Top 5 Deadly Diseases In Dogs

Top 5 Deadly Diseases In Dogs

Alpha Paw Sale

Jan 08, 2024

Chronic Diseases In Older Dogs

Whether you have a Dachshund or a Greyhound, your four-legged buddy is susceptible to a variety of health issues. And, the older they are, the more they tend to suffer from common chronic diseases such as diabetes, obesity, as well as heart health issues. If you are the owner of a dog that is older than 6 or 7, make sure that you go to the veterinary clinic as soon as you notice any symptoms. Read on to find out what the deadliest diseases that dogs can develop are.

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What Are The 5 Most Common Diseases In Dogs?

There are many medical inflictions that dogs and cats can develop throughout their life, but knowing which of them can be life-threatening and which require immediate veterinary assistance can help your dog live a long, healthy, and happy life. Here are the five most common diseases in dogs that can be deadly.

Dog Cancer

Cancer is a serious disease that affects humans and animals alike. The incidence of dog cancer has increased over the past decades. Not only are dogs now more exposed to carcinogenic substances from food, cleaning products, and other sources, but they live for many more years than they used to.

A dog may be more prone to developing cancer due to hereditary factors, but it could also come into contact with oncogenic viruses spread by other animals.

Depending on the body region where the neoplasm has grown, your pet could show a number of different symptoms. Here are the most common ones:

  • Weight loss
  • Lumps and bumps on your dog’s skin
  • Vomiting, diarrhea, or a commonly upset stomach
  • Difficulty breathing
  • Struggling to urinate or defecate
  • Bad breath
  • Lameness
  • Lethargy or weakness
  • Loss of appetite
  • A repetitive cough

Some dog breeds have a higher risk of developing certain types of cancers. For example, Golden Retrievers and Boxers have a higher likelihood of suffering from lymphoma.

By contrast, Saint Bernards and other large dog breeds can develop severe cancer of the musculoskeletal system.

Depending on the exact type of tumors that your dog might have developed, the vet can recommend a variety of treatments. The most common ones that exist now are surgery, radiotherapy, and chemotherapy.

Sometimes, the vet could also recommend combination therapy using two of these treatment methods. In any case, if you notice any of these symptoms and if the changes seem to affect your dog’s quality of life, it’s important to go to the vet hospital as soon as possible. A dog’s immune system might not be able to fight off all sorts of diseases, especially cancer, and you can never know if your canine friend has a potentially deadly form.

Canine Parvovirus

Despite it being completely preventable, canine parvovirus remains one of the highly contagious and life-threatening diseases that a dog can get. Puppies are more likely to have the deadly form of the disease as their immune response might not be up to par.

Dogs can get the pathogen from other infected animals if they are not vaccinated against the disease. Some of the symptoms that you can see in a dog that has this infection are the following:

The digestive symptoms themselves wouldn’t be as dangerous if they weren’t a result of this serious infection. The biggest problem is that the dog gets extremely dehydrated, and dehydration can quickly lead to death.

Mothers that are vaccinated against this condition usually transmit a partial immunity to their puppies, but it is not a long-term form. That is why vets recommend that all puppies are vaccinated against parvo when they get to six or eight weeks of age.

Parvo affects dogs regardless of gender or breed. Talk to your veterinarian about what vaccination plan they recommend.

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Canine Distemper

Canine Distemper is another potentially fatal disease that some dogs can get. The virus, in this case, affects a wide array of systems. Some dogs can develop the respiratory form while others can have their eyesight affected significantly.

Canine distemper is a serious and highly contagious disease that can be prevented through vaccination. Puppies can spread it through their bodily fluids, including their nasal discharge, saliva, and urine.

One type can lead to another, so the dog might start with breathing difficulties, then develop gastrointestinal complications, and finally lethargy and seizures. Here are some other symptoms that can be noticed in dogs that have this infection:

Distemper can initially produce symptoms that are similar to another infectious disease of dogs, kennel cough. Testing is available for this viral disease at most vet clinics across the country.

