Reviewed by Erica Irish, DVM
Does your dog smell like fish or have a fishy odor? It’s a distinct smell that certainly isn’t normal for any dog.
In fact, I recently experienced this with my dog (a lab/pitbull mix). He was sitting next to me on the sofa, and when he moved, I caught a whiff of a distinctly fishy odor. It was disgusting.
Unfortunately, I didn’t realize that it was a sign of a problem. In fact, I passed it off as being a one-time thing. I figured maybe he rolled in something rotten.
I was wrong.
It wasn’t until I spotted a drop of blood on the dog’s blanket that I called the veterinarian. What happened to my dog is, apparently, quite common. The details of what happened can be found in reason #7 below.
If you’re wondering why your dog smells fishy, this is the post for you!
We’ll go over some of the main reasons why dogs develop bad odors, including most likely reason why your dog smells like fish.
Always speak with your veterinarian when it comes to the health of your dog.
There are a number of medical reasons why your dog might smell like fish or give off an unnaturally foul odor, including:
- Periodontal disease
- Yeast infection
- Bacterial infections
- Viral infection
Keep reading for more information.
Why Do Dogs Love Rolling on Dead Things or Poop?
Generally speaking, dogs love to roll in anything dead.
Experts aren’t 100% sure why, but there is a theory that dogs that do this are reverting to the rituals of their ancestors when wolves rolled in dead carcasses to mask their own scent.
Doing this would have provided a way to hide the wolves’ scent to protect him on a hunt.
Other experts believe that dogs roll on rotting flesh as a way of creating a scent marker. If the dog had to hunt for its survival, leaving his scent behind could possibly keep predators away and protect the dog’s catch.
The following seven situations can leave your dog smelling foul or fishy. They all produce different types of odor, but it’s the last one on this list that is most likely to leave your dog smelling like fish.
1. Yeast Infections
Yeast infections are common in dogs and are usually caused by an underlying or secondary condition.
Your dog’s body carries a healthy amount of yeast on the skin. In fact, it’s part of your dog’s normal bacterial flora. Unfortunately, certain health conditions can disrupt the balance.
If too much yeast develops on the skin, it will create an unhealthy environment where bacteria and yeast can develop and spread.
If you hadn’t already noticed the unusual musty odor coming from your dog, you’ll likely notice the itching and reddened skin that comes with it.
Common places for yeast infections are on the skin (yeast dermatitis), on the paws, or in the ear (otitis). Any moist areas on the dog are prone to yeast infections. This also includes the armpit, groin, and folds of the face.
Yeast Infections Are Not Contagious
Yeast infections are not contagious, but they do need to be treated by a veterinarian. Get help from a veterinarian before trying over-the-counter products.
If your dog is already suffering from a bacterial infection, that will need to be cleared up before it gets worse. Adding over-the-counter anti-itch creams or balms won’t get rid of bacteria and could potentially make the situation worse.
Signs of Yeast Infections in Dogs
A yeast infection on a dog’s skin typically causes severe itching. Watch for red, irritated skin.
- Itchy skin
- Sweet or musty odor
- skin may become thicker.
- Skin may become discolored and appear gray, brown, or black.
The type of treatment option chosen by the veterinarian will vary depending on the severity of the problem.
Dogs with advanced yeast dermatitis may be prescribed a combination of oral and topical treatment.
2. Periodontal Disease in Dogs
Periodontal disease, which is an inflammation of the structures surrounding the teeth, is a common dental issue in dogs. It’s the result of dental plaque accumulation on your dog’s teeth.
It’s a common misconception that dogs have terrible breath, but that’s not true. Bad breath can point to a problem brewing in the dog’s mouth.
Signs of dental issues in dogs include the following:
- inability to chew normally
- discharge from the mouth
- bleeding from the mouth
- a growth inside of the mouth
- The dog might paw at his mouth.
- foul-smelling breath
If you suspect or notice any signs of dental disease in your dog, it’s important to take him or her to a veterinarian for a proper diagnosis and treatment plan.
