Getting Away: Rocky Mountain Spotted Fever

After working the last five weekends, I had plans to go to Boothbay Harbor this month for a three day weekend. I am a card-carrying workaholic that probably comes from being raised on a hog, chicken, and tobacco farm. My husband and I took a plane to Boston, and then drove to the Boothbay Harbor area of Maine.

My plans were to read a good summer ibook (Jet Set), visit the Coastal Maine Botanical Gardens, take a boat ride, and have a few lobster rolls. Let me say, “Mission Accomplished!" It was a fabulous time. From the first Lobster roll in Portland to the huge Delphinium flowers in the garden, observing the lobster boats at work in the bay to discovering the Eagle nest, and simply watching a sunset; I realized how blessed I was to have this opportunity. 

On the Saturday boat ride, besides the obvious wildlife, we saw the summer home of Margaret Hamilton, otherwise known as the Wicked Witch of the West in the Wizard of Oz. We learned she was only in the film 13 minutes, made $8,000 for her eight weeks of work, received no residual payments,  and almost died  from burns in the scene where she disappeared into the smoke (ignited copper in her green face makeup). In addition, she was  both a Sunday school teacher and the voice of Cora in the Maxwell House coffee commercials.

One glaring emphasis in this outdoors-centered community mentioned in all the travel books was “watch for ticks.".  Even in going that far north, the reality is that vector-borne diseases (diseases carried by ticks, fleas, mosquitoes, lice, etc.) are widespread. With that thought, I delve into the topic of one timely tick talk: Rocky Mountain Spotted Fever.

WHAT IS ROCKY MOUNTAIN SPOTTED FEVER? 

It is an acute, tick-borne bacterial infection (rickettsia) that both people and animals can get. It is most common between the months of April and October. In reality, the name is a misnomer as the Southeastern United States has reported a high infection rate in previous years. 

WHAT ARE THE CLINICAL SIGNS?

The clinical presentation is acute and 

vague: depression, joint pain, fever, appetite decreased, vomiting, cough, and often red eyes. Often a tick bite is the mitigating factor; however, not all owners can recall a lapse in tick prevention administration/application.

Juno, owned by Tom and Karan Moore

HOW IS IT SPREAD?

 It is not spread from dogs to owners or dog to dog. Rather the common denominator is ticks exposure in the area. Interestingly, it is now felt that a tick bite can transmit more than one disease at a time (ex. Ehrlichiosis). It has NOT been reported in cats. 

WHAT IS THE INCUBATION PERIOD? How long does the tick have to be attached to transmit this disease?

Two to 14 days is the average period between a tick bite and the manifestation of clinical signs.  At least five to 20 hours is the reported time between a tick attachment and transmission of disease. RMSF is not a chronic disease; patients either die or get over it within 21 days. 

WHAT IS THE NAME OF THE TICK AND THE BACTERIUM TRANSMITTED? WHAT CAUSES THE RASH IN ROCKY MOUNTAIN SPOTTED FEVER?

Dermacentor variabilis  is the American Dog tick in the eastern United States that carries the disease, and the bacterium is Rickettsia rickettsii. As the bacterium replicates in the lining of blood vessels of victims, it creates little holes that bleed, thus the rash as noted in RMSF is actually mini bruises. Owners will not see that in their dogs except on rare occasions; rather, it is more common with people. 

SIGNS APPEAR VAGUE, WHAT TESTING IS RECOMMENDED?

Complete blood count, chemistries, RMSF paired titers of serum collected two to three weeks apart (watch for a four fold increase in the antibody level). Titers may remain high for months to years.  Some hints of infection include low blood platelets, low protein, rising kidney values, lower calcium, and rising liver values. Note that some patients may have none of these abnormalities in the early stages. PCR testing is now available to detect the RMSF bacterium particles in the blood. It is important to test dogs with vague signs for RMSF, as once infected, and documented as such, it is reported a dog will never get the disease again (long lasting immunity).  Also it is fair warning to owners as their risk of infection is increased by exposure to that same environment and people do not use monthly tick control. 

HOW IS IT TREATED?

 It is most commonly treated with antibiotics such as Doxycycline, Minocycline, Enrofloxacin, and Chloramphenicol. Dogs most commonly treated with Doxycycline clearly respond within two to six days.

WHY DO PATIENTS DIE WITH RMSF?

Left untreated, the mini bleeds of the vessels lead to organ failure of the brain, kidney, and heart. 

HOW CAN IT BE PREVENTED IN DOGS?

Use good, effective, and consistent tick control while avoiding those environments infected with ticks. While no preventative is 100% effective, it is remains the forefront of lowering the risk of tick related illness. 

Betsy Sigmon DVM, Diplomate ABVP canine and feline

Hospital Director, Creature Comforts Animal Hospital

Remi owned by Jared B.Day