Veterinary Literature Research Articles

Canine and feline haemangiosarcoma.

Haemangiosarcoma (HSA) is a malignant neoplasm of dogs and cats that is suspected to originate from a pluripotent bone marrow progenitor with a complex and multifactorial pathogenesis. Pertinent literature was identified, reviewed, and summarized for inclusion in the manuscript. Dogs are more frequently diagnosed with HSA than cats, and primary sites of this disease include dermal, subcutaneous/intramuscular, and visceral (most commonly the spleen). Dogs and cats with HSA generally have a poor prognosis owing to the rapid and widespread metastasis typically associated with this disease. However, some forms such as cutaneous HSA behave in a less aggressive fashion with improved outcomes. Surgical excision and anthracycline-based chemotherapy remain the mainstays of treatment, although novel treatment modalities are currently under investigation for potential roles in treatment of this disease. This review aims to describe the clinical presentation and progression of the various forms of HSA in dogs and cats as well as to provide a systematic review of the veterinary literature with a focus on the various published treatment options and associated outcomes.

Recovering horses after general anaesthesia

The recovery phase after general anaesthesia in horses is associated with significant risk. Optimising recovery safety and improving outcomes is an active area of research in the equine veterinary literature. Several risk factors which may negatively influence recovery quality have been identified, but study results relating to treatment options have been conflicting in many cases. This review article describes the risks associated with recovery after equine anaesthesia and explores the evidence relating to physical and pharmacological options which may improve recovery quality.

A review of minimally invasive fracture stabilization in dogs and cats.

ObjectiveTo summarize and discuss peer‐reviewed studies on minimally invasive osteosynthesis (MIO) of long bone, physeal, and articular fractures in dogs and cats.Study DesignInvited review.MethodsA critique of literature was performed to assess MIO feasibility, outcomes, and complications through PubMed, Scopus, and CAB abstracts research databases (2000–2020).ResultsMore than 40 MIO articles have been published in the last 15 years, but most studies had small numbers, lacked control groups, and used limited outcome measures. Studies generally showed that MIO was feasible in dogs and cats with low complication rates. The current evidence does not demonstrate superior bone healing or functional outcomes with MIO when compared to standard methods. Although treatment principles, case selection, and techniques varied depending on the anatomical location, there were no salient differences in complication rates among long bones, physeal, and articular fractures treated by MIO.ConclusionThe current available evidence and the personal experience of the authors support MIO as a promising fracture management modality. MIO can yield excellent outcomes when applied in carefully selected cases, performed by surgeons experienced in the technique. We cannot, however, conclude that MIO is superior to open fracture stabilization based on the available evidence in veterinary literature. Randomized controlled studies are warranted to prospectively compare MIO with other osteosynthesis techniques and thereby validate its role in fracture management for dogs and cats.

Optimization of ultrasonographic ureteral jet detection and normal ureteral jet morphology in dogs.

Ureteral jets are visualized with ultrasound as echogenic streams extending from the ureterovesicular junction into the urinary bladder. In clinical practice, diuretics are sometimes administered to increase visibility of ureteral jets, however this has not been well described in the veterinary literature. The purpose of this prospective, crossover study was to describe the normal morphology of canine ureteral jets, determine an optimal protocol for diuretic administration to increase visibility of ureteral jets, and confirm in vitro the effect that differences in specific gravity and velocity have on visibility. Ultrasound of 10 normal dogs was performed at baseline and following 1mg/kg furosemide administered intravenously or subcutaneously. Increased numbers of ureteral jets were seen post-furosemide administration compared to baseline, with an overall increased number of ureteral jets identified following intravenous administration when compared to subcutaneous administration. Time to first ureteral jet was significantly shorter with intravenous compared to subcutaneous administration. Urine specific gravity significantly decreased following furosemide administration. For the in vitro study, saline solutions of varying specific gravities were infused into a bath of hypertonic saline with specific gravity of 1.037. There was good visibility in vitro with infusion of solutions of specific gravities of 1.010-1.025. Infusion of saline solution with a specific gravity of 1.030 had reduced visibility, while infusion of saline with equivalent specific gravity (1.037) was not visible with B-mode ultrasonography. Both intravenous and subcutaneous furosemide administration significantly increase ureteral jet detection with ultrasound secondary to differences in specific gravity, confirming results of prior studies.

