Dog health warnings: 10 illness signs and what to do now
You know your dog better than anyone. So, when something’s off, you’re usually the first one to notice.
Regular vet checkups build a baseline. That baseline is what makes it possible to catch trouble early, before a small problem turns into a big one.
If you’re worried, don’t sit on it. Call your vet, jump on a video visit, or head to the emergency room. Knowing which of those three to pick used to be a guessing game.
Dogs pick up illnesses from other dogs, so keep an eye on the pups your pup plays with, too, whether it’s the neighbor’s lab or a lost dog you’re helping get home.
Watch for change. That’s the golden rule. As a rule of thumb, monitor any changes in your dog’s behavior. If your usually zoomy dog naps through one afternoon, he’s probably just tired. But if that zoomy dog turns into a permanent couch potato, or your quiet, easygoing dog starts barking nonstop, pay attention. That shift is your dog’s way of telling you something’s wrong.
Nobody knows your dog as you do. If he’s acting different, book the checkup. Don’t let cost scare you off. Pet insurance covers many injuries and illnesses, and a pet insurance alternative can be a cheaper way to cover only emergency visits.
Below, you’ll find the common dog illness symptoms to watch for and what each one might mean, plus a quick guide to help you decide whether a phone call or a car ride is the right next move.
Telehealth or emergency vet? Know which one to call
Pet telehealth has exploded over the past couple of years. Now you can video chat with a vet at 2 a.m. instead of white-knuckling it until the clinic opens. That’s great news, but only if you know its limits.
Think of telehealth as a smart first stop, not a stand-in for hands-on care. A vet can see your dog on screen, ask sharp questions, and help you map out your next move. What a vet can’t do over video is run bloodwork, take an X-ray, or feel a lump. If your dog needs diagnostics, you’re heading to a clinic no matter what.
Reach for telehealth or a call to your regular vet when you’re dealing with:
● Mild, short-lived vomiting or diarrhea with no other symptoms
● Skin trouble that looks uncomfortable but not urgent: hot spots, mild itching, a new bump you want a second opinion on
● Minor behavior changes, like new chewing habits or a housetraining slip
● Prescription refills or follow-up questions on a condition your vet already diagnosed
● General ‘is this normal?’ questions
Skip the video call and get to the emergency vet for:
● Trouble breathing, choking, or blue-tinged gums
● Uncontrolled bleeding
● Seizures or collapse
● Suspected poisoning
● A swollen, distended belly or repeated retching with nothing coming up (classic bloat warning signs)
● Any sudden, dramatic change in condition
Here’s the rule of thumb: if you’re asking yourself, “should I just go?”, go. That instinct is worth listening to. A quick call to the ER on your way in also gives the team time to prep, which is a form of teletriage in its own right.
Quick triage chart: call today vs. go now
Use this as a starting point, not a diagnosis. When in doubt, call and describe what you’re seeing.
Common dog illness symptoms and what they mean
Appetite or weight change
Keep tabs on how much your dog eats. If the pounds are creeping up and you haven’t changed his food or his walks, something else is going on.
Rapid, unexplained weight gain often points to an underactive thyroid or Cushing’s disease, a condition caused by too much cortisol in the body.
Thyroid screening has gotten more precise lately, and it’s worth knowing the update. If your vet suspects hypothyroidism, don’t stop at a single T4 test.
Ask about a full panel: T4, free T4, and TSH together, since a low T4 by itself can be misleading in a dog who’s sick, stressed, or on certain medications. Running the fuller panel, per current veterinary endocrinology guidelines, gives your vet a far more reliable diagnosis than a single number ever could.
On the flip side, sudden weight loss or a dog who’s just not interested in food can signal something serious: cancer, liver trouble, a gastric ulcer, or kidney failure. It can also mean your dog is in pain, arthritis being a common, quiet culprit.
Dogs skip meals sometimes. Everybody does. But if it’s been more than 48 hours without eating, call your vet. Don’t wait this one out.
Vomiting
Dogs throw up. It happens. Sometimes food upsets their stomach. Sometimes nerves get the better of them.
