The Canine Ledger

Bloat (GDV): The Signs, the Odds, and What a Gastropexy Does

Bloat kills quickly, mostly in large deep-chested dogs. The early signs, why survival figures differ, and what a preventive gastropexy can and can't do.

Written by thecanineledger

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If your dog is retching without bringing anything up, has a swelling belly, is restless or drooling, or keeps looking at their belly: go to the nearest open vet now, and phone on the way. This is especially urgent in a large or deep-chested dog. Don’t wait to see whether it passes.

Compared with crossbred dogs, Great Danes seen at UK emergency clinics had 114 times the odds of a bloat diagnosis (O’Neill et al., Journal of Small Animal Practice 2017, abstract).

No other number on this page is that large. Most of the others are smaller, and less certain than they look.

While almost every owner of a big dog has heard of bloat, the details that matter in the moment are less well known: what the first signs look like, how long you have, and what a preventive operation actually prevents. This page sets out what the veterinary sources say, including where they disagree.

1. What happens

Bloat, properly gastric dilatation-volvulus (GDV), happens in two stages. The stomach fills with gas and food and swells (dilatation). Then it can twist on itself (volvulus).

The American College of Veterinary Surgeons (ACVS) describes it as “a rapidly progressive life-threatening condition of dogs that requires immediate medical attention” (ACVS, Gastric Dilatation-Volvulus). The swollen stomach presses on the large veins and the diaphragm. Blood stops returning properly to the heart, and the dog can’t breathe deeply. The twist can cut off the blood supply to the stomach and spleen.

Time is the whole story. The ACVS lists dogs “with clinical signs for more than 6 hours” among those with a higher death rate, and the Merck Veterinary Manual gives the same factor (Merck, Gastric Dilation and Volvulus in Small Animals). The ACVS puts it simply: “Increased severity and time since the onset of the GDV is associated with increased complication and mortality rates.”

2. The signs

The ACVS lists the early signs, which are mostly signs of belly pain:

  • an anxious look, or looking at the belly
  • standing and stretching
  • drooling
  • a swelling belly
  • retching without bringing anything up

As it gets worse, the dog “may begin to pant, have abdominal distension (bloated belly), or be weak and collapse and be recumbent.” The ACVS’s instruction: “If your pet has exhibited any of the above clinical signs, they should be evaluated by your primary care veterinarian immediately.”

The sign owners miss is the retching. A dog trying to be sick and producing nothing can look like a dog with something stuck in its throat. Merck lists “nonproductive retching, hypersalivation, and restlessness” among the first signs.

A swollen belly is not always visible. In a deep-chested dog, much of the stomach sits under the ribs. Don’t wait for the belly to look big.

Our note: “A swollen belly is not always visible” is our reasoning, not a quoted source. Don’t wait for a visibly bloated belly.

→ Emergency Signs in Dogs: When to Go Now, Not Tomorrow

3. Which dogs get it

Mostly large, deep-chested breeds. Merck names “Great Danes, German Shepherd Dogs, Irish Setters, Gordon Setters, Weimaraners, Saint Bernards, Standard Poodles, and Bassett Hounds.” It describes genetics as “a proven risk factor for GDV, including deep/narrow thoracic conformation and a first-degree relative with a history of the problem.”

It is still uncommon overall. In the UK emergency-clinic study, 492 of 77,088 dogs had a presumed GDV diagnosis, a prevalence of 0.64%. That was among dogs already sick enough to visit an emergency clinic.

The ACVS lists four factors with an established association. GDV is more likely in dogs that:

  • have a deep chest;
  • are fed a single large meal once a day;
  • are older;
  • are related to other dogs that have had it.

It adds others where “It has also been suggested” there is a link, including elevated feeding, previous removal of the spleen, large or giant size, and stress.

→ Choosing a Breed or a Mix: The Health Data Breeders Don’t Lead With

4. The odds: why the numbers disagree

If you look up the survival rate for bloat, you will find different numbers. They come from the same reputable places.

