Bloat, also known as gastric dilation and volvulus (GDV) is a syndrome in dogs where the stomach dilates and twists around its central axis which results on complex physiologic and pathologic changes both locally (involving the stomach itself) and systemically.
Fluid or food accumulates in the stomach in conjunction with some kind of obstruction to the outflow tracts from the stomach, and this causes dilation which further contributes to a functional obstruction. Twisting can occur without dilation, but will, ultimately, lead to dilation as the stomach is unable to empty. As the stomach becomes distended it presses on the main vein leading from the liver and the caudal vena cava, the large vein responsible for returning most of the blood supply from the body to the heart. This causes decreased blood return to the heart and leads to shock. Damage to the vessels of the stomach itself can cause tissue death within the stomach. Because of the damage to numerous tissues, toxic substances are released into the bloodstream and can cause problems such as cardiac arrhythmias (irregular heart beats) even days after corrective surgery.
The cause of bloat is unclear, and many theories have been advanced, but none proven. It is known that large, deep-chested dogs are at higher risk, with great Danes probably topping out as the most commonly seen breed. However, ANY dog can bloat. So, whether or not the breed profile fits, if your dog shows signs of bloat, seek help immediately. Things that are thought to help prevent bloat include feeding small, frequent meals of a high quality food, elevating food bowls for large dogs, limiting exercise before and after eating and avoiding stress. While stress is a common thread with many cases, no one really knows why dogs bloat, and many dogs bloat at home where there is no stress apparent at all.
The signs of bloat are fairly unique and progress rapidly. Initially, the dog may just seem restless, unable to settle down or get comfortable. Drooling (more than usual for our slobbery breeds) may be seen during this time. Heart rate usually begins to increase fairly early on. As things progress, unproductive retching (trying to vomit but bringing nothing up) begins, and the dog becomes progressively more uncomfortable. As gas builds in the stomach, abdominal distention occurs. A WORD OF CAUTION: because many of the breeds we deal with are very deep chested, the stomach lies well under the ribs, and distention may not be obvious until it is quite advanced. Don't wait to see it! If your dog is showing all the other signs, get help. Mucus membranes may become very dark red or very pale, depending on the time line. Know what your dog's gums look like when it's healthy so you can tell if there is a change. As the condition progresses, weakness and depression lead rapidly to collapse and shock. TIME IS OF THE ESSENCE! Dogs with GDV can die in a matter of minutes without medical intervention. Don't stand around wondering if your dog is bloating. If he/she is restless, trying to vomit but not bringing anything up (or just bringing up clear liquid), has an increased heart rate or respiratory rate, assume it is bloat until proven otherwise, and seek help immediately. In most of the giant breeds, it's fairly easy to feel the heart beating on the left side of the chest. Make a habit of doing this and know what your dog's normal heart rate is. It can vary considerably among individuals within the same breed, but you'll be much better prepared to assess your dog when there is a problem if you've learned how to monitor him/her in good health.
It is important to note that GDV can be prevented by a surgical procedure called gastropexy, whereby the stomach is permanently attached to the body wall. This is always done when surgical intervention is required to correct GDV, since there is an 80% chance that a dog that has bloated once will bloat again, but it can also be done as a preventative measure when the dog is in good health, with much fewer risks. We strongly recommend prophylactic gastropexy for all giant breed dogs.
The majority of snake bites in the United States are attributable to pit vipers (rattlesnakes, copperheads and water moccasins). All have venoms that are hematoxic (toxic to the blood), but many have neurotoxic components to their venom as well. Clinical signs may be delayed for up to eight hours, but treatment should not be postponed. If you see the snake bite, or hear the rattle of the rattlesnake when your dog is injured, assume it was bitten. Signs that your dog may have been bitten if you did not witness the event include: puncture wounds, local tissue swelling, pain surrounding the bite site, bruising of tissues and petechiation (small red spots) of the mucus membranes (gums are easiest to check), rapid heart rate, shallow respiration, rapid heart rate, bruising with possible tissue death at the bite site, nausea, excessive salivation, lethargy, depressing and, eventually, shock.
Bites on the tongue and torso tend to be more serious. First aid measures should be limited to calming the patient and transporting immediately to the nearest emergency animal hospital. Diphenhydramine (Benadryl) may be given at a dose of 1 mg. per pound of body weight. This will not have any effect on envenomation, but may help calm the patient and prevent reaction to the antivenin should it be needed. Be sure you tell the treating veterinarian if you have given any medication.
There is a specific antivenin for pit viper bites, but it is in very short supply and can be hard to find. Even many emergency hospitals are unable to obtain it at this time. It is still best to get your dog to the nearest ER and have them start supportive care until the antivenin can be located if the treating veterinarian feels it is indicated. Offer to serve as their courier and go get the antivenin if they are able to locate some at another hospital if the doctor feels it is needed. Most dogs do just as well with good supportive care, pain management and close monitoring of their platelet count and their blood's ability to clot. Some require plasma transfusions, but usually the antivenin is not necessary in large breed dogs. A recent study showed very little difference in recovery times in dogs treated with and without antivenin in our area. Snakes in different parts of the country are armed with different venoms, and the seriousness of the bite can often have a lot to do with what kind of snake, how many snakes and where on the body the bite occurred.
If you live in or travel frequently to areas where there is a high risk of snake bites, there is a vaccine available to help prevent the toxic effects of pit viper venom, and all dogs at high risk should be vaccinated. However, the vaccine does not protect against all the variations in venoms produced by different snakes, so it should be discussed with your veterinarian to determine its worth in each situation.
Many spider bites cause mild local reactions similar to what you would see with a bee sting. Often, we have no idea what the offending agent was, and are forced to treat symptomatically. Cool compresses to the affected area and diphenhydramine (Benadryl) at 1mg per pound of body weight may be helpful. Some spider bites can cause local tissue death, and these need to be treated by a veterinarian. If there is a tiny puncture one day, and a large area of dead and dying skin the next, it is time to seek professional help. The brown recluse spider is the most notorious of the spiders that can cause widespread tissue necrosis (death). Aside from the local effects, the brown recluse's venom can cause systemic problems, including severe anemia, which can be life threatening. Black widow spiders can be found in every state except Alaska. One of the most important differences between black widows and other spiders is that there is virtually NO local inflammation at the site of the bite. Thus, there has to be a high incidence of suspicion to make the diagnosis. Only the female is poisonous. The spider is 2-2 1/2 cm (about an inch) in length, shiny black with a red or orange hourglass mark on the abdomen. Immature females are brown with orange or red stripes on the abdomen that eventually form the hourglass as the spider matures and darkens. Their venom contains a potent neurotoxin which can cause muscle twitching, severe pain, cramping of large muscle masses, abdominal rigidity without pain, and facial swelling. Vomiting (and vomiting up the spider) is common. Without antivenin, the black widow spider bite can be fatal. Fortunately these bites are fairly rare, and most emergency vets have yet to see one. Obviously, if you have seen a black widow in your home and your dog exhibits any of the signs of toxicity, get to an emergency hospital, and call an exterminator! Antivenin is the only treatment for severe envenomation. Even with appropriate treatment, prognosis is uncertain for several days, and complete recovery can take weeks..