Aug 17, 2026

Dog Health Issues: The Complete Guide for Every Life Stage and Breed

[Published: July 30, 2026 | Last updated: August 17, 2026] | 16 min read

TL;DR

Puppies get 28 baby teeth by 8 weeks old and 42 adult teeth by 7-8 months (USDA APHIS).
Core puppy vaccines start at 6-8 weeks and continue every 2-4 weeks until at least 16 weeks (AAHA guidelines).
Apple cider vinegar rinses and diluted essential oils can help repel fleas naturally, but they don't kill an active infestation the way veterinary products do.
French Bulldogs, Corgis, Shih Tzus, and Labs each carry different inherited risks - airway problems, spinal disease, eye conditions, and joint disease, respectively.
Dental disease affects over 80% of dogs over age 3, making it the single most common health issue vets see (Royal Veterinary College study, cited by Dogster, 2026).

What Are the Most Common Dog Health Issues?

Dental disease tops the list. Over 80% of dogs older than 3 show some sign of active dental disease, according to a Royal Veterinary College study of first-opinion vet visits (Dogster, 2026). Ear infections, obesity, skin allergies, and joint disease round out the rest of the top five.

Most dog health problems fall into a handful of categories: dental, digestive, joint and orthopedic, skin and ear, and infectious disease. Age matters too. Puppies deal with teething, vaccination gaps, and parasites. Adult dogs deal with weight and joint wear. Senior dogs deal with arthritis, cataracts, and cancer risk.

Watch for these general warning signs at any age: changes in appetite, unusual thirst, lethargy, vomiting, diarrhea, scratching, or limping (AKC Pet Insurance, 2023). A dog that suddenly drinks more water than normal could be dealing with anything from a hormone issue to kidney disease, so don't wait out a persistent symptom before calling your vet.

This guide breaks down the specific issues Tanvir's readers ask about most: teething timelines, vaccination schedules, flea control, and the breed-specific risks tied to four of the most popular dogs in the US.

Puppy Teeth Chart by Age

A puppy's teeth follow a predictable, two-stage timeline. All 28 baby (deciduous) teeth erupt by about 8 weeks of age, and the full set of 42 adult teeth is usually in by 7 to 8 months (USDA APHIS Aging Puppies by Teeth guide).

Deciduous teeth start emerging around 3 to 5 weeks of age, and permanent teeth begin replacing them around 4 to 5 months (Merck Veterinary Manual). Because the timeline is so consistent, vets can often estimate a puppy's age just by counting which teeth are present.

Age	What's Happening
2-4 months	Adult first incisors come in
4-5 months	Last incisors and 1st and 4th premolars erupt
5 months	Adult canines replace baby canines
5-6 months	Lower first molars come in
6 months	Middle premolars erupt
6-8 months	Last molars erupt; full adult set of 42 teeth is complete

(Source: USDA APHIS, Aging Puppies by Teeth)

A puppy with fewer than 28 baby teeth and no adult teeth yet is likely under 8 weeks old. One still working through baby premolars with only the first bottom molars in place is likely under 6 months (USDA APHIS).

Small and toy breeds sometimes teethe on a slightly different schedule than large breeds - small dogs can start a bit earlier, and their baby teeth are also more prone to staying in place after the adult tooth has already come through, a condition called retained deciduous teeth (PetMD). If a baby tooth hasn't fallen out by the time the same adult tooth is visible, mention it at the next vet visit. Retained teeth trap food and cause faster tartar buildup.

Puppy Vaccination Schedule Chart

Core vaccines protect against distemper, adenovirus, parvovirus, and rabies - diseases that are common, often fatal, and in rabies' case, transmissible to humans (AAHA and AVMA guidelines). The standard series starts at 6 to 8 weeks and continues every 2 to 4 weeks until 16 weeks or later.

Age	Vaccines
6-8 weeks	First DHPP (distemper, hepatitis/adenovirus, parainfluenza, parvovirus) dose
9-11 weeks	Second DHPP dose
12-14 weeks	Third DHPP dose; leptospirosis often added here
12-16 weeks	Rabies vaccine (state law sets the exact minimum age)
16-18 weeks or later	Final DHPP booster
12 months	Adult booster round, then typically every 1-3 years

(Source: AAHA Canine Vaccination Guidelines; UC Davis School of Veterinary Medicine)

Timing the final dose matters more than most owners realize. AAHA now recommends the last DHPP dose land at 16 weeks or later, ideally closer to 18-20 weeks, because leftover maternal antibodies can block an earlier dose from working (Petful, 2026). A puppy that finishes the series too early can still be vulnerable to parvovirus.

