The most common health problems in dogs, according to Nationwide

Nationwide is the largest pet health insurance provider in the U.S. Each year it reviews the claims its policyholders file and identifies the conditions that send dogs to the veterinarian most often. The company covers a large pool of dogs across breeds, ages and regions. That scale makes its claims data a practical picture of canine health, drawn from everyday appointments rather than from a small research sample.

The pattern holds from year to year, and that consistency is the useful part. The most common dog health problems in Nationwide claims data are rarely dramatic emergencies. They are chronic, recurring and in many cases preventable or manageable with routine attention.

Ear infections, skin allergies and digestive upset turn up again and again. All three tend to come back over the course of a dog's life rather than resolve for good after one course of treatment. Other conditions track with age. Osteoarthritis and hypothyroidism grow more likely in middle-aged and senior dogs. Both often go undiagnosed until an owner notices that a dog has slowed down, gained weight or stopped jumping onto the couch.

Knowing which conditions recur most often helps an owner judge when a symptom warrants a vet visit and when it is likely to pass on its own. It also explains where the money goes. A condition that requires lifelong medication or repeated professional care costs more across a dog's lifetime than a single illness, even when that illness carries a more serious name.

This list is not a ranking of severity. Periodontal disease can be as painful and as expensive as a diagnosis that sounds far worse. It is a guide to what dog owners are statistically most likely to encounter, what causes each condition and what treatment usually involves. Breed, age, body size and coat type all shift individual risk — a basset hound and a chihuahua face different odds — but no dog is entirely exempt from what follows.

Illustration: Quartz

Ear infections appear near the top of Nationwide's dog claims year after year, and the cause is anatomical. A dog's ear canal drops downward and then turns close to a right angle before reaching the eardrum, leaving a warm, often damp pocket where wax and debris collect and yeast and bacteria multiply.

Breeds with long, heavy ear flaps carry the highest risk. Cocker spaniels and basset hounds are the usual examples, since a flap lying flat against the head cuts airflow and holds moisture in the canal. Dogs with narrow canals, dense ear hair, or regular swimming habits end up in the same position by a different route.

The signs tend to be visible to an owner who knows what to watch for. A dog shakes its head repeatedly, paws at one ear, tilts its head to a single side, or pulls away when the ear is handled. A sour odor and dark brown or black discharge are typical. Some dogs drag the side of the face along carpet or furniture for relief.

Treatment usually begins with a thorough flush of the canal, because drops cannot reach inflamed tissue buried under wax and debris. A vet may look at a swab under a microscope to identify whether yeast, bacteria, or ear mites are responsible, and that result determines the medication prescribed. Mild cases often clear in one to two weeks.

Recurrence is common. Allergic skin disease frequently sits underneath the infection, altering oil production and the microbial balance inside the ear, so a dog treated for the infection alone tends to develop another. Infections left to run can reach the middle or inner ear, producing balance trouble, a persistent head tilt, or hearing loss, and years of inflammation can permanently narrow the canal.

Weekly ear checks, and drying the ears after baths and swimming, catch most cases at the stage where treatment is simple.

Illustration: Quartz

Allergic dermatitis — skin inflammation set off by an allergic reaction — is one of the leading reasons dogs turn up in Nationwide's claims data. Flea bites, environmental allergens such as pollen, mold, and dust mites, and, less often, specific ingredients in a dog's food account for most cases.

The clearest sign is itching that does not let up. Dogs scratch, lick, and chew, usually targeting the paws, belly, armpits, and the base of the tail. Skin turns red, hair thins or disappears in patches, and months of repeated trauma leave the affected areas thickened and darkened. Hot spots — raw, weeping sores that spread quickly — form where a dog licks one spot obsessively and bacteria move into the broken skin.

Diagnosis takes time. Allergy testing in dogs is less definitive than it is in people, so vets work through possible causes in sequence. Fleas and mites get ruled out first. A strict elimination diet lasting several weeks follows if food is a suspect. Environmental triggers are weighed last, and they are the hardest to remove from a dog's surroundings.

