Effect of antivenin dose on outcome from crotalid envenomation: 218 dogs (1988–2006)

Clinical features and management of snake bites in 70 dogs in Korea

BACKGROUND

Snakebites remain a devastating and life-threatening environmental hazard. While the management of snakebites has been well described in humans, few clinical data and guidelines exist for dogs, especially in Korea.

OBJECTIVES

This retrospective study evaluated the clinical features of 70 dogs with snakebite wounds in Korea.

METHODS

The medical records of 72 dogs that presented to three animal hospitals from June 2008 to July 2021 were reviewed; among these, 70 dogs that met the inclusion criteria were enrolled. Their signalment, history, clinical signs, physical examination, blood analysis, treatment, and prognosis were also evaluated.

RESULTS

Of 70 dog owners, 35 (50%) witnessed the bite, with a mean time between bite and hospital presentation of 9.7 ± 4.1 h in 58 dogs. Blood smears were evaluated in 45 dogs, of which 28 (62%) showed echinocytosis. Anemia and acute kidney injury were found in 21 (29%) and 2 dogs (3%), respectively. A total of 37 dogs (53%) were hospitalized, 5 (7%) of which died.

CONCLUSIONS

The most significant finding was the high prevalence of echinocytosis. The data from this retrospective study could inform the management of dogs bitten by snakes in Korea.

In vitro evaluation of canine whole blood with the addition of Crotalus atrox (Western Diamondback Rattlesnake) venom and antivenom using thromboelastography

OBJECTIVES

To compare the efficacy of 2 equine-origin antivenom products on correction of coagulation abnormalities noted on thromboelastography (TEG) caused by Crotalus atrox venom in vitro.

DESIGN

Prospective in vitro controlled study.

SETTING

Veterinary teaching hospital.

ANIMALS

Six healthy dogs.

INTERVENTIONS

Blood from each dog was used for 4 separate kaolin-activated TEG analyses: A negative control (blood-saline) and positive control (blood-Crotalus atrox venom) were used to assess the dog's normal coagulation and the effect of venom on TEG parameters. Thromboelastographic analyses were then run with blood, venom, and either Argentinian or North American antivenom. All TEG analyses from each dog were compared for efficacy.

MEASUREMENTS AND MAIN RESULTS

The mean R values between the North American antivenom and negative controls were not significantly different (P = 0.681), but were significantly different (P = 0.024) between the Argentinian antivenom and negative controls. The mean fibrinolysis values measured 30 minutes after maximum amplitude achieved between the North American antivenom and negative controls were not significantly different (P = 0.198), but were significantly different (P < 0.001) between the Argentinian antivenom and negative controls. The mean K values between the Argentinian antivenom and negative controls were not significantly different (P = 0.274), but were significantly different (P = 0.043) between the North American antivenom and negative controls.

CONCLUSIONS

The North American antivenom normalized time to clot formation and fibrinolysis, while the Argentinian antivenom normalized rate of clot formation. Further studies in naturally envenomated patients are necessary to determine if these in vitro results would translate into different clinical outcomes.

Rattlesnake envenomation in 2 Visayan warty pigs

Rattlesnake envenomation is an important cause of morbidity and mortality in humans and animals in the southwestern United States and elsewhere. Two Visayan warty pigs (Sus cebifrons) from a regional zoo were submitted for autopsy after being found dead close to a southern Pacific rattlesnake (Crotalus helleri) in their enclosure. Both pigs had severe regionally extensive cutaneous, subcutaneous, and muscle hemorrhage and edema with myonecrosis. Additionally, both pigs had lesions consistent with puncture wounds within the oral cavity, and one pig had a similar wound on a forelimb. The history, and gross and histologic findings, were consistent with envenomation by rattlesnake bite. There are few documented cases of snakebite envenomation in pigs, and it had been suggested that pigs may have some degree of resistance to envenomation. Our results indicate that warty pigs are susceptible to the action of rattlesnake venom.

Retrospective comparison of three antivenoms for the treatment of dogs with crotalid envenomation

OBJECTIVE

To retrospectively compare clinical outcomes associated with 3 commercially available antivenom products (2 F[ab']2 products and 1 IgG product) in dogs with crotalid envenomation.