SourceFigure given
ACVS owner pageMortality “approximately 15%”
Merck, opening summary“a mortality rate of 20% in treated animals”
Merck, prognosis section“Overall mortality rate associated with GDV is approximately 25–30%”
Merck, key points“a mortality rate of 20–45% in treated animals”
UK emergency clinics, 2017“Approximately 80% of surgically managed cases survived to discharge”

Why they differ. The figures come from different groups of dogs. Some count only dogs who had surgery. Some may include dogs euthanised before surgery. Some count deaths in hospital; others longer. All of them show the same thing: most treated dogs survive, and a large minority do not.

What changes the odds. Merck lists factors linked to death in the short term, including signs for more than six hours before examination, and needing part of the stomach or the spleen removed. The ACVS adds heart rhythm problems before surgery. Most of these come down to how far the disease had gone before treatment started.

Our note: Sources give different death rates for bloat, so we give the spread. Our explanation of why they differ is ours.

5. What a gastropexy does, and doesn’t

In emergency surgery, the surgeon untwists the stomach, checks the stomach wall and spleen, and then fixes the stomach to the inside of the body wall. That fixing is the gastropexy. The ACVS explains that its purpose is “to prevent volvulus (rotation) if subsequent gastric dilitation occurs again.”

It prevents the twist, not the bloat. Merck: “A gastropexy, either prophylactically or after a GDV, has not been shown to prevent bloat (gastric dilation) but should prevent the life-threatening volvulus.” The ACVS notes that after surgery “some pets may experience some degree of gastric dilatation without volvulus”, usually after a very large meal. A dog with a gastropexy and bloat signs still needs a vet.

How well does it work? A 2025 evidence review appraised 16 studies of recurrence after gastropexy (Low, Veterinary Evidence 2025). Across them, “Recurrence of GDV after gastropexy, across all studies, was reported to be between 0% and 15.4%.” Its conclusion is honest about the quality: “Overall, the studies provide weak evidence that the rate of recurrent GDV is low after gastropexy.” Without surgery, Merck says, dogs treated by decompression alone “have an extremely high recurrence rate.”

Preventive gastropexy

Some owners of high-risk breeds choose a gastropexy before their dog has ever bloated. The ACVS says preventive gastropexy “is currently being recommended by many veterinary surgeons for breeds at risk”, and that it “can often be done at the same time as sterilization surgeries (spay/neuter).” Merck says the same. Keyhole (laparoscopic) techniques are also available.

What we could not find was a good estimate of how much a preventive gastropexy reduces the risk of dying of GDV in a given breed. The 2025 review looked at recurrence, mostly after an emergency, not at prevention in dogs who had never bloated. The recommendation is real, and widespread among surgeons. The evidence for the size of the benefit is thin.

Our note: ACVS and Merck recommend preventive gastropexy for high-risk breeds. We found no good estimate of the benefit.

6. Reducing the risk

Merck lists recommendations for owners of high-risk breeds:

  • “feeding multiple small meals rather than one large meal”
  • “restriction of exercise before and after meals”
  • “decreasing stress at mealtime”
  • “avoiding elevated feed bowls”
  • “not breeding dogs with a first-degree relative with a history of GDV”

How strong is that evidence? The once-a-day meal and family history are among the ACVS’s established associations. Elevated feeding and stress are among the factors it lists as only suggested. We did not read the studies behind each recommendation, and none of them shows that following the advice prevents bloat. They are cheap, low-risk changes, and we would follow them for a high-risk breed. The most useful thing is still knowing the signs.

Our note: ACVS mentions a 2006 study linking some dry foods to bloat in high-risk dogs. We haven’t read it.

7. What we could not verify

Commonly saidWhat we found
“Raised bowls prevent bloat”The opposite is suggested. The ACVS lists elevated feeding among suggested risk factors, and Merck advises avoiding raised bowls.
“Bloat only happens straight after a meal”Not what the sources say. The ACVS calls GDV “multifactorial”, though “commonly associated with rapid ingestion of large meals.”
“A gastropexy means my dog can’t bloat”Contradicted. It should prevent the twist, not the swelling.
“Survival is X%”Figures range from about 55% to 85% across the ACVS, Merck and the UK emergency study, depending on which dogs are counted.
“Preventive gastropexy cuts the risk by a set amount”We found no good estimate in the sources we read.
“Small dogs never get bloat”Not quite. The ACVS says “Nearly all breeds of dogs have been reported” to have had it, though large breeds dominate.

Sources

Always confirm with your vet before acting on anything on this page.