Treatment depends on the trigger and on how severe the itching has become. Year-round flea prevention, medicated shampoos that calm the skin and clear secondary bacterial or yeast infections, omega-3 supplementation, antihistamines, and prescription drugs that block the immune signals driving the itch all have a role. Dogs with confirmed environmental allergies may be candidates for immunotherapy — injections or oral drops that gradually desensitize the animal to a specific allergen — which can reduce the need for daily medication.

Allergies persist. Symptoms flare, settle, and return, often on a seasonal cycle tied to pollen. A dog treated in spring frequently comes back in late summer, so a single diagnosis turns into years of appointments, refills, and follow-up visits. That pattern is what keeps allergic skin disease high in the claims rankings, rather than any one expensive procedure.

Illustration: Quartz

Most lumps a dog develops turn out to be benign, but they drive a steady stream of vet visits and insurance claims because a new mass under the skin looks the same whether it is harmless or not. Lipomas and sebaceous cysts are the two that appear most often.

A lipoma is a soft, movable mass of fat cells sitting just beneath the skin, usually on the chest, abdomen, or upper legs. They turn up most often in middle-aged and older dogs, and Labrador retrievers are among the breeds that develop them frequently. A sebaceous cyst forms when an oil-producing gland in the skin becomes blocked, creating a firm bump that can rupture and release a thick, pale discharge.

Young dogs develop a different set of benign growths. Histiocytomas appear on the head, ears, or limbs of dogs under three and often shrink away on their own within a couple of months. Viral papillomas — warts — cluster around the mouth and lips of young dogs and also tend to clear without treatment.

A vet visit still matters because visual inspection cannot separate a lipoma from a mast cell tumor, which can imitate a harmless fatty lump. Veterinarians confirm the diagnosis with a fine needle aspiration, drawing a small sample of cells through a thin needle for examination under a microscope. The procedure usually requires no sedation and can often be done during the same appointment.

Once a growth is confirmed benign, the standard approach is monitoring rather than surgery. Removal is generally reserved for masses that restrict a leg's range of motion, sit where a collar or harness rubs against them, grow quickly, or repeatedly become inflamed or infected.

Older dogs tend to accumulate several of these over time, which is why a single senior dog can account for more than one lump-related claim over its lifetime.

Illustration: Quartz

Vomiting and diarrhea rank among the most frequently claimed conditions in Nationwide's data. Digestive upset is common, and alarming enough that owners call the vet rather than wait it out. Dogs eat things they shouldn't, and the consequences arrive fast.

The usual trigger is dietary indiscretion — a raided trash can, a handful of table scraps, an abrupt switch to a new food or a swallowed piece of a toy. Rich, fatty human food is a frequent culprit around holidays. Gastritis, inflammation of the stomach lining, often follows.

Most episodes are mild. A dog that vomits once or twice and otherwise stays alert will usually settle within a day or two on a bland diet of boiled chicken and plain white rice, fed in small portions, with water available at all times. Withholding food for a short period before restarting, then reintroducing the regular diet gradually over several days, is standard practice.

The signs that call for an appointment are more specific. Symptoms that persist beyond 24 hours point to something other than a passing stomach upset. So do repeated unproductive retching, blood in vomit or stool, a painful or distended abdomen and lethargy. Pancreatitis, inflammation of the pancreas often linked to a high-fat meal, presents this way. An intestinal blockage from a swallowed object can look the same. A blockage is a surgical emergency and will not clear on its own.

Dehydration is the other reason not to wait. Puppies and small dogs lose fluid quickly through repeated vomiting and diarrhea, and that fluid loss can become the more urgent problem.

A vet typically starts with a physical exam and a history of what the dog has eaten, then adds bloodwork or imaging if the picture stays unclear. Recurring digestive trouble sometimes traces to a food sensitivity or inflammatory bowel disease, both of which need long-term dietary management rather than a short course of medication. That range of possible causes is why these claims turn up across dogs of every age, size and breed.

Illustration: Quartz

Bladder infections show up repeatedly in dog insurance claims, and they occur more often in female dogs, whose shorter urethra gives bacteria a quicker route to the bladder. Most cases clear with a course of antibiotics, but the symptoms are easy to mistake for a behavioral problem.