Kidney Disease In Dogs

Even though kidney disease is more common in older dogs, it is a relatively common canine health issue in general. If its causes are medications and not infections, it is not contagious.

The biggest issue with kidney failure is that it produces unspecific signs. Some dogs might show bad breath and suffer from dental disease, which can produce renal complications.

All diseases of the urinary tract are preventable to one point. However, when the kidneys are affected, the treatment might not be as effective.

Urinary tract infections can be easier to treat but once the major functioning unit of the kidney, the glomerulus, becomes damaged, the animal can lose the organ’s ability to filter out toxins and produce urine. Some of the clinical signs that this condition is characterized by are the following:

Some dog breeds have a higher risk of developing kidney disease, such as Bull Terriers, German Shepherds, and English Cocker Spaniels. Kidney disease is also more common in animals that have a history of UTIs, but also those that suffer from diabetes.

Lyme Disease In Dogs

You might think that Lyme disease isn’t as serious as other medical problems that we have showcased in this selection, but this is an incorrect assumption.

There are many diseases that vectors such as ticks can transmit to our canine friends, including Lyme disease. The worst part is that some pet parents might not be aware of the symptoms that the bacterium causes, which is why they might not seek out vet assistance.

The infection can be deadly in some cases as it can produce severe nephritis. Although it is a side effect, it can lead to kidney failure, which as we have previously mentioned, is practically untreatable. The clinical signs of the infection are also unspecific and could be mistaken for any other infection:

  • Fever
  • Appetite loss
  • Reduced energy
  • Generalized pain
  • Inflammation of the joints
  • Lameness
  • Vomiting, diarrhea, weight loss, and anorexia

The kidney form is the most severe and fatal type of Lyme disease that dogs can develop. Infected animals cannot pass the pathogen to other dogs in their living environment as the primary vector is the tick, not body fluids.

Although mild forms of this disease can be treated with antibiotics such as doxycycline or azithromycin, the treatment might be ineffective if the kidneys were affected.

Top Dog Supplements for a Strong and Resilient Immune System

Empower your furry friend’s health with our carefully selected range of top dog supplements, specifically formulated to fortify and bolster their immune system. A robust immune system is crucial for dogs to ward off illnesses and maintain overall well-being.

