Everyday Medicine: Pulse Oximetry

pulse oximetry

Everyday medicine is an intermittent series of blog posts highlighting tests, treatments and procedures commonly used at AMC. Some past examples of this type of blog post include “What are Vital Signs” or “Five Reasons Veterinarians Love Fluid Therapy.” Today’s blog post will tackle the topic of pulse oximetry, a common monitoring tool used at AMC.

In the last publication of Everyday Medicine, I wrote about oxygen therapy and how veterinary patients depend on this vital element. Today, I am writing about a non-invasive method we use to monitor oxygen therapy, pulse oximetry.

The Device
A pulse oximeter is a portable device with two main parts: 1) a box that contains the software and a display panel, and 2) a sensor which attaches on one end to the box and on the other end to your pet. In people, the sensor is often attached to a finger, toe or ear lobe, but the hairy nature of paws and the thick pads make toes a less than ideal location in pets. Veterinarians typically attach the probe to the tongue or cheek, or the web of skin between the toes in anesthetized patients. In conscious patients, we use the ear flap.

The Measurement
The pulse oximeter measures how much oxygen is attached to the hemoglobin molecules within the red blood cells. The machine display reports the percent of the hemoglobin molecules that have oxygen attached to them, a value called the oxygen saturation. In a normal dog or cat, we expect the oxygen saturation to be near 100%. When oxygen saturation is less than approximately 94%, oxygen therapy is administered.

The Clinical Application
I bet AMC veterinarians use the pulse oximeter a couple of dozen times a day in a variety of situations. The most common use is as a monitoring tool for pets undergoing general anesthesia. Oxygen gas is used as part of the anesthetic protocol. If the pulse oximeter indicates the oxygen saturation is falling in an anesthetized pet, it is a clue for veterinarians and veterinary technicians monitoring the pet to adjust the anesthetic and oxygen levels. In pets with diseases affecting the lungs, like pneumonia or asthma, the pulse oximeter can assess the impact of oxygen therapy and also improvements in the pet’s underlying disease following administration of antibiotics or anti-inflammatory drugs.

Simple and indispensable, the pulse oximeter is an essential device for the daily practice of veterinary medicine.

Pancreatitis in Dogs

pancreatitis in dogsThe pancreas is a thin, elongated organ that is shaped a bit like a pounded piece of chicken tenderloin. The pancreas lies along the initial portion of the small intestine called the duodenum. As the bile duct leaves the gall bladder, it traverses the pancreas before it enters the duodenum. The pancreas is probably best known for producing insulin, the hormone deficient in patients with diabetes. The pancreas also produces digestive enzymes essential for breakdown of food into its nutrient component parts.

-itis = inflammation
When a body part is inflamed, the suffix “-itis” modifies the root word to indicate the disease process of inflammation. Tennis elbow is really inflammation of the elbow bone and in doctor speak is epicondylitis. Inflammation of the appendix is appendicitis. Inflammation of the pancreas is pancreatitis. Pancreatitis is the most common condition of the dog and cat pancreas.

Causes of pancreatitis in dogs
The exact trigger for pancreatic inflammation in dogs is elusive. High fat meals, such as one obtained illicitly from the kitchen trash can are often blamed. Miniature Schnauzers are a dog breed with an increased risk of pancreatitis. Some diseases, like diabetes, hyperadrenocorticism and hypothyroidism increase a dog’s risk for pancreatitis. Blunt force trauma, like an automobile accident or a fall from a height can injure the pancreas and set off the inflammatory cascade. Whatever the cause of the inflammation, it promotes release of the digestive enzymes from the pancreatic cells. The enzyme release worsens the inflammation and also the clinical signs.

Clinical signs of pancreatitis
Pancreatitis can be either an acute fulminant illness or a more insidious, chronic problem. The list of clinical signs attributed to pancreatitis is quite long: vomiting, anorexia, weakness, dehydration, abdominal pain and fever. Dogs may assume a “praying” position with their elbows on the floor and their rump held high. Veterinarians interpret this as a response of the dog to abdominal pain. Since the major signs of pancreatitis are nonspecific, vomiting and anorexia, a battery of blood tests, x-rays, and an abdominal ultrasound may be necessary to establish a diagnosis of pancreatitis.

