Journal Articles
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Item Mammary tubulopapillary carcinoma in a mare, requiring bilateral mastectomy.(Informa UK Limited, trading as Taylor & Francis Group, 2023-08-30) Beggan CP; Quinn GC; D'Amours GHMammary neoplasia is uncommon in the mare and often mistaken for mastitis (Reppas et al. Citation1996). Incidence rates of mammary tumours in horses of 0.1–1.9% are reported, with carcinomas the most common (Brito et al. Citation2008). Due to the low incidence, and similarity of initial signs to those of mastitis, diagnosis is often delayed until after antibiotic and anti-inflammatory treatment has failed (Boyce and Goodwin Citation2017). Mares are often, therefore, presented in an advanced stage of disease with a poor prognosis (Ferreira Júnior et al. Citation2019). Due to the infrequency of mammary neoplasia in horses it has been difficult to develop an evidence based approach to treatment. Studies in domestic animals report a low success rate with conservative management of these neoplasms. Combined with their highly aggressive and metastatic nature, surgical excision has been perceived as the treatment of choice in the initial management of these neoplasms (Seahorn et al. Citation1992).Item Cerebrospinal fluid Lyme multiplex assay results are not diagnostic in horses with neuroborreliosis(Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine., 2018-03) Johnson AL; Johnstone LK; Stefanovski DBACKGROUND: The accuracy of the Lyme multiplex assay for the diagnosis of neuroborreliosis in horses is unknown. HYPOTHESIS/OBJECTIVES: To describe Lyme multiplex results in horses with a postmortem diagnosis of neuroborreliosis. The hypothesis was that paired serum and cerebrospinal fluid (CSF) results and a CSF : serum ratio would allow differentiation of horses with neuroborreliosis from those with other neurologic diseases. ANIMALS: Ninety horses that had neurologic examinations, serum and CSF Lyme multiplex analyses, and postmortem examination of the nervous system performed. METHODS: Retrospective study. Data collected included signalment, ante- and postmortem diagnoses, and serum and CSF Lyme multiplex results. The CSF : serum ratio was calculated by dividing CSF median fluorescent intensity (MFI) by serum MFI for each result. RESULTS: Ten horses had a final diagnosis of neuroborreliosis, 70 were diagnosed with other neurologic diseases, and 10 had no neurologic disease. Not all horses with neuroborreliosis had positive results: 4/10 had at least 1 positive serum result, 5/10 had at least 1 positive CSF result, and 3/10 had at least 1 CSF result 4-fold higher than the corresponding serum result. Results were similar for the 70 horses with other neurologic diseases: 53% had at least 1 positive serum result, 50% had at least 1 positive CSF result, and 16% had at least 1 CSF result 4-fold higher than the corresponding serum result. CONCLUSIONS AND CLINICAL IMPORTANCE: Positive Lyme multiplex results were common in horses with neurologic diseases and did not adequately differentiate horses with neuroborreliosis from horses with other disorders.Item Prevalence and Sequence Analysis of Equine Rhinitis Viruses among Horses in Poland.(MDPI (Basel, Switzerland), 2024-07-26) Stasiak K; Dunowska M; Rola J; Troyer REquine rhinitis A (ERAV) and B (ERBV) viruses are respiratory pathogens with worldwide distribution. The current study aimed to determine the frequency of infection of ERAV and ERBV among horses and foals at Polish national studs, and to determine genetic variability within the viruses obtained. Virus-specific quantitative RT-PCR assays targeting a 5' untranslated region were used to screen nasal swabs collected from 621 horses at 16 national horse studs from throughout Poland, including 553 healthy horses and 68 horses with respiratory disease. A partial DNA polymerase gene was amplified and sequenced from the qRT-PCR-positive samples. The obtained sequences were analysed using phylogeny and genetic network analysis. None of the nasal swabs were positive for ERAV, whereas ERBV was found in 11/621 (1.78%) samples collected from 10 healthy horses and one foal affected by respiratory disease. Partial DNA polymerase gene sequence variability was correlated with individual horses and studs from which samples were collected when only Polish sequences were analysed, but there was no correlation between country of origin and ERBV sequence when Polish and international sequences were included in the network. The report presents the first detection of ERBV in Poland.Item Prevalence and genetic diversity of Theileria equi from horses in Xinjiang Uygur Autonomous region, China.