Non-core vaccines - Bordetella (kennel cough), canine influenza, and Lyme disease - depend on lifestyle. A puppy headed to daycare or a dog park needs Bordetella; one in a tick-heavy region may need the Lyme vaccine. Your vet will build this part of the schedule around where you live and how your dog spends time.

If a booster runs a week or two late, most vets simply continue the series rather than restarting it. The real risk is skipping doses entirely, not minor scheduling delays (Petful, 2026).

Natural Flea Treatment for Dogs

Natural flea treatment can help manage a mild flea problem or work as a prevention layer, but it will not replace veterinary flea control for an active, established infestation. That distinction matters because fleas multiply fast: a single flea can turn into roughly 1,000 within 21 days (AKC Pet Insurance, 2025).

Apple cider vinegar rinse. Vinegar makes a dog's skin more acidic, which fleas dislike. A common ratio is 1 part vinegar to 10 parts water, applied as a rinse after a bath (Dogs Naturally, 2026). It won't kill fleas outright, but it can make your dog a less appealing host.

Diluted essential oils. Lavender, lemongrass, cedarwood, and peppermint oils are commonly used as flea repellents. This is the part of natural flea control that requires real caution. Essential oils must always be diluted in a carrier oil or water before touching a dog's skin - concentrated oils can cause skin irritation, breathing problems, or toxicity (ASPCA Animal Poison Control Center guidance, cited by HolistaPet, 2026). Tea tree oil in particular is well known for causing adverse reactions in dogs at the wrong concentration. If you have a cat in the house, double-check that any oil you use on the dog isn't also toxic to cats, since cats groom whatever they brush up against.

Flea combing. A fine-toothed flea comb pulled through the coat, especially around the neck and tail base, physically removes adult fleas and eggs. Dip the comb in soapy water between passes to kill what you catch. This is evidence-supported and carries no safety risk (HolistaPet, 2026).

Diatomaceous earth. Food-grade diatomaceous earth is sometimes used in the home and yard rather than directly on the dog. It damages fleas' exoskeletons and dries them out, but the evidence for controlling a full infestation with it alone is limited, and the powder can irritate eyes and airways if it becomes airborne (HolistaPet, 2026).

Regular bathing and washing bedding. Weekly baths with a gentle, natural shampoo during an active flea period, combined with hot-washing all bedding and vacuuming floors and furniture, addresses fleas at every life stage - not just the adults on your dog (Dogs Naturally, 2026).

Natural methods work best for mild cases or as an added layer alongside a vet-recommended preventive. If fleas keep coming back, or if your dog has broken skin, hair loss, or signs of a flea allergy, that's the point to bring in a veterinarian rather than escalate home remedies.

Frenchie Dog Health Issues

French Bulldogs are the most popular dog breed in the US, and their flat-faced build is also what drives most of their health problems. As a brachycephalic breed, Frenchies are prone to Brachycephalic Obstructive Airway Syndrome (BOAS) - narrowed nostrils, an elongated soft palate, and a smaller windpipe that together make breathing harder than it should be (PetMD, 2023). Objective studies put clinically significant BOAS in roughly half of French Bulldogs (Humane World for Animals).

Breathing and heat sensitivity. Because of their airway structure, Frenchies overheat faster than most breeds and struggle more in hot or humid weather. Avoid walking them during peak heat, and treat excessive panting, weakness, or vomiting in warm weather as an emergency (All Breed Pet Care, 2025).

Hip dysplasia. A loose hip joint that leads to arthritis and chronic pain over time. Responsible breeders X-ray parent dogs before breeding to screen for it (PetMD, 2023).

Spinal issues. Frenchies are a chondrodystrophic (dwarf) breed, which puts them at higher risk for intervertebral disc disease (IVDD) - the same disc-related spinal condition that affects long-backed breeds (All Breed Pet Care, 2025).

Digestive and skin conditions. A 2025 survey-based study of French Bulldog owners in Germany found the breed is especially prone to gastrointestinal, respiratory, and dermatological conditions, with a median life expectancy of 8.3 years among the dogs surveyed (Companion Animal Health and Genetics, 2025).

Anesthesia risk. Frenchies are more sensitive to anesthesia complications than the average breed, which makes even routine surgery a higher-risk event (PetMD, 2023).

Buying from a breeder who health-tests for hip dysplasia and screens for airway function reduces the odds of these problems, but even well-bred Frenchies need owners who watch for labored breathing, reduced exercise tolerance, and heat stress.

