Understanding Dog Ultrasounds with Calusa Veterinary Center
What type of conditions or concerns typically require an ultrasound for dogs?
It's a good question. It's a very comprehensive answer. Almost any condition in the world can actually have an ultrasound used for it. The most common conditions we look for in dogs are when the dog shows symptoms like vomiting, diarrhea, abdominal pain, blood in the urine, excessive urination, accidents or trauma, and pregnancy. You might want to see if they're pregnant or if there's a foreign body. That may be obstructed with a foreign body. Some X-rays will show foreign bodies, but others won't show certain foreign bodies like clothes or underwear, and you need an ultrasound to see that. X-rays pass right through it. We also do ultrasounds to see what's happening in any sick animal. For example, with an unexplained fever, it can help us find an answer. Many times, ultrasounds are done just to show that everything's normal. A clear ultrasound is actually a very good ultrasound, and sometimes you do that to prove everything's normal. Those are the types of conditions we mainly use.
How does a dog ultrasound differ from other imaging methods like X-rays or radiograph?
Let's talk about X-rays first. X-rays use low doses of radiation, and they take a snapshot of what's going on at that time in the patient. It's really good for hard structures and dense structures like bones and foreign objects like metal balls or big, hard rubber balls that may be stuck there. It's very good at diagnosing things that have a lot of air associated with them. For example, the lungs, or if there's air in the abdomen from an injury. You'll see air very well, but it's not very good for soft tissue structures and looking inside organs. It doesn't see inside the organs at all, just the general shape. For example, a liver tumor would be like a bump on the liver, but it won't tell you if there's a tumor inside the liver. That applies to the spleen as well. The difference is that ultrasounds are made by sound waves. Ultrasonic high-frequency sound waves are put into the animal. The sound waves bounce back, get picked up by a computer, and are converted into an image. This allows you to take a live video of what's happening in the abdomen or chest at that time. You can see the heart beating if you look at the chest, and you can see the intestines moving, fluids moving, and everything like that. It's actually a live video that you can see inside the abdomen. It's like looking in the abdomen without having to do surgery.
What should pet owners expect during a canine ultrasound appointment?
It's actually a non-invasive procedure. The main things to consider are that the patient will be lying on a table, either on their side or back, depending on the ultrasonographer. If they lie on their back, there are special soft cushions they lie on to keep them comfortable. If they lie on their side, there will be a nice comfortable towel they lie on. Sometimes they can get anxious, and other times not. We also want to ensure they don't have any food in their bellies because food produces gas, and gas is the enemy of ultrasounds. It shows up as white lines on the ultrasound image, and you won't be able to diagnose anything. We don't want them to eat. Your preparation at home is to take away food from midnight the night before and come in without them eating, but they can drink. Water is fine. Water doesn't interfere and doesn't produce gas. We like the bladder to be a little bit full so we can compare the size and consistency of things on the ultrasound.
Once you've done that and you fasted them, we may, depending on the nature of the pet, advise you to give some tranquilizer or sedation pill, something like gabapentin or trazodone beforehand, which chills them so when they're lying down, it doesn't interfere with their mood and they're happy about it. It also takes the edge off and allows us to get better images. For example, if there's a painful tummy, you want to give them something that has a painkilling effect and a sedation effect. You don't hurt them when you press on the belly.
The whole procedure can take anywhere from 30 minutes to 60 minutes, depending on what we're looking for, the size of the pet, and the person doing the ultrasound. Images, videos, and still images are collected from the whole abdomen or the chest, depending on which ultrasound we're doing, and some specialists can interpret the images directly and give you an answer there. On the other hand, a lot of ultrasound technicians are just ultrasonographers, and we send the images to a specialist who looks at the ultrasound images and gives us the opinion and advice based on that. It really is minimally invasive, and the cats and dogs in this case don't seem to mind at all.
Can you explain how ultrasounds are used to monitor pregnancy in dogs and when the best time is to schedule one?
That's a good question because we can diagnose pregnancy on X-rays. X-rays can show the skeletons of puppies. They can see the ribs, spines, and skulls, but you have to wait about 7 weeks, which is 42 to 45 days from the time they became pregnant, to pick that up on an X-ray. Dog pregnancy is only 9 weeks, which is 63 days, so you're picking up pretty late in the pregnancy if you take an X-ray. In fact, by that stage, you can usually palpate the belly and feel the pregnancy there anyway. Ultrasounds are very useful for two reasons. One is that there is no radiation involved, so it doesn't harm the puppies, whereas radiation may, although we use low doses.
Secondly, you can pick up changes much earlier. We can see the little placental sac forming from about 3 and a half weeks, which is about 24 days into pregnancy. You can get 95% accuracy of pregnancy at that stage. By 4 weeks, that's 28 days, it's almost 100% accurate to diagnose pregnancy, and by that stage, we also see the little heart beating, and we can see that quite clearly on ultrasounds as well. The only time ultrasounds have a problem with pregnancy is that it's not easy to count the number of puppies compared to X-rays. X-rays allow you to count the number of separate skulls or spines, and you can get the puppies in ultrasounds because of the different depths of puppies. Sometimes you don't know what belongs to one puppy and what belongs to another. There may not be a 100% accurate count on that. It'll be one or two up or down.
What's the process for a cardiac ultrasound in dogs, and when is it recommended?
Cardiac ultrasounds are completely different from abdominal ultrasounds and have different reasons. A cardiac ultrasound, also known as an echocardiogram, is usually done by a well-trained specialist in the field, and that's usually to diagnose what's going on with the heart. How do we know something's going on with the heart? It's usually murmurs that the doctor picks up. A leaking heart valve or a severe arrhythmia where the heart doesn't go "boom-boom, boom-boom." It will go, "boom-boom... boom-boom, boom-boom-boom," something like that, and we'll have to find out what's going on with the heart, or if a dog comes in for certain types of coughing or fluid in the chest, and we need to diagnose what's going on with the heart.
