Common Signs of Illness in Dogs

Dogs cannot tell us when they feel unwell, so recognising early changes in their behaviour, appetite, or appearance can make a real difference. Many signs of illness are subtle at first, and spotting them early may help your dog get the right treatment sooner and avoid more serious problems developing.

In this guide, we explain some of the most common warning signs of illness in dogs, when to monitor at home, and when it is best to contact your veterinary surgeon. We will also touch on how ongoing preventative care, including routine flea and worm treatment, good nutrition, and responsible use of prescribed medication, can support your dog’s overall health.

This article is intended for general guidance only and should not replace professional veterinary advice. If your pet is unwell or showing concerning symptoms, please contact your veterinary surgeon.

Why early signs matter

Dogs are often very good at hiding discomfort, particularly in the early stages of illness. What may seem like a small change, such as sleeping more than usual or turning away from food, can sometimes be the first clue that something is wrong.

By paying attention to day-to-day habits, you are more likely to notice when your dog is not quite themselves. Early action can be especially important with issues such as infections, digestive upset, pain, breathing problems, urinary conditions, or long-term health concerns.

Common warning signs to look out for

Changes in appetite or thirst

A healthy dog’s appetite can vary slightly from day to day, but a clear loss of interest in food is worth noticing. Refusing meals, eating much less than normal, or suddenly becoming unusually hungry can all be signs that your dog needs checking.

Changes in thirst can also be important. Drinking much more than usual may be linked to conditions such as diabetes, kidney problems, hormonal disease, or infection. Drinking less, especially in unwell dogs, may increase the risk of dehydration.

• Missing more than one meal
• Sudden increase in drinking
• Vomiting after eating or drinking
• Difficulty chewing or dropping food

If your dog has ongoing digestive sensitivity, your vet may recommend diet support or specific products. You can also browse our dog digestion products if your veterinary surgeon has advised supportive care.

Vomiting or diarrhoea

An isolated episode of vomiting or mild diarrhoea may pass quickly, but repeated sickness, severe diarrhoea, or signs of lethargy alongside stomach upset should not be ignored. Puppies, older dogs, and dogs with existing health conditions can become dehydrated more quickly.

Contact your veterinary surgeon promptly if your dog:

• Vomits repeatedly
• Has blood in vomit or stools
• Seems weak or collapsed
• Cannot keep water down
• Has a swollen or painful abdomen

Lethargy or reduced energy

Most owners know their dog’s normal energy level. If your usually lively dog seems unusually tired, reluctant to walk, less interested in play, or generally withdrawn, this may be a sign of pain, infection, fever, or another underlying issue.

Lethargy is a general sign rather than a diagnosis, so it is important to consider it alongside other symptoms such as coughing, limping, reduced appetite, or changes in toileting.

Coughing, wheezing, or breathing changes

Breathing changes should always be taken seriously. Coughing may be linked to irritation, infection, heart disease, or airway problems. Noisy breathing, wheezing, panting at rest, or struggling to catch their breath can suggest a more urgent concern.

Seek veterinary advice quickly if your dog shows:

• Laboured breathing
• Blue, pale, or grey gums
• Persistent coughing
• Breathing faster than usual while resting
• Collapse or weakness during exercise

If your dog has an ongoing diagnosed respiratory condition, any prescribed treatment should only be used exactly as directed by your veterinary surgeon. For vet-approved ongoing support, you can explore our dog respiratory products where appropriate.

Limping, stiffness, or difficulty moving

Mobility changes can be caused by injuries, strained muscles, paw problems, joint disease, or pain in the back or limbs. Some dogs show obvious limping, while others simply slow down, hesitate on stairs, or struggle to get comfortable.

Older dogs may develop gradual stiffness linked to arthritis, but sudden pain or reluctance to move should be assessed by a vet, especially if your dog cries out, cannot bear weight, or seems distressed.

For dogs with diagnosed joint concerns, your vet may suggest long-term support such as weight management, supplements, or prescription medication. We offer a range of dog joint care products and dog pain relief products for pets receiving appropriate veterinary guidance.

Skin, coat, and itching problems

Persistent scratching, licking, chewing at the paws, hair loss, scabs, redness, or flaky skin can all point to a problem. Common causes include fleas, allergies, skin infections, or irritation from the environment.

