Penile spines are small, backward-pointing keratinised papillae on the glans of the sexually mature tom. They matter for two reasons: they are a visible marker of circulating androgens, and they provide the vaginal stimulus that triggers ovulation in the induced-ovulating queen.
Key facts
Penile spines at a glance- Species and system: cat, reproductive (male anatomy plus queen physiology).
- Structure: connective tissue core covered by cornified stratified epithelium, 0.1 to 0.7 mm long, covering about two-thirds of the glans; the tip stays smooth.
- Control: androgen dependent. They appear after puberty, regress within 5 to 6 weeks after castration and return if testosterone is given.
- Function: point caudally, so they rake the vagina during penile withdrawal and trigger the LH surge and ovulation.
- Clinical use: spines in a "castrated" tom mean an androgen source is still present.
What's inside
13 sections in the full guide- Key facts
- How the NAVLE tests this
- Anatomy
- Hormonal control and timeline
- Role in induced ovulation
- Clinical use: castrated or still producing androgen?
- Don't confuse these
- Examination technique and common pitfalls
- How a positive finding is followed up
- Why induced ovulation matters in practice
- Quick review
- Test yourself
- References
The full guide also has 4 tables, 3 self-test questions and 4 references, available to NAVLE members.
Read the full study guide
The full guide is part of every NAVLE plan, with diagnosis and treatment tables, figures, a quick review and self-test questions. Start a free trial to try the question bank, or log in if you are already a member.