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Visible health changes by life stage

Use these examples to notice and describe a change—not to identify a disease from a photograph. Age and appearance cannot establish an individual diagnosis.

Examples only — not a diagnosis. Different conditions can look alike.

Dog life stages

Dog life stage

Puppy

Close view of a dog's muzzle with a patch of thinning hair, scale, and redness.

Clinical image blurred

Skin & coat

Patchy hair loss with scaling or crusting

Examples only — not a diagnosis. Different conditions can look alike.

Juvenile demodicosis is one condition a veterinarian may assess. Ringworm, infection, allergy, and other skin problems can look similar.

What you may notice

Look for a localized area of thinning hair, redness, fine scale, or crusting. Note whether it is spreading or itchy.

Why it matters at this stage

Young dogs may show localized demodicosis while the immune system is still developing, but age and appearance do not confirm the cause.

What to do

Book a veterinary visit. Photograph the area in consistent light, note itch and spread, and arrange a veterinary skin examination.

Image: Julie Knicely ·source page ·CC BY 1.0 ·Wikimedia-generated resized derivative; locally format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Mange in dogs and cats · AAHA: Canine life-stage definitions

Close view of a dog's mouth showing a smaller retained baby tooth beside an adult tooth.

Mouth & teeth

A double row of teeth or visible crowding

Examples only — not a diagnosis. Different conditions can look alike.

A retained deciduous tooth is one explanation for a smaller baby tooth remaining beside an adult tooth. A veterinary oral examination is needed to assess crowding and gum effects.

What you may notice

Look for two teeth in one position, a smaller tooth beside a larger one, food trapping, or a tooth that appears out of line.

Why it matters at this stage

Tooth replacement occurs during puppy growth, so a baby tooth that remains as the adult tooth erupts is worth checking.

What to do

Book a veterinary visit. Note which side is affected and arrange a veterinary dental examination rather than trying to loosen the tooth.

Image: Ines Ott ·source page ·CC BY-SA 4.0 ·Resized and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Developmental abnormalities of mouth and dentition · AAHA: Canine life-stage definitions

Dog standing with the rear legs close together during an altered gait.

Mobility & joints

A narrow rear stance or altered gait

Examples only — not a diagnosis. Different conditions can look alike.

Hip dysplasia and other developmental, orthopedic, or neurologic problems are possible reasons for an altered gait. Movement alone cannot identify the cause.

What you may notice

Watch for bunny-hopping, rear-leg swaying, difficulty rising, reduced willingness to run or climb, or a stance with the hind feet close together.

Why it matters at this stage

During growth, a persistent altered gait deserves assessment because developmental joint conditions can affect comfort and movement.

What to do

Book a veterinary visit. Record a short video on a level surface and arrange an examination if the change persists, recurs, or appears painful.

Image: Malinaccier ·source page ·Public Domain ·Resized and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Hip dysplasia in dogs

Dog life stage

Young Adult

Close view of a dog's ear canal with redness, swelling, and dark discharge.

Clinical image blurred

Ears

A red, swollen, or discharging ear canal

Examples only — not a diagnosis. Different conditions can look alike.

Otitis externa is one condition a veterinarian may assess. Allergy, parasites, foreign material, moisture, and other problems can produce similar changes.

What you may notice

Look for redness, swelling, odor, dark or yellow discharge, head shaking, scratching, or sensitivity when the ear is approached.

Why it matters at this stage

Routine handling and grooming in young adulthood can help reveal a new or recurring ear change before it becomes more uncomfortable.

What to do

Book a veterinary visit. Note odor, discharge, scratching, swimming, and whether one or both ears changed, then arrange an ear examination.

Image: Joel Mills ·source page ·CC BY-SA 3.0 ·Wikimedia-generated resized derivative; locally format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Otitis externa in animals

Dog with red irritated skin and hair thinning around the face.

