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Journal of veterinary internal medicine2023; doi: 10.1111/jvim.16964

Common and atypical presentations of Anaplasma phagocytophilum infection in equids with emphasis on neurologic and muscle disease.

Abstract: Comprehensive descriptions of equids with granulocytic anaplasmosis (EGA) with neurologic or muscle disease and other atypical presentations are scarce in the literature. Objective: Describe the clinical signs, laboratory findings, treatment, and outcome of equids with EGA with emphasis on neurologic and muscle disease. Methods: Thirty-eight horses, 1 donkey. Methods: Retrospective study. Equids with EGA were included. The electronic data base was searched from January 2000 to December 2022 using the words anaplasmosis, ehrlichiosis, granulocytic, and rickettsia. Signalment and clinical data were reviewed. Data were evaluated for normality using Shapiro-Wilk test. Parametric and nonparametric statistics were used for normally and non-normally distributed data. Results: Common (41%) and other (59%) presentations were seen in horses ≥ 4 years of age (median, 14 years) with an overrepresentation of males (77%). Neurologic disease was common (41%), mainly presenting as diffuse symmetrical proprioceptive ataxia. Brain disease was less common manifesting as obtundation and cranial nerve deficits. Muscle disease was less common, with QH breeds with the variant causing myosin heavy chain myopathy (MYHM) having severe disease. Cavitary effusion, cardiomyopathy and disseminated intravascular coagulation (DIC) were uncommon. Clinical laboratory results varied depending on disease stage. Muscle enzyme activities were significantly higher in horses with muscle disease. Outcome was favorable with prompt tetracycline treatment. Death and long-term sequelae were not reported. Conclusions: Common and atypical presentations of EGA have a favorable outcome with prompt tetracycline treatment. Quarter horse breeds with muscle disease should be genotyped for MYHM.
© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.
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Publication Date: 2023-12-01 PubMed ID: 38038253DOI: 10.1111/jvim.16964Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates varying presentations of a bacterial infection, granulocytic anaplasmosis (EGA), in horses and donkeys with an emphasis on neurological and muscular diseases. The findings reveal the different symptoms, laboratory results, treatments and outcomes for EGA-infected equines, suggesting prompt treatment with tetracycline antibiotic yields favourable outcomes.

Research Methodology

This was a retrospective study conducted on 38 horses and 1 donkey with confirmed EGA. Data from January 2000 to December 2022 were extracted from an electronic database using relevant keywords. The researchers collected and analyzed information about the animals’ signs and symptoms, lab results, treatments, and outcomes. The data was tested for normality using the Shapiro-Wilk statistical test, and data distribution determined the statistical methods used.

Findings

  • EGA was found more frequently in male horses, particularly those aged four years or older, with a median age of 14 years.
  • 41% of the presentations were common, while the remaining 59% had other atypical presentations.
  • Neurologic diseases were also common and were primarily characterized by diffuse symmetrical proprioceptive ataxia, which is a loss of sense of the relative position of one’s own parts of the body and strength of effort employed in movement.
  • Brain diseases were less common, but symptoms included dulled attitudes and responsiveness and cranial nerve deficits or disorders.
  • Muscle diseases were less frequent than neurologic and brain diseases. These were particularly severe in Quarter Horse breeds with a genetic variation that causes myosin heavy chain myopathy (MYHM), a type of muscular disorder.
  • Cavitary effusion, cardiomyopathy, and disseminated intravascular coagulation (DIC), all serious conditions, were uncommon occurrences.
  • Laboratory results were dependent on the stage of illness with muscle enzyme activities significantly higher in horses with muscle disease.

Treatment and Outcome

The research found that fast treatment using the antibiotic tetracycline resulted in positive outcomes. Among the infected equids, there were no reported cases of death or long-term consequences post-treatment.

Conclusions

The study shows that varying presentations of EGA in horses and donkeys, both common and unusual, can result in a favourable prognosis with swift treatment using tetracycline. The researchers recommend genotyping Quarter Horse breeds with muscle disease for MYHM to ensure accurate diagnosis and appropriate treatment.

Cite This Article

APA
Aleman M, Vedavally U, Pusterla N, Wensley F, Berryhill E, Madigan JE. (2023). Common and atypical presentations of Anaplasma phagocytophilum infection in equids with emphasis on neurologic and muscle disease. J Vet Intern Med. https://doi.org/10.1111/jvim.16964

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English

Researcher Affiliations

Aleman, Monica
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.
Vedavally, Ujwala
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.
Pusterla, Nicola
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.
Wensley, Fiona
  • William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California, USA.
Berryhill, Emily
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.
Madigan, John E
  • Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA.

Grant Funding

  • #V435AM2 / Equine and Comparative Neurology Research Group at UCD (Aleman)

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Citations

This article has been cited 5 times.
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