Antihistaminic and cardiorespiratory effects of diphenhydramine hydrochloride in anesthetized dogs undergoing excision of mast cell tumors

Abstract

OBJECTIVE To evaluate the effects of IV diphenhydramine hydrochloride administration on cardiorespiratory variables in anesthetized dogs undergoing mast cell tumor (MCT) excision. DESIGN Randomized, blinded clinical trial. ANIMALS 16 client-owned dogs with MCTs. PROCEDURES In a standardized isoflurane anesthesia session that included mechanical ventilation, dogs received diphenhydramine hydrochloride (1 mg/kg [0.45 mg/lb], IV; n = 8) or an equivalent volume of saline (0.9% NaCl) solution (IV; control treatment; 8) 10 minutes after induction. Cardiorespiratory variables were recorded throughout anesthesia and MCT excision, and blood samples for determination of plasma diphenhydramine and histamine concentrations were collected prior to premedication (baseline), throughout anesthesia, and 2 hours after extubation. RESULTS Cardiorespiratory values in both treatment groups were acceptable for anesthetized dogs. Mean ± SD diastolic arterial blood pressure was significantly lower in the diphenhydramine versus control group during tumor dissection (52 ± 10 mm Hg vs 62 ± 9 mm Hg) and surgical closure (51 ± 10 mm Hg vs 65 ± 9 mm Hg). Mean arterial blood pressure was significantly lower in the diphenhydramine versus control group during surgical closure (65 ± 12 mm Hg vs 78 ± 11 mm Hg), despite a higher cardiac index value. Plasma histamine concentrations were nonsignificantly higher than baseline during maximal manipulation of the tumor and surgical preparation in the diphenhydramine group and during surgical dissection in the control group. CONCLUSIONS AND CLINICAL RELEVANCE IV administration of diphenhydramine prior to MCT excision had no clear clinical cardiorespiratory benefits over placebo in isoflurane-anesthetized dogs.

Dogs undergoing surgical excision of mast cell tumors are not at increased risk of incisional complications

“…First-generation type 1 antihistamines, such as diphenhydramine, competitively inhibit histamine H1 receptors and are commonly used clinically to prevent systemic and local tissue reactions to the release of histamine produced by MCTs. 30 Theoretically, antihistamine treatment may provide some protective benefit against an incisional complication by blocking the action of histamine at the local tumor excision site. However, 1 study 30 found that IV diphenhydramine administration had no significant effect on circulating plasma histamine concentrations in dogs undergoing MCT excision, and we found in the present study no protective effect of antihistamine treatment against incisional complications in the MCT group.…”

“…For all dogs combined and dogs in the STS group, the odds of incisional complication increased by 20% and 40%, respectively, for every 5-kg increase in body weight on simple regression analysis (Table 1). For the MCT group, mixed-breed dogs were most common (n = 46), followed by Boxers (30) and Labrador Retrievers (17). For the STS group, mixed-breed dogs were also most common (n = 24), followed by Labrador Retrievers (11) and Golden Retrievers (10).…”

Episiectomy and partial vaginectomy with urethroplasty for excision of vulvar mast cell tumour in a female dog

“…However, recent studies have shown that mast cell vasodilation is mediated by two receptors, H 1 and H 2 , in addition to a prostaglandin called D 2 , which is also released by canine mast cells. The used antihistamines act only on the H 1 receptor, leaving their action ineffective and/or unsatisfactory in dogs (Sanchez et al 2017). However, in this case, it occurred satisfactorily, with positive results.…”

Anesthetic management of a dog with severe subaortic stenosis and mitral valve disease complicated with atrial fibrillation undergoing ovariohysterectomy

“…Recommendations on the administration of antihistaminergic drugs to avoid cardiorespiratory effects of histamine through actions on H1 and H2 receptors in patients with mastocytoma is still controversial. Preventive treatment has been recommended (London and Seguin, 2003) but more recently, its true efficacy has been questioned in anesthetized dogs undergoing excision of mast cell tumors (Sanchez et al ., 2017). Both diphenhydramine and ranitidine were given following the former recommendations while no adverse effects were expected after their administration.…”