Ophthalmic abnormalities secondary to periocular or ocular snakebite (pit vipers) in dogs-11 cases (2012-2014)

Canine Retrobulbar Cellulitis and Abscessation in the Southeastern United States: A review of case management, diagnostic imaging, bacterial isolates, and susceptibility patterns

OBJECTIVE

To describe common bacterial organisms cultured from retrobulbar cellulitis and abscess lesions, in vitro susceptibility patterns, common diagnostic techniques utilized, etiologies encountered, and prevalence of blindness.

ANIMALS STUDIED

Thirty-eight dogs diagnosed with retrobulbar cellulitis or abscessation from 2007 to 2017.

PROCEDURE

For cases of orbital cellulitis or abscess, signalment, orbital imaging, cytology, histopathology, bacterial culture and susceptibility testing, presence of vision at the initial examination and resolution, and presumed cellulitis/abscess etiology were recorded.

RESULTS

Most cases were medically (78.9%) versus surgically managed (18.4%). Most common form of orbital imaging was computed tomography (48.5%) followed by ocular ultrasound (18.2%). Fifteen of eighteen cultures (83.3%) showed growth of aerobic bacterial organisms, anaerobic bacterial organisms, or both. Most common aerobic bacteria were gram-negative bacilli (40.0%) followed by Corynebacterium sp. (26.7%) and α-hemolytic Streptococci sp. (26.7%) but Micrococcus and Bacillus spp. were also identified. Most common anaerobic bacteria were gram-negative bacilli (40.0%). Antibiotics with highest susceptibility patterns included gentamicin, followed equally by amoxicillin/clavulanic acid, cephalothin, chloramphenicol, and imipenem. No bacteria were susceptible to cefovecin. Six cases presented with vision loss due to retrobulbar disease (15.8%). Idiopathic (50%) disease and tooth root abscessation (23.7%) were most commonly diagnosed cause of orbital disease.

CONCLUSION

Retrobulbar cellulitis/abscess is a serious and vision-threatening process, which can be effectively managed by broad-spectrum antibiotics such as gentamicin or amoxicillin/clavulanic acid, but not cefovecin. This study identified three organisms that have not been previously reported to be associated with orbital cellulitis (Corynebacterium sp., Bacillus sp. and Micrococcus sp.).

Subconjunctival haemorrhage in 147 dogs

OBJECTIVES

To identify differential diagnoses for subconjunctival haemorrhage in dogs.

MATERIALS AND METHODS

Retrospective case series.

RESULTS

Of 147 dogs with subconjunctival haemorrhage, 119 had a history of trauma. The most common types of injury were vehicular trauma (47/119) and dog attacks (32/119). Confirmed or suspected non-accidental injury was reported for 5/119. Of the 28 dogs without a history of trauma, 13 had a bleeding disorder and of these, immune-mediated thrombocytopenia was the most common diagnosis (9/13). Other causes included seizure disorders (4/28), vasculitis (3/28) and ocular or periocular disease (3/28).

CLINICAL SIGNIFICANCE

Subconjunctival haemorrhage in dogs can be secondary to a wide range of injuries and systemic diseases, bleeding diathesis or ocular disease.

Snakebite in domestic animals: First global scoping review

Snakebite is a Neglected Tropical Disease estimated to cause more than 100,000 human deaths and disable more than 400,000 victims each year. It primarily affects poor agricultural workers, farmers, and cattle herders living in rural areas of developing countries. It is thus an occupational disease. However, the impact of snakebite on these rural communities could be even higher if a One Health approach is taken to consider the direct impact on domestic animals and indirect impact on the livelihood of affected communities. To explore this hypothesis we developed the first scoping review to identify and characterize the global literature on snakebite in domestic animals. Three bibliographic databases (PubMed, Web of Science and Agricola) were searched using terms related to snake, snakebite and domestic animals for publications up to December 31^st, 2016. Two independent reviewers screened publications applying inclusion/exclusion criteria to select relevant material. Relevant information was then extracted from the selected literature. The global literature on snakebite in domestic animals (n = 143 observational studies, reviews and letters) mainly represented North America, Europe and Australia (69%) with less information from Central and South America, Asia and Africa (31%). Observational studies (n = 119) mostly concerned pets (78%) and to a lesser extent livestock (22%). Thirty-four snake species were reported as responsible for bites in domestic animals. WHO's Medically Important Venomous Snakes were more frequently involved. The social-ecological determinants of snakebite were poorly documented but the reviewed literature suggested a strong seasonality and a diversity of habitat. Snakebite in animals caused neurotoxic, cytotoxic and hemotoxic envenomation syndromes similar to humans and death. Half of publications on envenomed livestock reported a fatality rate above 47%. There was no literature on the indirect impact of snakebite on livelihood caused by animal morbidity and mortality. The results of this scoping review suggest a high and under-reported burden in terms of mortality in animals and a potential economic impact of snakebite in terms of losses in livelihood of affected communities. However, major knowledge gaps with respect to impact of snakebite on livestock and livelihood were identified. Filling these gaps is necessary for a full understanding of the impact of snakebite and to raise scientific, political and public awareness on this neglected issue.

Canine ocular and periocular snakebites requiring enucleation: A report of 19 cases

PURPOSE

To describe the clinical and histopathologic features secondary to ocular and periocular snakebites in dogs requiring enucleation.

METHODS

Retrospective review of patients with recorded snakebite envenomation from the archives of the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) and Texas A&M Veterinary Medical Teaching Hospital (1997-2017). The cases included in this study required witnessed snakebites to the dog by the owner, clinical signs supportive of periocular or ocular envenomation, and/or histopathologic lesions compatible with snakebites. Two groups were established: ocular bites (OB) and periocular bites (PB).

RESULTS

Nineteen cases were included in the study (OB = 16/19; PB = 3/19). Dogs affected were typically older (median 8 years; range 1-18), and both sexes were equally represented. Left eyes (14/19) were more likely to sustain snake-induced trauma compared to right eyes (5/19). Fifteen breeds were identified, with terriers (9/19) commonly represented. Snakes bites occurred in six US states, with the majority of cases from Texas (7/19), California (5/19), and Arizona (4/19). Common clinical signs included facial edema, corneal ulceration, keratomalacia, uveitis, hyphema, and secondary glaucoma. All eyes demonstrated vision loss prior to enucleation. Histologically, the ocular and periocular tissues contained extensive necrosis associated with envenomation. Retinal detachment, lens capsule rupture, and intraocular hemorrhage/inflammation were commonly found.

CONCLUSIONS

Snakebite envenomation is a largely necrotizing disease process that can result in profound infiltrative and destructive ocular changes presumed to be related to the proteolytic factors and necrotoxins in venom. Ocular alterations secondary to snakebites may be irreversible regardless of supportive therapy instituted.