3. Ear Infections in Dogs
Ear infections, also known as otitis externa, are common bacterial or yeast infections of the ear that can cause a strong odor. If you suspect your dog has an ear infection, be sure to have him or her seen by a veterinarian as quickly as possible. Ear infections are painful and will not likely get better on their own.
Prescription treatment could include antifungal drops, medicated ear cleaners, and possibly oral antifungal medication.
Signs of an ear infection in dogs:
- vigorous scratching at the ear
- pawing at the ear
- sliding his/her face on the ground or on bedding
- reddening of the skin around the ears
- brownish discharge from the ear
4. Vaginitis in Dogs
Vaginitis is an inflammation of the vaginal area. It can be caused by a number of things, including:
- Vaginal trauma
- urinary tract infection
- Contamination with urine or feces within the vulva
- abnormally located ureter.
- Urinary incontinence
- Vaginal tumors
- bacterial or viral infection
In addition, if there is a bacterial infection or abscess, there could be a foul smell coming from that area.
Signs of vaginitis in dogs may include:
- vaginal discharge of mucus or pus
- bad smell coming from the vagina
- blood in dog’s urine (may be coming from the vagina although rare)
- excessive licking around the vulva
- swelling of the vaginal area
Pyometra is an infection of the uterus. It can happen due to hormonal changes in the female reproductive tract.
After the dog has been in heat or estrus, the hormone “progesterone” can remain elevated for as long as two months.
This causes the lining of the uterus to thicken. If the dog does not become pregnant within the next couple of heat cycles, the uterine lining will continue to thicken.
Eventually, cysts will form and secrete fluid that promotes bacterial growth. Without treatment, the dog can develop a life-threatening infection.
Get more information on pyometra in dogs at this post by bluecross.org Pyometra in Dogs
In addition, signs of pyometra in dogs include:
- Pus draining from the uterus through the vagina, unless the pyometra is closed instead of open.
- abnormal discharge or pus on the skin or under the tail.
- An abnormal discharge was found in the dog’s bed.
Pyometra is a serious condition that needs to be treated by a licensed veterinarian.
6. Gastrointestinal Disorders in Dogs
If your dog is burping a lot, throwing up their food, suddenly drooling, or seems to be gulping air, he or she may have a food allergy or acid reflux disorder.
Canine acid reflux is similar to the type of reflux you or I might experience. It occurs when gastric fluids come up from the stomach and flow into the esophagus. In dogs, this condition is also known as gastroesophageal reflux.
Signs of dog acid reflux include:
- vomiting food
- vomiting bile
- regurgitating undigested food
- Weight loss over time
- reluctance to eat (because it is painful)
- shows other signs of pain, including whining or lip licking (anxiety).
Dogs with food allergies can also develop a skin rash and severely itchy skin. Constant licking can promote bacterial growth and lead to infection. It may not smell like fish, but the skin could develop a sour or foul smell.
Before coming to your own conclusion, have your dog seen by a licensed veterinarian.
A change in your dog’s diet may help solve the problem. However, it’s important for the veterinarian to rule out other conditions that need attention.
If your dog is having these kinds of health issues, talk to a veterinarian.
The veterinarian may check for environmental allergies and will possibly recommend a hypoallergenic diet or other course of treatment.
Every dog is different, and a veterinarian needs to determine the best course of action for your dog.
The Moore Animal Hospital in Fort Collins, CO has a great article about canine acid reflux: Can Your Dog Have Acid Reflux?
7. Anal Sac Problems
This is the problem my dog had. I noticed a distinctly fishy smell one day when he was on the couch with me. The only reason I noticed the smell, I think, was because he was sitting with his rear end facing me.
I didn’t notice the smell after that and chalked it up to nothing. A few weeks later, I noticed he was chewing the base of his tail. My other dog also suddenly started sniffing his butt a lot, which was odd.
