How to differentiate a subcutaneous tick from ringworm in a cat? - briefly
A subcutaneous tick forms a firm, often mobile nodule that may have a central puncture or be palpable as a tick body, while ringworm produces circular, hair‑free, scaly patches with a red, raised margin. Dermoscopy can identify the tick’s mouthparts, whereas a Wood’s lamp examination or fungal culture confirms dermatophyte infection.
How to differentiate a subcutaneous tick from ringworm in a cat? - in detail
Distinguishing a hidden tick from a dermatophyte infection in a cat requires careful observation, tactile assessment, and targeted diagnostics.
A subcutaneous tick typically presents as a firm, localized nodule beneath the skin. The overlying fur may be intact, and the lesion can feel slightly raised or nodular when palpated. Occasionally a tiny puncture hole or a faint, dark spot marks the attachment site. Systemic signs such as lethargy, fever, or anemia may accompany the infestation, especially if the tick is engorged or carries pathogens.
Dermatophytosis, commonly known as ringworm, produces circular patches of hair loss with raised, scaling borders. The lesions often have a clear demarcation between affected and healthy skin, may be erythematous, and can be pruritic. In many cases the affected area is moist or crusted, and the surrounding fur appears broken or ragged.
Key steps for differentiation:
- Visual inspection – look for a discrete, raised nodule versus a spreading, circular alopecic patch.
- Palpation – feel for a solid mass under the skin; fungal lesions are usually soft and flat.
- Wood’s lamp examination – many dermatophytes fluoresce bright green under ultraviolet light; ticks do not emit fluorescence.
- Skin scraping – collect superficial scales; microscopic examination reveals fungal hyphae in ringworm, while a tick will not be present.
- Fungal culture – inoculate a sample on Sabouraud agar; growth confirms dermatophyte infection, typically within 7–14 days.
- PCR testing – molecular analysis of skin swabs can identify dermatophyte DNA; separate PCR panels detect tick-borne pathogens if systemic signs exist.
- Ultrasound – high‑frequency imaging can reveal a hypoechoic structure consistent with a tick’s body beneath the epidermis.
- Tick removal and identification – carefully extract the organism, preserve it in ethanol, and send for species confirmation.
Treatment diverges sharply. Subcutaneous ticks require mechanical removal, possible incision if the mouthparts remain embedded, and administration of antiparasitic medication (e.g., ivermectin or a topical acaricide). Ringworm demands antifungal therapy, such as oral itraconazole or topical miconazole, combined with environmental decontamination to prevent spread.
By integrating visual cues, tactile findings, and laboratory diagnostics, a veterinarian can reliably separate a concealed tick infestation from a fungal skin infection in a cat and apply the appropriate therapeutic protocol.