Here’s what matters: watch for a pattern.
Is your dog throwing up after every meal? Check the food first. New bag? Did the manufacturer change the recipe?
Something in that bowl might not be sitting right anymore.
Did he get into something he shouldn’t have, like a sock or a toy? Vomiting might just be his body doing its job and getting it out.
But consistent, repeated vomiting is a red flag. It can point to gastric ulcers, viral or parasite infections, bloat, liver or kidney failure, gastrointestinal illness, pancreatitis, or poisoning.
If you see blood in the vomit, don’t wait and don’t wonder. Get to the vet now—every minute counts.
Diarrhea
Diarrhea deserves the same watchfulness as vomiting. One loose stool usually just means your dog ate something that didn’t agree with him or got nervous about something.
Repeated bouts are a different story, especially when accompanied by vomiting or fever. Your dog could be dealing with a bacterial, viral, or parasitic infection, inflammatory bowel disease, hemorrhagic gastroenteritis, parvovirus, or colitis.
Diarrhea can also point to cancer or liver or kidney disease.
If the struggle with diarrhea keeps dragging on, a designated indoor puppy potty can make the cleanup a lot less miserable while you sort out the cause.
Increased thirst
Excessive thirst and frequent urination are signs of some genuinely serious dog health problems: diabetes, kidney failure, liver disease, leptospirosis, and Cushing’s disease. A urinary tract infection or bladder stones can cause it too.
A dog who drinks more on a hot day is nothing to worry about. A dog who drinks noticeably more every day is a different matter, and it’s worth calling your vet.
Watch for other clues too. Is he asking to go out more often? Having accidents even though he’s been housetrained for years? Both are worth mentioning.
Dehydration is its own risk, so keep clean, fresh water available at all times.
Coughing
An occasional cough or sniffle isn’t cause for alarm. But constant, recurring coughing can point to something serious.
Infection: Kennel cough and canine influenza both cause coughing. A bacterial infection responds to antibiotics; a viral one needs rest, so keep your dog calm while he recovers.
Heartworm disease: Heartworms enter your dog’s body as larvae through a mosquito bite, then migrate to your dog’s heart and lungs, growing into spaghetti-like adults that cause serious, sometimes fatal, damage. Monthly heartworm preventative is the best protection you’ve got, since treatment is costly and can’t undo the damage already done.
Other culprits: congestive heart failure, mitral valve endocarditis, dilated cardiomyopathy, a collapsed trachea, chronic bronchitis, or cancer.
Hair loss and itchiness
Hair loss or itching can be a reaction to stress, food allergies, or bites from fleas, ticks, or mange mites. Shedding can also mean your dog isn’t getting the nutrients she needs from her food, or that her shampoo is irritating her skin.
But losing hair can also signal a hormonal imbalance, inflammatory bowel disease, thyroid disease, Cushing’s disease, ringworm, endocrine problems, or a fungal, yeast, or staph infection. When in doubt, talk to your vet.
If your dog experiences these symptoms, CBD products like Koi CBD oil can help reduce their pain.
Runny nose or watery eyes
Nasal discharge deserves more attention than it usually gets. A little discharge now and then isn’t a big deal, but persistent discharge, especially from just one nostril, is worth a closer look.
Here’s why: discharge that lingers on one side, especially alongside nosebleeds, sneezing fits, or pawing at the face, can be an early sign of a nasal tumor, most common in dogs over seven.
The tricky part is that antibiotics sometimes ease symptoms for a while, which can delay an accurate diagnosis if you assume it’s cleared up for good.
Don’t panic over every sniffle. Do pay attention if the discharge sticks around, comes from one side, or shows up with blood. That combination is your cue for imaging, not another round of home care. Nasal cancer is far more treatable when it’s caught before it spreads.
Severe nasal discharge more broadly can also point to infection, nasal mites, a weak immune system, pneumonia, or even dental disease.
Watery eyes are their own thing. Epiphora, the overproduction of tears, can result from eyelashes or eyelids turning inward or outward, sinus infections, blocked tear ducts, or tumors.
