food are needed. Certain behavior patterns, such as stress eating may also be to blame.

GDV in dogs can be dangerous, especially when stomach pressure affects the dog’s breathing. If the stomach is damaged, it may lead to a rupture and may also cause damage to other tissues, such as spleen tissue.

If not treated, canine bloat can become fatal.


It’s a good idea to keep an eye out for the following dog bloat symptoms: retching, no vomiting, salivating a lot, restlessness and a swollen stomach. If you spot any of these warning signs take your pet to the vet right away.

As the condition worsens, there may be signs such as rapid heartbeat, shortness of breath, weakness and collapse.


Treatment for bloat in dogs will depend on its seriousness. Your vet will insert a tube down your dog’s throat all the way to his stomach to release the built up pressure.

If the tube cannot pass, your vet may put a large needle through your dog’s abdomen to relieve pressure.

Severe conditions of shock will usually require IV fluids, steroids or antibiotics, with X-rays to diagnose whether the stomach is twisted.

The last thing you want is for bloat to kill your dog, which can happen if it’s not dealt with immediately. So if you know your dog has the symptoms, mention it to your vet as soon as possible. If bloat is caught within a few hours then a good prognosis can be made and treatment will have a decent success rate. If this warning sign.

9. Kidney Failure

Studies have found that kidney failure in dogs is often a result of complications from other diseases, certain medications or it may develop on its own.

Chronic kidney failure is a type of kidney disease that happens on its own with no known cause. Genetics is usually the reason this happens and it can’t be prevented.

One of the reasons for kidney failure is dental disease. Acute kidney failure is sometimes caused by a sudden, severe infection.

Both conditions can be just as fatal to dogs, but chronic kidney failure takes time to develop. For acute kidney failure, you can take action at once.

Other issues that may affect your dog’s health in old age can include kidney disease which is much more common in senior dogs. More than 1% of all dogs will develop kidney disease during their lifetime.


Excretory signs of kidney failure in dogs may be the following: increased thirst, increased or decreased urination, loss of bladder control, decreased appetite. Bad breath may also be present if kidney failure is caused by a dental problem.


Treatment for acute kidney failure is based on the underlying cause, if this can be determined. For example, antibiotics are often prescribed to treat an infected kidney, while antidotes are given to prevent poisoning.

Dialysis is used to remove toxins from the blood for people with chronic kidney disease. For dogs that are experiencing chronic kidney failure, dialysis is often recommended as treatment which can prolong life or at least provide gentle relief

Various techniques, such as fluid therapy and the use of medication, help patients with diarrhea. Other changes in diet can also be helpful too.

10. Chocolate Poisoning

Most dog owners know that chocolate is toxic to dogs. According to studies, 1 in 3000 cases ends in death so the chance of it being fatal isn’t very high. However, it remains one of the leading causes of canines being poisoned.

Chocolate, primarily containing theobromine and caffeine which are both methylxanthine alkaloids and up to ten times as toxic to dogs as they are humans.

All chocolates do not contain the same amount of these alkaloids. White chocolate, for example has lower levels of methylxanthines than dark/plain chocolate (high cocoa percentage).

Reports show that less than 100g of dark chocolate can kill a 20-pound dog

That’s why small dogs are very susceptible to chocolate as well as those that have a history of pancreatitis, diabetes or heart problems.


Symptoms of a cocoa intoxication in dogs include vomiting, diarrhea, increased urination, panting, pacing and shaking.

If left untreated, animals will go through symptoms like irregular heartbeat, heart attack, tremors and seizures. The symptoms might take up to 72 hours to disappear before the animal completely recovers.


A dog’s reaction to chocolate is very different from a person’s, so their treatment will often depend on the type of chocolate they eat and how much. The vet might prescribe medication to make them vomit and give them activated charcoal to absorb the methylxanthines in the chocolate.

For a minor dog problem, supportive care can help. Fluid therapy is really important for symptoms of hepatic, renal or gastrointestinal toxicosis. In more severe conditions beta-blockers can be used to modulate heart rate.

11. Cancer

Senior dogs over 10 years old are the most at risk for cancer. Cancer is one of the most common diseases in these senior dogs, but more than half its types can be cured before too much havoc has occurred.

A cancer is a group of diseases that are characterized by body cells that multiply rapidly and invade tissues around them.

Most canine cancers are solid tumors, except for leukemia and other blood-related types.

At the same time, environmental factors and genes probably also play a significant role in increasing the risk of cancer among dogs (and people).


Dog’s cancer symptoms are often hard to detect at first – they can be anywhere in the body. The most common are lumps on the skin, unusual odors, sores that won’t heal, weight loss, loss of appetite and lethargy.


The severity and location of cancer impacts how it is treated. Early detection can increase your chances of survival.

There are three treatments for cancer in dogs: chemotherapy, radiotherapy, and surgery. One of these is often enough in mild cases, but a combination of two or three is usually necessary.


While some deadly diseases come from the bite of a dog such as rabies, they can be prevented by vaccinating your pet or taking preventive medicine. Feeding your dog a high-quality diet and giving him/her time to exercise can also help avoid these diseases.

Early detection of these potentially deadly canine conditions can significantly increase the chances of successful treatment. You should go to the vet for regular checkups or if you see any changes in your dog’s health or behavior.

Please call Superior Compounding Pharmacy to speak with one of our licensed pharmacists today at 734-404-6065. We can help answer any medication questions that you may have.