Vomiting and diarrhea are very common in dogs and cats.  Such digestive upset can range from mild discomfort to serious life-threatening illness.  To understand the signs of vomiting and diarrhea, it is helpful to have an idea of how the digestive system works in general.

The digestive system The digestive tract performs the important function of bringing water and nutrients into the body.  It consists of several organs that have specialized functions.  Digestion begins as food is chewed and mixed with saliva, which lubricates the food and contains an enzyme that helps break down starches.  The food then passes through the esophagus to the stomach via a process known as peristalsis.  During peristalsis, muscles surrounding the esophagus contract in a rhythmic wave that pushes the food toward the stomach, much like a ball being pushed into a sock [suggest link to a fluoroscopic video of a barium swallow].

The stomach is an expandable sack that has muscular valves on each end.  These valves stay closed to hold food in the stomach over the 1-2 hours it takes to complete initial digestion.  Cells in the lining of the stomach secrete an enzyme called pepsin, which begins the process of breaking down protein.  Other cells in the stomach produce hydrochloric acid, which creates a very acidic environment that aids the digestive process.  Muscles in the wall of the stomach continue to mix the food and other substances in the stomach until it progresses into the small intestine.

The small intestine is a very long muscular tube that lies in numerous loops within the abdomen that are held in place by bands of fibrous tissue.  The small intestine consists of three sections called the duodenum, the jejunum, and the ileum.  As the contractions of peristalsis move food through these sections, bile is added (to the duodenum) from the gallbladder and digestive enzymes from the pancreas.  Bile breaks fat lumps into smaller particles, and digestive enzymes such as trypsin and sucrase continue the process of breaking down fats, proteins, starches, and sugars.  Useful nutrients are then absorbed through the lining of the small intestine, while the waste products are sent on to the large intestine.

The large intestine or colon is a larger muscular tube that connects the small intestine to the anus.  As peristaltic waves move the waste material through the colon, excess water is absorbed giving the feces its normal consistency.  This fecal matter is stored in the colon until muscular valves in the rectum are relaxed (usually a voluntary process), allowing elimination of feces outside the body.

Vomiting
Vomiting is caused by irritation of the stomach or first part of the small intestine.  During vomiting, the peristaltic waves reverse direction in an attempt to purge the digestive system of the irritation.  The most common cause of vomiting in pets is eating things such as sticks, leaves, bones, trash, or greasy table foods that irritate the lining of the digestive tract.  This irritation usually doesn’t last long, resolving after a few hours to a day or two.  However, foreign materials can sometimes get stuck within the digestive tract, causing an obstruction.  If the first parts of the digestive tract become obstructed, the peristaltic waves meet a dead end and reverse, resulting in severe, persistent, and often projectile vomiting.  Vomiting can also be caused by viral or (more rarely) bacterial infection of the digestive tract.  Parasites such as roundworms or hookworms are also common causes of vomiting in young pets.

Vomiting can also sometimes be caused by disorders outside the digestive tract.  For example, liver and kidney disease can allow toxins to build up in the body and lead to generalized illness and vomiting.  In older pets, cancers can invade the digestive tract, or impinge upon it, leading to irritation or obstruction and subsequent vomiting.

The character of the vomit can offer clues as to the problem.  For example, the vomit may contain bits of foreign material or white roundworms, which can resemble coiled spaghetti [suggest link to photo of a roundworm].  Vomit that contains red blood suggests bleeding at the very beginning of the digestive tract, while a “coffee-ground” appearance suggests digested blood from further down the tract.  If yellow bile is seen in the vomit, it may be because the stomach is empty or the duodenum is irritated.

Diarrhea
Irritation farther down the digestive tract in the small or large intestine usually results in diarrhea because muscle spasms speed up peristalsis and cause feces to be eliminated before digestion has been completed or excess water has been absorbed.  As with vomiting, irritating objects or foods, parasites, and viral infections are the most common culprits.  Obstruction further down the digestive tract is also a serious situation.  An obstructed bowel usually results in a very painful abdomen and straining to defecate, without producing feces or producing only small amounts of jellied blood.  In some cases, a foreign object can actually puncture the digestive tract, letting intestinal contents leak into the abdominal cavity, which is a situation known as peritonitis.  Obstruction or perforation of any area of the digestive tract is an emergency situation, requiring immediate evaluation and treatment by a veterinarian.

As with vomiting, the character of the diarrhea often provides clues about the problem.  For example, roundworms, sticks, or trash may be present in the feces.  Red blood and mucus usually suggest damage to the colon, while black, tarry feces suggest digested blood from higher up the tract.  Soft, but otherwise normal feces often indicate irritation of the colon, in which normal feces were expelled before excess water was removed.  Fetid, runny diarrhea often indicates incomplete digestion and absorption within the small intestine.