Histopathological Parameters of Canine Bone Marrow in Cell-Block Preparations

Studies using the cell-block technique for bone marrow (BM) analysis are limited in the veterinary literature. This work assessed whether the histopathological analysis of canine BM was feasible using cell-block cytoinclusions prepared from fine-needle sternal aspirate samples. Eight clinically healthy young-to-middle-aged dogs underwent both fine-needle sternal aspiration for BM cell-block (BM-Cb) processing and iliac-crest BM core biopsy (BM-B). Histopathologic parameters were compared between the 2 methods. There were no statistically significant histopathological differences between hematopoietic tissue areas (P = .6294) in the BM-Cb and BM-B sections, and they had similar microscopic characteristics and microarchitecture. Cellularity and reticulin-fiber staining were equivalent in the BM-Cb and BM-B preparations in 87.5% (7/8) and 100% (8/8) of the sections, respectively. However, the quantitative results of the megakaryocytic series differed between BM-Cb and BM-B in 37.5% (3/8) of the sections, and the myeloid:erythroid (M:E) ratios differed between the 2 methods in 25% (2/8). These preliminary data indicate that cell-block preparations made from sternal fine-needle aspiration samples warrant continued evaluation in a larger number of animals, including those with various diseases affecting the bone marrow.

A computed tomography–based method for the assessment of canine retrobulbar cone volume for ophthalmic anaesthesia

ObjectiveTo develop a comprehensive formula for calculating the volume of local anaesthetic solution used for retrobulbar anaesthesia in dogs with different skull morphologies. Study designRetrospective cohort imaging study. AnimalsSkull computed tomography (CT) images of 188 dogs of different breeds collected between January 2009 and December 2017. MethodsAnatomical integrity of the orbit and adjacent structures, presenting complaint, clinical signs and CT findings were verified to exclude ocular abnormalities. The volume of the retrobulbar cone of 376 eyes was calculated using CT scans of the dogs’ skulls. Additional data recorded included morphology of the skull, body weight, sex and size of the dogs, all of which were matched for possible association to the retrobulbar cone volume through univariable and multivariable linear regression models. Results of linear regression models were expressed as estimated beta coefficients with the corresponding 95% confidence intervals (95% CIs). ResultsUsing univariate analysis, the retrobulbar cone volume was positively associated with weight and male sex. In addition, brachycephalic and dolichocephalic dogs showed a larger retrobulbar cone volume than mesocephalic dogs, while sex was no longer significantly associated with the retrobulbar cone volume. In multivariate analysis, when considering all variables in the model, weight emerged as the strongest predictor (beta coefficient: 0.062 mL kg–1, 95% CI: 0.056–0.067 mL kg–1, p < 0.001). Conclusionsand clinical relevance In the veterinary literature, there is no agreement on the precise volume of local anaesthetic solution that should be used to achieve intraconal retrobulbar anaesthesia in dogs. Here we suggest a formula to calculate the retrobulbar cone volume and, accordingly, the injection volume of local anaesthetic solution for effective retrobulbar anaesthesia.

Owner compliance in veterinary practice:recommendations from a roundtable discussion

Many factors influence the success of a course of treatment prescribed by a veterinary surgeon. Even if the correct diagnosis is made and the most effective treatment prescribed, the therapeutic outcome may not be optimal if the owner does not administer the medication as prescribed. Some pet owners will give all the medication prescribed for their pets at the correct time intervals. Others may miss doses, give doses at the wrong time, and/or stop treatment prematurely. There is much in the human literature relevant to medication compliance (also termed adherence and occasionally concordance) but much less in the veterinary literature. There are various problems that arise if medication is not administered as prescribed — not the least of which is suboptimal response to treatment. It is therefore important that veterinarians are aware that owners may not follow their directions, the reasons why this may be the case and the potential consequences. By understanding more about these factors we can work to put in place strategies to improve compliance/adherence. The purpose of this roundtable was to discuss many of these aspects including what term is most appropriate to use in the veterinary context.