Stiffness
When a dog starts moving stiffly, most owners blame age. Sometimes that’s fair. Often, it isn’t.
Watch for real signs of pain: your dog limping, struggling to get up or lie down, or hesitating on the stairs. That’s your dog’s body telling you about a joint or bone problem.
That could mean hip dysplasia, disc disease, ruptured ligaments, or arthritis. The inflammation and swelling behind it is treatable, and treating it can make a real difference in how comfortable your dog feels day to day.
Red or swollen gums
Irritated gums usually indicate gingivitis, which is treatable before it progresses to full periodontal disease.
Brushing your dog’s teeth daily is still the best defense. Dogs get cavities, tooth decay, and gum disease just like we do.
Gum disease is so common that most dogs show early signs by age 3, according to the American Kennel Club.
Watch for bleeding gums, drooling, trouble chewing, receding gums, bad breath, loose teeth, or pawing at the mouth. Left untreated, gum disease can lead to infections that shorten your dog’s life.
Lethargy or excessive sleep
Lethargy is one of those symptoms that’s easy to wave off. Your dog’s just tired, right? Maybe. But lethargy is also one of the most overlooked signals of a health problem, especially pain.
Recent veterinary research keeps returning to the same finding: chronic pain in dogs is severely underdiagnosed.
Owners are quick to spot a sudden limp, but chronic, low-grade pain, the kind from arthritis or an old injury, tends to disguise itself as something else entirely: sleeping more, moving less, generally seeming “off.”
Dogs can’t tell us where it hurts, so body language is often all we get, and it’s easy to mistake that for normal aging. Cornell’s veterinary researchers point to slower movement, trouble getting up, and general tiredness as quiet, classic signs of pain, which owners often chalk up to “getting older.”
So, if your dog is sleeping more than usual, don’t stop at “he’s just getting older.”
Ask your vet to rule out pain specifically, not only infection or organ trouble. A pain trial, in which your vet tries pain medication and monitors for improvement, can uncover problems that bloodwork alone might miss.
Watch for company symptoms, too: loss of appetite, vomiting, diarrhea, coughing, or labored breathing, alongside lethargy. Any of those combinations means it’s time to call, not wait it out.
A thorough vet visit gets to the bottom of it and gets your dog back to his old self faster.
Keep your dog healthy
Good health isn’t an accident. A few habits, done consistently, go a long way.
Nutrition comes first. High-quality dog food suited to your dog’s age, size, and breed sets the foundation for everything else.
Exercise matters as much. Daily walks and playtime keep your dog fit, help maintain a healthy weight, and reduce the risks associated with obesity.
Don’t skip mental stimulation either. Puzzle toys and training keep boredom and the bad behavior it causes at bay.
Grooming rounds it out: brushing, ear cleaning, nail trims, and dental care. Floppy-eared breeds like beagles need extra attention to prevent ear infections.
And keep those regular vet checkups on the calendar. They catch small problems while they’re still small.
Preventive measures
Vaccinations and parasite control are the backbone of preventive care. Vaccines protect against rabies, distemper, parvovirus, and adenovirus, so stick to the schedule your vet recommends.
Fleas, ticks, and worms put both your dog and your household at risk.
Staying current with flea and tick prevention and deworming keeps that risk low.
Talk to your vet about building a preventive care plan tailored to your dog specifically, not a generic one-size-fits-all schedule.
Use dog illness symptoms to protect your dog
You know your dog. So, keep watching for change, and don’t second-guess that instinct when something feels off. If you spot any of these dog illness symptoms, get your vet involved. Whether that’s a video call, a same-day appointment, or a trip to the ER depends on what you’re seeing, and now you’ve got a clearer way to decide which one.
Working with your vet gets you a real diagnosis and a real plan: medications, physical therapy, or lifestyle changes, whatever your dog needs.
CBD oil is one option to help your aging or ill dog cope with various symptoms. If you’re unsure how to use CBD oil for dogs, consult your veterinarian.
Lauretta Williams is one of the co-founders of PawMaw.com, a website dedicated to creating happy endings by reuniting people with their lost pets.