9 Common Dog Diseases and Conditions (Treat and Prevent)

If it were up to us, no dog would fall sick or suffer from serious or chronic diseases. But reality says otherwise. Knowing these common dog diseases might prepare you and helåp you recognize them before they become a problem.

Genetic predispositions, bacterial and viral infections, parasite infestations, intoxication from flowers and plants, swallowing objects, and lack of proper care and nutrition, are all reasons that cause disease and sickness in dogs. 

9 of the most common dog diseases:

  1. Dental disease
  2. Otitis Externa
  3. Intestinal parasites (Roundworms, Hookworms, Tapeworms, & Whipworms)
  4. External parasites (Fleas, Ticks, Ear mites, & Mange mites)
  5. Heartworms 
  6. Lungworms
  7. Cancer
  8. Diabetes
  9. Cushing’s Disease

This article will give you the fundamental facts every dog owner should know about each of these dog diseases and health conditions. Let’s dive right in!

Dental Disease

The umbrella term dental disease describes the inflammation of the structures supporting teeth and gum tissues. It is one of, if not the most common dog diseases. In fact, a 2017 study by Statista lists dental disease as the most prevalent medical condition among dogs in the US, with 77 out of every 100 dogs suffering from dental disease. 

A dog being checked up by a doctor for dental disease.

The Veterinary Centers of America (VCA) also name dental disease among high prevalence dog diseases and indicates that 80% of dogs older than 3 years have active dental disease.

Those statistics are alarming and would leave anyone wondering: What causes canine dental disease?

Canine dental disease is caused by plaque buildup, the sticky food deposits that stay on teeth and create the environment for the proliferation of bacteria.

Symptoms of Canine Dental Disease

If your dog has dental disease, it will present the following signs and symptoms:

  • Inflamed and/or bleeding gums.
  • Bad breath.
  • Pain when drinking or eating.
  • Discolored teeth (yellow or brown).
  • Missing or loose teeth.
  • One-sided chewing.
  • Excessive drooling.
  • Bloodstains on toys or water bowls.
  • Dog is easily irritated.
  • Reduced appetite.
  • Loss of weight due to poor eating.

Types of Canine Dental Disease

There are several types of canine dental disease, including the following:

  • Periodontal disease (most common)
  • Fractured teeth.
  • Tooth cavities.
  • Tooth decay (least common).

Canine Dental Disease Treatment & Prevention

The treatment for canine dental disease entails dental cleaning to remove tartar buildup, dental scaling and polishing, and treatment with antibiotics pre or post-dental cleaning and scaling.

Check with your dog’s vet about the best dental disease treatment for your dog.

Preventative measures for canine dental disease include daily canine teeth brushing, routine dental cleaning, and appropriate dog food.

Otitis Externa

Otitis externa is the inflammation of the layers of cells in a dog’s ear canal, the tubular part of the outer ear that delivers sound to the eardrum. It is the most common infection of a dog’s ear.

Photo Credit: dr.zonramliao

In the US, Otitis Externa was found to be the third most common canine disease by the earlier mentioned Statista study, with 16 out of every 100 dogs suffering from the infection. In the UK, a recent 2021 study found that Otitis media was the second most prevalent dog disease after periodontal disease. 

Causes of Otitis Externa in Dogs

Otitis media in dogs can be caused by one of these risk factors:

  • Parasites. 
  • Foreign objects in the ear.
  • Allergies.
  • Bacterial and ear infections.
  • Infection of the middle ear.

Otitis Externa Signs and Symptoms

Your dog may have Otitis Externa if he’s showing the following signs and symptoms:

  • Head shaking.
  • Redness of the skin in the ear canal.
  • Swelling.
  • Itchiness and scratching.
  • Smelly discharge.
  • Scaly ear canal skin.

These symptoms can appear suddenly or be long-term. Also, Otitis Externa can affect one or both ears of your dog. 

