Equis ISSN 2398-2977

Mammary gland: mastitis

Contributor(s): William Ley, Nicola Menzies-Gow, Graham Munroe, Elaine Watson

Introduction

  • Mastitis is relatively rare in mares; most prevalent during lactation.
  • Cause: bacterial; Streptococcus spp most commonly isolated.
  • Signs: mammary swelling, local heat and pain, ventral edema, hindlimb lameness, pyrexia.
  • Diagnosis: cytology and microbiology of milk samples.
  • Treatment: frequent milking, hot packs or hydrotherapy, systemic and/or local antibiotics.
  • Prognosis: good.

Pathogenesis

Etiology

Predisposing factors

General
  • Lactation.
  • Recent weaning of foal.
  • Death of suckling foal.
  • Non-lactating mare.
  • Trauma to teat(s) or udder.
  • Insect feeding.

Pathophysiology

  • Lactating mares probably infected via the teat canal.
  • Non-lactating mares infected via teat orifice secondary to trauma or insect feeding.
  • Neonatal cases are also infrequently encountered.
  • Infection may occur in lactating or non-lactating mares.
  • Infection after weaning or death of foal may be due to accumulation of milk in udder.
  • Trauma or biting insects may allow entry of infectious organisms.
  • Chronic mastitis may persist in non-lactating mares   →   develop into clinical mastitis when lactation resumes.
  • Low incidence of mastitis in mares ascribed to:
    • Small size and concealed position of udder.
    • Frequent emptying of udder.
    • Rarely milked by hand or machine   →   reduced trauma.
    • Endocrine environment or local immunity may provide resistance to infection.

Timecourse

  • Usually acute onset.
  • Chronic, mild or subclinical cases also occur.

Epidemiology

  • Occurs in lactating and non-lactating mares.
  • Low incidence of mastitis compared with other species.
  • An insect vector has been suggested.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references fromPubMedandVetMedResource.
  • McGladdery A J (1998)Differential diagnosis and treatment of diseases of the equine mammary gland.Equine Vet Educ10(5), 266-268VetMedResource.
  • Perkins N R & Threlfall W R (1993)Mastitis in the mare.Equine Vet Educ5(4), 192-195VetMedResource.
  • Walker R Let al(1993)Coccidioides immitis mastitis in mares.J Vet Diagn Invest5(3), 446-448PubMed.
  • McCue P M & Wilson W D (1989)Equine mastitis - a review of 28 cases.Equine Vet J21(5), 351-353PubMed.
  • Jackson P G G C (1986)Equine mastitis - comparative lesions.Equine Vet J18(2), 88-89PubMed.
  • Roberts M C (1986)Pseudomonas aeruginosamastitis in a dry non-pregnant pony mare.Equine Vet J18(2), 146-147PubMed.


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