Quality Improvement: origins, purpose and the future for veterinary practice

Introduction&#x0D; Providing the highest quality veterinary care can often be a delicate balancing act: the client/owner’s wishes, financial parameters and emotional needs have to be considered, whilst also meeting the animal’s clinical needs. But what actually defines quality care? It is a term frequently used in both the human and veterinary healthcare literature, but often has little explanation or definition attached to it. ‘Quality’ in relation to care delivered is not a static concept and will hold different meanings to different individuals within a healthcare service. John Ruskin, a Victorian writer and critic of art and society observed: ‘Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skilful execution’.&#x0D; &#x0D;

Ductal Plate Malformations in Captive Snakes

Ductal plate malformations are abnormalities in the liver that arise from inappropriate or incomplete remodeling of the embryologic ductal plate. Various types of ductal plate malformations are reported in the human and veterinary literature, most commonly affecting domestic mammalian species but also fish. We investigated the occurrence and described the histopathologic features of ductal plate malformations in captive snakes. Malformations were identified in 18 snakes: 10 colubrids, 6 vipers, and 2 boids. There was no sex predilection, and the mean age was 17 years. The majority of lesions were incidental with most snakes having one or more comorbidities, most commonly neoplasia or systemic inflammation, that resulted in natural death or euthanasia. Ductal plate malformations in all livers were broadly characterized by a well-demarcated nodule of irregular bile ducts embedded within a varying amount of fibrous stroma. Malformations were further categorized based on the amount of fibrous stroma and dilation of the bile ducts as von Meyenburg complexes, cystic liver disease, and/or an intermediate hybrid subtype representative of cysts arising within von Meyenburg complexes. Histochemical and immunohistochemical staining, including Gomori's trichome and pan-cytokeratin, respectively, were applied on select cases to confirm histologic features. Malignant transformation was not identified within this population.

Characterizing Canine Hepatobiliary Neuroendocrine Neoplasia: A Proteomic Approach

Hepatobiliary neuroendocrine neoplasia is an extremely rare cancer in humans and other species. In humans, neuroendocrine neoplasia of the liver and gallbladder represents less than 2% of all gastroenteropancreatic neuroendocrine neoplasia. In the veterinary literature, there is a paucity of information on hepatobiliary neuroendocrine cancer with only a small number of published studies. Improved characterization of these tumors is needed to identify additional biomarkers for diagnosis and generate informed treatment protocols for human and veterinary patients. Here, we applied a proteomics strategy to identify differentially expressed proteins in canine hepatobiliary neoplasia as compared to normal canine adrenal and liver tissue from formalin-fixed paraffin-embedded samples. Our objective was to identify unique protein biomarkers and possible chemotherapeutic targets. Thirty-four up-regulated, differentially expressed proteins were identified in the hepatobiliary neuroendocrine neoplasia samples. Galectin-1, a multivalent carbohydrate binding protein known to play a role in lung and pancreatic neuroendocrine neoplasia development and progression, was among them. Drugs targeting the galectin family have shown promise as anticancer therapeutics in cervical cancer, prostate cancer, lung and pancreatic neuroendocrine neoplasia. Galectin-1 may represent a novel treatment target in hepatobiliary neuroendocrine neoplasia in both humans and dogs.

Advances in our understanding of canine atopic dermatitis.

Canine atopic dermatitis (cAD) is a genetically inherited clinical syndrome that encompasses a diversity of mechanisms and can have a variety of triggers. Development of clinical disease is the result of genetic factors and environmental conditions, which shape the resulting immunological response. Clinical disease becomes evident once a threshold of inflammatory response is achieved. Skin barrier impairment plays a role in promoting cutaneous dysbiosis and increased allergen penetration. Keratinocytes shape the response of dendritic cells and subsequent lymphocytic response. Thymic stromal lymphopoietin is one of the links between the damaged skin barrier and the modulation of a T-helper (Th)2 response. It is still unclear whether mutations in skin barrier genes exist in atopic dogs, as they do in humans, or whether the observed alterations are purely secondary to inflammation. A dysregulated immune response with increased Th2, Th17 and CD4+ CD25+ regulatory T cells has been reported. A variety of cytokines [interleukin(IL)-31, IL-34, Macrophage migration inhibitory factor] are proposed as potential biomarkers and treatment targets because they are increased in the serum of atopic dogs when compared to controls, although a correlation between serum levels of these factors and severity of disease is not always present. The main issue with many published studies is that atopic dogs are always only compared to normal controls. Thus, it is unclear whether the changes that we find are truly a signature of cAD or merely a manifestation of nonspecific broad inflammatory responses. Studies considering comparison with other inflammatory diseases different from cAD are urgently needed to correctly identify what is specific to this complicated syndrome.

Intravenous Fluid Administration and the Coagulation System.

