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

Near-infrared fluorescence cholangiography in dogs: A pilot study

OBJECTIVE

To determine the effect of indocyanine green (ICG) dose and timing of administration on near-infrared fluorescence (NIRF) imaging of the normal canine biliary tree.

STUDY DESIGN

Preclinical prospective study.

ANIMALS

Eight purpose-bred beagles.

METHODS

The dogs were randomized to receive two of four intravenous ICG dose (low [L]:0.05 mg/kg or high [H]:0.25 mg/kg)/time (0 and 3 h prior to NIRF) combinations. NIRF images were collected every 10 min for 120 min. Target (cystic duct)-to-background (liver) ratios were calculated for all timepoints and compared.

RESULTS

ICG cholangiography was successful in all dogs. The contrast ratio was above 1 in the L0 group by 20 min and reached its peak at 100 min. In the H0 group, the ratio was above 1 by 60 min and reached its peak at 90 min. Contrast ratios above 2 (fluorescence twice as bright in the cystic duct compared to the liver) were maintained from 180 to 300 min for L3 and H3 and was achieved after 80 min for L0.

CONCLUSION

Low dose ICG provided better ratios early after injection compared to the high dose which remained highly concentrated in the liver tissue after injection. Both doses provided excellent visualization of the biliary tree at 3 h post injection, low dose ICG provided better ratios from 3 to 5 h post injection. Based on these results, 0.05 mg/kg of ICG administered at anesthetic premedication, or as early as 3 h prior to laparoscopic surgery should yield optimal fluorescence images.

CLINICAL SIGNIFICANCE

This study provides guidelines for NIRF cholangiography in clinically normal dogs.

The indications, complications and outcomes of dogs undergoing partial penile amputation: 10 cases (2014-2021)

OBJECTIVES

To report the signalment, indications for surgery, postoperative complications and medium-/long-term outcomes in dogs undergoing partial penile amputation.

MATERIALS AND METHODS

Retrospective case series. The electronic medical records of a single small animal referral hospital were searched between January 2014 and January 2021 for dogs that underwent a partial penile amputation. Data collected included signalment, presenting clinical signs, indication for partial penile amputation, surgical technique, postoperative complications and outcome.

RESULTS

Ten dogs were included in the study. Indications for surgery were treatment of preputial neoplasia (n=5), penile neoplasia (n=1), idiopathic paraphimosis (n=3) and chronic urethritis (n=1). Five of five preputial tumours were cutaneous mast cell tumours, and the penile tumour was a squamous cell carcinoma. All dogs recovered uneventfully from surgery with a median postoperative hospitalisation time of 28.8 hours. Two of the three dogs treated for paraphimosis had major postoperative complications requiring further resection of the tip of the penis at 2 weeks and 24 months. Four dogs had minor complications managed without surgical intervention. The outcome was good to excellent in nine of nine dogs for which medium- or long-term follow-up data were available.

CLINICAL SIGNIFICANCE

In this group of dogs, partial penile amputation, performed with or without concurrent resection of the prepuce, was a well-tolerated surgical procedure with low intraoperative and postoperative complication rates and good functional outcomes. Partial penile amputation should be considered for conditions affecting the distal penis and prepuce.

Pharmacokinetics of diphenhydramine following single-dose intravenous and oral administration in non-fasted adult horses

Diphenhydramine is an H1 receptor antagonist used to control urticaria and other allergic signs caused by type I hypersensitivity reactions in horses (Equus caballus). Limited studies have been conducted on pharmacokinetics of this drug in horses, with no studies involving oral formulations. Our study investigated pharmacokinetics of an oral diphenhydramine formulation compared to intravenous administration in non-fasted adult horses. Six healthy horses underwent a single administration of three different doses of diphenhydramine (1 mg/kg intravenously, 1 mg/kg intragastrically, and 5 mg/kg intragastrically) with a two-week washout period between doses. Bioavailability of intragastric diphenhydramine was less than one percent and six percent for 1 mg/kg and 5 mg/kg intragastric doses, respectively. This poor bioavailability is similar to what is reported in dogs. Two of six horses experienced transient side effects after intravenous diphenhydramine administration, emphasizing the need for determining therapeutic plasma levels in efforts to determine the lowest effective dose minimizing risk of adverse effects. The main conclusion of our study was that oral diphenhydramine at doses up to 5 mg/kg are unlikely to achieve therapeutic plasma levels in adult horses.

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

This case report describes the surgical treatment of a grade II mast cell tumour in the vulvar region of a 4-year-old female Miniature Pinscher dog. The patient weighed 2 kg, and the tumour measured 2 cm in diameter. The surgery involved an episiotomy, a partial vaginectomy, and a subsequent urethroplasty. Due to the patient's small size, the surgical margins were set at 2 cm laterally and 2 cm deep, which meant that the entire vulva, as well as the ventral part of the vaginal canal had to be removed. Afterwards, the urethral ostium was elliptically fixed to the skin at the end of the urethroplasty. The follow-up evaluations revealed an excellent recovery without metastasis or recurrence over the following two years.

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

The anesthetic management in patients with subaortic stenosis and mitral valve disease should involve intensive monitoring and the anesthesiologist's main concern is to ensure oxygen delivery and tissue perfusion. Since anesthetic procedures in such patients are rare, there is no previous report about the anesthetic management. A 5.5-year old, 32-kg Boxer, suffering a severe heart disease due to a final stage subaortic stenosis and mitral insufficiency, was anesthetized for an ovariohysterectomy to remove an ovarian tumor that was producing high-volume ascites. Methadone (0.3 mg kg^-1) was administered intramuscularly (IM) for pre-anesthetic medication, etomidate (1.3 mg kg^-1) and midazolam (0.2 mg kg^-1) were used for the induction of anesthesia and after endotracheal intubation, anesthesia was maintained with sevoflurane vaporized in oxygen and air. Fentanyl (5-10 μg kg^-1 h^-1) and paracetamol (15 mg kg^-1) were administered to improve analgesia. Previous persistent atrial fibrillation was refractory to medication (digoxin, diltiazem, and pimobendan) and continued during the anesthetic procedure. Dobutamine (1.5-5 μg kg^-1 minute^-1) helped to maintain mean arterial blood pressure above 60 mmHg. Epidural morphine (0.1 mg kg^-1) and incisional bupivacaine (2 mg kg^-1) were administered at the end of surgery to provide postoperative analgesia. Anesthesia was otherwise uneventful, and recovery was considered excellent.