Breeds with floppy, hairy ears are more prone to Otitis Externa. They include the Miniature Poodles, the Cocker Spaniels, and the Old English Sheepdogs.

Otitis Externa Diagnosis

To diagnose Otitis Externa in your dog, the vet will seek a detailed history of your dog’s health, examine the dog’s ear with an otoscope, and make a thorough physical and skin, exam to determine the cause of the infection. 

A smear on a cotton applicator or a lab test of the discharge from the ear can also be done for precise diagnosis.

Otitis Externa Treatment

The general treatment for Otitis Extern combines antibiotics to control the infection, antifungal meds, and glucocorticoids to control the inflammation

Topical meds can also be applied, but your dog’s vet will first clean any ear discharge, which could inactivate the medication.

Intestinal Parasites

Intestinal parasites are organisms that live inside a dog’s digestive system, taking their nutrition from the dog.

Photo Credit: comfortathomepet

The parasites are often passed from dog to dog through infected stool when a dog eats contaminated soil, drinks contaminated water or licks contaminated paws and fur. 

Dogs with intestinal worms can become easily malnourished because of the stolen nutrients by the parasites, diarrhea, or loss of blood in feces in some cases.

Some of the common intestinal parasites in dogs include:

  1. Roundworms
  2. Hookworms
  3. Tapeworms
  4. Whipworms


Roundworms are the most common intestinal parasites in dogs. The majority of dogs get infected with roundworms at least once in their lifetime. 

Roundworms are highly passable from dog to dog and from mother to puppy. Some puppies are born already with roundworms, and others get them from ingesting worm larvae from their mother’s milk. Dogs can also swallow roundworm larvae in mice or other small animals when they eat them.

The symptoms of roundworms in dogs include:

  • Diarrhea. 
  • Vomiting.
  • Weight loss.
  • Dull coat.
  • A pot-bellied appearance
  • Cough (if the roundworms move to the lungs).
  • Adult roundworms in dog’s feces.

Roundworms are diagnosed by testing your dog’s stool through fecal floatation.

Monthly preventative medication is used for the prevention and treatment of roundworms. This is especially essential for pregnant dogs, so they don’t pass the roundworms to their pups. 

Keeping your dog’s space free of feces and preventing the dog from eating wild animals is also an important preventative move.


Hookworms are intestinal parasites that live in a dog’s digestive system. They attach themselves to the intestinal wall lining and feed on the dog’s blood.

Dogs get hookworms in several ways:

  • They ingest the eggs that drop into the soil from the feces of infected dogs.
  • Hookworm larvae penetrate the dog’s skin.
  • The mother passes hookworms to the puppy while pregnant.
  • The puppy ingests hookworm eggs from the mother’s milk.

Common symptoms of hookworms include:

  • Diarrhea (could be bloody).
  • Weight loss.
  • Anemia.
  • Dull coat.

Treatment and prevention of hookworm are successfully done with monthly dosages of anthelmintics. As with roundworms, it is important to keep your dog’s space free of feces and conduct regular fecal tests to ensure your dog is not silently harboring hookworms.


Tapeworms are flat and segmented intestinal parasites belonging to the Cestode class of intestinal worms

There are many types of tapeworms. In dogs, the most common type is known scientifically as Dipylidium caninum.

Dogs get tapeworms by ingesting fleas with tapeworm eggs. Fleas are the intermediate hosts, and dogs cannot get tapeworms directly from eating tapeworm eggs from the environment.

Once a dog ingests a flea with tapeworm eggs, the tapeworm attaches to the wall of the small intestines with its hook-like mouth.

Adult hookworms can grow up to 11ʺ (30cm) long. As hookworms mature, the segments (proglottids) are expelled in the feces. You can easily pick them from fresh dog excreta as they look like rice grains. You may also see them moving on the fur around your dog’s anus. A tapeworm segment can harbor up to 20 tapeworm eggs.

