Disseminated intravascular coagulation following melarsomine therapy for Dirofilaria immitis (D. immitis) is reported in a 9-year-old female intact pit bull-type dog. The dog had been diagnosed with D. immitis (antigen and microfilaria positive) and treated with imidacloprid, moxidectin, doxycycline and 3 doses of melarsomine over a 92-day period. Seven days after the third melarsomine injection, the patient was presented to her family veterinarian due to right pelvic limb swelling. Prothrombin and activated partial thromboplastin times were prolonged beyond the detectable range. Treatment included vitamin K1 and fresh frozen plasma (FFP) prior to referral to the authors' institution. At this time the patient remained coagulopathic. Further investigations included thoracic radiographs, abdominal ultrasound and an echocardiogram. The patient was administered multiple units of packed red blood cells and FFP, sildenafil, dexamethasone SP, aminocaproic acid and vitamin K1. Repeat CBC approximately 20 h after admission showed persistent anemia and thrombocytopenia. Despite ongoing administration of FFP, a repeat coagulation panel showed worsening of the coagulopathy with prothrombin time of 84.2s [reference interval (RI) 7.0-9.3s], activated partial thromboplastin time >140s (RI 10.4-12.9s) and fibrinogen <50 mg/dL (RI 109-311 mg/dL). Following discussion with the owners, the patient was euthanized. Necropsy was performed and confirmed heartworm infection with severe pulmonary arterial thrombosis, vascular remodeling, and intraluminal degenerate nematodes. Multifocal subcutaneous and organ hemorrhage was apparent. Although coagulopathy has been described in caval syndrome associated with heartworm disease and is listed as a potential side effect of melarsomine administration, this is the first report of documented disseminated intravascular coagulation following melarsomine treatment for D. immitis. Potential mechanisms for the coagulopathy are discussed and the case report highlights a rare, but serious complication of adulticide therapy.

Objective

To describe a serious adverse event of gastrointestinal obstruction requiring surgery following routine administration of multiple doses of activated charcoal (AC) granules, which were prescribed for carprofen toxicosis.

Case summary

A 2-year-old female neutered Airedale Terrier presented for ingestion of 207 mg/kg of carprofen. Decontamination was initiated with apomorphine to induce emesis. Along with additional supportive care, the dog received an initial dose of 75 mL of AC suspension containing sorbitol by mouth (15.6 g of AC, or 0.6 g/kg), followed by 50 g of AC granules every 8 hours for 4 additional doses. While hospitalized, the dog experienced clinical signs, including vomiting and black diarrhea, as well as bloodwork changes including mild to moderate elevations in kidney and liver enzymes. Given clinical improvement after 72 hours of hospitalization, the patient was discharged for monitoring and ongoing care at home. Two days later, the patient presented again for nausea, dark diarrhea with frank blood, and panting. Abdominal ultrasound showed findings suspicious for partially obstructive foreign material or atypical impacted fecal material partially occluding the distal ileum. Despite medical management overnight, recheck ultrasound the following day demonstrated persistent obstruction with ileal foreign material. Exploratory laparotomy and enterotomy revealed moderate distension and obstruction of the distal ileum with black granular foreign material consistent with charcoal granules. The patient remained in hospital for supportive care for 4 days following the procedure, and all clinical signs were resolved at the time of discharge.

New or unique information provided

This report documents a serious adverse event of gastrointestinal obstruction associated with routine multidose AC administration, which has been occasionally reported in people but not in dogs. The potential for this complication should be taken into account when prescribing multiple doses of AC granules.