The procedure is very simple, and I actually forgot to say this in the abdominal ultrasound preparation: we will shave the belly in the dogs to allow the ultrasound to see through the abdomen very well. You put some special gel there and maybe a little alcohol spray to make the contact very sharp so that you see good images. You do have to shave pretty much the whole belly in dogs. But with cardiac ultrasounds, they shave a very small amount of hair just by the heart area. They can see everything there, the right heart and left heart, with that. They'll see what the thickness of the heart is, what the wall thickness is. Do the valves leak? Do they close properly? Does the heart contract properly, called fractional shortening? Is it just doing this and not really contracting properly, or does it go like that to make sure that it's contracting properly? All these things are done with ultrasound. It takes literally 20 minutes, and you're in and out, and then the ultrasound images are sent to a cardiologist this time, and they will diagnose the condition and provide medication based on that and the other symptoms of the case.
How do you use ultrasound to diagnose issues like spleen tumors, pyometra, or kidney problems in dogs?
Spleen Tumors
Spleen tumors are quite common, particularly in larger-breed dogs. We put the probe in the abdomen and look in the region where we know the spleen is, and we'll look at the spleen. A spleen is usually a smooth and homogeneous structure of a certain thickness. If there's a tumor, we will see circles, either dark circles or white circles, light or dark, hyperechoic or hypoechoic, depending on what type of tumor it is. They can be different sizes. Sometimes it can bulge the capsule. Sometimes it's within the spleen itself. You can only see that from an ultrasound, never on an X-ray, because it's too small. Those are very helpful because it helps us decide what the treatment and prognosis are.
Pyometras
As far as pyometra goes, this is an infection in the uterus of unspayed female dogs that happens quite commonly when they get older. It can be a life-threatening condition. Usually, the uterus is a very small thing, less than two long tubes, usually about half to 1 cm in thickness at most, and when you have pyometra and the uterus becomes filled with pus, it becomes 2, 3, 4 cm thick, and you'll clearly see that on an ultrasound. Based on that, combined with, say, very high white cells on the blood test and the fever, you'll know it's a pyometra.
Kidney Conditions
So there are multiple kidney problems that can happen. Sometimes just age-associated, other times from stones in the kidneys or stones in the urine system, other times tumors or trauma to the kidneys. We know exactly by training where to look for the right kidney and the left kidney, and we can look at both of those. A kidney is made up of various structures, and we can tell if this layer is thicker, this layer is smaller, or if there are circles or balls or swellings, or fluid. We can then decide what exactly is going on with the kidney and how badly the kidney is affected. Even old dogs who have chronic kidney disease will have a classic sign where the kidneys start shrinking and get smaller. They also lose their structure, their classic structure, as they age. They become more fibrous, and we can determine how bad the kidneys look on ultrasound in old dogs to give us a hyperprognosis. Other things mentioned as well in this last question were bladder issues or liver disease.
Bladder Issues
Bladder issues, the common bladder issues we look for are dogs who come in either urinating frequently, having blood in their urine, and sometimes not even able to urinate; they're straining and nothing's coming out. The bladder is the first place we start with the ultrasound. We can see the wall thickness. We can see if there's sludgy material in the bladder. We can see if there are any tumors, obvious tumors, or stones, bladder stones. They shine up as very bright white areas on the ultrasound that have a shadow attached to it, called an acoustic shadow, not a light shadow. You see this classic line coming down, indicating that the sound waves cannot pass through a stone, and you know it's a stone. It can also tell you if the bladder wall is thickened in certain areas of the bladder. If it's thickened, for example, on the rounded portion of the bladder, that's more like an infection. But if it's thickened on the narrowing portion of the bladder, that's more likely a tumor.
Liver Disease
Ultrasounds are useful for evaluating liver disease. Again, tumors of the liver. You can see them the same way as I described for the spleen. The liver also contains the gallbladder. The gallbladder produces bile, and sometimes you get gallbladder stones or sludge in the gallbladder or obstruction of the bile ducts and things like that. You can see if the liver is very swollen, very white, if it's inflamed, if it's shrunken, or if it has nothing to it, like with liver cirrhosis in liver failure cases.
Locating Fluid in Body Cavities
One thing I didn't mention, as far as ultrasounds, is how useful they are in finding fluids. It's very good at finding fluid. X-rays, if you have fluid, make a white X-ray. Ultrasounds, because of the sound waves, make fluid look black, and it doesn't destroy the image; it just makes it very sharply demarcated. For example, if a tumor of the spleen ruptures and there's bleeding in the tummy or the abdomen, we will put the probe on the abdomen and see right away that there's fluid sitting in that abdomen, most likely blood in this particular case. Other reasons for fluid in the abdomen are many. Low protein can cause fluid in the abdomen, but also just an abscess or some cyst that will show up very clearly in ultrasounds. These are also very good advantages of an ultrasound over X-rays.
The final point is that when you use an ultrasound, you can do what's called an ultrasound-guided fine needle aspirate or a true cut biopsy of the organ you're looking at, because the ultrasound will put you right on the spot you want. If you see a tumor in the spleen that's this big, you put the ultrasound probe in the abdomen, you can see on the screen where the tumor is, and you put a needle directly using the ultrasound into that area and take a sample out of it. You can diagnose what type of tumor it is or what type of situation is going on there. These are very good pointers to why ultrasound is a fantastic tool in our arsenal.
I hope that was really informative to you all. If you have any questions about dog ultrasounds, please give us a call (561) 786-1100. We're always here for you. Remember, we are a 24-hour facility, so we're here for you day and night, 365 days a year.