Sunlight-skin cancer association in the dog: a report of three cases

Heat Tolerance of Siberian Husky Dogs Living in Brazil: A Case Study on the Perceptions and Attitudes of Their Owners

The management of the thermal environment to which dogs are exposed should be included in strategies to improve their welfare. An online questionnaire was administered to 624 owners of Siberian Husky dogs residing in Brazil, with the objective of assessing their perceptions regarding their dogs' capacity to adapt to heat, and its association with the owners' routine care. Owners who believed that dogs are low-heat-tolerant animals were more likely to report heat response behaviors from their dogs. Overall, owners reported walk with their dogs during early morning, late afternoon and nighttime. They also reported solar radiation as the primary criteria for determining the time to walk with their dogs. However, owners who reported walking with their dogs at noon mentioned time availability as their primary criteria. In conclusion, owners perceive Siberian Husky dogs living in Brazil as being poorly adapted to heat, and this perception appeared to influence their positive attitudes towards protecting their dogs from heat stress by choosing to walk them during times with less solar exposure. However, the lack of time for owners to walk with their dogs during cooler periods can still be a risk factor in exposing the animals to extreme hot conditions.

Breed and anatomical predisposition for canine cutaneous neoplasia in South Africa during 2013

Cutaneous neoplasia occurs commonly in dogs and owners in consultation with their veterinarian must decide when to perform surgery to obtain a histopathological diagnosis. The objective of this study was to identify breed predispositions for canine cutaneous neoplasms and determine factors associated with malignancy. This retrospective case-series evaluated histopathology reports from two veterinary pathology laboratories in South Africa during a six-month study period. Breed predispositions were analysed using log-linear models and risk factors for malignancy were evaluated using binary logistic regression. Data were available for 2553 cutaneous neoplasms from 2271 dogs. The most frequent neoplasms were mast cell tumours (21.1per cent), histiocytoma (9.4per cent), haemangiosarcoma (8.3per cent), melanocytoma (5.8per cent) and lipoma (5.1per cent). Boxers (relative proportion (RP)=38.9; 95% CI 2.3 to 646), pugs (7.6; 1.4 to 41.0), Staffordshire bull terriers (7.0; 1.9 to 26.3), boerboels (3.8; 1.3 to 10.7), Labrador retrievers (2.7; 1.0 to 7.0) and mixed breed dogs (2.2; 1.1 to 4.4) had a higher frequency of mast cell tumours. Jack Russell terriers (OR=2.5; 95% CI 1.8 to 3.5), Rottweilers (2.3; 1.3 to 3.9), pit bull terriers (2.2; 1.1 to 4.3) and Staffordshire bull terriers (1.6; 1.0 to 2.6) were more likely to have malignant neoplasms. Dog signalment might facilitate prognosis determination for cutaneous canine neoplasia before receiving a histopathological diagnosis.

Clinical features and outcome of dermal squamous cell carcinoma in 193 dogs (1987-2017)

Squamous cell carcinoma (SCC) is a frequently recognized dermal tumour in dogs and has been described as a common pathology induced by solar ultraviolet radiation exposure. Little has been published about this neoplasm with regard to clinical features and outcome in dogs. This retrospective study included 193 dogs from a single institution histopathologically diagnosed with SCC of the dermis. Thirty-eight percent of all dogs had documented histopathologic actinic change. The overall median survival time was 1004 days, with the population demonstrating actinic change associated with a significantly longer survival time (median 1359 days, range 16-3530 days) compared to dogs without actinic change (median 680 days, range 16-3066 days) and this achieved significance on multivariate analysis (hazard ratio 0.42, 95% confidence interval 0.193-0.930, P = 0.032). These data demonstrate increased survival of dogs with SCC demonstrating actinic change over those with non-actinic SCCs, and purports long-term survival for these animals. Dogs received a variety of treatment approaches as a retrospective study, and future prospective studies will be necessary to investigate whether adjunct therapies such as radiation or chemotherapy offer improvement in survival for dermal SCC in the dog.

