Dog Health Red Flags: Signs Worth Logging Immediately

Most health problems in dogs don't arrive suddenly. They start as something small - a slightly off day, a skipped meal, a limp that came and went. The issue is that small things are easy to explain away, and by the time they become obviously significant, the early history is gone. With 11.1 million pet dogs in the UK (PDSA PAW Mini Report 2025), identifying health problems early matters more than ever - particularly given that more than half of UK pet owners report worrying about affording veterinary care, making early intervention financially as well as medically important.

These are the signs worth logging the moment you notice them - not because each one is necessarily serious, but because having a date and a description turns a vague worry into useful clinical information.

Changes in appetite

Not eating for a single meal is normal. A dog that's off food for more than 24 hours, or that's eating noticeably less over several days, is telling you something. Log the first day you notice it, whether they're interested in food at all or have stopped engaging entirely, and whether they're still drinking normally.

The same applies to increased appetite - a dog that suddenly seems ravenous when they weren't before can be a sign of conditions like diabetes or Cushing's syndrome.

Gradual weight loss

This is one of the most commonly missed red flags because it happens slowly. You see your dog every day, you adjust to their new shape, and it isn't until someone who hasn't seen them for a month mentions it that you register the change. The PDSA PAW Mini Report 2025 found that 82% of UK dog owners are unaware of their dog's body condition score - the standard veterinary measure of healthy weight - and that veterinary professionals estimate 46% of UK dogs are currently overweight or obese.

Log your dog's weight monthly. If you notice visible rib definition increasing, a more prominent spine, or reduced muscle mass around the hindquarters, write it down with a date and do a weigh-in. A five percent loss over a couple of months is worth mentioning to your vet. Ten percent or more warrants an appointment.

Intermittent limping

A limp that comes and goes is actually harder to assess than a constant one, because by the time you're at the vet your dog may be walking normally. What helps enormously is a log entry with the date of first onset, which leg was affected, whether it was worse after rest or after exercise, and whether anything preceded it (a long run, jumping off furniture, rough play).

Note whether it's improving or staying the same. Orthopedic conditions often follow patterns - hip dysplasia tends to be worse after rest, soft tissue injuries tend to worsen with exercise. Your observations over time help your vet narrow this down.

Increased thirst or urination

If your dog is visiting their water bowl much more frequently than usual, or asking to go outside more often, log it. Increased thirst (polydipsia) and increased urination (polyuria) often occur together and are associated with a range of conditions including diabetes mellitus, Cushing's disease, kidney disease, and pyometra in unspayed females.

The challenge is that "more than usual" is only meaningful if you have a sense of what usual looks like. If you've been logging periodic notes about your dog's normal routine, you'll have a baseline to compare against.

Occasional vomiting

One vomit after eating grass or scavenging something questionable isn't a crisis. Repeated vomiting over several days, vomiting that contains blood, or vomiting accompanied by lethargy or refusal to eat is a different matter.

Log the date, the frequency, what the vomit looked like (undigested food, bile, blood or dark material), and whether it was preceded by anything unusual. This information changes the differential significantly for a vet.

Behavioural shifts

Behavioural red flags often map to specific conditions. See the monitoring guides for anxiety, UTI, arthritis, and cognitive dysfunction.

This is the one most owners dismiss, because it feels subjective. "Seemed quieter than usual" doesn't feel like a medical observation. It is.

Pain is often expressed behaviourally before it's expressed physically. A dog that becomes more withdrawn, less playful, less interested in greeting people, or more irritable when touched may be uncomfortable. A dog that starts having accidents indoors after reliable house training may have a urinary tract infection or cognitive changes. A dog that starts hiding, or sleeping in unusual places, may be unwell.

You don't need to interpret the behaviour - just record it. "Didn't want to go for a walk, unusually quiet in the evening" is a complete and useful entry.

Changes in breathing

Occasional coughing isn't unusual, especially after a run or in dusty environments. But a persistent cough, laboured breathing at rest, or breathing that seems noisier than normal warrants attention and a log entry. In breeds with flat faces (brachycephalic breeds like bulldogs, pugs, and French bulldogs), breathing should be assessed more carefully - what looks like normal breathing in these breeds may already represent compromised airways.

Coat and skin changes

A dull coat, increased shedding outside of normal seasonal moults, new lumps or bumps, persistent scratching, or changes in skin texture are all worth writing down. Many are benign - but some coat changes signal hormonal issues, and any new lump should be checked.

Log where any lump is, roughly how big, when you first noticed it, and whether it seems to be changing. Vets often ask "has it grown?" and "how long has it been there?" - questions that are much easier to answer with a dated entry.

When to skip the log and call the vet directly

Some signs warrant immediate veterinary attention rather than a journal entry and a wait-and-see approach:

• Suspected bloat (distended abdomen, unproductive retching, restlessness): this is an emergency
• Collapse or sudden weakness
• Pale or white gums
• Difficulty breathing
• Suspected poisoning
• Seizures
• Eye injuries or sudden loss of vision
• Any injury causing significant pain or distress

These aren't log-and-monitor situations. Call your vet or an emergency practice.

Frequently Asked Questions

How long should I monitor a symptom before going to the vet? It depends on the symptom. Vomiting or diarrhoea without other symptoms: monitor for 24 hours, withhold food for that period, and call if it continues or worsens. Lethargy or appetite changes: monitor for 24–48 hours. Any breathing difficulty, collapse, or signs of significant pain: call immediately. When in doubt, call your vet - most practices are happy to advise over the phone.

My dog seems fine now but was limping this morning. Should I still log it? Absolutely. Intermittent limping that resolves is actually more useful to log than a constant limp, because the pattern is harder to reconstruct from memory. Write down the date, which leg, when it happened, and whether anything preceded it. If it recurs, you have a timeline.

Are there symptoms that are especially easy to miss in older dogs? Yes. Cognitive decline (confusion, changed sleep patterns, apparent forgetfulness), reduced mobility, and weight changes all tend to be attributed to "just getting old" when they may be treatable conditions. Senior dogs benefit from twice-yearly vet visits and regular weight monitoring.

What if the vet says nothing is wrong but I'm still concerned? Keep logging. A single visit with a normal examination is reassuring, but if you have a strong sense that something is different, your observations over time matter. A pattern of notes - even if each individual entry seemed minor - can prompt more investigation and can be valuable for a second opinion.