Treatment of pancreatitis
There is no specific treatment for pancreatitis like there are antibiotics for bacterial infection. Veterinarians treat dehydration with fluids, control vomiting with anti-nausea medications, and manage pain with pain medications. We also rest the gastrointestinal tract of patients with pancreatitis by withholding food and water until the vomiting ceases, followed by a low fat, bland diet. Dogs may take several days to recover from a serious case of pancreatitis.

To help prevent pancreatitis, restrict your dog’s intake of human foods, especially fatty ones. There will be less dieting for him in the new year and hopefully no pancreatitis to spoil his fun.

Everyday Medicine: Oxygen Therapy

oxygen therapyEveryday medicine will be an intermittent series of blog posts highlighting tests, treatments and procedures commonly used at the AMC. Some past examples of this type of blog post include “Vital Signs” or “Five Reasons Veterinarians Love Fluid Therapy.” Today’s blog post will tackle the topic of oxygen therapy, a common treatment at the AMC.

Oxygen is a colorless, odorless and tasteless chemical and despite this seemingly innocuous profile, we can’t live a minute without it. Every veterinary hospital has a stash of green metal cylinders containing compressed oxygen for use in patients needing oxygen therapy.

What pets need oxygen therapy?
The lungs collect oxygen from inspired air and transfer it to the red blood cells. The heart distributes blood throughout the body and thus moves oxygen to every organ. Any disease that impairs lung, blood or heart function, if severe enough, may impair oxygen delivery. Examples of diseases where oxygen delivery is compromised include: pneumonia, bruised lungs, anemia, and congestive heart failure.

How do veterinarians know a pet patient needs oxygen therapy?
Nearly any emergency patient showing signs of difficulty breathing will be immediately treated with oxygen therapy, while initial testing is performed to determine the cause of the breathing impairment. The AMC ER uses a device called a pulse oximeter to measure the amount of oxygen in the bloodstream. The probe clips onto the ear, lip or tail. Pets with low oxygen levels will continue to receive oxygen therapy.

How is oxygen administered?
The AMC’s ER and ICU both have specially designed cages for administering oxygen. Instead of bars, the doors are solid Plexiglas and the cage features a valve to control the amount of oxygen delivered into the cage. Oxygen might also be administered via a mask held over the dog or cat’s nose. For pets needing to move about the hospital for tests and procedures, this is a portable oxygen delivery method. This method is commonly used if a pet in congestive heart failure needs an EKG or a cardiac ultrasound. Really big dogs don’t fit into most oxygen cages. In those dogs, veterinarians administer oxygen directly into the nasal passages using special tubes.

What other uses are there for oxygen?
Pets undergoing general anesthesia for surgery or teeth cleaning receive oxygen as part of the anesthesia protocol. Once the breathing tube is placed into their trachea or windpipe, a mixture of oxygen and anesthetic gas is pumped through the breathing tube to maintain the pet under anesthesia. When the procedure is finished, the anesthetic gas is discontinued and the pet breathes only oxygen until adequately awake from anesthesia.

Oxygen, a chemical element required by all living things, is critical to veterinarians’ ability to provide lifesaving treatments to our patients.

Understanding Cat Tail “Language”

cats | animal medical centerJune is the ASPCA’s Adopt a Shelter Cat Month, and June 4 was International Hug Your Cat Day. I need no better reasons to write a blog on cat “language” than those two cat celebrations.

Cat Talk
Some cat words are universally used by cats and understood by humans. For example, consider the wail emitted by your cat when you accidently step on their toes as they dance under your feet in the kitchen; you can hear that sound from another room and immediately know some kitty toes got crunched. How about the cat morning alarm sound which is readily translated to: “Get up you slug and serve breakfast!” Everyone knows purring is the sound of a happy, contented cat. Veterinarians quickly recognize the yowl of a male cat with a urinary obstruction. Certain cats have a large vocabulary, trilling and chirping about their day when you come home.

Cat Body Language
A recent scientific study demonstrated changes in facial features are one way a cat exhibits pain. But observing your cat’s tail may be the best method of listening to what your cat is trying to tell you.

