Preliminary evaluation of the effects of grapiprant compared with carprofen on acute pain and inflammation following ovariohysterectomy in dogs

OBJECTIVE

To compare the analgesic efficacy of grapiprant to carprofen for the treatment of postoperative pain and inflammation in dogs following ovariohysterectomy.

ANIMALS

12 purpose-bred adult sexually intact female Beagles.

PROCEDURES

Dogs were randomly assigned to 1 of 2 treatment groups: grapiprant (2 mg/kg, PO; n = 6) or carprofen (4.4 mg/kg, PO; n = 6), 1.5 hours prior to ovariohysterectomy (OVH) and every 24 hours afterward for 3 total doses. An ultrafiltration probe was placed within the OVH incision to collect interstitial fluid (ISF). Pain and inflammation were assessed by masked investigators via mechanical nociceptive threshold testing and the short form of the Glasgow Composite Pain Scale before drug administration and at multiple time points for 72 hours following dosing and surgery. ISF samples were collected at the same time points to assess prostaglandin E2 concentrations at the site of inflammation.

RESULTS

In both groups, pain scale scores were highest in the immediate postoperative period and decreased over time. In both treatment groups, there were significant (P = 0.003) differences in mechanical nociceptive threshold results over time when compared with baseline, but there was no difference between groups. Prostaglandin E2 concentrations in ISF were higher in dogs receiving grapiprant compared with carprofen (P < 0.001). One dog in the carprofen group required rescue analgesia.

CLINICAL RELEVANCE

Results of this preliminary study suggested both carprofen and grapiprant may be effective for postoperative pain following OVH in dogs; however, additional studies are warranted to determine grapiprant’s effectiveness in a larger and more diverse population of dogs.

Detection of Bartonella spp. in dogs after infection with Rickettsia rickettsii

Background

Dynamics of infection by Bartonella and Rickettsia species, which are epidemiologically associated in dogs, have not been explored in a controlled setting.

Objectives

Describe an outbreak investigation of occult Bartonella spp. infection among a group of dogs, discovered after experimentally induced Rickettsia rickettsii (Rr) infection.

Animals

Six apparently healthy purpose‐bred Beagles obtained from a commercial vendor.

Methods

Retrospective and prospective study. Dogs were serially tested for Bartonella spp. and Rr using serology, culture, and PCR, over 3 study phases: 3 months before inoculation with Rr (retrospective), 6 weeks after inoculation with Rr (retrospective), and 8 months of follow‐up (prospective).

Results

Before Rr infection, 1 dog was Bartonella henselae (Bh) immunofluorescent antibody assay (IFA) seroreactive and 1 was Rickettsia spp. IFA seroreactive. After inoculation with Rr, all dogs developed mild Rocky Mountain spotted fever compatible with low‐dose Rr infection, seroconverted to Rickettsia spp. within 4‐11 days, and recovered within 1 week. When 1 dog developed ear tip vasculitis with intra‐lesional Bh, an investigation of Bartonella spp. infection was undertaken. All dogs had seroconverted to 1‐3 Bartonella spp. between 7 and 18 days after Rr inoculation. Between 4 and 8 months after Rr inoculation, Bh DNA was amplified from multiple tissues from 2 dogs, and Bartonella vinsonii subsp. berkhoffii (Bvb) DNA was amplified from 4 of 5 dogs' oral swabs.

Conclusions and Clinical Importance

Vector‐borne disease exposure was demonstrated in research dogs from a commercial vendor. Despite limitations, our results support the possibilities of recrudescence of chronic subclinical Bartonella spp. infection after Rr infection and horizontal direct‐contact transmission between dogs.

Bartonella henselae in a dog with ear tip vasculitis

BACKGROUND

Bartonella henselae, a Gram-negative, zoonotic, alpha-proteobacteria has been previously implicated in association with cutaneous vasoproliferative lesions (bacillary angiomatosis), nodular panniculitis and multifocal erythema (erythema multiforme) in dogs.

OBJECTIVE

Describe clinical, microbiological and histological lesions in a dog with ear margin vasculitis and B. henselae infection.

ANIMALS

A 12-month-old, specific pathogen-free intact female beagle dog maintained in a vector-free laboratory animal resource facility.

METHODS AND MATERIALS

Bartonella and Rickettsia serological evaluation, Bartonella and Rickettsia PCR, Bartonella alpha-proteobacteria growth medium (BAPGM) enrichment blood culture/PCR, histopathological investigation and confocal immunohistochemical evaluation.

RESULTS

Serological investigation (seroreversion) and PCR testing of aural tissue biopsies failed to support Rickettsia rickettsii as a cause of the aural vasculitis; however, B. henselae, genotype San Antonio 2 DNA was amplified and sequenced from both ear tip margins and from normal-appearing abdominal skin. Seroconversion to B. henselae was documented retrospectively by IFA testing. Bartonella henselae organisms were visualized by confocal immunostaining within all three biopsies. Histopathology revealed small vessel necrotizing vasculitis and dermal necrosis. Bartonella henselae seroreversion and complete resolution of skin lesions occurred in conjunction with administration of oral doxycycline and enrofloxacin for six weeks.

CONCLUSIONS AND CLINICAL IMPORTANCE

Bartonella henselae is an emerging zoonotic pathogen that has been associated with leucocytoclastic vasculitis in humans and may have had a contributing or causative role in the development of the cutaneous aural margin vasculitis in this beagle.