Zesty paws 8-in-1 multivitamin mini soft chews for small dogs – glucosamine & chondroitin for hip
  • Zesty Paws Multifunctional Bites are made with premium ingredients that support physical performance, antioxidants, hip and joint, heart, immune, skin, liver and gut health.
  • For animals with sensitive skin, this formula contains cod liver fish oil and vitamin E to help maintain normal moisture plus CoQ10 to help reduce oxidative stress.
  • Each dog chew features a premium form of MSM for muscular support, which works synergistically with glucosamine HCl and chondroitin sulfate for hip and joint support—plus, cod liver oil and B-complex vitamins support normal physical performance.
  • These chews also contain a six-strain gut health blend—with over 500 million CFU per chew—and a digestive health blend to promote gut flora while supporting normal bowel function for dogs.
  • Paw-fect for dogs of all ages, breeds and sizes.
Zesty paws multifunctional bites
  • Zesty Paws Multifunctional Bites are made with premium ingredients that support physical performance, antioxidants, hip and joint, heart, immune, skin, liver and gut health.
  • For animals with sensitive skin, this formula contains cod liver fish oil and vitamin E to help maintain normal moisture plus CoQ10 to help reduce oxidative stress.
  • Each dog chew features a premium form of MSM for muscular support, which works synergistically with glucosamine HCl and chondroitin sulfate for hip and joint support—plus, cod liver oil and B-complex vitamins support normal physical performance.
  • These chews also contain a six-strain gut health blend—with over 500 million CFU per chew—and a digestive health blend to promote gut flora while supporting normal bowel function for dogs.
  • Paw-fect for dogs of all ages, breeds and sizes.
Googipet 10 in 1 dog multivitamin with dog probiotics for gut health, dog vitamins and supplements w
  • Tasty chicken and veggie flavored chews offer 10 benefits and are paw-some for small, medium and big dogs.
  • Glucosamine supports joint health, mobility and flexibility.
  • Probiotics, pumpkin and vitamins support improved digestion for happier tummies.
  • Egg shell meal and omegas from krill oil and flaxseed help to heal dry skin and support coat strength, shine and health.
  • Vitamin blend supports immune system and heart health.
Nutri-vet senior-vite chewables for dogs - daily vitamin and mineral support for senior dogs to help
  • Made in the USA with your dog’s wellbeing in mind.
  • Paw-fect for boosting the general health of all ages, breeds and sizes.
  • Packed with vitamins, minerals and essential fatty acids.
  • The delicious taste of liver makes it hard to turn down these chewables.
  • Created from quality ingredients with the highest standards.
Ancient elements 8-in-1 bites for dogs - joint, skin, gut, immune, heart, antioxidant, performance &
  • Ancient Elements 8-in-1 Bites are a multifunctional soft chew that supports 8 areas of dog functional wellness for any small, medium, and large breed.
  • Includes Glucosamine, Chondroitin Sulfate, and OptiMSM support hips, joints, and cartilage. B-Complex vitamins in this daily pet formula aid muscles, mobility, and physical performance.
  • Includes DE111 a proprietary digestive health blend (with Amylase & Bromelain) and vitamin C to support digestion and immune function.
  • Each chew provides antioxidants for free radical support, while Vitamins A, C, and E maintain liver function for dogs.
  • Vitamins E, B Complex vitamins (including Biotin) support skin health, while Kaneka Q10 (CoQ10) and Vitamin D3 support cardiovascular health.

Other Potentially Deadly and Common Health Problems of Dogs

There are many other common dog diseases and they range from ear infections to intestinal parasites, viral and bacterial infections, and kennel cough, which is known to be highly contagious.

In the section below, we’ve showcased some other potentially deadly diseases that a dog may develop throughout their life.

Top 5 deadly diseases in dogs


Gastric dilatation volvulus is a relatively common canine health problem that affects all dogs, but particularly large breeds. It is an emergency and should be treated as such, so if you notice any of the following symptoms in your dog, you should go to the vet clinic as soon as possible.

Bloat occurs when a dog eats their food too fast or drinks too much water at once, after spending time in the sun or exercising for a long time. In this case, the dog’s stomach becomes so full that it twists around its own axis, blocking the blood flow to and from other organs.

The stomach can be compared to a fatal ball that puts pressure on other abdominal organs and in some cases, it even modifies their position. It’s not uncommon for dogs that have developed bloat to have their spleen removed, and this is merely an example. If your dog ate a large amount of food and they’re showing the following signs, get to the veterinary hospital right away:

  • Retching without being able to produce any vomit
  • Restlessness
  • A large abdomen (could be challenging to tell in fluffy or deep-chested dog breeds)
  • Excessive salivation

This condition is more common in breeds such as Great Danes, Standard Poodles, German Shepherds, or Boxers.

Addison’s Disease In Dogs

Addison’s Disease is an autoimmune dog disease that is characterized by the inability of the pet’s adrenal glands to function properly. These glands are in charge of secreting two essential hormones, cortisol and aldosterone, which are extremely important in regulating a variety of processes in your dog’s body.

Although the causes of this disease remain unknown to date, it is more likely to affect certain dog breeds such as Bearded Collies, Standard Poodles, Soft Coated Wheaten Terriers, or West Highland White Terriers.

Moreover, the condition is one of the most confusing dog diseases that affect this species as it often produces unspecific symptoms. Dogs can experience loss of appetite, gastroenteritis, or other health problems such as diarrhea, abdominal pain, weight loss, lethargy and depression, or hair loss.