It wasn’t until I noticed blood on the blanket that I realized there was a problem. I checked him over to see if the blood was coming from his paws, ears, nose, or mouth.
I lifted his tail and noticed a bright-pink abscess on the right-side of his anus.
My dog was diagnosed with an anal sac abscess, a painful infection that required antibiotics and an anti-inflammatory to resolve.
Anal Gland Issues in Dogs
In order to understand how a dog’s anal sacs can become infected, you first need to know about the dog’s anal glands.
Anal sacs (glands) are small sacs that are located on either side of the anus. If you look at the anus like a clock, picture the sacs lying at 5 pm and 7 pm.
These sacs (also known as anal glands) are lined with scent glands that release a fishy-smelling fluid that is used as a scent marker.
Anal glands in dogs are kind of like the appendix in people. The secretions may assist in defecation, making it easier for dogs to poop.
Anal Gland Secretions Have a Fishy Smell
When dogs have healthy bowel movements, fluid from the dog’s anal sacs is emptied by the pressure of feces. If your dog frequently has soft stool, there might not be enough pressure to release the glands properly.
If your dog has problems with constipation or loose stools, there’s a chance those anal sacs will not empty properly. If that continues over time, the fluid can become impacted and clogged.
This can happen in any dog, however, even in the absence of any other problem.
Symptoms of Anal Sac Disease
- butt scooting
- chewing around the base of the tail
- A visible abscess near the anus.
- Your dog will smell fishy.
- the dog’s butt smells fishy
If the anal sac isn’t manually expelled, the fluid will become bloody, and eventually the sacs will fill with pus.
These are very common but very painful for dogs . Any sign of anal sac inflammation should be seen by a veterinarian ASAP because they can rupture.
The good news is that they are treatable.
The veterinarian will have to manually express the fluid. Your dog won’t love this, but it needs to be done. Afterwards, the veterinarian will be able to tell if the fluid is normal or if it appears curdled and abnormal, which would indicate a bacterial infection.
Treatment for Anal Gland Problems in Dogs
If the abscess doesn’t appear severe and the dog is otherwise healthy, the veterinarian may prescribe oral antibiotics and anti-inflammatory medication for pain.
He/she may recommend using a warm water compress that has been soaked in Epsom salts.
If these medical attempts to resolve the issue do not work, your dog may need to go into surgery to have the anal sac lanced.
Anal Gland Tumors
Anal gland tumors in dogs consist of cells that come from the anal sac. These tumors are typically found during a routine examination when the veterinarian feels a mass. The only way to know for sure that it is a tumor is by fine needle aspiration.
Anal sac tumors have a moderate risk of spread. Most will metastasize. The veterinarian will want to determine if this has already happened through a series of tests including:
- abdominal ultrasound
- blood work
- urine testing
Possible signs of anal sac tumors include:
- straining to defecate
- producing ribbon-like stool
- increased drinking and thirst
- increased urination
- kidney disease/failure due to high levels of calcium in the blood
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As pet parents, it’s important to understand that a foul or strong fishy smell is not normal. The cause of a fishy smell in dogs can be due to anal gland impaction. It’s a common problem in dogs that can be treated medically or (in severe cases), surgically.
Some dogs can express glands on their own. This produces a fishy smell. However, not every self-expresser will have a true issue with their glands. Most secrete them when they’re scared or if they bump their butts a little too hard.
Anal gland disease is more common in small dog breeds and overweight dogs. It can, however, happen to any dog. A few ways to help prevent anal sac impaction include feeding your dog a healthy diet with enough fiber to make the feces solid.
The best way to ensure your dog is healthy and happy is through regular wellness checkups with the veterinarian. Keep your dog on a healthy, high-fiber diet, and make sure he/she gets appropriate exercise.
At the end of the day, take note of any unusual odors or behavior from your dog. Dog owners are pretty in tune with their pets. If you notice anything weird, be sure to report it to the veterinarian.
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I hope something great happens to you today!