Clinical image blurred

Skin & coat

Red, itchy, or repeatedly licked skin

Examples only — not a diagnosis. Different conditions can look alike.

Canine atopic dermatitis is one possible allergic condition. Parasites, infection, contact irritation, food-related reactions, and other skin problems can look similar.

What you may notice

Look for redness, hair thinning, repeated licking or chewing, rubbing of the face, or recurring changes around the paws, ears, belly, or skin folds.

Why it matters at this stage

Allergic skin disease may first become noticeable in younger dogs, but the pattern and age do not establish a diagnosis.

What to do

Book a veterinary visit. Photograph affected areas, note itch timing and recent exposures, and arrange an examination if the change recurs or persists.

Image: Maja Dumat ·source page ·CC BY 2.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Atopic dermatitis in dogs

Dog standing with the rear legs close together during an altered gait.

Mobility & joints

A narrow rear stance or altered gait

Examples only — not a diagnosis. Different conditions can look alike.

Hip dysplasia and other developmental, orthopedic, or neurologic problems are possible reasons for an altered gait. Movement alone cannot identify the cause.

What you may notice

Watch for bunny-hopping, rear-leg swaying, difficulty rising, reduced willingness to run or climb, or a stance with the hind feet close together.

Why it matters at this stage

As activity increases in young adulthood, recurring gait changes or reduced willingness to exercise are worth documenting and assessing.

What to do

Book a veterinary visit. Record a short video on a level surface and arrange an examination if the change persists, recurs, or appears painful.

Image: Malinaccier ·source page ·Public Domain ·Resized and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Hip dysplasia in dogs

Dog life stage

Mature Adult

Close view of a dog's teeth and gums with plaque and red gum margins.

Clinical image blurred

Mouth & teeth

Red gums, visible plaque, or new mouth odor

Examples only — not a diagnosis. Different conditions can look alike.

Periodontal disease is one condition a veterinarian may assess. Broken teeth, oral masses, foreign material, and other mouth problems can also affect comfort or odor.

What you may notice

Look for red or bleeding gum margins, yellow-brown deposits, drooling, dropping food, chewing on one side, or reluctance to eat hard food.

Why it matters at this stage

Dental deposits and gum inflammation can accumulate through adulthood, so a visible change is worth addressing before comfort or eating worsens.

What to do

Book a veterinary visit. Record eating and chewing changes and arrange a veterinary oral examination; do not rely on appearance to judge disease depth.

Image: MarialeegRVT ·source page ·CC BY-SA 4.0 ·Cropped, resized, and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Periodontal disease in small animals · AAHA: Senior care guidelines for dogs and cats

Veterinary body-condition score diagram showing dog silhouettes from thin to obese.

Weight & body condition

A fading waist or ribs becoming harder to feel

Examples only — not a diagnosis. Different conditions can look alike.

Excess body condition can affect mobility and overall health. A body-condition chart is a screening aid, not a diagnosis or an individualized feeding target.

What you may notice

From above, look for whether the waist is still visible. With gentle touch, note whether the ribs are easy to feel without pressing through a thick fat layer.

Why it matters at this stage

Energy needs and activity can change in mature adulthood, making a trend in waist shape or body weight useful to record.

What to do

Monitor and record. Track weight and body condition consistently and discuss a sustained change at the next veterinary visit.

Image: Connor Long, DVM ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally format-optimized by My Petland; full diagram preserved.

Medical sources:AAHA: Nutrition and weight management guidelines

Hip radiograph showing altered joint shape and arthritic change in a dog.

Mobility & joints

Stiffness, slower rising, or reduced activity

Examples only — not a diagnosis. Different conditions can look alike.

Osteoarthritis is one possible cause. Injury, neurologic disease, weakness, and other orthopedic problems can produce similar movement changes.

What you may notice

Watch for stiffness after rest, hesitation on stairs, slower rising, shorter walks, reduced jumping, limping, or difficulty settling comfortably.