Intravenous fluid administration in veterinary patients can alter coagulation function by several mechanisms. Both crystalloid and colloid fluids cause hemodilution, reducing platelet count and plasma coagulation protein concentrations. Hemodilution is associated with a hypercoagulable effect at low dilutions and a hypocoagulable effect at higher dilutions. Composition of crystalloid fluids likely has a minor effect, primarily dependent on fluid ion composition. Hypertonic crystalloids may also cause hypocoagulability. Colloids, both synthetic and natural, can cause hypocoagulability by several mechanisms beyond the effects of hemodilution. These include impaired platelet function, decreased plasma coagulation factor activity, impaired fibrin formation and crosslinking, and accelerated fibrinolysis. The vast majority of the veterinary literature investigates the hypocoagulable effects of hydroxyethyl starch–containing fluids using in vitro, experimental, and clinical studies. However, results are inconsistent, likely due to the varying doses and physicochemical properties of the specific fluid products across studies. In addition, some evidence exists for hypocoagulable effects of gelatin and albumin solutions. There is also evidence that these colloids increase the risk of clinical bleeding in people. Limitations of the veterinary evidence for the hypocoagulable effects of colloid fluids include a predominance of in vitro studies and in vivo studies using healthy subjects, which exclude the interaction of the effects of illness. Therefore, clinical relevance of these effects, especially for low-molecular-weight hydroxyethyl starch, is unknown. Firm recommendations about the most appropriate fluid to use in clinical scenarios cannot be made, although it is prudent to limit the dose of synthetic colloid in at-risk patients. Clinicians should closely monitor relevant coagulation assays and for evidence of hemorrhage in at-risk patients receiving any type of fluid therapy, especially in large volumes.

Aggressive squamous cell carcinoma of the cranium of a dog

BackgroundThe authors report a case of keratinized squamous cell carcinoma (SCC) in a 14-year-old dog with extensive cranial bone invasion. To our knowledge, this is the first description of such a case of cranial keratinized SCC with aggressive generalized osteolysis described in a dog.Case presentationThe 14-year-old dog was referred for radiological examination with suspicion of head trauma with clinical signs of head deformation, exophthalmos and nasal discharge. The skull radiographs showed a large osteolytic defect of the frontal bone and parietal bone in the region of the external sagittal crest. Findings from the skull CT scan included generalized osteolysis in the region of parietal bone, frontal bones, maxilla on the right side and the nasal bone including the dorsal nasal concha. In the area of bone loss, new soft tissue formation with multifocal foci of mineralization was visible. The ultrasound examination revealed hypoechogenic changes with hyperechoic foci consistent with mineralization and poor vascularization. The brain and ocular structures were without visible changes. Fine needle aspiration cytology (FNAC) was performed, and squamous cell carcinoma was suspected. After 3 months, the re-presented to the clinic. The dog became progressively listless, his appetite was decreased, and he became acutely blind. Follow-up skull CT scan revealed significant osteolysis, which affected a significant aspect of the cranium. All bone defects had been replaced by new 3.5 cm-thick soft tissue formations with multifocal small 1–2 mm areas of mineralization. There was no evidence of metastasis. Histological examination confirmed the suspicion of squamous cell carcinoma.ConclusionsThis paper is the first report of cranial SCC in a dog causing extensive bone osteolysis. The lesions in this dog originated from the frontal and parietal bones including frontal sinuses.There are variants of tumors that arise from squamous epithelium or resemble SCC in the skull. These examples include adenosquamous carcinoma and proliferating trichilemmal tumours. In addition, there is possible malignant transformation caused by papilloma viruses. In the veterinary literature, there is only one similar description of adenosquamous carcinoma in a cat with similar clinical manifestations. It is justified to suspect a process of neoplastic epithelial origin in all cases of aggressive and extensive skull bone lysis. This issue should be subject to further investigation.

Epizootic situation on IRT of cattle in the territory of the Moscow and Tver regions

Currently, despite all the measures taken by the Ministry of Agriculture of the Russian Federation and the Rosselkhoznadzor to regionalize the territory of the Russian Federation for infectious animal diseases, the status of subjects for many of them has not yet been determined. As of March 09, 2021, the status of infectious bovine rhinotracheitis has not been determined for 69 subjects of the country, including for the Moscow and Tver regions. At the same time, the official veterinary literature indicates the widespread distribution of cattle IRT in our country. In fact, the current epizootic situation for this disease both on the territory of the whole country and in individual subjects remains unknown. In this paper, we tried to clarify the epizootic situation of infectious bovine rhinotracheitis in the Moscow and Tver regions of the Russian Federation using active monitoring methods. As a result of sample studies in farms located on the territory of these regions, it was found that the results of serological studies do not always correlate with the status of vaccination of animals. In some farms, animals are vaccinated against cattle IRT, however, the results of serological studies in these farms indicate that the young animals in these farms are not immune to IRT. This fact clearly indicates the weak effectiveness of anti-epizootic measures aimed at specific prevention of infectious rhinotracheitis of cattle in individual livestock farms and the lack of a unified approach to the organization of this issue as a whole. Nevertheless, we found that the livestock farms in which the circulation of the cattle IRT virus is registered are not evenly located on the territory of the surveyed regions. Such farms are located in the north, north-west, south-west and east of the Moscow Region. In the Tver region - in the south-west, north-west, north-east and east of the region.