ANIMALS

282 dogs with evidence of crotalid envenomation treated with antivenom at a single high-volume private emergency facility in southwestern Arizona from 2014 to 2018.

PROCEDURES

Data were collected on all dogs regarding signalment, coagulation test results, snakebite characteristics, type and number of units of antivenom received (1 of 3 products), survival to hospital discharge (yes or no), and complications following discharge. Survival rates and other variables were compared among antivenoms by means of bivariable analyses.

RESULTS

271 of 282 (96.1%) dogs survived to discharge; 11 (3.9%) were euthanized or died in the hospital. No significant difference in survival rates was found among the 3 antivenom products. Infusion reaction rates were higher for the IgG product than for each F(ab')2 product. A higher percentage of dogs treated with the IgG product (vs either F[ab']2 product) received only 1 unit of antivenom. Variables associated with a lower probability of survival included older age and lower body weight, thoracic (vs other) location of snakebites, and presence of an antivenom infusion reaction.

CONCLUSIONS AND CLINICAL RELEVANCE

Given that survival rates were high for all 3 antivenom products, clinicians may consider other factors when selecting an antivenom, such as preference for a fractionated versus whole immunoglobulin product, risk of infusion reaction, cost, shelf life, availability, ease of use and administration, species of crotalids used for antivenom production, approval by federal regulatory bodies, and clinical preference.

A prospective multicenter observational study of Viperidae polyvalent immune F(ab')2 antivenom administration for the treatment of viper envenomation in dogs

OBJECTIVE

To test an equine-derived polyvalent viperid antivenom (EPVA) in the treatment of dogs with evidence of viper envenomation.

DESIGN

Prospective, multicenter observational study.

SETTING

Veterinary emergency and critical care hospitals.

ANIMALS

A total of 82 client-owned dogs with progressive clinical signs after viperid snakebite were enrolled in the study.

INTERVENTIONS

Equine-derived polyvalent viperid antivenom was administered at a dosage of 1 mL/kg body weight, either by IV infusion or SC injection.

MEASUREMENTS AND MAIN RESULTS

A standardized snakebite severity score (SSS) was used to characterize the severity of envenomation and the clinical course after EPVA treatment. Most dogs had improved SSS both at 4 (65.8%) and 8 hours (81.7%) following EPVA administration. Five dogs died. At the 4-week assessment, 3 dogs had slightly abnormal hematological or coagulation parameters; all other surviving dogs showed no abnormalities. Antivenom-related acute or intermediate reactions occurred in 12 dogs (14.6%).

CONCLUSIONS

In the first study on antivenom in dogs in Italy, the effects of progressive viper envenomation were stabilized or reversed in the large majority of dogs receiving EPVA, as confirmed by the SSS analyses.

Antivenin-associated serum sickness in a dog

OBJECTIVE

To describe a case of documented serum sickness in a dog following administration of a single dose of a novel antivenin crotalidae polyvalent.

CASE SUMMARY

A 4-year-old female neutered mixed breed dog developed recurrent signs of hypersensitivity (swelling, edema, urticaria/hives, gastrointestinal signs, vasculitis) at 1 and 2 weeks following administration of a single unit of a novel antivenin crotalidae polyvalent plasma product. Both episodes were treated with antihistamines and glucocorticoids and signs improved rapidly, with a prolonged course of glucocorticoids and antihistamines administered following the second occurrence. Diagnosis of serum sickness was based on clinical appearance of delayed hypersensitivity following exposure to novel biologic product, absence of other inciting cause of hypersensitivity, complement testing, and skin biopsies confirming vasculitis.

NEW OR UNIQUE INFORMATION PROVIDED

This case documents the first report of delayed hypersensitivity with a novel antivenin plasma product. This is the only case report of serum sickness to a single unit of antivenin. Additionally, the dog developed recurrence of hypersensitivity following the initial episode at 1 week; appropriate identification and prolonged treatment could have prevented recurrence and additional hospitalization. Cost and benefit analysis should be considered with antivenin administration.

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.

