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There's nothing like the bond between a pet owner and their furry friend. But occasionally, something odd might catch your attention — like an unexpected fishy odor coming from your canine companion. An anal sac issue is the most common reason for a dog to smell like fish. These sacs produce a smelly, oily substance, and when they're not emptied correctly or become infected, they can emit a strong fish-like odor.
While this might be a little surprising and slightly off-putting, understanding the cause and knowing how to handle it can help both you and your dog feel more comfortable. So, if you're wondering, "Why does my dog smell like fish?" you've come to the right place. Keep reading to learn more about that fishy odor and why it happens.
- What to Know About Your Dog's Anal Sacs
- Why Does My Dog's Rear Smell Like Fish?
- Treating Anal Sac Issues
- Final Notes
What to Know About Your Dog's Anal Sacs
Anal sacs are two small pouches located on either side of a dog's anus.  These sacs produce a thick, oily fluid historically used for territory marking and as a form of communication among wild dogs to convey information. 
While the pressing need for communication is diminished in domesticated dogs, the glands still produce this secretion. When your dog defecates, the pressure exerted during the process naturally empties these sacs with the secretion spread on their feces. 
This is one of the reasons why dogs sniff each other's rear ends and feces; they're "reading" these chemical signals and communications. Unfortunately, problems can happen that affect the anal sacs, causing a fishy odor.
Why Does My Dog's Rear Smell Like Fish?
If you're wondering why your male or female dog smells like fish, it's likely because of an anal sac or anal gland issue.
The most common issue is impaction, which happens when the sacs don't empty properly, leading to a buildup with the sac becoming thicker, enlarged, and uncomfortable.  Dogs with impacted anal sacs may scoot on the ground, lick or bite at the area, or show signs of general discomfort.
Another common issue is infection, which can occur due to impaction. If the secretion in the sacs becomes infected with bacteria and can't empty, it can cause pain, swelling, and sometimes even lead to an abscess. 
Besides the fishy odor emanating from your dog's rear, other warning signs to watch for include:
- Scooting : Dogs may drag their rear on the ground to try to relieve discomfort.
- Excessive licking or biting: Affected dogs often pay excessive attention to their rear.
- Abscess: If untreated, an infected anal sac might form an abscess, which can eventually rupture and become an open, painful wound.
- Tumors: Although less common, tumors can develop in or around the anal sacs. 
If you're wondering, "Why does my female dog smell like fish?" or "Why does my male dog smell like fish?" you might be shocked to learn that there's no predisposition based on sex. While any dog, regardless of breed, size, or sex, can experience anal sac issues, smaller breeds are generally more prone to these problems than larger ones. 
Among the larger breeds, German Shepherds might be more predisposed than others.  However, these issues don't seem to favor male or female dogs, but it's typically seen in dogs at least one year old.
Other potential contributing factors include the following:
- Dietary and health issues: Food allergies and atopic dermatitis can exacerbate anal sac issues, leading to a fishy odor.
- Anatomical abnormalities: Some dogs have differently structured or positioned anal sacs.
- Digestive issues: Chronic diarrhea or constipation can influence anal sac health.
- Dietary factors: Obesity and a diet low in fiber can also lead to complications. 
Treating Anal Sac Issues
Anal sac issues are common in many dogs, and while not usually life-threatening, they can cause significant discomfort. Understanding the available treatments can help pet parents address these problems.
The first step is to consult a vet. Your vet will inspect the area to determine whether the fishy odor results from an anal sac issue. Once they've identified that your dog's fishy odor is due to anal sac impaction or another issue, they can try a few treatments, including:
- Manual expression: Manual expression is the most common treatment for dogs with impacted anal sacs. This procedure involves gently squeezing the sacs to release the built-up fluid. Ideally, manual expression should be performed by a veterinarian or trained groomer with the knowledge to do it correctly and safely. The need for manual expression varies from dog to dog. Some may require it monthly, while others may never need it. 
