Mammary hyperplasia
Introduction
- Cause: benign but potentially clinically significant proliferation of fibroglandular mammary tissue due to increased progesterone or estrogens.
- Signs: mammary swelling, pain, can progress to ulceration, excoriation and necrosis.
- Diagnosis: clinical signs and history.
- Treatment: symptomatic, withdraw exogenous therapy if present, administration of antiprogestins or antiprolactins as indicated and as available.
- Prognosis: guarded to good - often resolve spontaneously. Ovariohysterectomy or ovariectomy will prevent future episodes if endogenous progesterone/estrogen causal.
Presenting signs
- Firm, non-painful mammary swelling in a non-lactating individual.
- May be bilateral, multiple or solitary.
- Evidence of inflammation if swelling is dramatic.
- Brown fluid may be expressed.
- Excoriation, necrosis of tissue in severe cases.
Age predisposition
- Young 2-5 years (range 3 months - 10 years).
- Any age if exogenous progestins administered.
Pathogenesis
Etiology
- Reaction to exogenous prostagens
- Megestrol acetate Megestrol acetate.
- Medoxyprogesterone acetate Medroxyprogesterone.
- Inadvertent exposure to human transdermal products.
- Abnormal response to endogenous progesterone
- Post-estrus.
- Pregnancy Pregnancy / gestation.
- Pseudopregnancy Pseudopregnancy.
- Ovarian pathology: luteal ovarian cysts or luteoma.
- Rarely progesterone precursors.
Predisposing factors
General
- Diestrus.
- Exogenous progestogen administration.
Specific
- Hormonal dependent non-neoplastic proliferation of ductal epithelium and stroma.
- Increased response to endogenous progesterone or reaction to exogenous progestagens.
- May → direct action on progesterone receptors in mammary gland.
- Possible indirect action via alteration of action of other hormones, eg estrogen, glucocorticoids or growth hormone.
Pathophysiology
- Benign proliferation of fibroglandular (typically young postestrus queens) or ductal tissue (progestogen therapy).
Timecourse
- Days to weeks.
- Common onset:
- 2-4 weeks after estrus.
- First month of pregnancy.
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 from PubMed and VetMedResource.
- Jurka P, Max A (2009) Treatment of fibroadenomatosis in 14 cats with aglepristone - changes in blood parameters and follow-up. Vet Rec 165 (22), 657-660 PubMed.
- Görlinger S, Koostra H S, van den Broek A et al (2002) Treatment of fibroadenomatous hyperplasia in cats with aglépristone. JVIM 16 (6), 710-713 PubMed.
- Wehrend A, Hospes R & Gruber A D (2001) Treatment of feline mammary fibroadenomatous hyperplasia with a progesterone-antagonist. Vet Rec 148 (11), 346-347 PubMed.
- Center S A, Randolph J F (1985) Lactation and spontaneous remission of feline mammary hyperplasia following pregnancy. JAAHA 21 (1), 56-8 VetMedResource.
- Dorn D R, Legendre A M, McGavin M D (1983) Mammary hyperplasia in a male cat receiving progesterone. JAVMA 182 (6), 621-2 PubMed.
- Hayden D W, Johnston S D, Kiang D T et al (1981) Feline mammary hypertrophy/fibroadenoma complex - clinical and hormonal aspects. Am J Vet Res 42 (10), 1699-1703 PubMed.
- Seiler R J, Kelly W R, Menrath V H et al (1979) Total fibroadenomatous change of the mammary glands of two spayed cats. Feline Pract 9 (2), 25 VetMedResource.
Other sources of information
- Hayden D W & Johnston K H (1986) Feline mammary hypertrophy - fibroadenomatous complex. pp 477-480. In: Kirk (Ed) Current Vet Therapy IX. WB Saunders, Philadelphia.