Visiting with K-State’s Gregg Hanzlicek.
Angus Talk host Doug Medlock visited with Gregg Hanzlicek, veterinarian and director of production animal field investigations with the Kansas State University (K-State) Veterinary Diagnostic Laboratory, about the risks of anaplasmosis and what cattle producers should do to protect their herds. Here are some outtakes from their conversation.
Tell us a little bit about yourself. How did you end up at the K-State diagnostic laboratory?
I’m a Kansas native. I received an animal science degree at K-State and then my DVM (doctor of veterinary medicine) from Mississippi State University, then spent 16 years as a cow-calf veterinarian in the upper Midwest before coming back to K-State to pursue a Ph.D. in epidemiology. When I finished, the diagnostic lab asked me if I would head up the field investigation team, and I said, “Yes.” I’ve been here since 2011.
Epidemiology is the study of epidemics?
Well, it kind of is. It’s the study of the distribution and determinants of disease. Basically, it’s herd health medicine.
What is anaplasmosis and what are its symptoms?
Anaplasmosis (anaplas) is a disease that affects the red blood cells of cattle. It’s caused by a bacteria with the name of Anaplasma marginale.
In time, the immune system of the cow or the bull will remove those red blood cells, so these cattle become anemic. That’s the clinical sign. A producer will be checking pastures and will find one or more adult animals dead. Other signs of anaplasmosis common in animals that haven’t succumbed to the disease are staggering and open-mouth breathing. Their bodies are starved for oxygen because their red blood cell levels are so low.
They actually can look like they have pneumonia even though they don’t. A lot of times their tissues around the eyes or in the vulvas will turn a yellow color called icteric. Occasionally, some of these animals become very, very aggressive. That’s because their brain is starved for oxygen and they’re just not performing as they normally would if they weren’t anemic.
The clinical signs are typically only going to be seen in animals that are over a year of age. Those are the animals that are affected. Those are the animals that are most likely to actually succumb to the disease.
Are we seeing more anaplasmosis this year than before?
We’re not sure. Certainly in this area we are finding more positive herds within the counties that we’re looking at, but we don’t know if that’s because there actually is more anaplas in the Midwest or if that’s a reflection of the fact that we’ve been out there talking to producers and veterinarians a lot about this disease. It might be that producers and veterinarians are testing and looking for it more.
How does it spread between cattle?
The only way that it can be spread is through the movement of blood, so blood from a positive animal to a negative animal, so anything that does that.
Typically, one of the things that we talk about is it’s a vector-borne disease. Vectors are living organisms that transmit disease between animals. In this case we’re talking about primarily ticks. Flies can transmit infected blood to a non-infected animal.
Is there a way to keep ticks away from the cows if ticks are what’s transmitting it?
There are. There are really good insecticide ear tags that do a pretty good job for ticks. There are pour-ons, back rubbers. Those kind of things are really important for producers to use in their herds. One of the things that we’ve learned from livestock entomologists is that ticks really like cedar trees and other kinds of brush. If we can do a good job of keeping the cedar trees from overtaking the pastures, we’ll cut down the tick population by doing that also.
If you pull a tick from an animal, what’s the chance they are going to be infected?
We don’t know that, but I can tell you that we collected a lot of ticks in eastern Kansas from many locations two years ago. Thirty percent of the ticks we found actually were positive for anaplasmosis.
What’s the first thing you should do if you pull a tick off an animal? Is there a way to test for that early? You don’t just wait for symptoms do you?
Well, you shouldn’t. If they’re interested, we can absolutely test the tick to see if it is positive. That doesn’t necessarily mean they transmitted it, but they probably did. We can test the tick. There’s also two really good blood tests that we can take blood samples from cows or bulls and send it to a laboratory and determine whether they’re positive or not.
Are there pests other than ticks that can spread anaplasmosis?
Yes. We don’t really think mosquitoes participate much in the spread of anaplasmosis because they transfer such a small amount of blood. However, there are three flies — horse flies, stable flies and deer flies, especially the horse flies. They definitely can move positive blood to negative animals. The horn flies that producers see on the backs of animals and the sides, we don’t really think they’re a big player in anaplasmosis because they typically spend most of their life on the same animal. They’re not moving back and forth to animals and feeding.
You’re saying almost anything that’s going to bite my cows could spread this disease, but you can’t protect against all that stuff, right?
No, you can’t. Those flies that I talked about — the horse fly, deer fly and stable flies — we really don’t have real good control of those. We’ve got good control on horn flies, but those three flies we don’t have great control. Nevertheless, producers should have a good fly control program to minimize the risk of spread.
Are there ways cattle producers help spread anaplasmosis?
Tthere are. If you’re a positive herd, reusing needles can spread the disease if you inject an animal that’s positive, keep the same needle on the syringe, and then inject another one. We’ve shown here in research that there’s enough blood on that needle to transfer to the next animal.
When people tattoo their calves either with registration IDs or for brucellosis testing, those tattoo pliers can carry enough blood from a positive animal to a negative animal.
