Bloat is a life-threatening emergency that affects dogs in the prime of their life. The mortality rate for gastric dilatation-volvulus (GDV) approaches 50 percent. The keys to survival are early recognition and prompt treatment.
Anatomy of Bloat
Bloat occurs initially when the stomach suddenly distends with gas and fluid. Them the distended stomach rotates on its long axis, a result called volvulus. As the spleen is attached to the wall of the stomach, it rotates as well.
Not all cases of gastric dilatation become complicated by volvulus. The stomach can undergo torsion, and twist 180 degrees or less, whereas a full volvulus is a twist of 180-360 degrees or more.
The pylorus portion of the stomach is pulled out of position during volvulus, and becomes displaced to the left of the junction of the esophagus and stomach. This squeezes down the duodenum, which prevents fluid and air from escaping the stomach via the pylorus. At the same time, the esophageal-stomach junction is twisted and obstructed, preventing the dog from belching gas and vomiting. Thus, gas and fluid are trapped in the closed-off stomach, which becomes hugely distended as the food ferments. The stomach wall undergoes necrosis once the blood supply is compromised.
This sequence of events typically leads rapidly to acute dehydration, bacterial septicemia, circulatory shock, cardiac arrhythmias, gastric perforation, peritonitis and death.
Bloat usually occurs in middle-aged to older dogs, but can occur at any age. There is often a familial or breed association. Large-breed dogs with deep chests are anatomically predisposed, and include:
- Great Dane
- German Shepherd Dog
- Saint Bernard
- Labrador Retriever
- Irish Wolfhound
- Great Pyrenees
- Boxer
- Weimaraner
- Old English Sheepdog
- Irish Setter
- Collie
- Bloodhound
- Akita
- Borzoi
- Bullmastiff
- Chow Chow
- Curly Coated Retriever
- Scottish Deerhound
- German Longhaired Pointer
- Grand Bleu de Gastogne
- Mastiff
- Neopolitan Mastiff
- Newfoundland
- Bernese Mountain Dog
- Doberman Pinscher
- Gordon Setter
- Greater Swiss Mountain Dog
- Greyhound
- Rhodesian Ridgeback
- Standard Poodle
Chinese Shar-Pei and the Basset Hound have the highest incidence among mid-size dogs. Small dogs are rarely affected, with the exception of the Dachshund varieties, who are also deep-chested.
The clinical history of bloat cases often includes a sudden onset in a healthy, active dog. He may have just eaten a large meal, exercised vigorously before or after eating, or had a large amount of liquid immediately after eating.
Signs of Bloat
The classic signs of bloat are restlessness and pacing, salivation, retching, frequent attempts to vomit, and an enlarging abdomen. The dog may whine or groan when you press on his belly. Thumping on the abdomen produces a hollow sound, like a kettle drum.
Unfortunately, not all cases of bloat present with classical signs. In the early stage, the dog may not appear distended, although the abdomen usually feels slightly tight. The dog appears lethargic, is obviously uncomfortable, walks stiff-legged, and may hang his head. At this stage, one cannot distinguish dilatation from volvulus.
Late signs of impending shock are obvious, including pale gums and tongue, delayed capillary refill time, rapid heart rate, weak pulse, rapid and labored breathing, weakness, and collapse.
Treating Bloat
Whenever there is even a slight suspicion of bloat, take the dog immediately to a veterinary hospital. If is too late for that, be brave and take a clean, sharp knife and insert it quickly into the bloated side of the dog to let the trapped gas escaped from his distended stomach. This emergency procedure has saved lives – then immediately go to the closest veterinary hospital.
At the veterinary clinic, gastric dilatation without torsion or volvulus is relieved by passing a long rubber or plastic tube through the dog’s mouth into the stomach. As the tube enters the dog’s stomach, a rush of air and fluid from the tube will bring relief. The stomach is then washed out. The dog should not eat or drink for the next 36 hours, and will need to be supported with intravenous fluids. If symptoms do not return, the regular diet can be gradually restored.
In contrast to simple dilatation, abdominal x-rays reveal a normal gas pattern but an excess amount of it in the stomach. With volvulus, however, x-rays have a “double bubble” gas pattern, with gas appearing in two sections separated by the twisted tissue.