Corgi Dog Health Issues

Corgis - both Pembroke and Cardigan Welsh - are built with a long spine and short legs (a trait called chondrodysplasia), and that shape drives most of their major health risks.

Intervertebral disc disease (IVDD). Roughly 15% of Corgis develop IVDD in their lifetime, and it runs slightly higher - up to 20% - in Cardigan Welsh Corgis specifically (Dr. Michelle Burch, DVM, cited by Walkin' Pets, 2024). IVDD comes in two forms: a sudden disc rupture that can cause hours-to-days-long paralysis, and a slower, age-related version that shows up gradually in older dogs. Keeping a Corgi at a healthy weight is the single biggest modifiable risk factor, since excess weight adds mechanical stress to the spine.

Degenerative myelopathy (DM). A progressive, incurable spinal cord disease that causes gradual hind-limb weakness and eventually paralysis, similar in mechanism to ALS in humans. DM shows up more often in Pembroke Corgis than Cardigans and typically starts around age 8, though it can range from 4 to 14 (Canine Journal, 2026). Unlike IVDD, DM isn't painful, and dogs can stay mobile for a long time with physical therapy, hydrotherapy, and mobility aids like a wheelchair cart.

Hip dysplasia. A separate inherited joint condition where the femur doesn't sit correctly in the hip socket, leading to progressive pain and reduced mobility. Corgis tend to mask discomfort well, since they were bred as stoic herding dogs, so early signs like reluctance to jump or a swaying gait are easy to miss (DogMD, 2026).

Obesity. Because Corgis are food-motivated and low to the ground, extra weight compounds every other risk on this list - it's a major driver of both IVDD and hip dysplasia severity, not just a standalone issue (PetMD).

The practical takeaway for Corgi owners: weight management isn't cosmetic, it's the main lever you control for spinal and joint disease risk. Limiting jumps off furniture and using ramps for cars or stairs also reduces the odds of triggering a disc injury.

Shih Tzu Dog Health Issues

Shih Tzus are a brachycephalic breed with an especially flat face, and that structure creates two main problem areas: breathing and eyes.

Brachycephalic airway syndrome. Like other flat-faced breeds, Shih Tzus can have narrowed nostrils and airway abnormalities that make breathing harder and heat tolerance lower. Severe cases sometimes need corrective surgery, ideally done while the dog is still young (PetMD).

Eye conditions. This is where Shih Tzus stand out even among brachycephalic breeds. Their shallow eye sockets leave the eyes more exposed, which raises the risk of several conditions:

Corneal ulcers, from minor trauma the shallow socket doesn't protect against
Dry eye (keratoconjunctivitis sicca), caused by incomplete eyelid closure and reduced tear coverage
Cataracts and glaucoma, both of which can lead to vision loss if untreated
Proptosis, where the eyeball displaces out of the socket - a true medical emergency that needs immediate veterinary care (Dogster, 2025; UFAW)

Because Shih Tzus often can't fully close their eyelids (a condition called lagophthalmos), their eyes stay more exposed to irritants even during normal daily activity, not just during accidents (Puppy Heaven, 2026).

Liver shunt. A less common but serious condition where blood bypasses the liver instead of being filtered through it. Signs include stunted growth, chronic digestive issues, and in more advanced cases, neurologic symptoms like a wobbly, "drunken" gait (PetMD).

Ear infections. Shih Tzu ears are floppy, which traps moisture and reduces airflow - a setup that makes ear infections more common than in breeds with upright ears (PetMD).

For Shih Tzu owners, daily eye checks are worth the habit. Redness, squinting, discharge, or excessive tearing are all reasons to call the vet rather than wait, since eye conditions in this breed can progress to vision loss quickly if left alone.

Lab Dog Health Issues

Labrador Retrievers are one of the most popular breeds in the US, and most of their health issues trace back to two things: their joints and their appetite.

Hip and elbow dysplasia. The Orthopedic Foundation for Animals estimates roughly 12% of Labs have hip dysplasia, making it one of the most frequently affected breeds (DogMD, 2025). Watch for reluctance to climb stairs, a "bunny hop" gait when running, and stiffness after rest. Keeping a Lab lean, especially during the growth phase as a puppy, is one of the most effective ways to reduce severity.

Obesity. This is arguably the Lab's biggest health risk. A genetic mutation in the POMC gene, present in roughly 25% of Labradors, disrupts normal hunger signaling and makes them more prone to overeating (Vetlens, 2025). Combined with their famous food drive, this makes obesity extremely common - one study cited by Dog Artists found close to 60% of Labs are overweight or obese, and excess weight can shorten a dog's life by up to two years.