Why it matters at this stage

Subtle mobility changes in mature adulthood are useful to record because joint discomfort can alter activity before a constant limp appears.

What to do

Book a veterinary visit. Record when the change occurs and a short walking video, then arrange an examination if it persists, recurs, or affects normal activity.

Image: Joel Mills ·source page ·CC BY-SA 2.5 ·Wikimedia-generated resized derivative; locally format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Osteoarthritis in dogs and cats · AAHA: Senior care guidelines for dogs and cats

Dog life stage

Senior

Close view of a dog's eye with visible lens clouding.

Eyes

New lens clouding or a vision change

Examples only — not a diagnosis. Different conditions can look alike.

Cataract, age-related nuclear sclerosis, inflammation, and other eye disorders can look cloudy. A veterinary eye examination is needed to distinguish them.

What you may notice

Look for new white, grey, or blue clouding, bumping into objects, hesitation in dim light, redness, squinting, discharge, or unequal pupils.

Why it matters at this stage

Eye appearance and vision can change with age, but a new or sudden change still needs assessment rather than being assumed normal.

What to do

Contact a veterinarian promptly. Note whether the change was sudden, affects one or both eyes, or includes pain or vision loss. Emergency care now is appropriate for sudden vision loss, severe eye pain, or major eye trauma.

Image: André Koehne; derivative crop by Anka Friedrich ·source page ·Public Domain ·Cropped, resized, and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Disorders of the lens in dogs · AAHA: Senior care guidelines for dogs and cats

Close view of a dog's teeth and gums with plaque and red gum margins.

Clinical image blurred

Mouth & teeth

Red gums, visible plaque, or new mouth odor

Examples only — not a diagnosis. Different conditions can look alike.

Periodontal disease is one condition a veterinarian may assess. Broken teeth, oral masses, foreign material, and other mouth problems can also affect comfort or odor.

What you may notice

Look for red or bleeding gum margins, yellow-brown deposits, drooling, dropping food, chewing on one side, or reluctance to eat hard food.

Why it matters at this stage

Senior dogs may hide oral discomfort; new odor, chewing changes, or gum inflammation should not be dismissed as normal aging.

What to do

Book a veterinary visit. Record eating and chewing changes and arrange a veterinary oral examination; do not rely on appearance to judge disease depth.

Image: MarialeegRVT ·source page ·CC BY-SA 4.0 ·Cropped, resized, and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Periodontal disease in small animals · AAHA: Senior care guidelines for dogs and cats

Hip radiograph showing altered joint shape and arthritic change in a dog.

Mobility & joints

Stiffness, slower rising, or reduced activity

Examples only — not a diagnosis. Different conditions can look alike.

Osteoarthritis is one possible cause. Injury, neurologic disease, weakness, and other orthopedic problems can produce similar movement changes.

What you may notice

Watch for stiffness after rest, hesitation on stairs, slower rising, shorter walks, reduced jumping, limping, or difficulty settling comfortably.

Why it matters at this stage

Mobility and comfort deserve regular attention in senior dogs; reduced activity should not automatically be attributed to age.

What to do

Book a veterinary visit. Record when the change occurs and a short walking video, then arrange an examination if it persists, recurs, or affects normal activity.

Image: Joel Mills ·source page ·CC BY-SA 2.5 ·Wikimedia-generated resized derivative; locally format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Osteoarthritis in dogs and cats · AAHA: Senior care guidelines for dogs and cats

Cat life stages

Cat life stage

Kitten

Kitten with discharge around the eyes and nose.

Clinical image blurred

Eyes

Eye or nose discharge in a kitten

Examples only — not a diagnosis. Different conditions can look alike.

Feline respiratory disease complex, including feline herpesvirus infection, is one possible context. Irritation and other eye or respiratory problems can look similar; the photograph does not confirm a cause.

What you may notice

Look for watery or thicker discharge, red conjunctiva, squinting, sneezing, nasal discharge, reduced appetite, or increased breathing effort.