In volvulus cases, emergency surgery is required as soon as the dog is stable enough for anesthesia. At surgery, the stomach and spleen are re-positioned, unless there is necrosis which requires removing the spleen and even a portion of the stomach.
Preventing Bloat
The risk of recurrence for dogs responding to nonsurgical treatment is 70%. For that reason, dog caregivers and breeders may elect to have the dog’s stomach tacked down to the rib cage to prevent volvulus (gastropexy). Other preventives measures are critical, and include:
- Divide the day’s ration into 3 equal meals, spaced well apart.
- Do not use a raised food bowl.
- Avoid dry dog food.
- If you cannot avoid dry dog, moisten it.
- Avoid food high in fat (listed in the first 4 ingredients on the label).
- Avoid foods that contain citric acid.
- Limit water intake.
- Restrict access to water for 1 hour before and after meals.
- Never let the dog drink a large amount of water all at once.
- Avoid strenuous exercise on a full stomach.
Research
Bloat is a prime example of the complicated interplay between genetics and environment. Environment not only refers to surroundings, but also to lifestyle and food. Indeed, a small retrospective study from 1996 found that 60% of dogs with bloat also had inflammatory bowel disease (IBD). While research is ongoing to discover if the two diseases originate from a common cause, whether one influences the other, or if they so happen to exist independently but work together; we still do not have a definitive answer.
One may argue that at least two genes were associated with both disorders in one study (Harkey et al.), but that study focused on Great Danes.
Another study (Piras et al.) highlighted that not all breeds are alike and the complexity of bloat. This study identified multiple cross-breed and breed-specific single-nucleotide polymorphisms (SNPs – variation at a single position in a DNA sequence) associated with disease protection or pathogenicity of bloat specifically.
A similar Great Dane study (Hullar et al.) demonstrated that the microbiome in patients with bloat was impacted or associated with certain innate and adaptive immunity genes by co-examining gut bacteria abundance and diversity in feces between controls and dogs with bloat.
We do not disagree that these associations show that immune-related genes may play a role in predisposition to bloat by altering the gut microbiome. However, this second Great Dane study found no significant association between dietary intake and bloat simply by comparing the amount of protein, fat, carbohydrate, crude fiber, calories and age between the control group and dogs with bloat. They did not account for the type of food (raw, kibble, canned, etc.), or sources of protein, fiber, carbohydrates or fat. Conventional and traditional veterinary clinical experience over the years has shown that wet foods can help prevent episodes of bloat. In essence, they are looking at it from a nutrient-fed perspective yet dismissing nutrient source and absorption, and how genes could interact with those two factors.
References
Gazzola, Krista M, and Laura L Nelson. “The relationship between gastrointestinal motility and gastric dilatation-volvulus in dogs.” Topics in companion animal medicine vol. 29,3 (2014): 64-6. doi:10.1053/j.tcam.2014.09.006, https://www.sciencedirect.com/science/article/abs/pii/S1938973614000415?via%3Dihub.
Harkey, Michael A et al. “Associations between gastric dilatation-volvulus in Great Danes and specific alleles of the canine immune-system genes DLA88, DRB1, and TLR5.” American journal of veterinary research vol. 78,8 (2017): 934-945. doi:10.2460/ajvr.78.8.934, https://avmajournals.avma.org/view/journals/ajvr/78/8/ajvr.78.8.934.xml.
Hullar, Meredith A J et al. “The canine gut microbiome is associated with higher risk of gastric dilatation-volvulus and high risk genetic variants of the immune system.” PloS one vol. 13,6 e0197686. 11 Jun. 2018, doi:10.1371/journal.pone.0197686, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5995382/.
Piras, Ignazio S et al. “Identification of Genetic Susceptibility Factors Associated with Canine Gastric Dilatation-Volvulus.” Genes vol. 11,11 1313. 5 Nov. 2020, doi:10.3390/genes11111313, https://www.mdpi.com/2073-4425/11/11/1313.
Understanding Gastric Dilatation-Volvulus or “Bloat,” AKC Canine Health Foundation, https://www.akcchf.org/canine-health/top-health-concerns/bloat/understanding-bloat.html.
Originally Published: March 22, 2015
Updated: May 18, 2024