Digital Radiography and Ultrasound

In our continued drive to grow and enhance our young Equine Veterinary practice, we’ve made some improvements. Eggleston Equine is proud to announce the recent acquisition of Eklin Digital Radiography (x-ray) technology and Universal Digital Ultrasonography!

Why is this news so exciting? Digital technology gives us superior imaging and diagnostic capabilities–in the areas of lameness and pre-purchase and in all aspects of veterinary medicine where a radiograph or ultrasound is required. These new systems will allow for real-time imaging, meaning better and faster care for you and your horses. These systems will allow us to image areas where we couldn’t previously–the back, neck and pelvis. The quality of digital imaging is simply better vs. traditional means meaning better ability to identify subtle or elusive problems. All of this improved capability is available stall side.

The digital technology also broadens the accessibility of Eggleston Equine with equine practices throughout the country and world since images captured can be easily sent to colleagues for second opinions. Images can also be easily transferred to clients for their own records.

These improvements are part of our continued commitment to our clients to provide advanced diagnostics. These improvements reflect the progressive nature of Eggleston Equine. These improvements represent a commitment to your horses and to the highest level of veterinary care.

Featured Article: Lyme Disease Primer

Growing up, my parents imparted a healthy fear of ticks to me and my two brothers. I remember the constant reminders to “check myself” after coming in from a day playing outside. I remember the ashtray and matches my father used to burn ticks and the kerosene jar where we would drown them. And I remember the first time I saw an embedded, engorged tick on my brother Rick. It remains a vivid memory to this day.

Despite these memories and 25 years of growing up and living in the Northeast, it was not until I started private veterinary practice in Connecticut, that I began to realize the devastating effect of tick born disease on humans and horses alike. In horses, ticks can cause Ehrlichiosis infection, Rocky Mountain Spotted Fever, and, the focus of this discussion, Lyme disease.

Lyme disease is caused by the Borrellia burgdorferi bacterium. This bacterium is hosted and transmitted by ticks of the Ixodes genus. We commonly call ticks of this genus “deer ticks” or “black legged ticks,” though the Ixodes genus actually contains over 250 species of ticks. The Borrellia burgdorferi bacterium is contracted by ticks of this genus by feeding on mice during their first or second blood meal. As ticks molt between each life stage, from larvae to nymph to adult, they take what is called a blood meal. It is the blood meal where the tick molts from larvae to nymph or from nymph to adult that the tick contracts the bacterium.

For transmission of the Borrellia bacterium to horses to occur, it takes a prolonged attachment (at least 24 hours in duration) of an infected nymph or adult tick. Ticks in the larvae life stage cannot transmit the bacterium, to our knowledge. Every time an infected tick feeds on a horse, though, that horse is not going to have an active Lyme infection. Many horses are able to mount an immune response against the bacterium and clear an infection without symptoms. In fact, if we were to test all the horses in Connecticut for exposure to the Borrellia bacterium, a large percentage would show such exposure. Lyme ticks are endemic to this area and horses are going to be exposed. But exposure does not mean a horse has Lyme disease. It is only when exposure is coupled with physical symptoms that Lyme can be diagnosed.

Many of the documented clinical signs of Lyme disease are musculoskeletal in nature. Stiffness, shifting leg lameness, multi-limb lameness, swollen joints, muscle hypersensitivity, laminitis, and joint pain have all been identified in horses with Lyme disease. In addition to the musculoskeletal signs, there are often behavioral changes in horses with Lyme disease. Owners often comment that their horse’s behavior has changed dramatically and inexplicably in a very short period of time. Some horses may be more irritable while others are more lethargic, dull, and unwilling. Additionally, horses with Lyme disease have been reported to suffer from neurological disorders, uveitis (also called moon blindness), and dermatologic (skin) disorders.