Why it matters at this stage

Kittens can become unwell quickly when eye or respiratory signs interfere with eating, hydration, or comfortable breathing.

What to do

Contact a veterinarian promptly. Record eating, energy, sneezing, discharge, and breathing effort, then contact a veterinarian promptly if signs are new or affect normal activity. Emergency care now is appropriate for difficulty breathing or blue, grey, or very pale gums.

Image: Freddy2001 ·source page ·CC BY-SA 3.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Feline respiratory disease complex · AAHA/AAFP: Feline life-stage guidelines

Close view of a cat's ear with dark debris.

Clinical image blurred

Ears

Dark ear debris with scratching or head shaking

Examples only — not a diagnosis. Different conditions can look alike.

Ear mites are one possible cause. Infection, inflammation, allergy, polyps, and other ear problems can produce similar debris or discomfort.

What you may notice

Look for dark crumb-like debris, redness, odor, repeated scratching, head shaking, or sensitivity when the ear is approached.

Why it matters at this stage

Ear mites and other contagious ear problems are important to assess in kittens, especially when several animals share a home.

What to do

Book a veterinary visit. Note whether one or both ears changed and whether other pets are scratching, then arrange an ear examination.

Image: Uwe Gille ·source page ·CC BY-SA 3.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Mite infestation of cats · AAHA/AAFP: Feline life-stage guidelines

Cat with a patch of hair loss and scaling on the skin.

Clinical image blurred

Skin & coat

Patchy hair loss, broken hairs, or scaling

Examples only — not a diagnosis. Different conditions can look alike.

Dermatophytosis, commonly called ringworm, is one possible cause. Parasites, allergy, grooming trauma, and other skin disorders can look similar.

What you may notice

Look for circular or irregular hair loss, short broken hairs, scale, crusting, redness, or similar changes in another pet or person.

Why it matters at this stage

Kittens are a group in which ringworm is commonly considered, but appearance alone cannot distinguish it from other skin problems.

What to do

Book a veterinary visit. Photograph the area, limit sharing of grooming items, note other affected household members, and arrange a veterinary skin examination.

Image: Caroldermoid ·source page ·CC BY-SA 3.0 ·Cropped, resized, and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Dermatophytosis in dogs and cats · AAHA/AAFP: Feline life-stage guidelines

Cat life stage

Young Adult

Overweight cat viewed from the side while standing.

Weight & body condition

A rounder outline with less waist definition

Examples only — not a diagnosis. Different conditions can look alike.

Excess body condition can affect mobility and health. A photograph cannot replace hands-on body-condition scoring or an individualized nutrition assessment.

What you may notice

From above and the side, look for reduced waist definition and a rounder abdomen. With gentle touch, note whether the ribs are harder to feel.

Why it matters at this stage

After growth slows, portions and activity may no longer match energy needs, so a gradual body-shape trend is useful to record.

What to do

Monitor and record. Track weight and body condition consistently and discuss a sustained trend with the veterinary team.

Image: Merielle213 ·source page ·CC BY-SA 3.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:AAHA: Nutrition and weight management guidelines · AAHA/AAFP: Feline life-stage guidelines

Close view inside a cat's mouth showing localized gum inflammation beside a molar.

Clinical image blurred

Mouth & teeth

Localized gum redness or eating discomfort

Examples only — not a diagnosis. Different conditions can look alike.

Tooth resorption, periodontal disease, broken teeth, inflammation, and other oral problems can cause similar visible changes or discomfort.

What you may notice

Look for a red gum margin near one tooth, drooling, dropping food, chewing on one side, jaw chattering, pawing at the mouth, or reluctance to eat.

Why it matters at this stage

Oral discomfort can begin before obvious appetite loss, so a localized gum or eating change is worth documenting in young adult cats.

What to do

Book a veterinary visit. Record eating and chewing changes and arrange a veterinary oral examination; do not probe a painful area at home.