Then we talk about dehorners and scalpel blades. Those are probably minor players compared to needles and tattoo pliers.
If left unchecked, what are the long-term effects anaplasmosis can have on cattle?
Most likely we’re talking about a reduction in production in the older cows and the bulls and then also a reduction in reproduction. Then, of course, there’s also the death loss that is incorporated with it, too. So, it’s a combination of those three things.
Is anaplasmosis more common in older cattle, or can cattle of any age get it?
That’s a really important point. Any age of cattle, including baby calves, can become infected. However, typically we do not see the clinical signs unless an animal’s at least a year, if not 2 years of age, or older.
Once you know you’ve got it, how is anaplasmosis treated?
If we actually see clinical signs, with the staggering, the open-mouth breathing, we have multiple injectable tetracycline products that are labeled for the treatment of anaplasmosis. They’re very effective at reducing the clinical signs of this disease.
If you do treat anaplasmosis, what are the odds they’ll recover?
There’s no treatment that’s 100%, but that treatment is very effective. We also know that most animals, whether we treat them or not, are going to clear the clinical signs in time on their own. The danger of treating them is that we have to take them to an alleyway or a chute to inject them, and sometimes that will be enough stress to cause them to succumb to the disease.
So you’re walking a fine line there. I guess you still need to treat it, right?
Well, there’s two schools out there. I’m from the veterinary school that says we have a good treatment. Let’s handle these animals very calmly. Walk them calmly to the working facility, mindful that some of them might be aggressive. Treat them. The other school is, hey, let’s just leave them alone. Let’s don’t stress them, because most of them are going to clear the clinical signs in time anyway.
So you won’t lose the majority of them, hopefully.
Typically you’re not going to lose the majority. I think the biggest death loss that we’ve seen here in our area was about seven dead adults in a herd of about 120 adults.
Let’s say you treat the animal and it survives. Are they cured forever, or is there a chance of it coming back?
That’s a great question. Whether they’re treated or not, if they survive they will become lifelong carriers. It is very difficult, if not impossible, to get rid of the carrier state of anaplasmosis in cattle. If they recover, they’re a source of infection to other animals. The good thing is that even if they become reinfected in later years, they won’t show the clinical signs.
Do you have to keep them separated then?
There are several ways producers can do that. First of all, if a herd has anaplas, probably the first thing the producer needs to do is to determine how much. From there, we can determine whether we need to separate the positives from the negatives. You really only need to separate them during the pasture season when those vectors are out. In the wintertime, you’re not going to transfer it except through needles and tattoo pliers.
There are herds that separate; they have a positive and negative anaplas herds. There are herds where they find one or two positive animals and they just cull those animals to make the herd negative. So, there are several ways of controlling this disease.
Anaplasmosis isn’t the only thing that can be transmitted between biting bugs and stuff, right?
That’s exactly right. Bovine leukosis virus would be the other one that we talk a lot about that’s transferred through blood.
Will an anaplasmosis-positive cow pass the disease on to her calves?
A lot of research has looked at that in the past. The numbers are anywhere from they don’t pass it on to 17% of the cows or heifers that are positive will actually give birth to a positive calf. We don’t know what the chance is, but there is a chance.
If a producer suspects anaplasmosis in his or her herd, what should he or she do?
The first thing to do is to call their veterinarian. The reason I say that is there are other diseases that can cause the same clinical signs, so it’s important that the veterinarian is involved, and he or she will do whatever sampling they need to do to make sure that it’s anaplasmosis. It’s really important that we have a correct diagnosis before we start talking about treatment and prevention management.
How has the Veterinary Feed Directive (VFD) affected beef producers’ ability to protect their herds from anaplasmosis?
You cannot use feed-grade antibiotics in any manner that’s not on the label. Every label for tetracycline, which is the drug that we use for anaplasmosis, every label says, “For the aid and the treatment of active infection.” The label doesn’t say for prevention. The question is, “What is the definition of active infection so that a veterinarian can actually write a VFD for producers to use?”
Talking to the FDA, they’re going to leave that definition basically up to the veterinarian. Some veterinarians are saying if it’s in the county, then it’s likely this herd is positive. I may have diagnosed anaplas in this herd 10 or 20 years ago, so I’m pretty sure it’s still here.
So you’re stopping an outbreak at that point.
Exactly. That’s a good point: The feed-grade antibiotics that we’re going to use in the pasture do not prevent infection at the level that the animals are going to eat it. What they do is they reduce the clinical signs that we talked about.
Is there a place where readers can go to find out more about anaplasmosis?
The first place, again, is to always go to their local veterinarian. That’s the best resource they have. If they have a state extension service, use their extension personnel. Then, by all means, give the Kansas State Veterinary Diagnostic Laboratory a call, and we can certainly talk about it, too.
Editor’s Note: Hosted by Doug Medlock, the American Angus Association’s Angus Talk radio show features conversations with industry personalities from across the country. The program is broadcast each Saturday at 10 a.m. CT on Sirius XM’s Rural Radio, Channel 147. Outtakes featured here are edited.