Persistent pit viper envenomation in three dogs

INTRODUCTION

North Central Florida is the home to several venomous snakes. The most clinically significant pit vipers include the Eastern Diamondback Rattlesnake, the Water Moccasin, and less commonly the Timber Rattlesnake. Many of the dogs and cats that become envenomated by these particular snakes have moderate to severe clinical signs requiring the use of antivenom in doses that can range from 1 to 20 vials with the average case requiring two vials. Oftentimes, the pet owners' financial limitations restrict the amount of antivenom that can be administered initially to severely envenomed cases. Most of these patients will become clinically stable after the first 48 hours of treatment, but there are rare instances where some patients will follow this same initial course, and then revert back to the initial signs of envenomation associated with delayed absorption of redistributed venom from other tissue sites in addition to the bite site. This report describes three dogs that showed signs of persistent and/or recurrent envenomation requiring additional doses of antivenom.

METHODS

The medical records of three dogs showing signs of persistent envenomation were reviewed by the author who was available and provided assistance during the course of the dogs' respective hospitalizations. The dog's signalment, time of year of the envenomation, clinical signs, treatment, and outcome are provided in each case.

RESULTS

Each of these three dogs showed severe signs of envenomation characterized by marked mental depression, prostration, hemorrhagic lymphedema, and evidence of prolonged coagulation times. Initial treatment in each consisted of intravenous crystalloid solution and polyvalent crotalid antivenom that exceeded the usual average dose as reported in the literature. After the coagulation test normalized during the first three days, all of them reverted to abnormal prolonged clotting times with signs of clinical deterioration requiring additional doses of antivenom. Clinical stability was eventually reached and all dogs survived to be discharged.

CONCLUSIONS

The clinical course of the three dogs described in this study showed that veterinary patients can experience persistent envenomation in a similar manner as described in humans. It behooves the veterinary practitioner to be aware of this complication and to be prepared to extend antivenom treatment as deemed necessary.

272 cases of rattlesnake envenomation in dogs: Demographics and treatment including safety of F(ab')2 antivenom use in 236 patients

Medical records of 272 rattlesnake envenomations of canines from 5 veterinary emergency centers in Maricopa County, Arizona between 2010 and 2012 were investigated. The objectives were to examine the patient demographics, severity of clinical signs, and treatment modalities employed, in order to discuss the outcomes of certain therapies including glucocorticoid use, antibiotic use, rattlesnake vaccination, and safety of antivenom administration in dogs. Evaluation was performed to model each response (survival, proposed canine snakebite severity score (cSSS), and length of stay) as a function of multiple variables. Of the 272 bite incidences, 8 dogs had a fatal outcome. In dogs older than 10 years, there was a greater likelihood of fatal outcome associated with a longer delay between the bite and presentation. 236 of the envenomated patients were treated with a F(ab')2 antivenom, 24 with a whole immunoglobulin antivenom, and 12 with both products. Overall incidence of acute hypersensitivity reaction was 0.7% with one incident observed in each antivenom group and F(ab')2 antivenom administration having the lowest rate of acute hypersensitivity reactions; no reactions were life-threatening. Antivenom administration was found to be generally safe in treatment of canine rattlesnake envenomation. In view of the results of this study, in dogs with rattlesnake envenomation, there is no evidence that use of glucocorticoids, diphenhydramine, prophylactic antibiotics, or vaccination lessen morbidity or mortality.

Prospective evaluation of the incidence of wound infection in rattlesnake envenomation in dogs

OBJECTIVE

To evaluate the incidence of wound infection following crotalidae envenomation in dogs and determine if the use of prophylactic antibiotics is warranted.

DESIGN

Prospective observational study.

SETTING

A 24-hour private practice specialty and emergency center in Murrieta, California.

ANIMALS

One hundred and two dogs with acute rattlesnake envenomation.

INTERVENTIONS

One hundred and forty-three consecutive cases of suspected acute rattlesnake envenomation were evaluated between March of 2012 and May of 2013. One hundred and two cases received no antimicrobials as part of management. Eight cases were placed on prophylactic antimicrobials by the primary care veterinarian prior to referral and were excluded. Two cases were excluded because they were initiated on antimicrobials during hospitalization for reasons unrelated to snakebite. Three cases involved cats and were excluded. Three patients died acutely near the time of presentation and were excluded. Twenty-one cases of suspected envenomation were excluded for lack of strong evidence of snakebite. Four cases were lost to follow-up and were excluded. Follow-up was conducted within 2 weeks either by phone or by direct inspection of the wound.