After being presented with the clinical signs of Lyme disease, it may seem that Lyme can cause just about anything! In fact, the diversity of the reported clinical signs is one reason some people doubt the existence of Lyme disease. Certainly, because the signs are so varied, a veterinarian needs to be careful when diagnosing Lyme disease. And there is a point to be made that Lyme disease is over diagnosed; it’s an easy out when a lameness or behavioral change confounds. On the other hand, if you simply don’t “believe” you will miss Lyme even when confronted with direct and overwhelming evidence. Horses do contract Lyme disease; they experience a wide range of clinical signs; they can experience serious illness related to acute and chronic Lyme infection.

Lyme disease is difficult to definitively diagnose. For a diagnosis of Lyme disease there must be documented clinical signs and supportive blood test results. The blood work used to diagnose Lyme consists of two tests: an ELISA titer and a Western Blot. It is incomplete to do a titer without a Western Blot. In fact, simply doing a titer provides almost no useful information. The titer screens for the presence of antibodies in the horse’s system against tick borne disease. The Western blot will then be used to measure the specificity of those antibodies against the Borrellia bacterium. A positive titer and a Western Blot indicating strong specificity do not guarantee active Lyme disease. There must be the presence of clinical signs.

What makes diagnosis even more difficult is that a horse may be infected with the Borrellia bacterium but may simply not be showing signs clinically or serologically–at the moment in time when a physical exam is performed and when blood is pulled. It takes time, usually 6 to 8 weeks, for the blood tests (titer and Western Blood) to register the horse’s immune response to the Borrellia bacterium–or to register a response to treatment. In cases where a traditional titer and Western Blot are inadequate to diagnose Lyme, a test called a PCR test can be performed. However this test requires a biopsy of the tissue inside a horse’s joint and is an invasive procedure not typically performed on the farm. Similar to how a horse’s serological response can lag infection, a horse’s physical clinical signs can also lag in response to initial infection–and in response to treatment.

If your horse has been diagnosed by a veterinarian with Lyme disease, what are the treatment options? Traditionally, there are three treatments to combat the Borrellia organism: Oxytetracycline, Doxycycline, or Ceftiofur (Naxcel). In some sense all of these options are a form of the same thing: an antibiotic treatment against a bacterium. These three treatments, though, do have varying degrees of effectiveness as well as other pluses and minuses. Studies have been done, specifically at Cornell University, showing that a once a day intravenous administration of Oxytetracycline most effectively clears the Borrellia organism. Intravenous Oxytetracycline administration is typically done for 21 days; the treatment is done by a veterinarian, typically in a clinic environment. Twice a day oral administration of Doxycycline tablets is done for a prolonged period–for as long as 6-8 weeks or longer. Oral Doxycycline administration involves a high dose of antibiotics and can be done by the horse owner as part of daily feedings. Oral Doxycycline is typically less effective at clearing the Borrellia infection; effectiveness can also vary dramatically from horse to horse due to differences in absorption of the medication by the horse. Ceftiofur (Naxcel) is an intramuscular medication administered twice a day. Horse owners usually feel comfortable giving this medication themselves. However, Ceftiofur has not been proven more effective than Doxycycline tablets and it is significantly more expensive than either Oxytetracycline or Doxycycline. For these reasons it is typically not preferred over the other options.

A few last points about Lyme disease:

While the treatment and diagnosis of Lyme disease makes for interesting conversation, prevention of Lyme disease is more important. As a horse owner, you should carefully observe and examine your horse daily, looking for signs or the presence of ticks. Look into sprays and “spot-ons” that help with deterring the attachment of ticks.

Get your horse tested for the Borrellia organism (the ELISA titer and Western Blot) every 6-12 months, even in the absence of clinical signs or evidence of tick attachment. Such testing will establish baseline levels for your horse and will make diagnosis and treatment easier if Lyme disease is ever suspected in the future.

There is no vaccine for Lyme disease in horses.

Understanding Lyme disease can be difficult. It can present in confounding ways and its treatment is not always straightforward. Contact me at dr@egglestonequine.com with your questions about Lyme disease and about how the above picture relates to your horse.

Aimee M. Eggleston, DVM