Image: Stef ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Tooth resorption in small animals · Merck Veterinary Manual: Periodontal disease in small animals

Close view of a cat's skin with small crusted bumps and hair thinning.

Clinical image blurred

Skin & coat

Small crusts, itching, or over-grooming

Examples only — not a diagnosis. Different conditions can look alike.

Feline atopic skin syndrome and flea allergy are possible allergic contexts. Parasites, infection, pain, stress-related grooming, and other problems can look similar.

What you may notice

Look for small crusted bumps, broken hair, redness, scratching, licking, or thinning hair along the neck, back, abdomen, or inner legs.

Why it matters at this stage

Recurring itch or over-grooming in young adulthood is worth assessing because several skin and behavioral causes can share the same outward pattern.

What to do

Book a veterinary visit. Photograph the distribution, note itch and grooming frequency, and arrange an examination if the change persists or recurs.

Image: Caroldermoid ·source page ·CC BY-SA 3.0 ·Cropped, resized, and format-optimized for display by My Petland.

Medical sources:Merck Veterinary Manual: Feline atopic skin syndrome

Cat life stage

Mature Adult

Close view inside a cat's mouth showing localized gum inflammation beside a molar.

Clinical image blurred

Mouth & teeth

Localized gum redness or eating discomfort

Examples only — not a diagnosis. Different conditions can look alike.

Tooth resorption, periodontal disease, broken teeth, inflammation, and other oral problems can cause similar visible changes or discomfort.

What you may notice

Look for a red gum margin near one tooth, drooling, dropping food, chewing on one side, jaw chattering, pawing at the mouth, or reluctance to eat.

Why it matters at this stage

Tooth resorption and other dental problems become important differentials in mature cats, but the mouth must be examined to identify the cause.

What to do

Book a veterinary visit. Record eating and chewing changes and arrange a veterinary oral examination; do not probe a painful area at home.

Image: Stef ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Tooth resorption in small animals · Merck Veterinary Manual: Periodontal disease in small animals

Five feline knee radiographs illustrating increasing osteoarthritis scores.

Mobility & joints

Reduced jumping, stiffness, or stair hesitation

Examples only — not a diagnosis. Different conditions can look alike.

Degenerative joint disease and osteoarthritis are possible causes. Injury, weakness, neurologic disease, and other problems can produce similar behavior.

What you may notice

Watch for lower jumps, hesitation before stairs, stiffness after rest, difficulty grooming the back, irritability when handled, or changes in litter-box access.

Why it matters at this stage

Cats may adapt their routine instead of showing an obvious limp, so reduced jumping or grooming can be an early practical clue in mature adulthood.

What to do

Book a veterinary visit. Record changes in jumping, stairs, grooming, and litter-box use, and arrange an examination if they persist or affect normal activity.

Image: Joanna Bonecka, Michał Skibniewski, Paweł Zep, and Małgorzata Domino ·source page ·CC BY 4.0 ·Resized and format-optimized for display by My Petland; full diagram preserved.

Medical sources:Bonecka et al. 2023: Knee joint osteoarthritis in overweight cats · Merck Veterinary Manual: Osteoarthritis in dogs and cats

Thin cat viewed from the side with a narrow body outline.

Weight & body condition

Visible weight or muscle loss

Examples only — not a diagnosis. Different conditions can look alike.

Weight or muscle loss can occur with inadequate intake, dental, digestive, kidney, endocrine, inflammatory, and other health problems. Appearance cannot identify the cause.

What you may notice

Look for a more prominent spine or hips, reduced muscle over the back or hind legs, a looser collar, reduced appetite, or a downward weight trend.

Why it matters at this stage

An unplanned downward trend in weight or muscle during mature adulthood deserves investigation rather than being treated as a cosmetic change.

What to do

Book a veterinary visit. Record recent weights, appetite, portions, vomiting, stool, thirst, and urination, then arrange an examination for an unexplained trend.