A dog with tapeworms will show the following signs:

  • Retarded growth, especially in puppies.
  • Diarrhea 
  • Anemia.
  • Intestinal blockage.
  • Scooting (dog drags their bottom on the ground).
  • Irritability.
  • Unpredictable appetite.
  • Shaggy coat

Tapeworms in dogs are diagnosed by observing the presence of the proglottids in a dog’s feces or through fecal flotation

Occasionally, an entire tapeworm may detach from the intestinal wall and be expelled through the anus or vomited.

The treatment of tapeworms is done with deworming medications such as Epsiprantel, Praziquantel, and Nitroscanate

The primary preventative measure for tapeworms in dogs is flea control, as fleas are the intermediate hosts that bring tapeworm eggs to your dog’s intestines.


Whipworms are intestinal parasites that live between the small and the large intestines or inside the large intestines

These worms can grow up to a quarter-inch (6mm) and cause a lot of irritation. In fact, compared to roundworms, hookworms, and tapeworms, whipworms cause the most disease.

Dogs are infected with whipworms by ingesting their eggs from soils or other substances contaminated with the feces of infected dogs.

Typical symptoms of whipworms in dogs include:

  • Watery, bloody diarrhea.
  • Loss of weight.
  • General weakness.

Note that whipworms can be fatal if left untreated.

Whipworms in dogs are diagnosed by testing multiple stool samples under a microscope to detect the presence of whipworm eggs.

The treatment of whipworms in dogs is done with several drugs, including Febantel, Milbemycin, Fenbendazole, Oxante, and Moxidectin. Because whipworms are extremely hard to treat and recur easily, dogs diagnosed with whipworms should be treated every 3 to 4 months.

Whipworms infection in dogs can be prevented by maintaining high hygienic standards in your dog’s space and ensuring dog feces are removed immediately. Also, annual tests for whipworms can facilitate an early diagnosis.

External Parasites

External parasites or ectoparasites are organisms that live on the external of a dog’s body. These parasites cause skin itching and irritation through their bite or movement. In addition, they can transmit other diseases and cause health complications for your dog if not addressed on time.

Ear mites is a common disease for dogs
Photo Credit: mirzoovet

The most common external parasites living on dogs are:

  1. Fleas
  2. Ticks
  3. Ear Mites
  4. Mange mites


Fleas are blood-sucking parasites that bite and cause irritation and itchiness on your dog’s skin. Different types of fleas can live on your dog’s coat, including:

  • Cat fleas,
  • Dog fleas,
  • Rat fleas, and 
  • Human fleas.

Your dog can get fleas from other dogs and pets or by visiting areas infested by the parasites. Some examples might be dog boarding and training centers or grass in the outdoors.

The best way to treat and prevent fleas on your dog is to give a monthly flea preventative pill. Some of the most common flea preventative pills include Sentinel, Trifexis, and Bravecto.

You can also prevent fleas on your dog by maintaining high hygienic standards and using natural flea deterrents such as citronella, lavender, cedar, eucalyptus, and rosemary.  


Ticks are tiny blood-sucking parasites with a shape similar to that of spiders. Your dog can pick ticks from grass or bushes or other pets carrying them

Once on your dog’s coat, ticks attach to the dog’s skin with their mouthparts and continuously feed on the pet’s blood. 

If you live in grasslands or woodlands, your dog is more likely to get ticks. Ticks are more active in autumn and spring.

You can easily notice ticks on your dog’s coat, especially if they are puffed up from sucking blood. The skin where the tick attaches turns red and sore with time and can feel itchy or painful.

Ticks are also known to transmit diseases. One of the most common tick-transmitted diseases is Lyme disease.

Lyme disease is a serious bacterial infection that can manifest in a range of symptoms. Some examples are fever, loss of appetite, depression, lethargy, swollen and painful joints, swollen lymph nodes, and eventually lameness.

