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Masculinizing Sex Hormone Deficiency in Dogs

Hypoandrogenism in Dogs

Hypoandrogenism, a condition characterized by the deficiency of masculinizing sex hormones like testosterone and its derivatives, affects dogs. These hormones, known as androgens, are produced by the adrenal cortex, located above each kidney, as well as by the testes in males and ovaries in females. The condition presents in two forms: primary and secondary.

Primary hypoandrogenism is rare in males and is often marked by symmetrical hair loss, particularly in older castrated male dogs such as the Afghan hound. It can be associated with testicular damage stemming from inflammatory testicular disease, although this typically manifests as a lack of libido and spermatogenesis without other clinical signs. While primary hypoandrogenism can occur in females, it is uncommon.

On the other hand, secondary hypoandrogenism is more prevalent and is caused by conditions like hyperadrenocorticism (an endocrine disorder) and hypothyroidism. It is typically observed in older animals, though congenital forms also exist. Symptoms may appear during puberty and may manifest as behavioral or anatomical abnormalities.

Symptoms and Types

  • Absence of reproductive cycling
  • Reduced libido
  • Dry, lackluster coat
  • Changes in coat color
  • Underdeveloped, small testes
  • Diminished semen quality
  • Infertility
  • Incontinence
  • Stunted body growth, resulting in a smaller size compared to breed norms
  • Male dogs exhibiting squatting behavior rather than raising a leg to urinate


  • Use of steroid compounds
  • Degeneration of the testicles
  • Surgical castration
  • Pituitary tumors
  • Failure of testes to descend (cryptorchidism)
  • Additionally, Boston terriers have a predisposition to hypoandrogenism. It is believed that low fetal androgen production contributes to the occurrence of hypospadias, a male urethral birth defect.


Your veterinarian will conduct a comprehensive blood profile, including a chemical blood profile, complete blood count, and urinalysis, along with additional tests to pinpoint the underlying cause, such as hypothyroidism. Evaluating thyroid function will be crucial. The physical examination and medical history you provide will also aid in diagnosis. A detailed history of your dog’s health, symptom onset, and any relevant incidents will be necessary. In cases of hair loss, a skin biopsy may be performed, while a testicular biopsy can help identify inflammatory testicular disease.


The course of treatment will vary based on the underlying cause, but your veterinarian may consider hormone replacement therapy to assess whether it elevates androgen levels.

Living and Management

Your veterinarian will request that you monitor any responses to the prescribed therapy and will schedule follow-up appointments to conduct periodic tests, assessing clinical signs to ensure the effectiveness of the treatment plan.


If you intend to use your dog for breeding, it’s important to steer clear of medications known to induce hypoandrogenism, such as steroid compounds.

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