Graziana Gambino

Skin diseases are among the most frequently diagnosed conditions in companion animals and have historically been treated empirically with antibiotics, contributing to the emergence and persistence of antimicrobial resistance (AMR). In recent years, greater awareness of AMR has led to a reduction in antibiotic use in veterinary medicine, particularly in dermatology. To assess AMR trends in skin infections and evaluate the use of diagnostic tools to guide antimicrobial prescriptions, we conducted a retrospective study of medical records from a veterinary hospital in northwestern Italy between 2013 and 2024. A total of 447 antimicrobial susceptibility tests from dogs and cats with clinical signs of skin disease were analyzed. Of these, 391 yielded positive bacterial cultures, and 56 were negative. Most positive samples came from dogs (83.4%), with cats accounting for 16.6%. The most frequently isolated bacterial families were Staphylococcaceae, Enterobacteriaceae, and Pseudomonadaceae. Amoxicillin-clavulanic acid was prescribed in 36.6% of patients, fluoroquinolones in 25.9%, while 17% received only detergent–disinfectant products. Among first-line drugs, ampicillin showed the lowest susceptibility, with resistance exceeding 60%, whereas imipenem (used as an indicator of carbapenemase production but avoided in veterinary medicine) retained high activity, with susceptibility rates of 77.2% in dogs and 90.3% in cats. These findings are clinically relevant, but continuous AMR surveillance remains essential within a One Health framework to limit the spread of resistant bacteria and resistance genes to cohabiting humans.

Antimicrobial resistance (AMR) is an increasingly concern in both human and veterinary medicine, complicating the management of common clinical infections. Surgical site infections (SSIs) and bite wounds in pets are especially challenging due to their polymicrobial nature and multidrug-resistant strains. Laboratory records from a referral veterinary hospital in northwestern Italy were retrospectively analyzed. Bacterial cultures and antimicrobial susceptibility testing results from canine and feline surgical and bite wounds collected between 2013 and 2024 were reviewed. Data were analyzed descriptively to identify bacterial distribution and resistance trends. A total of 35 isolates (23 dogs; 12 cats) were obtained from 26 surgical and 9 bite wounds. In dogs, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus pseudintermedius were most frequently identified. In cats, Enterobacter cloacae, Escherichia coli, and Pasteurella multocida predominated. High resistance rates were recorded for amoxicillin–clavulanate, cephalexin, enrofloxacin, and marbofloxacin. Methicillin resistance emerged in most Staphylococcus aureus and several S. pseudintermedius isolates, while subsets of E. coli and K. pneumoniae were ESBL. Resistance to carbapenems remained low. Although samples were limited, these findings underscore the ongoing impact of AMR in surgical and bite wounds and highlight the importance of implementing rigorous antimicrobial stewardship practices in veterinary medicine.

Companion animals, including dogs and cats, share close living environments with humans, making antimicrobial stewardship essential to prevent zoonotic transmission of resistant pathogens. The overuse and misuse of conventional antibiotics in veterinary medicine have accelerated the emergence of multidrug-resistant (MDR) microorganisms, prompting the need for alternative strategies. Natural compounds, such as antimicrobial peptides (AMPs), phytochemicals, chitosan-based polymers, and nutraceuticals, offer promising solutions due to their broad-spectrum activity, low resistance potential, and additional health-promoting properties. This review provides a comprehensive analysis of recent advances of the aforementioned compounds for companion animals, including their mechanisms of action, applications in feed and nutraceuticals, and therapeutic use in dermatological, gastrointestinal, and systemic infections. We discuss the current challenges related to bioavailability, safety, standardization, and regulatory frameworks, as well as future perspectives for integrating these agents into veterinary practice. Emphasis is placed on clinical evidence in dogs and cats, highlighting how natural antimicrobials can contribute to sustainable infection control and antimicrobial resistance mitigation under the One Health paradigm.