Tail Straight Up
A happy cat has its tail straight up when it greets you at the door. This should be the normal position of your cat’s tail most of the time because she telling you what a good mood she is in. Some happy cats will wave their straight up tail back and forth, not like the wag of a dog, but more like the wave of Queen Elizabeth.

Tail Straight Out
This tail position is usually seen when your cat is crouched low to the ground in attack mode. The ancestral cat hunted for food. In order to disguise their intentions to their intended lunch, cats crouched low to avoid being sensed by their prey. Your cat probably exhibits this behavior when you bring out a new fur mouse or when hunting your slippers or another cat.

Tail Puffed Up
Bigger is better when you are facing enemies and the wild beast in your cat comes out when they are frightened by a strange human or the neighbor’s drooly dog. The tail puffs up as part of the “fight or flight response” mediated by adrenaline in an effort to say, “I am big and bad. Go away.”

Tail Flicking
When your cat is flicking her tail, leave her alone and teach your children to do the same. Tail flicking is your cat’s way of saying, “I am angry and about to go ballistic.” Remove the cause of her anger and steer clear until she calms down or someone could really get hurt.

Tail Injuries and Illness
Doors inflict a number of injuries on tails: lacerations, fractures and degloving (scraping) injuries. These are reasonably easy to recognize. A tail that is not moving may indicate a neurologic disorder. Tails can also develop tumors. If your cat holds her tail in a strange way, she is telling you a visit to the veterinarian is in order. Tail amputation may be the recommended treatment for certain diseases of the tail. Here is more information about tail amputations.

Pay close attention to the tail language of your cat as she may have something important to tell you!

A Living Legend Because of a PDA

Molly is a cute fluff ball of a Ganaraskan. Although her name sounds like she belongs in a Tolkien novel, the Ganaraskan is a modern dog breed, developed only a few decades ago in Canada near the Ganaraska River in Ontario. The originators of this breed set out to develop the ideal therapy dog from English Cocker, Bichon Frise, Poodle and Miniature Schnauzer stock. Molly is typical of the breed: curly coated, anxious to please and weighing just about 20 pounds. But Molly is anything but typical; she is a legend in her own time a survivor of a major cardiac procedure necessary to save her life.

An Early Beginning of a Legend
Molly’s story starts when she is just a young pup and is diagnosed with a heart murmur at ten weeks of age. An echocardiogram did not identify a cause for the murmur and since the murmur was not very loud, no treatment was prescribed. Two years later, Molly came to The Animal Medical Center for evaluation of a fractured tooth. Dr. Stephen Riback, one of The AMC’s dentists, heard the murmur and recommended an echocardiogram.

The “Heart” of the Problem
The echocardiogram, performed by one of The AMC’s board certified cardiologists, Dr. Dennis Trafny, revealed an enlarged heart and a 4mm (1/8 inch) wide abnormal blood vessel known as a patent ductus arteriosus (PDA). Normal before birth, the PDA typically closes shortly thereafter. In Molly, the PDA did not close, allowing blood to traverse between two major blood vessels, the aorta and the pulmonary artery. The abnormal blood flow caused the heart murmur. But the murmur was just a harbinger of a future, more serious problem: the potential risk of heart failure if the abnormal blood flow was not halted.

The first technique available to veterinary cardiologists for repairing PDAs in dogs required a thoracic surgery to ligate the PDA vessel using suture material. The incision scar was the size of your hand on the dog’s chest. Now, veterinary cardiologists use fluoroscopy, a special video x-ray machine, to guide a special catheter with a disc occluder up through a blood vessel in the leg, into the heart and right to the site of the PDA. When the disc occluder was deployed on both sides of Molly’s PDA, it corrected the abnormal blood flow. All it took was an incision the size of your fingertip on the inside of her leg and a highly skilled team of AMC veterinarians and medical staff.

Screen Legend: A Movie of Blood Flow
The video clips of Molly’s procedure come from The AMC’s fluoroscopy machine. It is a special x-ray machine which makes a video x-ray of a procedure.

In the first video clip, before the PDA was occluded, the rapidly moving black material is a special contrast agent administered intravenously to highlight the PDA. The contrast agent should all stay in the big blood vessel (aorta), but instead it circulates throughout the lungs and the blood vessels highlighted by the contrast agent represent blood vessels in the lungs.