Do not wait for ticks to cause illness to your dog. Ticks can be removed from your dog using a tick removing tool like the TickCheck Tick Remover from Amazon.com. 

However, the best way to deal with ticks is to use tick preventative and/or deterring drugs. These can be topical spot on treatments or oral tablets. Talk to your dog’s vet about the best tick treatment for your dog.

Ear Mites

Ear mites are tiny parasites that live on the surface of your dog’s ear canal and are barely visible to the human eye

A dog whose ear is infested by ear mites will present these symptoms:

  • Brownish ear wax that mimics coffee grounds.
  • Consistent ear scratching or head shaking due to itchiness and irritation.
  • Red and inflamed ears.
  • Skin rashes around the ears.

Successful treatment and prevention of ear mites can be done with spot-on flea treatments. Your dog’s vet may also prescribe eardrops to get rid of ear mites.

Mange Mites

Mange mites are microscopic parasites that cause a serious disease called canine mange. Depending on the type of mange your dog is suffering from, mange mites will:

  • Live under the skin surface of your dog –  Sarcoptic Mange
  • Live in the oil glands or air follicles of your dog’s skin – Demodectic mange

Sarcoptic mange is passed from dog to dog through direct contact, while Demodectic mange is passed from mother to puppy in the first days after birth. 

The symptoms of Sarcoptic mange include intense itching, loss of hair, red and inflamed skin, open skin sores, crusty skin, and yeast and bacterial infections

The symptoms of Demodectic mange include red, inflamed skin, skin crusts, and secondary skin infections.

In both types of mange, treatment consists of dips, topical creams, and oral meds. Talk to your doctor about the best mange treatment for your dog.


Heartworm is a serious disease in dogs caused by a parasitic worm known as Dirofilaria immitis. These worms are spread in dogs through mosquitos.

Heart of a deceased dog with heartworms.
Photo Credit: january_emberrr

Mosquitoes are only an intermediate host for heartworms. Dogs however are the definitive host of heartworms where these parasites mature and reproduce. Adult heartworms can live in your dog’s heart, lung, or other blood vessels.

Dogs with heartworms are at the risk of heart failure, severe lung disease, and other organ damage.

According to the U.S. Food & Drug Administration (FDA), heartworm disease is most common along the Gulf and Atlantic coasts. This is including the Gulf of Mexico, New Jersey, and the Mississippi River. However, heartworms have been reported in all the other states.

Symptoms of Heartworms in Dogs

Dogs with heartworms will show the following signs and symptoms:

  • Coughing (which becomes persistent in later stages).
  • Fatigue.
  • Difficult breathing and signs of heart failure.
  • Changes in heart and lung (seen through x-rays).
  • Caval syndrome (blockage of blood flow from the heart by the worms in some dogs).

Heartworm Diagnosis

Vets diagnose heartworms by testing blood for heartworm proteins (antigens) or microfilariae in the bloodstream.

Heartworm Treatment and Prevention 

The treatment of heartworms in dogs can be done with:

  1. Melarsomine dihydrochloride (Immiticide & Diroban) – given in deep injection into the dog’s back muscles.
  2. Advantage Multi (imidacloprid & moxidectin) – a topical solution used to remove microfilariae in the dog’s bloodstream.

However, it is best to prevent your dog from getting heartworms by giving heartworm preventative topical or oral drugs. Talk to your dog’s vet about these medications, as they are prescription-only drugs.

The American Heartworm Society advocates for the ‘Think 12’ approach. This means testing your dog for heartworms every 12 months, as a preventative and timely detection measure.


Lungworms are emerging parasites in dogs caused by one of the many parasitic roundworms. According to the VCA, there are many types of parasitic lungworms. The one that affects dogs in North America is the Eucoleus aerophilus.