Owners usually notice changes in the bathroom routine first. A dog may strain to urinate, squat repeatedly and produce only a few drops, ask to go outside far more often than usual, or start having accidents indoors after years of reliable house training. Urine may look cloudy or carry a pink tinge of blood. Some dogs lick the genital area more than normal or flinch when the lower abdomen is touched.

A urinalysis is the standard diagnostic step. The lab checks the sample for bacteria, white blood cells, and crystals, and a urine culture can identify the specific organism when an infection keeps returning or fails to clear. Treatment typically runs one to two weeks, and finishing the full prescription matters even after symptoms disappear, since a partially treated infection is more likely to come back.

An untreated bladder infection does not always stay in the bladder. Bacteria can travel upward to the kidneys, a far more serious illness, and chronic inflammation can contribute to bladder stones, which sometimes require surgical removal or a prescription dissolution diet.

Dogs with diabetes or Cushing's disease face higher odds of repeat infections, because both conditions alter the composition of the urine in ways that favor bacterial growth. A dog with recurring urinary infections is worth screening for an underlying hormonal disorder rather than treating round after round in isolation.

Steady access to fresh water helps, since dogs that drink more urinate more and flush bacteria out of the tract more often. Letting a dog out on a regular schedule, rather than asking it to hold urine for long stretches, works the same way.

Illustration: Quartz

Osteoarthritis is the gradual breakdown of cartilage inside a joint, and it ranks among the costliest conditions in pet insurance claims because it never resolves — it is managed for the rest of a dog's life. Large and giant breeds such as German shepherds and Great Danes carry higher risk, as do dogs that injured a joint years earlier.

The cartilage that cushions the ends of bones wears thin, bone begins to contact bone, and the joint becomes inflamed and painful. Hips, elbows, knees, and the lower spine are the usual sites. Dogs that tore a cruciate ligament or were diagnosed with hip or elbow dysplasia as puppies often develop arthritis in those same joints well before old age.

Owners tend to notice stiffness first, particularly after a nap or a long rest, which loosens as the dog moves around. Other signs include hesitation at stairs, reluctance to jump into a car or onto furniture, a shortened stride, and a limp that worsens in cold or damp weather. Some dogs show it as irritability or withdrawal rather than obvious lameness, since the pain is constant rather than sudden.

Diagnosis combines a hands-on exam with X $TWTR-rays. The vet flexes and extends each joint to gauge range of motion and pain response, while imaging shows narrowed joint space and the bone spurs that form along the edges of a worn joint.

Treatment usually layers several approaches. Anti-inflammatory medication controls pain. Weight management matters as much as any prescription, because every extra pound adds load to an already compromised joint. Controlled exercise preserves the muscle that supports the joint, and swimming is often recommended for that reason — it builds strength without impact.

Joint supplements containing glucosamine and chondroitin are widely used, though results vary from dog to dog. Household adjustments reduce strain on worn joints, including raised food bowls, ramps in place of stairs, padded bedding, and rugs over slick floors that make footing harder. Because the condition is progressive, costs accumulate steadily across a dog's later years rather than arriving as one large bill.

Illustration: Quartz

Hypothyroidism is the most commonly diagnosed hormonal disorder in dogs. The thyroid gland stops producing enough hormone to sustain a normal metabolic rate, and the body slows down in ways owners often read as ordinary aging. A daily pill controls it.

Two causes account for most cases. In lymphocytic thyroiditis, the immune system gradually destroys thyroid tissue. In idiopathic atrophy, working glandular tissue is replaced by fat. Both progress slowly, which is why signs usually surface in middle age rather than in young dogs, with most diagnoses falling between the ages of four and 10. Golden retrievers, Doberman pinschers, Irish setters, boxers and dachshunds are diagnosed more often than the general dog population, though any breed can develop it. Toy breeds are affected less frequently.

Symptoms accumulate rather than arrive at once. Weight gain with no change in diet or portion size is a classic sign. Others include lethargy, a dull coat that thins across the trunk and tail, flaky skin and a new habit of seeking out warm spots in the house. Some dogs develop skin and ear infections that return repeatedly after treatment, because low thyroid hormone weakens the skin's barrier function.