Diagnosis
Many times, a detailed history, physical examination, and fecal examination can rule out serious conditions and allow conservative medical treatment of the digestive upset.  However, additional diagnostic evaluation is sometimes necessary.  For example, your vet may recommend blood tests to check for problems such as liver or kidney disease, or abdominal x-rays to look for signs of foreign bodies or obstruction.  More involved or complicated cases may require additional, more specialized diagnostic tests such as ultrasound, a contrast study, or a CAT scan or MRI.  Contrast studies involve giving your pet barium or some other contrast medium that highlights the inside surfaces of the digestive tract on x-ray [link to barium radiograph].  The contrast medium is administered either orally or via an enema, depending on the suspected problem.

Treatment
Often, digestive upset can be handled with conservative medical therapy.  For example, your vet may recommend withholding food or feeding several small, bland meals to rest the digestive tract so that it can heal.  A prescription diet or medication to soothe the tract or inhibit vomiting may be prescribed.

More serious or persistent cases may require hospitalization and possibly surgery.  Vomiting or diarrhea for even a day or two can lead to dehydration, and your pet may need fluid therapy.  Fluids are usually administered intravenously, but are sometimes also given under the skin, where they are absorbed gradually over several hours.  Hospitalized pets may also receive treatment with antibiotics, nutrients, or other medications.

Pets with a suspected obstruction or perforation require emergency surgery to remove the foreign material and to check for bowel damage or peritonitis.  In an obstruction, blood flow can be cut off to a section of the intestine, causing the tissues of that part of the bowel to die, resulting in serious inflammation and infection.  In some cases, one or more sections of dead bowel may need to be removed, with the healthy ends sewn together [possible link to a diagram of anastamosis surgery].  If there are no complications after surgery (eg, infection) and with good follow-up care, most pets are back to normal within a few weeks.

Dog nails often crack or tear when caught on objects.  Although this is a relatively minor injury, it is very painful and can bleed quite a bit.

The canine nail consists of a central bundle of blood vessels and nerves that are informally known as the “quick,” which is surrounded by a layer of horny material called keratin.  The central quick is living tissue, while the brittle keratin is not.  Normally, there are five nails on each front foot, and four nails on each rear foot.  The front nails that are found slightly higher up the foot are called dew claws.

Nails normally wear down as dogs walk on hard surfaces.  However, in dogs that are sedentary or that walk mostly on soft surfaces, the nails tend to grow longer, placing them at greater risk of being cracked or torn.  The quick tends to grow out as the nail grows, so injuries often include this living tissue, which accounts for the pain and bleeding.

Nails can become caught on a variety of surfaces, such as floor grates and loosely woven fabrics (eg, afghans).  A sudden tug or twist can cause the nail to crack or tear off.  Dogs frequently yelp in pain and hold up the injured paw.  Any nail can be involved, but those on the front feet are most at risk.  The dew claws are especially vulnerable because they are often only loosely attached.

Treatment for a broken nail consists of removing the damaged portion (if necessary), stopping the bleeding, and protecting the damaged area until it heals and new nail regrows.  Broken nails need to be trimmed above the break, so that the injury can heal cleanly.  This is best done by your veterinarian.  However, first-aid procedures at home can help stop the bleeding and protect the foot until you can take your dog to your vet.  Ideally, a styptic pencil, silver-nitrate stick, or cauterizing powder can be pressed into the torn end of the nail to stop the bleeding.  Alternatively, corn starch or flour can be pressed firmly into the broken end of the nail.  Pressure from a folded cloth or paper towel can also stop the bleeding; firm pressure against the wound is needed for at least 5-10 minutes.  The foot can then be bandaged temporarily to protect the injured area and to prevent bleeding from starting up again.

Again, because a broken nail is a painful injury, make sure your dog is well controlled for any first-aid procedures.  Remember that any animal in pain may bite, so a muzzle may be in order.  If you are squeamish or unable to adequately control your dog, it is probably best to simply temporarily bandage the foot with a cloth and take your pet to the vet for immediate treatment.  Even with successful first-aid at home, you should have your vet examine the injury within the next few days in case further treatment is needed (eg, in case of infection).

Prevention consists of regular nail trimming and adequate exercise on hard surfaces.  Dew claws are often removed at the time of tail docking (for specific breeds) or when the pup is spayed or neutered.

Many household items are potentially toxic to pets.  Antifreeze is among the most problematic poisons for a variety of reasons:

• Antifreeze is commonly changed by do-it-yourself mechanics who may allow the coolant to drain into the street where pets can drink it.

• Antifreeze has a sweet taste that pets like.

• Antifreeze is a potent poison that can cause kidney problems and even death.

In northern climates, antifreeze poisonings are most common around those times when automotive coolant is changed: typically fall, winter, and early spring.  

Automotive coolants typically contain the chemical ethylene glycol.  This chemical is similar in structure to alcohol, so that signs of intoxication are similar to those of drunkenness.  Poisoned dogs or cats may vomit and show nervous system signs, such as staggering and tiredness.  They tend to drink and urinate large amounts.  Within a few hours of ingestion, byproducts of ethylene glycol produce crystals that cause kidney damage as the body tries to remove them.  Kidney damage can be severe and life-threatening, even after ingestion of only a few teaspoons of antifreeze.  