Other symptoms include the following:

  • Blood in the stools
  • Increased thirst and urination
  • Hypoglycemia
  • Hyperpigmentation of the skin
  • Shaking

Even though it might not be one of the most common dog diseases that can affect our canine friends, Addison’s disease is one of the most challenging one to manage. Even the diagnosis is difficult since the dog often shows so many symptoms that a lot of tests have to be performed to find out what they are suffering from.

After being diagnosed, most dogs have to take steroids for the remainder of their life, usually prednisone and a monthly shot of a mineralocorticoid. Some dogs might also need increased doses of cortisol and aldosterone if they’re about to go through stressful events such as moving homes or surgery.

Liver Disease In Dogs

Liver health problems are some of the most common dog diseases that exist today and the condition can be of an infectious nature or it can appear as a result of diet deficiencies, obesity, and other complications that senior dogs are likely to experience as they age.

On the other hand, Canine Hepatitis is a viral disease that can often be mistaken for Canine Distemper as it produces somewhat similar symptoms. It is highly contagious and can pass from one dog to the next.

Infected dogs spread it through their urine, feces, saliva, and blood. For this reason, if you notice any signs, you should get in touch with your vet and also confine your dog so that they do not come in contact with other animals. Rubarth disease can produce the following symptoms:

  • Loss of appetite
  • Depression
  • Abdominal pain
  • Coughing and nasal discharge
  • A high body temperature
  • Vomiting
  • Pale gums
  • Jaundice

Some signs of liver disease can appear in other conditions, too, such as Canine Babesiosis, which a dog can get if they were bitten by a carrier tick.


Even though intoxication is not a dog disease per se, we decided to include it on this list as it can be very dangerous and even lethal. After becoming a dog parent, we recommend that you do a bit of research as to what things in your household could be toxic to dogs.

You wouldn’t believe the number of household products that can be toxic to pets, from food to decorative plants and cleaning supplies. Here are several examples:

  • OTC medications such as Tylenol or Advil
  • Prescription medications for kidney failure, ulcers, depression, or lowering blood pressure
  • Food such as avocados, macadamia nuts, grapes and raisins, chocolate, onion, or garlic
  • Rodenticides (rat and mouse poison)
  • Plants such as tulips, daffodils, azaleas, or sago palms
  • Antifreeze
  • Fertilizers, pesticides, weed killers, heavy metals

Poisoning is a veterinary emergency and it can cause a variety of symptoms. Not all of them are specific, so you might not notice the same signs if your dog ate rat poison or if your dog got into the medicine cabinet and somehow ingested Tylenol. Here are some general poisoning signs to be on the lookout for:

  • Digestive distress signs such as loss of appetite, diarrhea, vomiting, retching
  • Internal bleeding can lead to pale gums, vomiting blood, lethargy, increased pulse
  • Liver failure can cause vomiting, diarrhea, tarry stool, or collapse
  • Kidney failure can cause clinical signs such as increased thirst and urination and loss of appetite

Time is of the essence if you believe your dog has been poisoned. You should get to the veterinary hospital in your area as soon as possible, but it definitely wouldn’t hurt if you also called ASPCA’s Animal Poison Control to know what to do until you reach the clinic.

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Kennel Cough

As its name suggests, kennel cough is is a common dog disease that affects the respiratory system of pets that live in larger communities. For this reason, breeders have to vaccinate all of their dogs against kennel cough as soon as that is possible.

Kennel cough is not a viral disease as it is produced by a bacterium called Bordetella bronchiseptica. It is a highly contagious disease and a pet that gets it can show the following signs:

  • Sneezing
  • Nasal discharge
  • A strong and recurring cough
  • Lethargy
  • A low fever
  • Tiredness after exercising for just a couple of minutes

One of the best things about kennel cough (if there are any) is that it can be treated with antibiotics. In fact, the kennel cough pathogen is quite sensitive to many antibiotics currently used by veterinary professionals, including Doxycycline or Clavamox.