In clinical practice in dogs and cats, antimicrobials are frequently used, sometimes overused or misused, increasing antimicrobial resistance (AMR). In order to limit the phenomenon, laws have been enacted and guidelines for prudent and rational use of antibiotics have been developed. Interestingly, old molecules such as nitrofurantoin could be used to achieve therapeutic success and overcome AMR. To better understand the suitability of this molecule in veterinary medicine, the authors performed a revision of the literature, searching on PubMed and entering the following keywords: nitrofurantoin, veterinary medicine, dog, and cat connected by the Boolean operator “and”, without restrictions on the date of publication. Thirty papers were finally selected. It is possible to appreciate that papers dealing with nitrofurantoin have been written from the early 1960s to the middle of the 1970s, and then a long period passed without publications. Only at the beginning of the new century, nitrofurantoin was included or was sometimes the focus of papers dealing with its efficacy in veterinary medicine, mainly in the treatment of urinary tract infections. One recent paper dealt with pharmacokinetic features, and none was dedicated to pharmacokinetic/pharmacodynamic integration or modeling. Nitrofurantoin appears to be still effective against several pathogens that rarely develop resistance to this molecule.

Transient receptor potential vanilloid type 1 (TRPV1) has been investigated in humans and mammals; in recent years, some researchers have focused on this receptor in fishes. The present study aimed to identify TRPV1 receptors in cultures of RT-gill W1 cells and in the organs of rainbow trout (Oncorhynchus mykiss), in addition to evaluating the possible modulation induced by super critical fluid extract of basil (Ocimum basilicum), named F1-BEO. In vitro evaluation consisted of cell cultures and immunocytochemistry assays. During in vivo experimental sessions, eighty trout were divided into five groups that received a fish diet supplemented with 0, 0.5, 1, 2 and 3% w/w F1-BEO. Forty trout were euthanized after 15 and 30 days; organs were collected and processed according to the immunohistochemistry technique. Receptor expression was quantitatively measured using Image Pro Plus software. TRPV1 was identified in RT-gill W1 cells and in all organs, with a higher positivity in the muscle layers of the stomach, intestine and kidneys. F1-BEO induced an increased expression of TRPV1 in the stomach while a lower expression was appreciated in the bowel. No morphological alterations have been highlighted in the liver or kidneys. Further investigation will be necessary to evaluate the functionality of this receptor in rainbow trout.

Osteosarcoma (OSA) is the most frequently diagnosed primary malignant bone tumor in humans and dogs. In both species, standard chemotherapy can be limited by multidrug resistance of neoplastic cells, which prevents intracellular accumulation of cytotoxic drugs, resulting in chemotherapy failure. In this study, a lipophilic ester of doxorubicin (C12DOXO) was loaded into nanoparticles (NPs) using the “cold microemulsion dilution” method. The resulting NPs were then coated with calcium phosphate (CaP) in two different ways to have calcium or phosphate ions externally exposed on the surface. These systems were characterized by determining mean diameter, zeta potential, and drug entrapment efficiency; afterward, they were tested on human and canine OSA cells to study the role that the coating might play in increasing both drug uptake into tumor cells and cytotoxicity. Mean diameter of the developed NPs was in the 200–300 nm range, zeta potential depended on the coating type, and C12DOXO entrapment efficiency was in the 60–75% range. Results of studies on human and canine OSA cells were very similar and showed an increase in drug uptake and cytotoxicity for CaP-coated NPs, especially when calcium ions were externally exposed. Therefore, applications in both human and veterinary medicine can be planned in the near future.

Myxomatous mitral valve degeneration (MMVD) is the most common acquired cardiac disease in canine species, and valvular interstitial cells (VICs) are considered the main responsible for the development of this pathology. The scientific interest is focused on isolating and characterizing these cells. The aims of the present study were to verify a novel VICs mechanical isolation method and to characterize isolated cells using immunocytochemistry and immunofluorescence, with parallel histological and immunohistochemistry assays on bovine and canine healthy and MMVD mitral valves. Antibodies against vimentin (VIM), smooth muscle actin (SMA), von Willebrand (vW) factor, Transforming Growth Factor (TGF) β1, and Transient Receptor Potential Vanilloid 1 (TRPV1) were used. The isolation method was considered reliable and able to isolate only VICs. The different assays demonstrated a different expression of SMA in healthy and MMVD mitral valves, and TRPV1 was isolated for the first time from bovine and canine VICs and the correspondent mitral valve leaflets. The novelties of the present study are the new isolation method, that may allow correlations between laboratory and clinical conditions, and the identification of TRPV1, which will lead to further investigations to understand its function and possible role in the etiology of MMVD and to the design of new therapeutic strategies.