Diagnosis rests on bloodwork — a thyroid panel measuring total T4 alongside free T4 and thyroid-stimulating hormone. Routine bloodwork often shows elevated cholesterol and mild anemia, which is sometimes what prompts the thyroid panel in the first place. One low T4 result is not enough to confirm the disease. Other illnesses and some medications suppress thyroid values in dogs whose glands work normally, a pattern vets call euthyroid sick syndrome.

Treatment is levothyroxine, a synthetic version of the hormone, given by mouth daily for the rest of the dog's life. Follow-up bloodwork sets the dose and confirms it is holding. Energy and appetite tend to improve within a few weeks; coat and skin changes take longer. The cost is not one large bill but a steady one — medication plus periodic monitoring, repeated for years.

Illustration: Quartz

Conjunctivitis — inflammation of the pink membrane lining the eyelid and covering part of the eyeball — is one of the most frequent eye complaints that brings dogs to the vet. Allergies, dust, smoke, a lodged grass seed, and bacterial or viral infection can all trigger it.

The white of the eye and the inner lid turn red. The dog squints or holds the eye partly closed. Tears run down the face, and a yellow or greenish discharge can dry overnight and seal the lids shut. Many dogs paw at the eye or drag the side of the face along carpet and furniture, which worsens the irritation and can push bacteria into the tissue.

Allergy and infection typically affect both eyes at once. A foreign body, a scratch, or a blocked tear duct usually affects just one, which gives the vet an early clue about the cause.

Flat-faced breeds and dogs with prominent eyes or deep facial folds — pugs, bulldogs, Pekingese — face a higher risk. Their eyes sit closer to the surface with less bony protection, and skin folds trap moisture and debris against the lids.

A vet exam goes beyond confirming the redness. Corneal ulcers and scratches produce the same squinting and tearing. A fluorescein stain — a dye that highlights damage to the eye's surface under blue light — is a standard part of the workup. Treating a corneal injury as ordinary conjunctivitis lets real damage progress.

Treatment usually means a prescription drop or ointment applied several times a day, often for one to two weeks, sometimes paired with a cone to stop rubbing. Human over-the-counter eye drops are not a substitute and can make some conditions worse.

Irritation that keeps returning points to something structural or systemic. Entropion, in which the eyelid rolls inward so the lashes rub against the cornea, is a frequent cause and is corrected surgically. Skin allergies and inadequate tear production also drive chronic cases. Repeat episodes warrant a fuller diagnostic look rather than another round of drops.

Illustration: Quartz

Periodontal disease — infection of the gums, ligament, and bone that anchor a dog's teeth — ranks among the most widespread conditions in adult dogs and among the most overlooked. It begins with plaque hardening into tartar at the gumline, then spreads below the gum where no owner can see it.

The first stage is gingivitis: red, swollen gums that bleed when touched or brushed. Damage at this point can still be reversed. Once the infection reaches the ligament and bone holding the tooth in its socket, the loss is permanent. Teeth loosen, roots become exposed, and abscesses can form beneath the gumline.

Signs an owner can catch at home include breath that smells rotten rather than merely doggy, yellow or brown crust along the outer surface of the back molars, bleeding from the gums, food dropped mid-meal, chewing on one side, or lost interest in hard toys. Dental pain rarely stops a dog from eating altogether, which is part of why the problem runs unnoticed for years.

Small breeds carry the highest risk. Yorkshire terriers, chihuahuas, dachshunds, and toy poodles have near-standard-sized teeth crowded into a much smaller jaw, which traps debris and accelerates tartar buildup. Flat-faced breeds face a similar crowding problem from a shortened muzzle.

Treatment means a professional cleaning under general anesthesia. Scaling below the gumline and taking dental X $TWTR-rays cannot be done on a conscious dog. Advanced cases call for extractions, and most dogs eat comfortably within days once the painful tooth is gone.

Bacteria from inflamed gums can pass into the bloodstream, which is why chronic dental infection is treated as a whole-body problem and associated with added strain on the heart, liver, and kidneys. Daily brushing with toothpaste made for dogs slows new plaque, and dental chews help, but neither removes hardened calculus already bonded to the enamel.