Photo Credit: paulinka_vet

Dogs are infected with lungworms by eating their larvae in infected frogs, slugs, or snails. Once in the dog, the lungworm larvae grow to adulthood. Then the worm move through the dog’s body to thrive in the trachea, bronchi, heart, or other blood vessels.

Lungworm Symptoms

The symptoms of lungworms in dogs include:

  • Coughing, sneezing and wheezing.
  • Fatigue.
  • Difficult breathing and pneumonia.
  • Longer-than-usual bleeding in case of a cut.
  • Atypical blood clotting.

Lungworm Diagnosis

Veterinarians will diagnose lungworms by examining a sample of your dog’s stool. X-rays are also taken to detect abnormal nodules or spots in the chest, the lung lobes, or the upper airways

Lungworm Treatment and Prevention

The treatment for lungworms consists in giving antiparasitic meds. Examples of these are Fenbendazole (Panacur™), Ivermectin, Milbemycin Oxime+praziquantel (Interceptor Plus™), and Moxidectin+Imidacloprid (Advantage Multi™). Hospitalization and oxygen therapy may be considered for dogs with severe disease.

Prevention for lungworms can be enhanced by regular lungworm treatment. Talk to your vet if your dog shows signs of lungworms and you’ve noticed slugs or snails in your compound.


Canine cancer is one of the most common killer diseases among dogs. As a matter of fact, cancer is responsible for almost half of all deaths among dogs over 10 years of age. Approximately 6 million new dog cancer cases are diagnosed each year

Photo Credit: welovecuddly

As in humans, the cause of canine cancer is elusive. However dogs suffer from the same cancers that humans suffer from, including prostate cancer.

The most common cancers among dogs include:

  • Lymphoma
  • Mast cell tumors
  • Osteosarcoma
  • Melanoma
  • Mammary gland carcinomas
  • Hemangiosarcoma

Canine Cancer Warning Signs

If you suspect that your dog may be suffering from cancer, pay attention to these warning signs. Some of which are similar to those in humans: 

  • A lump or bump or any kind of swelling.
  • A wound that does not heal.
  • Changes in normal functions (eating, drinking, sleeping, peeing, and defecating).
  • Loss of appetite and weight loss.
  • Bleeding or body discharges.
  • Difficulty breathing, eating or swallowing.
  • Difficulty defecating or urinating.
  • Lameness.

Canine Cancer Diagnosis

Vets will usually ask you to give a history of your dog’s health and pay attention to any lumps and swellings on your dog’s body. X-rays, abdominal ultrasounds, and biopsies are common ways of testing your dog for cancer. 

Your dog’s vet may also use abnormal blood work results to proceed to more conclusive cancer tests.

Canine Cancer treatment

Even though not every cancer in dogs is treatable, most cancers in dogs can be treated if detected early

Until recently, cancer in dogs was treated with the same meds used in humans. Today, however, there are meds specifically approved for treating cancer in dogs.

The FDA has approved these four drugs for the treatment of canine cancer:

  • Palladia (Toceranib Phosphate).
  • Stelfonta (Tigilanol Tiglate Injection).
  • Tanovea-CA1 (Rabacfosadine Injection).
  • Laverdia-CA1 (Verdinexor Tablets).


Canine diabetes is a chronic insulin deficiency disease caused by insufficient insulin production in a dog’s pancreas

Photo Credit: havepumpwilltravel

Depending on the type, insufficient insulin production makes your dog’s body respond poorly to the hormone insulin. This will cause poor glucose absorption into the bloodstream or incorrect urine concentration in the kidneys.

Types of Canine Diabetes

There are two different types of canine diabetes, each with subtypes:

  1. Canine diabetes mellitus: a chronic metabolic disorder that destroys the insulin-producing beta cells in the pancreas and causes imbalanced blood glucose levels. 

There are two types of canine diabetes mellitus, type 1 and type 2. 

