Useful dog-health guidance. No scare stories.

Dog Health8 min read16 Aug 2026

Dog skin problems and coat changes: what to check first

An owner gently parts a relaxed dog's coat to look at the skin at home

A new skin or coat change is something to notice, not a diagnosis to make from a photograph or a label. If your dog has trouble breathing, facial swelling, collapse or seems severely unwell, call a vet now. Blood, pus, marked pain or a rapidly worsening change needs prompt veterinary advice. Otherwise, record what changed and arrange a check if it persists, returns or worries you.

start with urgencyFour safe routes before guessing the causeChoose the urgency, then bring a useful observation record to the right conversation.
  1. 01
    Call now

    Trouble breathing, facial swelling, collapse or a dog that seems severely unwell is an emergency. Call your usual or out-of-hours vet.

  2. 02
    Contact promptly

    Blood, pus, marked pain, a wet area or a change worsening quickly needs veterinary advice without a home experiment.

  3. 03
    Book a check

    Arrange a check when a skin or coat problem lasts for a few days, keeps returning, or is making your dog uncomfortable.

  4. 04
    Note and recheck

    For a small, comfortable change with no red flag, take a dated photo, note what changed and call sooner if it persists or worsens.

These escalation boundaries follow current PDSA skin-problem guidance. They are a reason to contact a veterinary team, not a way to name the cause.

Make one calm observation pass

Skin or coat change means a new, persistent or recurring difference in the skin surface, comfort, smell, moisture, colour, scaling, coat texture, shedding or coverage. It is an observation category, not a diagnosis. Start with what you can describe rather than what you think it is.

a useful recordFive things to noteYou do not need to inspect every inch of your dog or identify a condition.
  1. 01
    Location

    Where is the change? Is it one patch, both sides, paws, ears, belly or somewhere else?

  2. 02
    Surface

    Note dryness, flakes, moisture, scabs, a smell, or any blood or pus. Do not try to label the condition.

  3. 03
    Itch behaviour

    Record scratching, licking, chewing, biting or rubbing, and whether it interrupts rest.

  4. 04
    Coat change

    Note shedding, thinning, a bald patch or a change in coat texture without assuming a nutrient problem.

  5. 05
    Timing and whole-dog health

    Take dated photos and note progression, recent changes and whether appetite, energy or comfort is different.

The outline is only a location prompt. It carries no medical meaning and cannot identify a skin condition.

What a sign can and cannot tell you

keep the interpretation honestObservation helps the next step; it does not prove the cause
What you notice What it cannot prove Useful next step
Scratching, licking, chewing or rubbing Itch, also called pruritus, is a sign. It does not prove an allergy, infection, parasite or food cause. Record the behaviour and location; ask a vet if it persists, recurs or affects comfort.
Thinning coat, bald patches or fur loss Alopecia means hair is absent where it would normally be present. It does not name the cause or prove a nutritional deficiency. Make hair loss the main reason for the appointment. Use the fur-loss guide when thinning or a bald patch is the main concern.
A change after a food, treat or season change Timing alone does not show that food is responsible. Do not begin a DIY elimination diet from a skin photograph. Bring the timing and every food/treat change to the vet; use the food-allergy guide only if that becomes the agreed question.
Flea dirt, a flea or paw-focused licking One visible clue does not explain every skin or coat change. Use the dedicated flea or paw guide for that dominant concern rather than treating this page as a cause list.

Merck defines pruritus as itch behaviour and alopecia as hair loss. Those definitions describe a sign, not its cause.

Why food is only one possible question

In pruritic dogs with atopic dermatitis, clinical appearance alone cannot distinguish food-induced from non-food-induced disease. That means a skin or coat pattern cannot prove that food is responsible. The finding comes from a prospective study of dogs already assessed for atopic dermatitis; it does not mean every skin problem is allergic, or that food is never relevant. (Favrot et al., 2010)

Choose the next owner guide only when the concern is clear

one next question at a timeFollow the dominant concern, not a guessed diagnosis
flea evidenceFound fleas or flea dirt?Use the dedicated flea guide for identification and next steps. paw-focused itchIs licking or chewing paws the main problem?Use the paw guide for that body-part route. food and rash questionWondering what a food-allergy rash can tell you?That guide explains the limits and the diagnostic route. food investigationHas food become the real question?Read how food-allergy symptoms are investigated, not guessed. food choiceComparing food approaches for an itchy dog?Keep that commercial comparison separate from this first check. routine careIs your dog otherwise well and you want coat-care basics?Use the routine coat-maintenance guide instead.
take this to the appointmentA short history is more useful than a guessed cause
  • Two or three dated photos in the same light, if you can take them safely.
  • Where it started, whether it is spreading, and the main itch or coat change.
  • Recent food, treat, environment or routine changes without assuming they caused it.
  • Any earlier episodes, what has already been tried, and whether your dog seems otherwise well.

A veterinary team can decide whether more examination or testing is useful. This checklist stores nothing and does not replace that assessment.

Common questions

Can I tell whether my dog's skin problem is an allergy from a photo?

No. A photo can be useful to show change over time, but appearance alone cannot distinguish food-induced from non-food-induced atopic dermatitis, and it cannot diagnose other causes. Use it as part of the history you take to your vet.

When should I call a vet about a skin or coat change?

Call now for breathing trouble, facial swelling, collapse or a dog that seems severely unwell. Seek prompt advice for blood, pus, marked pain or rapid worsening. Book a check when the problem lasts for a few days, recurs or makes your dog uncomfortable.

Does a dull coat or hair loss mean my dog needs a supplement?

No. A coat or hair change does not prove a nutrient problem, and this guide does not recommend supplements. Make hair loss or bald patches the main reason for a veterinary conversation.

Could a food change be causing my dog's itchy skin?

It is one history detail to note, not a conclusion. A skin pattern cannot prove that food is responsible. Keep a complete food and treat history and discuss the next diagnostic step with your vet.

What should I write down before the appointment?

Note location, surface change, itch behaviour, coat change, timing, progression and whether your dog seems otherwise well. Dated photos can help show change, but do not replace an examination.

Sources: current PDSA owner guidance; the Merck pruritus overview; the Merck alopecia overview; and Favrot et al., 2010. This guide gives no diagnosis, treatment, medicine, home remedy, diet trial, supplement recommendation or Some Grub product recommendation.