However, in some cases, especially in puppies or dogs that are already suffering from other chronic health issues, the prognosis might not be as optimistic. The infection can be lethal if the pet’s immune response is not up to par.

Fungal Diseases

You might not be tempted to think that canine fungal diseases can be fatal, especially since they tend to affect the dog’s skin and rarely cause any severe symptoms. But the truth is that there are four different types of fungi that are likely to affect dogs in North America and some are worse than others, being able to produce damage in a variety of organs, including the internal ones.

Valley Fever is one of the most common dog diseases that is produced by fungi. It tends to affect dogs in California, Texas, and Arizona the most, and it produces a range of symptoms, mostly relating to the respiratory tract.

Blastomycosis tends to affect our canine friends in the Eastern U.S. river basins and the Great Lakes area. Like Valley Fever, this canine disease can produce respiratory symptoms, but it can also cause other clinical signs such as skin lesions (including hair loss) and loss of appetite.

Because they are not as common as viral disease or bacterial infections, conditions caused by fungi can often be misdiagnosed. It’s true that the pathogens are less widespread in the animal world compared to other microorganisms, but extensive testing can lead to a correct diagnosis and a correct treatment.


Unfortunately, diabetes in dogs has become one of the most common canine diseases to date. According to a study performed by the Banfield Pet Hospital, which included over 2 million dogs, there was a 32% spike in diabetes diagnoses between 2006 and 2010.

Diabetes affects your pet’s pancreas, and since the pancreas is one of the most important organs in your dog’s body, treating the disease can be quite challenging. The amount of insulin secreted by the pancreas might be insufficient or the organ might completely lose its ability to secrete any.

Some of the symptoms you can see in a dog that suffers from diabetes are the following:

  • Continuous thirst
  • Excessive urination
  • Inexplicable weight loss (some dogs are ravenous and consume large amounts of food and still lose weight)
  • Problems with eye vision (cloudy eyes, incoordination, or hitting themselves on furniture by accident)
  • Lackluster skin and coat

If your pet is showing any of these symptoms, contact your vet right away. Diabetes can be fatal if your dog doesn’t receive the insulin shot that it might need. Any animal in such a situation can slip into a diabetic coma and die within two to three days if they don’t get veterinary assistance.


The Leptospira bacterium can commonly affect dogs across the world. If a pet gets infected, they begin eliminating the pathogen through their body fluids. Another way dogs can get the disease is by eating a rodent since rats are usually vectors of Leptospirosis.

Even though the survival rate of Leptospirosis is estimated to be 90% in dogs, it is highly contagious, and worst of all, it can be transmitted to humans. There is a vaccine available, so if you do not want to risk your health and that of your family, we strongly advise you to ask your vet to add the shot to your puppy’s vaccination plan.

Leptospirosis can cause the following symptoms:

  • Exercise intolerance
  • Lethargy
  • Increased thirst
  • Increased urination
  • Shaking
  • Loss of appetite
  • Muscle stiffness

On a positive note, we would like to add that in spite of the symptoms it causes and their potential severity, leptospirosis is treatable with antibiotics that can be commonly found in all vet hospitals — such as penicillin and doxycycline.


Rabies is considerably less common these days as pet parents typically vaccinate their dogs against it, so they’re less likely to get it, rabies is extremely dangerous. Infected animals spread the virus through their saliva, so if your dog gets bitten by a wild animal as you walk them through the woods, this can be a very serious health problem.

The worst thing about rabies is that there is no treatment available at this time. The virus can spread through the dog’s body gradually and it causes three different forms, one of which will make the animal become extremely aggressive and likely to bite anything and anyone in their surroundings.

It’s also not uncommon for dogs that have been infected with rabies to experience significant behavioral changes. A dog that might have been energetic could experience pain or lethargy while one that was affectionate for all of its life could suddenly become very violent.