RESULTS

Of the 102 patients included in the study only 1 infection developed. This patient developed an abscess subsequent to suspected compartment syndrome.

CONCLUSION

The incidence of wound infection in rattlesnake envenomation is low, and the use of prophylactic antimicrobials is not recommended. The use of antimicrobials should be reserved for wounds with necrosis or abscess and the choice of antimicrobial should be based on a culture and sensitivity of the wound.

Effects of the canine rattlesnake vaccine in moderate to severe cases of canine crotalid envenomation

This is a retrospective multicenter study (2006–2012) examining a population of dogs with moderate to severe crotalid envenomation for protective effects of the canine rattlesnake vaccine. Five nonacademic emergency and referral veterinary hospitals in Southern California were involved in the study and contributed records regarding a total of 82 client-owned dogs that were treated for naturally occurring rattlesnake envenomation. All dogs received antivenin (Crotalidae) polyvalent, with dosages ranging from one to three vials (mean: 1.3±0.6). Fourteen dogs (17%) had a history of prior vaccination against crotalid venom. In univariate logistic regression modeling, cases with lower body weight (P=0.0001) or higher snakebite severity scores (P<0.0001) were associated with greater morbidity. No statistically significant difference in morbidity or mortality between vaccinated and unvaccinated dogs was found. The findings of this study did not identify a significantly protective effect of previous vaccination in the cases of moderate to severe rattlesnake envenomation that require treatment with antivenin.

Copperhead (Agkistrodon contortrix) Envenomation of Dogs: 52 Cases (2004–2011)

Copperhead envenomation is common within the US, and no studies exist describing the clinical course of copperhead envenomation in dogs. Almost all treatment decisions regarding those bites are extrapolated from retrospective studies evaluating the clinical course of rattlesnake bites. Because copperheads and rattlesnakes produce venom with different potency, assumptions that treatment of the different envenomations should be similar may be incorrect. The purpose of this retrospective study was to evaluate the clinical course of copperhead envenomation in dogs and administered treatments. Medical records of 52 dogs treated for copperhead envenomation were reviewed, and owners were contacted regarding outcome. The most common clinical signs associated with copperhead envenomation included swelling, pain, and ecchymosis. Clinicopathological abnormalities (e.g., thrombocytopenia, elevated clotting times, leukocytosis) were mild, and red blood cell morphology changes and coagulopathies were rare. Most dogs were treated with antimicrobials, analgesics, and fluid therapy. No dogs in this study required the use of antivenin and all survived to discharge. This study found that the clinical course after copperhead envenomation is generally limited to local rather than systemic illness. Copperhead envenomation in dogs is largely self-limiting and responsive to supportive care with hospitalization for monitoring.

North American snake envenomation in the dog and cat

Snake envenomation can be a cause of significant morbidity in dogs and cats in North America. Being familiar with the venomous snakes in your area and understanding the mechanisms of action of their venom will allow for successful treatment of envenomation cases. Treatment of snake envenomation revolves around supportive care in mild to moderate cases and venom neutralization with antivenom in severe cases. Dogs and cats envenomated by North American snakes have a good prognosis if treated appropriately.

Rattlesnake envenomation in horses: 58 cases (1992-2009)

OBJECTIVE

To characterize signalment, clinical and laboratory findings, treatment, and outcome in horses with rattlesnake envenomation in northern California.

DESIGN

Retrospective case series.

ANIMALS

58 client-owned horses evaluated for rattlesnake envenomation at 2 referral hospitals from 1992 to 2009.

PROCEDURES

Records of horses with rattlesnake envenomation were reviewed, and data concerning signalment, clinical and laboratory findings, treatment, and outcome were collected. In addition, a rattlesnake-bite severity score (RBSS) was assigned to each horse. Variables were compared between horses that survived and those that did not.

RESULTS

The overall mortality rate was 9%. Nine horses received antivenin; no complications were reported and none of the 9 died. The most common laboratory findings associated with severity of envenomation were thrombocytopenia, hypoproteinemia, hyperlactatemia, and a high RBSS.

CONCLUSIONS AND CLINICAL RELEVANCE

Most horses in this study had a good prognosis after being bitten by rattlesnakes. Laboratory and clinical examination findings may be useful for identifying horses with a poorer prognosis. Treatment with antivenin may be beneficial and warrants further evaluation.