Eye disease. Labs are prone to progressive retinal atrophy (PRA), a genetic condition that leads to gradual, irreversible vision loss, along with hereditary cataracts. Genetic testing can identify PRA risk before symptoms appear (ManyPets, 2025).

Exercise-Induced Collapse (EIC). A genetic disorder where a dog appears completely normal at rest but collapses after 5 to 20 minutes of intense exercise. It's manageable once diagnosed, mainly by avoiding the specific triggers that bring it on (Vetlens, 2025).

Bloat (GDV). A life-threatening emergency where the stomach fills with gas and can twist on itself. Labs aren't as high-risk as deep-chested breeds like Great Danes, but it still happens. Signs include a visibly distended abdomen, unproductive retching, and restlessness - this always warrants an immediate emergency vet visit, not a wait-and-see approach (Vetlens, 2025).

Ear infections. Floppy ears plus a love of water is a reliable recipe for ear infections in Labs. Drying ears thoroughly after swimming or baths helps reduce the risk (ManyPets, 2025).

Because so many Lab health risks connect back to weight, portion control and regular low-impact exercise like swimming do double duty - protecting the joints and reducing obesity risk at the same time.

Common Mistakes to Avoid with Dog Health Issues

Treating breed-specific stats as universal. A Corgi's 15% IVDD risk or a Lab's 12% hip dysplasia rate doesn't mean every dog of that breed will develop the condition - genetics, weight, and breeder health-testing all shift individual risk.
Skipping vaccine boosters because a puppy "seems fine." Maternal antibodies can block early doses from working, which is exactly why the multi-dose schedule exists even for a healthy-looking puppy.
Applying undiluted essential oils for flea control. Concentrated oils, especially tea tree, can cause real toxicity in dogs. Always dilute, and check that anything used around a dog is also safe for any cats in the house.
Waiting out symptoms in brachycephalic breeds. Labored breathing, bulging or red eyes, and heat distress in Frenchies and Shih Tzus escalate fast. These are same-day vet situations, not wait-and-see ones.
Letting extra weight slide in Corgis and Labs. For both breeds, obesity isn't a separate issue - it's a multiplier that makes their top inherited conditions (IVDD, hip dysplasia) worse.

Frequently Asked Questions About Dog Health Issues

What is the most common health issue in dogs overall?

Dental disease is the most common issue vets see, affecting more than 80% of dogs over age 3, according to a Royal Veterinary College study (Dogster, 2026).

At what age do puppies get all their adult teeth?

Puppies typically have their full set of 42 adult teeth by 7 to 8 months of age, after losing all 28 baby teeth (USDA APHIS).

When should a puppy get its first vaccine?

Most puppies start their core vaccine series at 6 to 8 weeks of age, with boosters every 2 to 4 weeks until at least 16 weeks (AAHA Canine Vaccination Guidelines).

Are natural flea treatments as effective as vet-prescribed flea medication?

No. Natural methods like flea combing, apple cider vinegar rinses, and diluted essential oils can help with mild flea activity or prevention, but they don't match the effectiveness of veterinary flea preventives for an established infestation.

Which dog breed has the most health problems?

Brachycephalic (flat-faced) breeds like French Bulldogs and Shih Tzus tend to carry the highest number of breed-linked health risks, largely due to airway and eye anatomy. Long-backed breeds like Corgis carry a concentrated risk of spinal disease instead.

Is hip dysplasia preventable in Labradors and Corgis?

Not entirely - it's genetic. But keeping a dog at a lean weight, especially during puppy growth, and choosing a breeder who screens parent dogs both reduce severity and delay onset.

What are the emergency warning signs every dog owner should know?

Difficulty breathing, a distended or bloated abdomen, sudden collapse, a visibly displaced eye, or paralysis in the hind legs all need immediate veterinary attention rather than a wait-and-see approach.

Key Takeaways

Teething and vaccination both follow predictable age-based timelines - use the charts above to know what's normal and when to call the vet.
Natural flea treatment works best as prevention or for mild cases, not as a replacement for veterinary flea control.
Frenchies and Shih Tzus carry brachycephalic-linked airway and eye risks; Corgis carry spinal disease risk; Labs carry joint and weight-related risk.
Weight management is the single biggest owner-controlled factor across nearly every breed-specific condition covered here.
When in doubt about a symptom, especially in a brachycephalic or long-backed breed, treat it as a same-day vet conversation, not a wait-and-see situation.