In the second video clip, you can see the PDA has been closed off with a disc occluder. It blocks the blood flow through the PDA. You see the blood does not circulate abnormally through the lungs like in the first video.

Two weeks following surgery, Molly’s cardiac size decreased by 25% and she is doing well today. She is no longer at risk for developing heart failure and is expected to live a long, full life!

If you liked Molly’s story, you might want to hear other stories of medical triumphs at the 7th Annual Living Legends Luncheon on May 12th. Learn more about this event.

Canine Flu: An Update

For the last few months, veterinarians and dog owners in the Chicago area and other Midwestern states have been faced with an outbreak of canine influenza. Over 1,100 dogs have been diagnosed with the virus and sadly, some have died. First identified in an outbreak of what was believed to be “kennel cough” in greyhounds, the canine influenza virus was initially described in 2005. Canine influenza virus is just one of the causes of “kennel cough” which is really a general term for canine upper respiratory tract infections. The canine influenza virus reported in 2005 is an H3N8 strain of the virus which has been documented nationwide. The current Chicago outbreak is caused by an H3N2 virus, which is the virus circulating in Asian dogs. Exactly how the Asian strain came to the Windy City is not currently known. Canine influenza seems to be moving east and cases have now been confirmed in the state of Indiana. Just yesterday, dog flu was diagnosed in Iowa.

Dog to Dog Transmission
Canine flu is transmitted from dog to dog and dogs can transmit it prior to showing symptoms of the virus. That feature of the disease is probably responsible for its rapid transmission within a population. Inanimate objects, leashes, collars, bowls and bedding used by an infected dog could be a source of infection for other dogs coming in contact with those objects. Petting a sick dog and then petting a healthy dog can also spread the infection.

Clinical Signs of Canine Influenza
The clinical signs of canine influenza run the gamut of respiratory disease. Twenty percent of dogs infected with the virus will never show any signs, but still can infect other dogs. Most dogs develop what we might think of as a cold– sneezing, runny nose and a cough. Dogs with the flu feel out of sorts with a fever and a poor appetite. About ten percent of infected dogs will develop a serious complication of influenza – bacterial pneumonia.

What precautions should dog owners take?

  1. Avoid doggie day care, the boarding kennel, the dog park, obedience classes and any other areas where dogs congregate. The canine flu spreads most rapidly in situations where many dogs come in contact with each other or with infected dogs’ coughs and sneezes.
  2. Wash your hands well. The canine influenza virus can live on human hands for 12 hours, unless they are washed with soap and water.
  3. Talk to your veterinarian about the canine influenza vaccine. The available vaccine is for the typical H3N8 virus. Because the virus in this outbreak is H3N2, we don't know if the flu vaccine will protect dogs against this new virus, but it is being recommended in the Chicago area. The canine flu vaccine is like the human flu vaccine; it lessens signs of flu and shortens their duration, but does not prevent the disease.
  4. If your dog contracts the flu, wash bedding, dishes, leashes and clothing which can transmit the virus for up to 24-48 hours after coming in contact with a sick dog.
  5. Keep your cat away from your sick dog since the H3N2 strain can be transmitted to cats. The H3N8 strain is not believed to infect cats.

Treatment of Allergies in Pets

Spring officially arrived nearly three weeks ago, but the onset of allergy season may not arrive too soon this year, given our harsh winter. But once it warms up, pollen, dust mites, fleas, grass, weeds and mold will kick off allergy season in pets.

Clinical Signs of Allergies
Does your dog rub his face along the front of your sofa or scratch incessantly? Has your cat scratched all the fur off her head and made is scabby? Are you constantly putting in ear drops or giving antibiotics to treat skin infections? All these represent clinical signs of allergies in pets.

Control Parasites
One of the top causes of canine and feline allergic skin disease stems from an allergic reaction to flea saliva. A flea bites your dog or cat, setting off an allergic reaction. This disease presents a double-whammy to your pet: discomfort from fleas crawling all over its skin and the discomfort of being itchy. Fortunately, numerous options for control of fleas are available and your choice of product can be tailored to your pet’s exact needs.

