Canine, feline, and equine corneal vascular neoplasia: A retrospective study (2007-2015)

Novel ocular immunotherapy induces tumor regression in an equine model of ocular surface squamous neoplasia

Ocular surface squamous neoplasia (OSSN) is the major cause of corneal cancer in man and horses worldwide, and the prevalence of OSSN is increasing due to greater UVB exposure globally. Currently, there are no approved treatments for OSSN in either species, and most patients are managed with surgical excision or off-label treatment with locally injected interferon alpha, or topically applied cytotoxic drugs such as mitomycin C. A more broadly effective and readily applied immunotherapy could exert a significant impact on management of OSSN worldwide. We therefore evaluated the effectiveness of a liposomal TLR complex (LTC) immunotherapy, which previously demonstrated strong antiviral activity in multiple animal models following mucosal application, for ocular antitumor activity in a horse spontaneous OSSN model. In vitro studies demonstrated strong activation of interferon responses in horse leukocytes by LTC and suppression of OSSN cell growth and migration. In a trial of 8 horses (9 eyes), treatment with topical or perilesional LTC resulted in an overall tumor response rate of 67%, including durable regression of large OSSN tumors. Repeated treatment with LTC ocular immunotherapy was also very well tolerated clinically. We conclude therefore that ocular immunotherapy with LTC warrants further investigation as a novel approach to management of OSSN in humans.

Corneal Surgery in the Cat: Diseases, considerations and techniques

PRACTICAL RELEVANCE

The ability to recognize, diagnose and treat corneal disease is essential for maintaining vision and comfort in feline patients. Being able to correctly identify appropriate techniques for surgical cases is of particular importance for success when performing corneal surgery.

CLINICAL CHALLENGES

Many different corneal diseases present with similar clinical signs, and it can be hard to determine the appropriate treatment for individual patients. It is essential for the clinician to understand the indications for corneal surgery, instrumentation needed and microsurgical principles prior to attempting these procedures. The prognosis following surgery and potential complications should be discussed with the client.

AUDIENCE

This review article aims to assist in decision-making and to provide detailed guidance for primary care clinicians considering referral of cats for corneal surgery. The review outlines common feline corneal diseases and associated surgical therapies performed by veterinary ophthalmologists, highlighting appropriate instrumentation and case selection. Some surgeries are explained in depth for ophthalmologists and residents in training.

EQUIPMENT

Although some procedures may be performed with common surgical equipment and supplies, most require specialized ophthalmic instrumentation and expertise, which entails significant microsurgical training and practice, as well as financial investment. Most of the procedures require an operating microscope for the best surgical outcomes; however, surgical loupes may be sufficient in some cases. Evidence base: This review article compiles information from many published references on feline corneal diseases and surgeries, complemented by the experience of the authors.

Retrospective evaluation of canine primary, multicentric, and metastatic intraocular neoplasia

OBJECTIVE

To provide an updated characterization of the prevalence of primary, multicentric, and metastatic intraocular tumors in the canine patient.

PROCEDURES

Medical records databases from 4 veterinary referral hospitals were reviewed from 1999 to present to identify dogs with a diagnosis of intraocular neoplasia histopathologically confirmed following enucleation or necropsy.

RESULTS

One hundred seventy-two dogs with 173 intraocular neoplasms met the inclusion criteria. Primary intraocular neoplasms were the most common tumors in the study (128); the two most common types were melanocytic neoplasia (90), followed by iridociliary neoplasia (33). There were 28 cases of intraocular involvement secondary to round cell neoplasia, with 18 cases of lymphoma, seven histiocytic sarcomas, and three undifferentiated round cell neoplasms. There were 17 cases of metastatic intraocular neoplasia, with hemangiosarcoma being the most common (9).

CONCLUSIONS

The majority of intraocular tumors in dogs arise from the ocular tissues. However, the eye may also be involved in patients with multicentric neoplasia, and, less commonly, as a site for metastatic disease. Ocular screening for patients with multicentric neoplasia should be considered during staging, and ocular signs should be viewed with suspicion in dogs with neoplasia in other sites.

Surgical treatment of conjunctival hemangioma and hemangiosarcoma: A retrospective study of 52 dogs

OBJECTIVE

To review cases of canine conjunctival hemangioma (HA) and hemangiosarcoma (HSA) treated surgically at a referral center to establish success of surgical management, recurrence rates, and long-term outcomes for patients.

ANIMALS STUDIED

Retrospective record review of dogs that underwent surgery to remove histologically diagnosed conjunctival HA or HSA between April 2004 and April 2020 to collect data on signalment, tumor location, interval between initial presentation and surgery, tumor diagnosis, surgical dose, surgical margins, tumor size, recurrence and survival times.

RESULTS

A total of 52 dogs (60 tumors) were included. The mean age of affected dogs was 8.69 years; the most affected breed was the Border collie (n = 13, 25%). 28 tumors were HA (46.67%) and 32 HSA (53.33%). Tumors occurred in three locations: the lateral bulbar conjunctiva (n = 37, 61.67%), the third eyelid margin (n = 19, 31.67%), and the ventral conjunctival fornix (n = 4, 6.67%). There was no site predilection for HA versus HSA. 97% of tumors occurred in non-pigmented tissue. Corneal invasion was more likely to be a feature of malignant tumors. Five tumors were incompletely excised, one of which recurred. There was no statistical difference in likelihood of incomplete excision between HSA and HA. Six tumors (10%) recurred. HSA was not statistically more likely to recur than HA. Recurrence times ranged from 5 weeks to 1 year.

CONCLUSION

Surgical treatment of conjunctival HA and HSA is likely to be curative. There is a recurrence rate of 10% regardless of tumor type, and recurrence may be late in the course of the disease.

Endothelial cells and angiogenesis in the horse in health and disease-A review

The cardiovascular system is the first functional organ in the embryo, and its blood vessels form a widespread conductive network within the organism. Blood vessels develop de novo, by the differentiation of endothelial progenitor cells (vasculogenesis) or by angiogenesis, which is the formation of new blood vessels from existing ones. This review presents an overview of the current knowledge on physiological and pathological angiogenesis in the horse including studies on equine endothelial cells. Principal study fields in equine angiogenesis research were identified: equine endothelial progenitor cells; equine endothelial cells and angiogenesis (heterogeneity, markers and assessment); endothelial regulatory molecules in equine angiogenesis; angiogenesis research in equine reproduction (ovary, uterus, placenta and conceptus, testis); angiogenesis research in pathological conditions (tumours, ocular pathologies, equine wound healing, musculoskeletal system and laminitis). The review also includes a table that summarizes in vitro studies on equine endothelial cells, either describing the isolation procedure or using previously isolated endothelial cells. A particular challenge of the review was that results published are fragmentary and sometimes even contradictory, raising more questions than they answer. In conclusion, angiogenesis is a major factor in several diseases frequently occurring in horses, but relatively few studies focus on angiogenesis in the horse. The challenge for the future is therefore to continue exploring new therapeutic angiogenesis strategies for horses to fill in the missing pieces of the puzzle.