MORTALITY REVIEW FOR THE NORTH AMERICAN SNOW LEOPARD (PANTHERA UNCIA) ZOO POPULATION FROM JANUARY 1999 TO DECEMBER 2019

The objective of this 20-yr retrospective study was to review and summarize causes of mortality in the North American (NA) snow leopard population to inform and enhance animal health and husbandry practices. Pathology reports were requested from all NA zoological institutions housing snow leopards that died between 01 January 1999 and 31 December 2019. Data were reviewed and cause of death (COD) and concurrent diseases were summarized and compared by age group, organ system, and disease process. The 241 snow leopards in this report include 109 males, 130 females, and two of undetermined sex. Among them were 116 geriatric snow leopards (>15 yr), 72 adults (15-3 yr), 16 juveniles (3 yr to 2 mo), 32 neonates (2 mo to 0 days), and five fetuses (<0 days). Overall, noninfectious diseases were the most common COD across all age groups (73%). In adult and geriatric snow leopards, chronic renal disease (CRD) (38.8%) and malignant neoplasia (19.7%), including oral squamous cell carcinoma (6.4%), were a common COD. In juveniles and neonates, perinatal death and congenital diseases, including ocular coloboma (15.6%), were a common COD. Individuals with CRD were 13.5 and 4.36 times more likely to have veno-occlusive disease and cardiac fibrosis, respectively. Snow leopards with urolithiasis were 5.27 times more likely to have CRD. Infectious (14.1%) and inflammatory diseases (8.7%) for which no specific etiology was identified were less common overall and more common in juveniles and neonates (25% and 21%, respectively). Neoplasms not previously reported in snow leopards or that are generally uncommon in the veterinary literature included transitional cell carcinoma of the urinary bladder (n = 7) and mesothelioma (n = 1).

Effect of light exposure on growth rate of veterinary clinical dermatophyte isolates

Veterinary textbooks and literature suggest that exposure to light is inhibitory to growth of clinical dermatophyte isolates. We hypothesized that this idea was derived from experiments that examined the effect of high doses of ultraviolet and visible light exposure on dermatophyte growth, and that exposure to typical room lighting would not adversely affect dermatophyte growth rate. Isolates of common veterinary dermatophytes (three each of Microsporum canis, Nannizia gypsea and Trichophyton benhamiae) were exposed to typical fluorescent room lighting, incubated in a closed drawer, or exposed at close range to fluorescent wide-spectrum light. Dermatophytes were grown on Sabouraud Dextrose Agar (SAB) and Dermatophyte Test Medium (DTM). Colony diameter was measured and growth rate (expressed as colony diameter increase mm/day) calculated at the linear portion of the culture growth curve. Statistical analyses compared growth rates across the various incubation conditions and among dermatophyte isolates. There was little difference in growth rate between cultures incubated under typical fluorescent room lighting and those placed in the dark. Exposure to the close-range light increased growth rate as a consequence of the elevated incubation temperature created by the lamp. Significant differences in growth rate were noted among strains of the same dermatophyte species. Dermatophytes grew more rapidly on SAB than DTM agar. Exposure to typical lighting conditions in a clinical environment does not inhibit growth of dermatophyte colonies. Veterinary clinicians may conduct routine dermatophyte cultures without incubating them in the dark.

Current Evidence on Using Platelet Rich Plasma as a Therapeutic Modality for Veterinary Orthopedic Conditions

This review evaluates the findings of available clinical literature on the use of platelet-rich plasma (PRP) to develop evidence-based recommendations for treating various musculoskeletal issues that arise in veterinary practice. The use of PRP-based treatments for various orthopedic conditions is rapidly evolving as a promising treatment modality; however, its true effectiveness has yet to be elucidated. Application of PRP has been reported in humans for a variety of orthopedic conditions. Although the majority of the veterinary literature on PRP reports its use in equine patients, there is a dearth of evidence addressing its use in canine patients. Nevertheless, evidence of the efficacy of PRP has appeared to be highly variable depending on its specific indication, particularly in musculoskeletal disorders. This review aims to present the available information on the efficacy of PRP therapy in veterinary orthopedic conditions and describes factors influencing its use, the limitations of PRP therapy, and future directions of PRP research and therapy.