Modify the Diet
Food allergies are typically an ongoing problem, not seasonal like pollen, grass or flea saliva allergies. Veterinarians think the allergen in food is the protein source contained in the diet, but it may be other ingredients as well. The standard method for determining if food is the cause of skin disease is a food elimination trial. Elimination diets contain a limited number of ingredients and protein sources not typically found in common pet food and not previously fed to your pet. Novel protein sources include bison, herring or rabbit. Some elimination diets avoid common carbohydrate sources and include potatoes or oats, rather than corn or soy. An elimination diet requires determination on the part of the pet owner, as the skin improves slowly in response to a diet change. Patience is required to tough out a month or more of strict diet control.

Administer Immunotherapy
Immunotherapy, a medical word for allergy shots, involves specialized testing to determine whether it is pollen, dust mites, fleas, grass, weeds or mold revving up your pet’s itch-scratch pathway. Once the cause of the allergy is determined, a custom allergy vaccine can be developed for your pet. You learn to give the injections at home one to two times per week. These injections contain minute amounts of the offending antigen (pollen, dust mites, fleas, grass, weeds or mold) which trains your pet’s immune system to be tolerant of these agents.

Quell the Immune System with Drugs
A variety of drugs can be used to turn off the allergic reaction underlying the itch-scratch cycle in your pet. The most well-known, but not necessarily the most effective in pets, is antihistamines. Steroids can be very effective and rapidly reduce the clinical signs of allergies, but have unpleasant side effects, such as increasing water drinking, urination and appetite, as well as increasing the risk of infection. Another effective drug for allergy management is cyclosporine, although cost is a concern. New to the market, oclacitinib, inhibits the cells initiating the itch-scratch cycle by attacking allergies at the cellular level.

With so many options to manage pet allergies, no pet should have their summer fun spoiled by constant itching and scratching. Watch The AMC’s Dr. Mark Macina talk about managing allergies in pets.

Nicotine Intoxication: A Danger for Pets of Smokers

This week, March 15-21, 2015, is National Poison Prevention Week. I am using this week’s blog to alert dog owners of a new toxin found in our homes – nicotine. Nicotine has been around a long time, but the new nicotine substitutes, designed to help people stop smoking, are poisoning dogs. A recent article in the press highlights the dangers of nicotine from e-cigarettes.

Sources of Nicotine
If you smoke around your pet, she will develop an increased concentration of nicotine in their blood stream, but the increases will not reach toxic levels. Ingestion of an e-cigarette or the super concentrated nicotine liquid used to refill the e-cigarette can cause serious and even fatal toxicity. Due to their indiscriminate eating behavior, dogs may help themselves to nicotine-containing gum or candies from your bag or backpack. Another source of nicotine toxicity is discarded nicotine patches snatched from the bathroom trash basket. Cats can also develop nicotine toxicity, but are more likely to find a discarded patch inadvertently stuck to their fur after you have removed it from your skin. Cats will ingest the nicotine while trying to remove the sticky patch by grooming.

Signs of Nicotine Toxicity
If your pet ingests one of these nicotine products, she will show signs in less than an hour and possibly in minutes if the dose is high. Common clinical signs include: vomiting, diarrhea, agitation, elevations in heart and respiration rate, depression, tremors, ataxia, weakness, seizures, blue gums, coma, and cardiac arrest. Just one e-cigarette cartridge can make a big dog really sick and can be lethal in a small dog.

Prevent Pet Poisoning

Erin Go Daugh!!! St. Patrick’s Day for Pets

New York City, and other cities are about to get green. Not green with envy or ecologically green, but St. Patrick’s Day green. Many of us will don green hats or a sweater with an embroidered shamrock emblazoned on the front. Pets wearing St. Patrick’s Day finery are adorable, but some of the other St. Paddy’s Day traditions can be downright dangerous for pets.

Green Beer and Irish Whiskey
For those hosting a St. Patrick’s Day party, monitor the coffee table and other low surfaces for unfinished alcoholic beverages. Your dog might decide to take a nip or two of these available beverages in honor of the Irish saint, but because dogs are smaller than we are and are not used to drinking alcohol, they can quickly develop alcohol poisoning.

Another tip to avoid a pet crisis during your St. Patrick’s Day party: give Fluffy and Fido their own party space away from your guests. Their own space will protect them against unwanted escape as your guests arrive or depart. But just to be safe, be sure your pets are wearing their collars and name tags under their St. Paddy’s Day garb.