Basal cell carcinoma in a dog with chronic solar dermatitis

A seven-year-old, entire male, American Staffordshire bull terrier was diagnosed with chronic solar dermatitis and basal cell carcinoma, based on physical examination, cutaneous cytology and histopathology. Immunohistochemistry revealed that the tumour cells did not express p53. To the authors' knowledge this is the first reported case of canine basal cell carcinoma developing as a complication of chronic solar dermatitis.

Squamous cell carcinoma of the nasal planum in 17 dogs

Squamous cell carcinoma of the nasal planum was diagnosed in 17 dogs over a period of 11 years. Ulceration, bleeding and sneezing were the most common clinical signs. One dog had cytological evidence of metastasis to the local lymph node. The dogs were treated by surgical resection, fractionated megavoltage irradiation, or a combination of the two. Surgical resection gave the most favourable results; four of six dogs were cured but a recurrence of the tumour was predicted in the other two on the basis of incomplete or marginal resection. Radiotherapy alone was not as effective; one of four dogs was cured, and the tumour recurred in the others within 24 weeks (median eight weeks). Combined surgical resection and radiotherapy did not produce a cure in any of the seven remaining dogs, and the tumour recurred within 12 weeks (median nine weeks). Three dogs had cytological evidence of lymph node metastasis when the tumour recurred. The dogs' prognosis was adversely affected by the interval between their initial examination and treatment, but there was no apparent association between the histological grade of the tumour and the clinical outcome.

Intralesional sustained-release chemotherapy with therapeutic implants for treatment of canine sun-induced squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most frequently reported malignant epithelial tumour in dogs. Canine sun-induced SCC represents a useful animal model to evaluate new therapeutic modalities for possible human applications. We evaluated the safety and efficacy of treating sun-induced SCC in dogs with intralesional sustained-released chemotherapeutic gel implants that contained collagen, epinephrine (epi), and either 5-fluorouracil (5-FU) or cisplatin (CDDP). Dogs with large, single SCC or fields of multiple SCC were treated with 5-FU/epi gel for a minimum of three weekly injections. Dogs without a complete response were then treated with CDDP/epi gel for a minimum of three weekly treatments. We treated from one to 11 primary, recurrent, or refractory SCC per dog (tumour size 0.2-92.4 cm2; mean cumulative tumour area of 40.7 cm2 per dog). All dogs had at least 50% reduction in cumulative tumour area after treatment with 5-FU/epi gel. More than half (seven of 13) had complete resolution of SCC after treatment with 5-FU/epi gel or CDDP/epi gel. Minimal local tissue reactions were noted; no systemic toxicity occurred. Sustained-release chemotherapy using intralesional 5-FU/epi gel and CDDP/epi gel therapeutic implants is effective in treating canine sun-induced SCC of the skin.

Dorsal skin reactions to sunlight and artificial ultraviolet light in hairless descendants of Mexican hairless dogs

Dorsal skin reactions to irradiation with two different types of ultraviolet (UV) light sources (sunlight and artificial UV light) were investigated in hairless descendants of Mexican hairless dogs. The total energy dose of solar UV exposure and artificial UV irradiation was 90 kJ/m2 and 40 kJ/m2, respectively. Histological examinations were done up to 7 days after UV irradiation (7 DAI). At 1 DAI, the solar UV-exposed skin did not show marked changes, while artificial UV irradiated skin exhibited a visible erythematous reaction and prominent histological alterations such as epidermal thickening, appearance of sunburn cells and deformation elastic fibers. At 4 DAI of solar UV-exposure, the skin color became moderately dark and noticeable pigmentation developed in the epidermis. In contrast, at 4 DAI of artificial UV irradiation, there still remained moderate degeneration in the epidermis and dermis, and delayed tanning was weak. At 7 DAI of solar exposure, delayed suntan reactions became more prominent. Histologically, there were heavy pigmentation of melanin granules mainly in the stratum basale. On the other hand, artificial UV irradiated skin showed less pigmentation. Thus, solar exposure provoked remarkable pigmentation while artificial UV irradiation brought about severe sunburn reactions in the dorsal skin of hairless dogs.