Treatment for antifreeze poisoning needs to be instituted as soon as possible, so you should take your pet to the veterinarian immediately if you suspect that it has drunken antifreeze.  Treatment is often begun based on suspicion of antifreeze poisoning, without being able to confirm it.  Your vet may perform a blood test for ethylene glycol, but this is only effective when a fairly large amount has been consumed.  Your vet may also check the urine with an ultraviolet light, because some types of antifreeze fluoresce, although this test is not always accurate.  Blood and urine tests are needed to monitor the status of the kidneys, as well as to look for suspicious crystals in the urine.

If anitfreeze poisoning occurred within the past few hours, the vet may induce vomiting or flush the stomach in an attempt to remove unabsorbed coolant.  Intravenous fluids are given to keep your pet well hydrated and to flush the kidneys.  A special drug can be injected to decrease the formation of crystals, thereby sparing the kidneys from serious damage.  This drug is ineffective in cats, so alcohol is used instead.  Alcohol competes with the ethylene glycol for metabolism, thereby decreasing the production of crystals.  These treatments are most effective if given within a few hours of ingestion, before serious kidney damage has occurred. 

The anal sacs are a pair of marble-sized glands in dogs and cats found beneath the skin around the anus at about the 4 o’clock and 8 o’clock positions. These scent glands (similar to those of skunks) normally squeeze out a small amount of bad-smelling fluid onto the feces during a bowel movement. Sometimes, when dogs get excited, the anal sacs will discharge some of their characteristic foul-smelling contents. When the sacs become infected or the opening through the skin becomes plugged, the anal area can become irritated, inflamed, itchy, and painful.

The most common sign of an anal sac problem is “scooting,” or rubbing the butt along the ground or floor, which can leave behind a small, smelly stain. Dogs often also lick, chew, or bite at the anal area to try to relieve the itch and irritation. Swollen, infected sacs can eventually rupture, oozing bloody pus through a hole underneath and to one side of the anus.

Your veterinarian will insert a gloved finger into the anus to determine if the anal sacs are enlarged. He or she will often be able to express the sacs by applying gentle pressure to “milk” the contents through the normal opening in the skin. The anal sacs need to be expressed regularly in many dogs to prevent the contents from becoming impacted, leading to infection. In some cases, a small tube may need to be inserted into the opening in the skin to remove any obstruction and flush out thickened material. In cases of severe or repeated obstructions, your vet may recommend surgery to remove the glands. Surgery provides a permanent solution but is associated with a slight risk of fecal incontinence from injury to the nerves or muscles around the anus.

 

If you're interested in learning how to express anal glands yourself, you should discuss the proper technique and potential complications with your veterinarian first.

Dental disease in dogs and cats can be a serious problem.  As in people, plaque buildup on dog and cat teeth leads to red, irritated gums, a condition called gingivitis.  Plaque begins as a film of food particles and bacteria that can harden over time into a dark, rock-like scale.  Bacteria invade the gap between the gum and the tooth, causing inflammation.  Over time, bacteria can destroy the bone that holds the tooth in place, leading to tooth loss or the need for extraction.  On occasion, bacteria can even invade the bloodstream, leading to serious infections in other organs such as the heart.

Unfortunately, quite a bit of damage due to dental disease can occur before you notice anything.  Pets with early gum disease generally don’t show any signs at all, except for a little bad breath.  As the problem progresses, the gums can become very red and sore, and your pet may not want to chew hard food.  You might see smears of blood on your pet’s chew toys.  Pets often rub their mouths with their paws or against other surfaces.  The bad breath gets progressively worse, and pets with severe dental disease can have very foul mouth odors.

Just like us, our pets need regular dental checkups to keep their teeth and gums healthy.  Lifting the lips along the sides of the mouth can reveal dark-colored plaque or a line of reddish inflammation where the teeth meet the gums.  Teeth must be cleaned regularly to remove the buildup, and on a more thorough examination of the teeth, gums, and entire mouth, your veterinarian may identify teeth that need additional treatment or possibly extraction.  Because a thorough dental examination and cleaning in pets requires general anesthesia, your vet may also recommend blood work ahead of time to make sure your pet is a good candidate for the procedure.

Fortunately, you can do quite a bit to prevent dental problems before they start.  Feeding your pet a balanced diet of dry food helps to limit plaque buildup.  Chew toys and nylon bones are another good way to stimulate gums and scrape away plaque, and many toys that have been specifically designed for dental care are available.  It’s also a good idea to brush your pet’s teeth regularly with a toothpaste specifically developed for pets.  Do not use human toothpaste, because your pet is likely to swallow it, which irritates the stomach.  Your vet can show you how to brush and maintain your pet’s teeth as part of an overall dental health program.