Shamrock Plants
The shamrock, or white clover, is a plant traditionally associated with the Emerald Isle and St. Patrick. History suggests the Irish wore shamrocks on their clothing to honor St. Patrick on his feast day. Today, shamrock plants can be found in your neighborhood grocery store and brighten up window sills at this gloomy time of year. Shamrocks contain oxalate which, if the plant is eaten, is irritating to the intestinal tract. Pet familes should find decorations other than live shamrock plants for the St. Paddy’s holiday season.

Irish Soda Bread
Out of financial necessity, the Irish popularized soda bread. Irish soda bread uses inexpensive ingredients like flour, sour milk and a bit of sugar. Today this tasty, raisin loaded loaf appeals to everyone, including your dog. But keep your loaf away from your dog, since ingestion of even a few raisins or currants can permanently damage your dog’s kidneys.

Green Foil Wrapped Chocolate Shamrocks
Leprechauns often leave foil wrapped chocolate shamrocks as gifts in honor of the patron saint of Ireland. They intend for the chocolate to be eaten by humans. Dogs will happily consume the chocolate and the foil wrapping, leading to an upset stomach. If a large number of these chocolate treats are consumed, dogs can become excitable and develop a very elevated heart rate. Find some shamrock shaped dog biscuits if you are looking for a special dog treat.

If you are wearin’ the green be safe and have a happy St. Patrick’s Day!

Bladder Stones: Now You See Them, Now You Don’t

The two x-rays seen below are from the same canine patient, taken one month apart. The one on the left shows two bladder stones. On the right you can see the stones are no longer present in the bladder. How did this magic happen? Surgery? Laser therapy? Antibiotics? Food? Magic wand?

Surgery?
Nope. Surgery may be the fastest and most common treatment for bladder stones, but for this lucky duck dog surgery was not necessary. Bladder surgery is performed under general anesthesia. The surgeon makes an incision in the abdomen near the back legs and finds the bladder just inside the body wall. Because the bladder is a hollow organ, it will collapse when the surgeon makes an incision in the bladder wall. Special sutures are placed in the bladder to hold it up and keep it open while the stones are scooped out of the bladder with a bladder stone spoon.

PCCL?
Huh? This acronym stands for per cutaneous cystolithotomy. Using laparoscopy equipment, a pinhole incision is made in the bladder. A small camera is threaded into the bladder and its magnifying properties are used to visualize the tiniest stones. Using this non-invasive method, stones are busted up using the laser and then easily removed.

Laser therapy?
Guess again. For dogs of the right size with not too many stones, non-invasive bladder stone removal is possible. Stones can be fragmented using a special laser which is passed up the urethra and into the bladder. Once the stones are broken into small enough pieces, they are either flushed out of the bladder or removed with a special stone-removing basket which is passed up the urethra and into the bladder to gather up the stone fragments.

Antibiotics?
Yes, but only in part. I can hear you saying, “Wait a minute, this makes no sense. Stones are hard chunks of mineral. Antibiotics treat bacterial infections, they do not dissolve stone.” But, this dog’s urinalysis showed an infection in addition to the stones. The infection played a role in the development of the stones and without treating the infection, the stones will not disappear.

Diet?
Stones form in the bladder as a sequel to infection and also because there are too many minerals in the urine. Drinking more water dilutes the minerals and helps dissolve the stones. Taking advantage of that information, a diet was formulated to promote water drinking in dogs fed the special stone dissolving diet. The diet is also low in magnesium and phosphorus, the building blocks of a type of bladder stone called struvite. This diet does not work in every type of bladder stone, only the struvite ones. Antibiotics are necessary since as the stone dissolves, it releases bacteria, and thus the dog needs antibiotics until the stones are completely gone. Antibiotics alone will not dissolve the stone and diet won’t work unless the infection is controlled, so the correct answer for the magical disappearance of the bladder stones in this dog is diet AND antibiotics.

Signs of bladder stones
Dogs with bladder stones urinate more frequently than is normal, have accidents in the house and blood in their urine. If you see any signs like this, be sure to have your dog evaluated immediately by your veterinarian. View a prior blog post on bladder stones to see diagnostic images of stones.