receptor blocker)
a Potent arachidonic acid inflammatory pathway blocker (inhibiting phospholipase A2), histamine blocker, and inhibitor of mast cell degranulation.
Large‐Volume Bleeders/Effusions
In lesser numbers of canine AX cases, “large‐volume bleeding,” AFS 3 and 4 (modified AFS system ≥3), occurs (Lisciandro 2014a, 2016b). When detected, the challenge is again not to overreact because in our experience, dogs with PT and aPTT times that range no more than 25% over upper reference often do not need replacement of clotting factors as long as standard therapy, including glucocorticoids and histamine‐2 receptor blockers (second‐line medications), is used upfront (without delay) in patient management (see Table 7.7). AFS 3 and 4 (modified AFS system ≥3) cases are often confirmed as AX‐related heparin‐induced hemoabdomen because the free intraabdominal fluid is safely accessible for abdominocentesis and fluid characterization. These cases require close monitoring and coagulation profile(s). In cases with initial or serial coagulation profiles of >25% of upper reference range, clotting factors should be replaced. However, PCV, vital signs, physical exams, and repeating AFAST with AFS (or Global FAST) can help monitor (track) the patient, whether coagulopathic or not. See Table 7.7 for suggested management guidelines.
Clinical Examples
Let's look at a couple of case scenarios of large‐volume canine AX‐related heparin‐induced bleeders. For example, if the high normal aPTT is 102 seconds, then an acceptable elevation not requiring FFP would be up to 129 seconds. The author has managed many cases with an AFS of 3 and 4 on admission that responded favorably to resuscitation with epinephrine, intravenous crystalloid fluid therapy, histamine‐1 and histamine‐2 receptor blockers, and glucocorticoids (see Table 7.7). These cases are continued on a short course of antiinflammatory glucocorticoids and histamine‐2 receptor blockers for the next several days with documented hemorrhagic effusion (and others highly suspected that fit the canine AX clinical profile). Often the AFS 3 and 4 is completely resolved (AFS 0) or nearly resolved (AFS 1) the following day on patient rounds. An excellent up‐to‐date anaphylaxis webinar and additional information regarding this unique and fascinating medically treated canine AX‐related complication is available free of charge at www.FASTVet.com
In uncommon to rare instances, packed red blood cells (pRBCs) are additionally needed. In the author's experience, some general guidelines for a clinical course and need for transfusion products would be that 1 in 5–7 AX‐hemoabdomen dogs (of any positive AFS) require replacement of clotting factors, 1 in 15 AX‐hemoabdomen dogs require a second round of FFP, and 1 in >25 AX‐hemoabdomen dogs require pRBCs treating as in Table 7.7, with the caveat that glucocorticoids and histamine‐2 receptor blockers are administered initially without delay. A recent case report documented a canine AX‐hemoabdomen without gallbladder wall edema, which in our experience is the vast exception rather than the rule (Caldwell et al. 2018; Lisciandro and Lisciandro 2019). Without saving the ultrasound gallbladder image for radiologist review, more subtle sonographic striation could have been missed (Caldwell et al. 2018; Lisciandro and Lisciandro 2019) (see Figure 7.11B).
Lastly, nearly all of our canine AX cases (100+) have had Global FAST performed and we have found a couple more important observations: pericardial and pleural hemorrhage has not been documented as a complication of the acquired AX‐related heparin‐induced hemoabdomen coagulopathy, and lung has always been “dry” with “absent B‐lines All (Vet BLUE) views (ABAV)” initially and on serial Global FAST examinations (Lisciandro et al. 2016; Hnatusko et al. 2019), in contrast to a single case report in the literature of massive bee envenomation accompanied by marked pulmonary edema (Walker et al. 2005). Importantly, these AX cases are single witnessed or witnessed Hymenoptera sp. envenomation and not massive bee envenomations, a much different subset of dogs. Anecdotally, AX‐related hemabdomen has occurred with vaccine‐induced AX.
Speculated Pathogenesis
There is only a single report of which we are aware in the human literature of an AX‐related hemoabdomen (Borahay et al. 2011). The case involved a near‐term pregnancy in a woman, interestingly from Galveston, Texas, with previous AX to contrast agents. She was anemic and received a blood transfusion prior to a scheduled C‐section and tubal ligation. During the procedure, she was given a cephalosporin antibiotic and complained of pruritus and had cutaneous and vital signs supporting a diagnosis of AX. She was started on epinephrine as a constant‐rate infusion. Postoperatively she became hypotensive and bedside point‐of‐care ultrasound was performed and she was positive for free fluid. Coagulation profile supported an acquired coagulopathy and disseminated intravascular coagulopathy (DIC) was diagnosed. She was reoperated after receiving histamine‐1 and histamine‐2 receptor blockers and glucocorticoids. At surgery, no discrete bleeding was found but only generalized oozing; topical hemostatic agents were placed intraoperatively and FFP was administered. She survived and her coagulopathy corrected within 24 hours (Borahay et al. 2011).
The case is interesting because likely the acquired coagulopathy