Keeping parasite prevention up to date is an important part of routine care. You can browse our dog flea and worming products or our wider flea, tick and worming collection to help support preventative care, but if your dog already has sore, inflamed, or infected skin, a veterinary examination is the best place to start.

For dogs with diagnosed skin conditions, our dog skin and coat products may also be helpful as part of a vet-guided care plan.

Eye or ear problems

Red eyes, discharge, squinting, head shaking, scratching at the ears, unpleasant ear odour, or sensitivity around the face may indicate infection, inflammation, injury, or irritation. Ear and eye problems can become painful quickly, so it is best not to delay checking with your veterinary surgeon.

If your vet has recommended ongoing cleaning or support products, you can explore our dog eye products and dog ear products.

Changes in urination or toileting

Straining to urinate, passing urine more often, accidents in the house, blood in the urine, or signs of discomfort when toileting can all indicate a urinary problem. In male dogs in particular, inability to pass urine is an urgent medical emergency.

Changes in bowel habits also matter. Constipation, diarrhoea, mucus, or blood in stools should all be monitored and discussed with your vet if they persist or are severe.

Where a urinary condition has already been diagnosed, your vet may advise ongoing dietary or medical support. Our dog urinary products may be useful in suitable cases.

Behaviour changes

A dog that becomes unusually quiet, clingy, restless, irritable, or withdrawn may be feeling unwell. Behaviour changes are sometimes the earliest sign of discomfort or pain, particularly in dogs who hide physical symptoms well.

Not all behaviour changes are caused by illness, but if your dog is acting out of character and especially if this is combined with other physical signs, a veterinary check is sensible. In some cases, your vet may also recommend supportive products for stress or behaviour alongside a management plan. We stock a range of dog behaviour products and dog pheromones.

Signs that need urgent veterinary attention

Some symptoms should never be left to wait. Contact your veterinary surgeon urgently, or an out-of-hours service, if your dog shows any of the following:

• Difficulty breathing
• Collapse, fainting, or severe weakness
• Repeated vomiting or severe diarrhoea
• Seizures
• A swollen abdomen
• Inability to urinate
• Heavy bleeding
• Suspected poisoning
• Severe pain or distress

It is always better to seek advice promptly if you are unsure. Your veterinary practice can help you decide how urgently your dog needs to be seen.

How to monitor your dog at home

If your dog has mild symptoms and is otherwise bright, your vet may advise careful monitoring. Helpful things to note include:

• When the symptoms started
• How often they are happening
• Any changes in food, treats, or routine
• Whether your dog is eating, drinking, and toileting normally
• Any recent medication or parasite treatment given

Photos or short videos can also be useful, especially for changes such as limping, coughing, or unusual behaviour.

The importance of preventative care

Preventative healthcare helps reduce the risk of some common illnesses and can make problems easier to spot early. This includes:

• Routine flea, tick, and worm treatment
• Regular weight checks
• A balanced diet
• Dental care
• Keeping up with vaccinations and vet check-ups
• Using supplements or supportive products only where appropriate

At Vetscriptions, we aim to make it easier for UK pet owners to access genuine pet healthcare products and prescribed medication responsibly. You can explore our wider dog collection, including everyday health products, supplements, and prescription treatments where suitable.

Ordering prescription medication responsibly

If your dog has been diagnosed with a health condition and your vet has prescribed treatment, it is important to follow their instructions carefully. Never give medication intended for another pet or use leftover treatment without veterinary advice.

If you need help accessing prescribed medication online, you can read our guide on how to order a prescription medicine and find answers in our prescription FAQs. If you are unsure what information is needed, our contact page is always available, and some orders may require completion of an animal health form.

Conclusion

Knowing the common signs of illness in dogs can help you act early and get the right support for your pet. While some mild symptoms may pass quickly, ongoing or worrying changes should always be taken seriously. If your dog is off their food, lethargic, vomiting, limping, itching excessively, or simply not behaving like themselves, it is wise to check in with your veterinary surgeon.

At Vetscriptions, we are here to support pet owners with reliable information and access to genuine pet healthcare products, from preventative treatments to prescribed medication. If your dog has already been assessed by a vet, you can browse our dog health products, explore our prescription medicines, or learn more about us.

If you are ever in doubt about your dog’s symptoms, please contact your veterinary practice for professional advice. For ongoing pet health support and trusted products, we are always here to help at Vetscriptions.