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Definition

The development of serious local swelling due to excessive oedema formation at the site of cryosurgery

Risk factors

 Tumoral masses with a (very) large base

 Dependant antomical locations (ventral abdomen, chest, prepuce, etc.)

Pathogenesis

Local edema develops almost immediately after thawing (Figures 11.2a, b) and results from the vascular damage in the frozen tissue. It augments in the next 24–48 hours with subsequent gradual resolution over the following days (up to 1 week) [13]. This is more obvious in dependant anatomical locations more prone to develop edema such as ventral abdomen, ventral chest, prepuce or distal limbs. Cryosurgery of limbal squamous cell carcinomas also results in some corneal edema and corneo‐conjunctival inflammation [5]. This is considered to be normal.

When treating very large tumors, the amount of tissue necrosis after freezing can be very extensive, resulting in excessive local swelling and associated pain. In some cases, local infections or lymfangitis may develop [13, 14].

Ocular pain evident as blepharospasm and/or miosis has been observed in 4 out of 10 horses treated with cryosurgery for limbal squamous cell carcinomas [5].

Diagnosis and monitoring

Obvious oedematous swelling at the site of cryosurgery

Figure 11.2 Equine sarcoid on the medial aspect of the right elbow of a horse before (a) and after (b) cryosurgery using a liquid nitrogen circulation probe. The tumor has been debulked at the base and 1 freeze‐thaw cycle has already been applied resulting in pronounced edema, which will even increase after the second freeze‐thaw cycle. This is not a complication but a normal biological response after cryosurgery. Note the thermocouple needles inserted at the periphery of the lesion to ensure a sufficiently low temperature.

Source: Ann Martens.

Prevention

Application of a compressive bandage immediately after cryosurgery will limit the development of oedema. This is recommended for cryosurgery of large masses at the level of the distal limbs but is technically challenging or impossible at other locations (e.g. axilla, prepuce, inguinal region, chest, etc.).

Treatment

Excessive local swelling and pain can be managed by strong analgesic and anti‐inflammatory medication and the application of bandages at the distal limbs.

Management of excessive ocular pain includes non‐steroidal anti‐inflammatory medication and topical application of 1% atropine [5].

Expected outcome

The oedema commonly resolves in 1 to 2 weeks.