Rabies can be transmitted to humans through the bite of animals, so contacting your local animal control so that they can restrain and confine your dog is of utmost importance. To date, there is no report of humans surviving after being infected with the rabies virus, so it is considered highly infectious and lethal.

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Preventing Fatal Disease in Dogs


As you might have noticed from the information that we have included in this article, many of the deadly diseases in dogs are completely preventable. Some, such as kidney failure or liver failure might not be preventable and they can affect dogs depending on a variety of factors.

However, all of the other conditions that are caused by microorganisms such as viruses and bacteria can be prevented by getting your dog immunized against the infections.

There are various veterinary vaccination plans depending on the area where you live. For example, your veterinarian might not necessarily insist your puppy get the vaccine against Lyme disease if you don’t live in a region of the country where there’ve been many cases reported.

On the other hand, even if the kennel cough vaccine is considered a non-core one, your veterinarian might advise you to get your puppy vaccinated, especially if you are a breeder and there is more than one animal living in your household.

The best way of going about things is to get your dog immunized against as many diseases as possible, especially since some of them, such as rabies or Leptospirosis, can be transmitted to humans.

Regular Check-Ups

All dogs should get a checkup at least once a year. Although you might think that a regular check-up might be completely unnecessary as your dog seems to be perfectly healthy, the truth is that tests can reveal conditions that might not have caused severe symptoms yet.

For example, diagnosing cancer in one of its incipient stages can prevent it from spreading to other organs. Therefore, treatment will be easier and more effective and your dog isn’t going to develop tumors in other parts of its body.

A simple blood test can reveal deficiencies and potential autoimmune or hormonal imbalances and if your dog has a cough or has been vomiting for a while, they could be diagnosed with a specific infection and receive the right antibiotics after a bacteriologic culture and antibiogram.

Protecting Your Dog Against Poisoning

Keeping your dog away from poisonous products or things in any home isn’t that difficult. For example, you could keep your antifreeze in a designated locked cabinet, and your dog will have no means of getting into it.

Keep your medications in a safe place and label them correctly so that in case your dog does ingest anything, you know what they’ve had and you can tell your veterinarian. Never keep poisonous plants in your home and try to keep an eye for any when you walk your dog outdoors.

Don’t allow your dog to receive food and treats from other people, especially strangers, as this could lead to a habit and they could be poisoned by a person. It might not be a common occurrence, but it shouldn’t be overruled.

Use pet-friendly cleaners that don’t risk irritating your dog’s mucous membranes or respiratory tract. Don’t ever give an animal any low-calorie products, especially those that could contain artificial sweeteners such as xylitol.

Teach your dog not to beg for food at the dinner table so as to avoid having them ingest potentially dangerous ingredients such as raisins or grapes, onion, or garlic.

Alpha Paw Sale
author image

Dr. Christina Vulpe, DVM

Member of Alpha Paw’s Board of Pet Experts

Dr. Cristina Vulpe is a board-certified small animal veterinarian. She earned her veterinary degree in 2011 from USAMV in Iasi, Romania, and her PhD in Canine Oncology in 2015 from USAMV in Cluj-Napoca, Romania. She is passionate about anything from animal nutrition & welfare to veterinary parasitology & infectious diseases. As a responsible pet parent herself, she enjoys giving reliable medical advice that pet owners can trust, which is why she joined Alpha Paw’s Board of Pet Experts on our mission to help our readers give their pets the happy & healthy lives they deserve.


The medical, nutritional, or behavioral advice we provide is intended for informational and educational purposes only. Our editorial content is not a substitute for formal or personalized medical advice from a veterinary professional. Only board-certified veterinary specialists who have examined your pet should diagnose medical conditions, provide personalized treatment, or prescribe appropriate medication. For questions regarding your pet’s health, or if your pet is exhibiting signs of illness, injury, or distress, contact your veterinarian immediately. Never disregard professional medical advice or delay in seeking it because of something you have read on our site.