Image: Manucherian ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Longitudinal study: Body and muscle condition in ageing pet cats · AAHA: Senior care guidelines for dogs and cats

Cat life stage

Senior

Close view of a cat's eyes with visible lens clouding.

Eyes

New eye clouding, pupil change, or vision difficulty

Examples only — not a diagnosis. Different conditions can look alike.

Cataract, inflammation, retinal disease, glaucoma, hypertension-related eye damage, and other eye disorders can alter appearance or vision. An examination is needed to distinguish them.

What you may notice

Look for new clouding, unequal or persistently enlarged pupils, redness, squinting, bumping into objects, hesitation in dim light, or sudden disorientation.

Why it matters at this stage

Eye and blood-pressure-related disease becomes an important consideration in senior cats, but a new or sudden change is not a normal-aging diagnosis.

What to do

Contact a veterinarian promptly. Note whether the change was sudden, affects one or both eyes, or includes pain or vision loss. Emergency care now is appropriate for sudden vision loss, severe eye pain, or major eye trauma.

Image: Sven Volkens ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Merck Veterinary Manual: Disorders of the lens in cats · ISFM: Hypertension in cats consensus guidelines · AAHA: Senior care guidelines for dogs and cats

Five feline knee radiographs illustrating increasing osteoarthritis scores.

Mobility & joints

Reduced jumping, stiffness, or stair hesitation

Examples only — not a diagnosis. Different conditions can look alike.

Degenerative joint disease and osteoarthritis are possible causes. Injury, weakness, neurologic disease, and other problems can produce similar behavior.

What you may notice

Watch for lower jumps, hesitation before stairs, stiffness after rest, difficulty grooming the back, irritability when handled, or changes in litter-box access.

Why it matters at this stage

Mobility and access deserve regular attention in senior cats; reduced activity should not automatically be attributed to age.

What to do

Book a veterinary visit. Record changes in jumping, stairs, grooming, and litter-box use, and arrange an examination if they persist or affect normal activity.

Image: Joanna Bonecka, Michał Skibniewski, Paweł Zep, and Małgorzata Domino ·source page ·CC BY 4.0 ·Resized and format-optimized for display by My Petland; full diagram preserved.

Medical sources:Bonecka et al. 2023: Knee joint osteoarthritis in overweight cats · Merck Veterinary Manual: Osteoarthritis in dogs and cats

Thin cat viewed from the side with a narrow body outline.

Weight & body condition

Visible weight or muscle loss

Examples only — not a diagnosis. Different conditions can look alike.

Weight or muscle loss can occur with inadequate intake, dental, digestive, kidney, endocrine, inflammatory, and other health problems. Appearance cannot identify the cause.

What you may notice

Look for a more prominent spine or hips, reduced muscle over the back or hind legs, a looser collar, reduced appetite, or a downward weight trend.

Why it matters at this stage

Senior cats can lose muscle even when body weight changes only slightly, so repeated weights and body observations are more useful than one photograph.

What to do

Book a veterinary visit. Record recent weights, appetite, portions, vomiting, stool, thirst, and urination, then arrange an examination for an unexplained trend.

Image: Manucherian ·source page ·CC BY-SA 4.0 ·Wikimedia-generated resized derivative; locally cropped and format-optimized by My Petland.

Medical sources:Longitudinal study: Body and muscle condition in ageing pet cats · AAHA: Senior care guidelines for dogs and cats

How to use these images safely

  • Compare only broad visible features, then record what changed and when.
  • Do not use color, shape, age, or one photograph to name a condition.
  • Contact a veterinarian for a new, persistent, worsening, painful, or activity-limiting change.
  • Use the calculator’s emergency section for severe or rapidly worsening signs.

Image credit and licensing describe permission to reuse the photograph. Medical-source links separately support the educational explanation. Neither source endorses My Petland or diagnoses an individual pet.