  1. Canine diabetes insipidus: a chronic disorder caused by poor urine concentration in the kidneys.

There are two types of diabetes insipidus recognized in dogs: 

  • Central diabetes insipidus
  • Nephrogenic diabetes insipidus

Canine Diabetes Symptoms

If your dog has high blood sugar levels, you are going to notice the following symptoms:

  • Extreme thirst and frequent water consumption.
  • Frequent urination.
  • Increased appetite.
  • Loss of weight.
  • Lethargy.
  • Cloudy eyes.
  • Shaking. 
  • Sweet breath.
  • Poor coat quality.

Canine Diabetes Diagnosis

Canine diabetes is diagnosed by testing the dog’s blood and urine sugar levels. Dogs with diabetes will show persistently high blood sugar or glucose levels in the urine.

Canine Diabetes Treatment

Canine diabetes is not curable. Instead, you have to manage your dog’s blood sugar levels through these five strategies:

  1. Daily insulin shots.
  2. A healthy high-protein diet.
  3. Regular exercise.
  4. Regular monitoring of blood sugar.
  5. Management and treatment of diabetes-related complications.

Cushing’s disease

Cushing’s disease (also Hyperadrenocorticism or Cushing’s syndrome) is a serious condition in dogs. This occurs when the adrenal glands overproduce the cortisol (cortisone) hormone

Photo Credit: greenleafguypa

As a result, the dog’s kidneys can be damaged, your dog can develop diabetes, or the condition can be fatal.

Types of Cushing’s Disease

There are 3 different types of Cushing’s disease differentiated by their cause, and each is diagnosed and treated differently.

  1. Pituitary gland tumor is the most common type of Cushing’s disease, making up 85-90% of the cases. It is caused by a pituitary gland tumor at the base of your dog’s brain. 
  2. Adrenal gland tumor is Cushing’s disease caused by a benign or malignant tumor at the adrenal gland.
  3. Iatrogenic Cushing’s disease is caused by the overuse of oral or injectable steroids.

Cushing’s Disease Symptoms

Symptoms of Cushing’s disease are universal for all 3 types and include: 

  • Increase in appetite.
  • Frequent water consumption.
  • Frequent urination.
  • Lethargy.
  • Poor coat quality and thin skin.
  • A bloated or pot-bellied appearance.
  • Chronic skin infections and poor skin healing.
  • Hyperpigmentation (dark-colored spots), 
  • Skin mineralization (calcinosis cutis).
  • Recurrent bladder infections.

Cushing’s Disease Diagnosis

Vets use several tests to diagnose Cushing’s disease. The two most common are:

  1. ACTH stimulation test – to detect the levels of adrenocorticotropic hormone in the blood. 
  2. Low-dose Dexamethasone Suppression (LDDS) test – to detect hyperadrenocorticism (usually reporting 90-95% in sick dogs). This test is considered more reliable.

A complementary abdominal ultrasound exam may be performed to assess the adrenal glands for the presence of a tumor.

Cushing’s Disease Treatment

Treatment for Cushing’s disease varies depending on the type: 

  • Pituitary gland tumor – Treatment can be done with Trilostane (Vetoryl®), Mitotane (Lysodren®), Selegiline Hydrochloride (Anipryl®), and Ketoconazole (Nizoral®). The first two are considered most effective.
  • Adrenal gland tumor – treated with surgery to remove the tumor.
  • Iatrogenic Cushing’s disease – treatment entails the gradual cessation of the triggering steroid treatment.

Common Dog Diseases Summary

Dogs are our long-time companions and friends, and we want the best for them. However, our canine friends sometimes get sick and often chronically.

Some dog diseases are more common than others. Cancer, dental disease, Otitis Externa, intestinal and external parasites, diabetes, and Cushing’s disease are among the common diseases that affect your dog.

Knowing the causes and symptoms of the most common diseases that can affect your dog is a great help. Another is working with your dog’s vet for diagnosis and proper treatment. If a dog disease is preventable, prevention is always better than cure!