- Medicated flushes: If the sacs are infected, or there's an abscess, your vet might clean them out with a medicated solution.  Medicated flushes help to eliminate bacteria and soothe the area. A catheter is often used to introduce the solution, ensuring a thorough clean. 
- Antibiotics and anti-inflammatories: If an infection is present or inflammation is causing discomfort, your vet might prescribe certain medications. These can be given orally or, in the case of severe infections, directly into the anal sacs.
- Warm compress: A warm compress can help reduce swelling and is something you can do at home. Although, we always recommend avoiding treating your dog at home. If, after visiting your vet, they advise you to provide your dog with a warm compress, you can soak a cloth in warm water, wring out the excess, and hold it gently against the affected area several times a day to alleviate any discomfort.
- Surgical removal: Vets might recommend the surgical removal of your dog's anal sacs if issues are chronic or severe. The surgery, called an anal sacculectomy, involves removing the sacs completely to avoid future issues.  Dogs typically recover quickly, but as with any surgery, there are potential risks, and post-operative care is necessary.
- Diet and weight management: Because obesity and a low-fiber diet are risk factors, ensuring your dog has a balanced diet with sufficient fiber can help prevent and manage anal sac issues. A high-fiber diet can promote firm stools, allowing the anal sacs to express naturally.
- Regular checkups: Regular veterinary check ups can help in the early detection of potential problems and ensure that any issues are addressed before they worsen.
How do I get rid of the fishy smell on my dog?
More often than not, the scent comes from issues related to the anal sacs. However, there are potential culprits of your dog smelling like fish. Unfortunately, a fishy odor can sometimes come from your dog's mouth due to dental issues. A buildup of plaque and tartar can sometimes cause a bad odor that resembles fish.
If your dog's fishy odor is emanating from their mouth, consult a vet to determine the exact cause. Since bad dog breath can be a sign of periodontal disease, it's always better to err on the side of caution. Once your vet examines your dog's mouth, they may suggest regular brushing, dental treats and toys, and regular professional cleanings to prevent serious issues.
Your dog's diet can also contribute to the odor. Poor quality dog food can lead to digestive issues, which can affect the anal glands, causing a fishy odor. You can consult your vet about adding probiotics to your dog's diet to improve their digestive health.
Ultimately, the best way to eliminate the fishy smell on your dog is to consult a vet.
What happens if anal sac issues aren't treated?
If anal sac issues in dogs aren't addressed, they can lead to a series of complications. Initially, they may be uncomfortable. However, untreated impaction can result in painfully swollen sacs with a secretion that solidifies over time and can lead to bacteria growth and infections.
As symptoms intensify, redness, swelling, and foul-smelling discharge can become more evident, possibly affecting the dog's overall health and temperament. Left unchecked, the infection can escalate and form an abscess. If the abscess ruptures, it can create an open wound near the anus, increasing the risk of further complications.
Why does my dog smell after a bath?
Dogs can still emit an unexpected odor after a bath for several reasons. Residual moisture trapped in their fur or underlayers can lead to a musty scent. This dampness can promote the growth of yeast and bacteria on the skin.
Additionally, using human shampoos or soaps that aren't pH-balanced for dogs can disrupt their skin's natural protective barriers, leading to increased secretion of bodily oils and odors.
Another factor might be your dog's anal sacs if they aren't cleaned properly. This odor can be persistent after a bath.
Hopefully, by now, you have the answer to your question, "Why does my dog's rear smell like fish?" While anal sac issues are common, they're usually manageable with the right care and treatment. If you suspect your dog might have a problem with their anal sacs, consult a Dutch vet.
Sign up today to quickly connect with qualified veterinarians, ensuring your canine companion receives the best care from the comfort of home.
"Anal Sac Diseases." Cornell University College of Veterinary Medicine, 18 Apr. 2023, www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information/anal-sac-diseases.
Burke, Anna. "Why Your Dog Smells like Fish." American Kennel Club, 27 Oct. 2021, www.akc.org/expert-advice/health/real-reason-dog-smells-like-fish/.