Common Dog Health Issues by Life Stage

Last updated May 18, 2026 · 8 min read

Different health issues show up at different dog ages. Knowing what’s common at each stage helps you spot trouble early and avoid alarming yourself about things that aren’t urgent. This isn’t comprehensive, it’s the issues a small-animal vet sees most often by age group, with the symptoms that warrant a call.

Puppy (0–6 months)

Parvovirus

The most dangerous puppy disease. Highly contagious, often fatal in unvaccinated puppies. Symptoms: severe bloody diarrhea, vomiting, lethargy, refusing food. Any unvaccinated puppy with these signs is a medical emergency. Vaccine-preventable.

Intestinal parasites

Roundworms, hookworms, tapeworms, giardia, coccidia. Common in puppies even with one round of deworming. Signs: pot belly, soft stool, blood or mucus in stool, poor weight gain. Standard practice is to deworm at every puppy visit.

Hypoglycemia (toy breeds)

Small puppies, particularly toy breeds, can develop dangerously low blood sugar if they go too long between meals. Signs: weakness, wobbliness, seizure. Frequent small meals prevent it.

Upper respiratory infections / kennel cough

Common from shelters and group socialization. Honking cough, sometimes nasal discharge. Usually self-limiting; antibiotics for secondary infections.

Congenital issues

Patent ductus arteriosus, liver shunts, hip dysplasia (visible in some breeds before maturity), patellar luxation. Many are screened at the first vet visit.

Adolescent (6 months to 2 years)

Behavioral “regression”

Not strictly health, but worth flagging. Trained behaviors break down, sudden fearfulness appears, training feels like it’s stopped working. Normal adolescence, ends around 18–24 months. Continue consistent training; resist the urge to surrender.

Cranial cruciate ligament (CCL) injuries

The dog version of an ACL tear. Common in athletic adolescent dogs, especially Labs, Goldens, and Rottweilers. Sudden hind-limb lameness during play. Surgical repair (TPLO) is the standard treatment for medium and large dogs.

Gastrointestinal foreign bodies

Adolescent dogs chew and swallow things they shouldn’t. Socks, corn cobs, toys, rocks. Vomiting that won’t stop, especially with abdominal pain, is an emergency. Surgical removal often needed.

Allergies

Atopic dermatitis (environmental allergies) typically appears between 1 and 3 years. Itchy paws, ears, belly, armpits. Lifelong management.

Adult (3 to 6 years for most dogs)

Dental disease

Begins accumulating in this stage. By age 3, most dogs have some tartar. Regular brushing, dental treats, and professional cleanings every 1–3 years.

Ear infections

Particularly common in floppy-eared breeds (Cockers, Bassets, Labs). Head shaking, scratching, dark discharge or odor.

Hip and elbow dysplasia

Often becomes clinically apparent in this stage in predisposed breeds (German Shepherds, Goldens, Labs, Newfoundlands, many giant breeds). Limping, stiffness, reluctance to exercise.

Weight gain

The silent issue. Most dogs slowly add weight through their adult years, particularly after spay/neuter. Body condition score monitoring at each visit catches it early.

Mature (5–10 depending on size)

Arthritis onset

Begins for most dogs in this stage, often years before visibly limping. Joint supplements proactively, weight management critical.

Hypothyroidism

Common in middle-aged medium and large breeds. Weight gain, lethargy, skin and coat changes, cold intolerance. Easily diagnosed with bloodwork; treatable with daily medication.

Diabetes mellitus

Type 1 diabetes in dogs, often presenting in mature stage. Increased thirst, increased urination, weight loss despite a good appetite. Requires insulin and dietary management; many dogs do well with treatment.

Cushing’s disease (hyperadrenocorticism)

Excess cortisol from adrenal or pituitary tumor. Symptoms: pot belly, increased thirst and urination, thin skin, recurrent skin infections, panting. Diagnosis through specific bloodwork; treatable.

Heart murmurs

Mitral valve disease is common in small breeds in this stage. Detected on routine exam. Often progresses slowly; medication delays heart failure.

Senior (7–13 depending on size)

Chronic kidney disease (CKD)

Progressive kidney decline. Detected on bloodwork; symptoms (increased thirst/urination, weight loss, appetite changes) often appear after the disease has progressed. Annual senior bloodwork from age 7 catches earlier stages where dietary management has the most benefit.

Cancer

Leading cause of death in older dogs. Common: lymphoma, hemangiosarcoma, osteosarcoma (large/giant breeds), mast cell tumors, lipomas (mostly benign). Treatment options have expanded significantly.

Heart disease progression

Dilated cardiomyopathy in large breeds (Dobermans, Boxers, Great Danes), mitral valve disease in small breeds. Coughing, exercise intolerance, breathing changes. Cardiology referrals improve outcomes considerably.

Dental disease (advanced)

By this stage, professional cleaning is often needed even with home care. Modern anesthesia with senior protocols and bloodwork is safer than it used to be.

Geriatric (10+ large breeds, 13+ small)

Cognitive dysfunction (CCD)

Canine dementia. Disorientation, broken house-training, sleep/wake cycle reversal, social withdrawal. Real medical condition with management options (selegiline, dietary support, environmental modifications).

Advanced kidney disease

Many geriatric dogs are managing CKD. Subcutaneous fluids at home, prescription diet, phosphate binders, blood pressure medication when needed.

Severe arthritis

Many geriatric dogs have substantial joint disease. Newer treatment options (Librela monoclonal antibody) have significantly changed comfort levels for this group.

Vision and hearing loss

Common in geriatric dogs. Most adapt well with environmental support; familiar layouts, hand signals introduced earlier, gentle approaches.

Universal warning signs, any age

Always call the vet for:

• Bloat (GDV) signs in large breeds: unproductive retching, distended abdomen, restlessness. Same-day emergency.
• Difficulty breathing, blue gums, collapse.
• Sudden hind-end weakness or paralysis.
• Inability to urinate or pass stool.
• Persistent vomiting or diarrhea (more than 24 hours).
• Suspected toxin exposure (chocolate, xylitol, raisins, certain plants, medications).
• Seizures. First-time seizures or seizures lasting more than 2–3 minutes.
• Profuse bleeding or open wounds.

Knowing your dog’s current life stage shapes what to watch for. Use our dog age calculator to place your dog on the AAHA scale using the size-adjusted formula. The stage determines which issues become statistically likely.

The habit that pays back most

Twice-yearly vet visits with bloodwork starting in the mature stage (age 5–7 depending on size). Catches kidney disease, thyroid issues, early cancers, and metabolic disorders years earlier than waiting for symptoms ever will. Nothing else moves senior dog quality of life more.