Clinical evaluation of etretinate for the treatment of canine solar-induced squamous cell carcinoma and preneoplastic lesions

BACKGROUND

Tumors of the skin and subcutaneous tissue account for 30% of all canine neoplasms. Canine solar-induced squamous cell carcinoma (SCC) is the most frequently reported canine cutaneous neoplasm.

OBJECTIVE

The purpose of this study was to provide preliminary observations on the safety and efficacy of etretinate for the treatment of solar-induced SCC and associated preneoplastic lesions in dogs.

METHODS

Etretinate was administered to 10 dogs at 1 mg/kg twice daily for a minimum of 90 days.

RESULTS

Clinically, two dogs showed complete resolution of their preneoplastic lesions, three dogs had partial responses, two dogs maintained stable disease, and three dogs showed progression of lesions after 90 days of etretinate administration. Three dogs showed histologic improvement, four dogs showed no changes, and three dogs showed evidence of progressing SCC. Treatment-related biochemical abnormalities included reversible hypertriglyceridemia and transient serum liver enzyme elevations in three dogs.

CONCLUSION

These preliminary findings suggest that etretinate, at the dosage administered, may provide therapeutic efficacy for solar-induced preneoplastic lesions in the dog, particularly for those multifocal lesions not easily managed by local methods of therapy.

A retrospective clinicopathologic study of 212 dogs with cutaneous hemangiomas and hemangiosarcomas

The relationship between skin pigmentation and piliation and the development of hemangiomas and hemangiosarcomas in the dermis and subcutaneous tissue was studied in 212 dogs. These 212 dogs had a combined total of 306 tumors; 38 of these 212 dogs had two or more of the same tumor in a different location or a combination of hemangioma and hemangiosarcoma. The average age of the dogs at the time of excision of these tumors was greater than 10 years. There was no sex predilection for the presence or absence of tumors. Cutaneous hemangiomas (73%) were more common than cutaneous hemangiosarcomas (27%). Hemangiomas had no predilection for dermis (51%) or subcutaneous tissue (47%), but hemangiosarcomas had a marked predilection for dermis (73%) over subcutaneous tissue (7%). Dogs with short hair coats and lightly pigmented skin had more hemangiomas and hemangiosarcomas of the dermis (65%) than did dogs with variable length hair coats and pigmentation (28%). Dogs with short hair coats and lightly pigmented skin had fewer hemangiomas and hemangiosarcomas of the subcutaneous tissue (10%) than did dogs with variable length hair coats and pigmentation (22%). Dogs with short hair coats and lightly pigmented skin also had more hemangiomas and hemangiosarcomas of ventral glabrous skin (65%) than did dogs with variable length hair coats and pigmentation (22%). In addition, there was no predilection of subcutaneous hemangiosarcoma for haired (33%) versus glabrous (33%) skin, but dermal hemangiosarcoma had a marked predilection for the glabrous skin (63%) when compared with haired skin (10%). The increased incidence of dermal hemangiomas and hemangiosarcomas in ventral glabrous skin suggests an association between solar radiation and the biologic properties of glabrous skin in the genesis of these tumors.

Synthetic retinoids in veterinary dermatology

The synthetic retinoids, isotretinoin (Accutane) and etretinate (Tegison) are vitamin A analogs. They affect epithelial differentiation and thus have potential for therapy for disorders of epithelial maturation such as keratinization defects of cutaneous neoplasia. The pharmacology, indications for use, clinical experience, potential toxicities, and recommended monitoring of these drugs are discussed.

Controlled localized heating and isotretinoin effects in canine squamous cell carcinoma

Controlled localized radiofrequency heating and systemic isotretinoin were used serially as therapy in a hairless dog that developed multiple cutaneous squamous cell carcinomas in chronically sun-damaged skin. During the course of therapy, four superficial tumors regressed completely, both clinically and histologically. Two larger, deeper tumors showed clinical signs of regression but histologic clearing did not occur. Both treatment modalities are known to have antitumor effects independently and may exert their effects in an additive fashion. However, it is also possible that heat-induced injury to tumor cells could lead to retinoid-mediated enhancement of an immunologic response to tumor antigens or some other process that might lead to regression.