Feline cardiopulmonary resuscitation: Getting the most out of all nine lives.

Cardiopulmonary arrest (CPA) can occur in any veterinary or animal care setting and is a particular risk in scenarios involving ill, injured or anesthetized patients. Education of all staff on the prevention and recognition of CPA, as well as the performance of cardiopulmonary resuscitation (CPR), is vital to influencing outcome. While there is a plethora of information regarding CPA and CPR in human medicine, there are comparably few studies in the veterinary literature. Many of the current veterinary guidelines are extrapolated from human medicine or studies based on animal models. Ongoing work is needed to tailor guidelines and recommendations to our domestic feline (and canine) patients in a clinical setting. The aim of this article, which is intended for veterinarians in all areas of small animal practice, is to provide an evidence-based review of CPA and CPR in feline patients. The authors have drawn heavily on detailed recommendations published by the Reassessment Campaign on Veterinary Resuscitation (RECOVER) initiative - one of the few resources specific to the veterinary clinical setting - as well as reviewing the available peer-reviewed literature studies, in constructing this article. Among the topics discussed are recognizing and preventing CPA, staff training and clinic preparedness, basic life support and advanced life support interventions, and appropriate post-cardiac arrest care.

Magnetic resonance imaging of the normal dromedary camel tarsus

BackgroundMagnetic resonance imaging (MRI) is the most versatile and informative imaging modality for the diagnosis of locomotor injuries in many animal species; however, veterinary literature describing the MRI of the dromedary camel tarsus is lacking. Our purpose was to describe and compare the MRI images of twelve cadaveric tarsi, examined in a 1.5 Tesla MRI scanner, with their corresponding anatomical gross sections. Turbo spin-echo (TSE) T1-weighted (T1), T2-weighted (T2), proton density-weighted (PD), and short tau inversion recovery (STIR) sequences were obtained in 3 planes. Tarsi were sectioned in sagittal, dorsal, and transverse planes. MRI images from different sequences and planes were described and compared with the anatomical sections.ResultsThe soft and osseous tissues of the dromedary camel tarsus could be clearly defined on MRI images and corresponded extensively with the gross anatomic sections. The obtained MRI images enabled comprehensive assessment of the anatomic relationships among the osseous and soft tissues of the camel tarsus. Several structure were evaluated that cannot be imaged using radiography or ultrasonography, including the transverse inter-tarsal ligaments, the talocalcaneal ligament, the short dorsal ligament, branches of the short medial and lateral collateral ligaments and the tarsometatarsal ligaments. Specific anatomical features regarding the dromedary camel tarsus were identified, including the fused second and third tarsal bone, an additional bundle of the short medial collateral ligament connecting the talus and metatarsus and the medial and lateral limbs of the long plantar ligament.ConclusionsMRI images provided a thorough evaluation of the normal dromedary camel tarsus. Information provided in the current study is expected to serve as a basis for interpretation in clinical situations.

Fluid Therapy in Dogs and Cats With Sepsis.

Sepsis is currently defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis may occur secondary to infection anywhere in the body, and its pathogenesis is complex and not yet fully understood. Variations in the host immune response result in diverse clinical manifestations, which complicates clinical recognition and fluid therapy both in humans and veterinary species. Septic shock is a subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone. Although septic shock is a form of distributive shock, septic patients frequently present with hypovolemic and cardiogenic shock as well, further complicating fluid therapy decisions. The goals of this review are to discuss the clinical recognition of sepsis in dogs and cats, the basic mechanisms of its pathogenesis as it affects hemodynamic function, and considerations for fluid therapy. Important pathophysiologic changes, such as cellular interaction, microvascular alterations, damage to the endothelial glycocalyx, hypoalbuminemia, and immune paralysis will be also reviewed. The advantages and disadvantages of treatment with crystalloids, natural and synthetic colloids, and blood products will be discussed. Current recommendations for evaluating fluid responsiveness and the timing of vasopressor therapy will also be considered. Where available, the veterinary literature will be used to guide recommendations.