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  Discussion on ? resistant to lyme treatment
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New Member:
dearborn

Posted on Saturday, Sep 19, 2009 - 4:11 pm:

My 10 year old 1/2 arab/quarter horse mare originally had an Elisa titer of 280's about 2 years ago. The vet at the time felt her hocks were the actual problem and both back were injected with no problems. She began improving and had no problems again until this year. She first experienced stiffness coming out of the corners progressing to a kind of bobbing gait. Her lyme titer at that time was 360(elisa). She began doxy and initially DrOpped,then leveled off and went back up . At the end of 3 months on doxy her titer remained 330's on 40 100 mg tablets b.i.d.. At that time her gait had improved dramatically so the decision was made to stop the doxy and see. Two weeks later she began with the stiffness thru corners.At that time we decided to try the I.V. oxytet.After 1 month of iv therapy her titer is 302 and gait coming out of corners is stiff. My vet is at a loss and I am desperate to find a therapy that will help. Do we go back on orals? Increase dosage? She is a lovely mare and I feel I am failing her.
Moderator:
DrO

Posted on Sunday, Sep 20, 2009 - 10:24 am:

Welcome Shannon,
Though you did not ask I would first like to discuss the possibility that despite a titer to the Lyme organism that this may not be the cause of your horses lameness. I wrote the words below in 1999 and now 10 years later and despite intensive efforts to find it, there still is no clear evidence this organism causes persistent disease in horses:
Lyme disease in horses is a controversial subject. Lyme disease is caused by the organism Borrelia burgdorferi. It is transmitted to mammals by ticks. If use to be thought that only the deer tick was responsible but the organism may be transmitted by other types of ticks.

We know horses can become infected with this microbe. Both experimental infection and serum antibodies to this organism in endemic areas have been found. The controversy is over what type disease, if any at all, is caused by Borrelia in horses. When horses where experimentally infected the organism reproduced in the blood, settled in the kidneys, and was excreted out the urine for several weeks, until the horse cleared became seropositive and cleared the organism from their body. The problem is horses that have been experimentally infected showed no signs of illness during the acute and recovery phases. Also many horses with high titers to the organism had no past history of infection.

In other species, I believe, Borrelia has been shown to cause recurrent fevers, polyarthritis, muscle soreness, and neurological disease. In horses from endemic areas veterinarians feel they see the same constellation of symptoms that are responsive to tetracycline, the best choice of antibiotic for this infection. There have been some surveys to suggest a higher seroprevalence in horses having some of the signs of Lyme disease, some have not found a relationship.

So do horses get sick from Lyme disease? Possibly, but there is no proof yet and a lot of work that suggest the vast majority of the horses exposed get infected but show no signs of the infection.

Currently, it is recommended that horses suspected of this infection have paired serum samples run 14 days apart while being treated for it. A significant rise during the infection and treatment phase is strong evidence of disease due to infection with Borrelia. A high titer alone is common in healthy horses in endemic areas.


I would like to add that the fairly potent antiinflammatory activity of the tetracyclines alone can make it seem as though the treatment of the organism is helping. However you didn't ask about the diagnosis of Lyme related lameness and if you believe this is the problem clearly the IV tetracycline is the most effective treatment.

Vet Microbiol. 2005 May 20;107(3-4):285-94. Antibiotic treatment of experimentally Borrelia burgdorferi-infected ponies.

Chang YF, Ku YW, Chang CF, Chang CD, McDonough SP, Divers T, Pough M, Torres A.
College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. yc42@cornell.edu

The objective of this study is to determine whether doxycycline, ceftiofur or tetracycline could be effectively used to treat equine Lyme disease. Ponies experimentally infected with Borrelia burgdorferi by tick exposure were treated with doxycycline, ceftiofur or tetracycline for 4 weeks (28 days). Doxycyline and ceftiofur treatment were inconsistent in eliminating persistent infection in this experimental model. However, tetracycline treatment seems to eliminate persistent infection. Although serum antibody levels to B. burgdorferi in all ponies declined gradually after antibiotic treatment, three out of four ponies treated with doxycline and two out of four ponies treated with ceftiofur, serum KELA titers were raised again 3 month after treatment was discontinued. Five months after antibiotic treatment, tissues aseptically collected at necropsy from ponies with increased antibody levels after antibiotic treatment also showed culture positive to B. burgdorferi in various post-mortem tissues. However, all four-tetracycline treatment ponies showed a negative antibody level and culture negative from post-mortem tissues. Untreated infected ponies maintained high KELA titers throughout the study and were tissue culture positive.


DrO
New Member:
dearborn

Posted on Sunday, Sep 20, 2009 - 10:45 am:

Thank you! Your answer gives me some hope. Can you tell me about lyme related lameness? She is not consistently lame thru corners or after at present and better if kept framed up. My trainer is feeling it most in her right shoulder.
Moderator:
DrO

Posted on Monday, Sep 21, 2009 - 8:31 am:

shannon, the current state of Lyme diagnosis is "a undiagnosed lameness in a horse with a titer to the Lyme organism". I have seen and heard of many different lameness presentations that were attributed to Lyme disease.

Rereading your initial post, I noted that the titer you give is less than the one before you started the tetracycline. It does not come down quickly, but slowly declines following treatment. If the titer starts to go back up following treatment you should consider the idea that your horse has been reexposed to the organism after treatment.
DrO
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