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Testicular hypoplasia
Synonym(s): Testicle, congenital
Introduction
- Cause: lack of development of the spermatogenic epithelium in utero.
- Signs: the presence of one or two small testes.
- Diagnosis: physical examination of the testes after puberty.
- Prognosis: testicular hypoplasia can result in permanent reduced fertility or infertility.
Age predisposition
- Although congenital in origin, presentation may not be recognized until puberty.
Breed/Species predisposition
- In the Swedish Highland breed, testicular hypoplasia has been demonstrated to be a heritable defect caused by a recessive gene with incomplete penetrance.
- Testicular hypoplasia may be seen in other breeds as a consequence of XXY trisomy.
Cost considerations
- May be associated with complete loss of use for breeding bulls, which may represent significant value in pedigree animals.
- Costs of veterinary investigation and other professional fees such as legal and insurance with loss of use claims.
- Costs to commercial herds as a consequence of poor reproductive performance; failure to successfully achieve pregnancies may be associated with significant financial loss in cattle herds, especially with tight seasonal calving patterns.
Pathogenesis
Etiology
- Lack of development of the spermatogenic epithelium.
- Chromosomal abnormalities may interrupt meiosis.
- Reduced fertility in bulls carrying a 1/29 Robertsonian translocation has been reported and bulls with 61 XXY chromosomes are completely sterile.
- It is theoretically possible that toxic agents such as such as heavy metals, pesticides, pharmaceuticals & hormones or infectious agents such as BVD virus BVD virus BVD disease affecting the dam at a critical stage of organogenesis of the testes could also cause bilateral TH.
Pathophysiology
- Failure of development of seminiferous tubules and interstitial cells.
Timecourse
- Congenital presentation, but may not be apparent until puberty.
Epidemiology
- Risks based on genetics and individual herd level environmental exposure to toxic insults.
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.
- Statham, J M E (2010) Differential diagnosis of scrotal enlargement in bulls. In Practice 32, 2-9.
- Penny C (2009) The development of a UK bull breeding soundness evaluation certificate. Cattle Practice 17, 64-70.
- Eppink E (2006) A survey of bull breeding soundness evaluations in the south east of Scotland. Cattle Practice 13, 205-209.
- Penny C (2005) Practical semen collection and examination techniques for breeding soundness evaluation of bulls. Cattle Practice 13, 199-204.
- McGowan M (2004) Approach to conducting bull breeding soundness evaluations. In Practice 26, 485-491.
- Logue D N, Harvey M J A & Lennox B (1979) Hormonal and histological studies in a 61 XXY bull. Vet Rec 104, 500-503.
- Logue D N & Harvey M J A (1978) Meiosis and spermatogenesis in bulls heterozygous for a presumptive 1/29 Robertsonian translocation. J Reprod Fert 54, 159-165.
Other sources of information
- Aiello S E & Moses M A (2016) Reproductive System. In: Merck Veterinary Manual. 11th edn. Kenilworth, USA. pp 1321-1408.
- Chenoweth P (2015) Bull Health and Breeding Soundness. In: Bovine Medicine. 3rd edn. Wiley-Blackwell Publishing, UK. pp 246-261.
- Logue D N & Crawshaw W M (2004) Bull infertility. In: Bovine Medicine – Diseases and Husbandry of Cattle, 2nd edn. Wiley-Blackwell Publishing, UK. pp 594-626.
- Entwistle K & Fordyce G (2003) Evaluating and reporting bull fertility. Australian Association of Cattle Veterinarians, Brisbane, Australia.