Aggressive hoof cancer successfully treated in 20-year-old mare

Veterinarians in Italy have successfully used electrochemotherapy in combination with surgery to successfully treat an aggressive cancer in a mare’s hind hoof.

Electrochemotherapy is a way of getting chemotherapy agents into cancer cells. Following introduction of the drug, electric pulses are used to get the agent into the cancer cells. The pulses change the outer layer of the cancer cells, which makes it easier for the chemical to enter them.

In humans, it is most commonly used to treat skin tumors.

The mare in question was a 20-year-old saddle horse who was referred to an equine hospital for evaluation of a non-healing erosive lesion in her right hind hoof. It had persisted for seven months and was accompanied by bleeding in the underlying soft tissues.

The lesion had been twice surgically treated as a canker but rapidly recurred.

Microscopic examination following its removal the second time revealed a squamous cell carcinoma.

The mare was mildly depressed, lame, and was partially non-weight-bearing on the affected leg, where the growing 10cm-by-10cm ulcerative lesion was remodeling the hoof.

Enrico Pierluigi Spugnini, Carlo Bolaffio, Licia Scacco and Alfonso Baldi, in a case report in the Open Veterinary Journal, described their approach, tackling the cancer with surgery combined with the use of electrochemotherapy in the area during the operation.

The chemotherapy drug bleomycin was used with the electrochemotherapy in the lower limb.

A second session of surgery and electrochemotherapy was performed a month later, followed by three additional monthly sessions of electrochemotherapy.

The mare showed continuous improvement.

One year after presentation, the mare was assessed as being in complete remission and her gait had markedly improved.

The authors reported that the electrochemotherapy was well-tolerated and resulted in improved local control of a tumor in what they described as a challenging anatomical district.

The researchers said squamous cell carcinoma of the equine hoof was rarely reported, with the scant scientific reports suggesting the outcome was generally unfavorable due to the tumor location and clinical aggressiveness.

The study team noted that electrochemotherapy had been successfully employed to increase the effectiveness of chemotherapy in cats affected by squamous cell carcinoma.

“Our group has been able to successfully treat malignant equine neoplasms,” they noted.

A major issue that needed to be addressed in treating hoof cancers was how to deliver the drug to the area, considering the lack of soft tissue. They opted to resort to isolated lower limb perfusion using bleomycin for its reported higher effectiveness against squamous cell carcinoma in other species and its much lower toxicity compared to cisplatin.

In this case, the drug was delivered by adapting a currently used protocol for the delivery of antibiotics to lower limbs in horses.

“The present protocol controlled the advanced [cancer] in our patient and was well-tolerated in terms of local and distal toxicoses.”

Osteomyelitis – bone infection – was observed, but this was probably induced by the aggressive surgical excision as well as by the electrochemotherapy, although the exact contribution of each component could not be assessed.

“Regardless, these side effects were successfully controlled by using systemic antibiotics and nonsteroidal anti-inflammatory drugs.”

Ongoing microscopic examinations confirmed complete regression of the tumor and the resolution of the bone infection.

“In light of its high efficacy and high tolerability with good cosmetic and functional results, electrochemotherapy has been adopted at our hospital as the standard adjuvant therapy of incompletely excised solid tumors in horses.”

The study team are variously affiliated with Equivet Roma Hospital, Biopulse S.r.l., and the Department of Environmental, Biological and Pharmaceutical Sciences and Technologies at Campania University in Caserta.

Isolated limb perfusion electrochemotherapy for the treatment of an advanced squamous cell carcinoma of the hoof in a mare
Enrico Pierluigi Spugnini, Carlo Bolaffio, Licia Scacco and Alfonso Baldi
Open Veterinary Journal, (2017), Vol. 7(2): 192-196 DOI: http://dx.doi.org/10.4314/ovj.v7i2.18

The study can be read here.