(Elsevier B.V., 2023-07-01) Zhang Y; Shi Q; Laven R; Li C; He W; Zheng H; Liu S; Lu M; Yang DA; Guo Q; Chahan BTheileria equi is a tick-borne intracellular apicomplexan protozoan parasite that causes equine theileriosis (ET). ET is an economically important disease with a worldwide distribution that significantly impacts international horse movement. Horses are an essential part of the economy in Xinjiang which is home to ∼10% of all the horses in China. However, there is very limited information on the prevalence and genetic complexity of T. equi in this region. Blood samples from 302 horses were collected from May to September 2021 in Ili, Xinjiang, and subjected to PCR examination for the presence of T. equi. In addition, a Bayesian latent class model was employed to estimate the true prevalence of T. equi, and a phylogenetic analysis was carried out based on the 18S rRNA gene of T. equi isolates. Seventy-two horses (23.8%) were PCR positive. After accounting for the imperfect PCR test using a Bayesian latent class model, the estimated true prevalence differed considerably between age groups, being 10.8% (95%CrI: 5.8% - 17.9%) in ≤ 3-year-old horses and 35.7% (95%CrI: 28.1% - 44.5%) in horses that were > 3 year-old. All T. equi isolates had their 18S rRNA gene (430bp) sequenced and analyzed in order to identify whether there were multiple genotypes of T. equi in the Xinjiang horse population. All of the 18S rRNA genes clustered into one phylogenetic group, clade E, which is thus probably the dominant genotype of T. equi in Xinjiang, China. To summarize, we monitored the prevalence of T. equi in horses of Xinjiang, China, with a focus on the association between age and the occurrence of T. equi by Bayesian modelling, accompanied by the genotyping of T. equi isolates. Obtaining the information on genotypes and age structure is significant in monitoring the spread of T. equi and studying the factors responsible for the distribution.Item Survival of formalin intoxication in a 13-year-old Thoroughbred gelding.(John Wiley and Sons, Inc., 2024-04-05) Lovett A; Vokes J; Loghides N; Johnstone L; Sykes BBACKGROUND: Formalin intoxication via the gastrointestinal route has not been previously reported in the horse. Whereas ingestion of formalin in humans, although rare, is well documented. Majority of human cases are either accidental, suicidal or homicidal and often lead to fatality, with a reported lethal formaldehyde dose equating to 0.12 - 0.16 g/kg bwt. OBJECTIVES: To describe a single case report of the clinical management of an adult horse referred to a veterinary teaching hospital following accidental administration of 10% formalin via nasogastric tube. METHODS: A 13-year-old Thoroughbred gelding originally presented to the referring veterinarian for colic where 1.8 L of 10% formalin was accidentally administered instead of mineral oil via nasogastric intubation, a potentially lethal dose of formaldehyde (0.12 g/kg bwt). Approximately 20-hours following 10% formalin administration the horse was admitted to the referral hospital with moderate tachycardia, occasional ectopic beats, tacky and hyperaemic mucous membranes, delayed capillary refill time, reduced borborygmi, and pronounced digital pulses. Diagnostic investigations included laboratory blood analysis, urinalysis, electrocardiogram, abdominal ultrasound, palpation per rectum and gastroscopy. RESULTS: Patient assessment found evidence of toxicity to the gastrointestinal tract, hypovolaemia and risk for laminitis. Intensive care included fluid and electrolyte therapy, anti-inflammatories and analgesia, continuous digital cryotherapy, gastro-protectants and other methods of gastrointestinal support. The horse was discharged from hospital on day 14 with no long-term complications and the client-veterinarian relationship was preserved. DISCUSSION: In human cases of ingestion, gastrointestinal injury is typically accompanied by severe metabolic acidosis and multiple organ dysfunction syndrome due to toxicity of other body systems that can contribute to non-survival. Formaldehyde toxicity in the present case predominantly affected the gastrointestinal tract, most likely a direct result of the route of administration. Aside from gastrointestinal injury, primary toxicity of other body systems was not confirmed. To prevent this medical error recurring, the referring veterinary clinic revised their labelling and storage of 10% formalin. CONCLUSION: This is the first report of systemic formalin intoxication in the horse. Following a high dose of 10% formalin (0.12 g/kg bwt formaldehyde) enterally, the horse survived having received intensive supportive care based on human guidelines for ingested formalin.Item Tetanus prophylaxis in horses: guidelines for New Zealand and Australia based on a critical appraisal of the evidence.(Taylor and Francis Group, 2024-06-23) Lovett AL; Riley CB; Chapman V; Bell B; Bishop B; Grierson A; Johnstone LJ; Sykes BWHorses are exquisitely sensitive to tetanus neurotoxin and are exposed to the risk of infection with Clostridium tetani throughout life. The vaccine against tetanus is highly effective at preventing disease, whereas tetanus in unvaccinated populations is associated with high mortality rates. Current guidelines in New Zealand and Australia for the available vaccine contain contradictions and limitations surrounding the optimal tetanus immunisation protocols for both adult horses and foals. This review critically evaluates the scientific literature on tetanus prophylaxis in horses within the context of equine practice and available products in New Zealand and Australia. The review was conducted by a panel of industry and specialist veterinarians to obtain agreement on nine equine tetanus prophylaxis guidelines for practising veterinarians. The primary protocol for tetanus toxoid (TT) immunisation consists of a three-dose series IM for all horses ≥ 6 months of age, and a four-dose series IM is proposed if commencing vaccination in foals between 3 and 6 months of age. Tetanus prophylaxis in foals < 3 months of age relies on passive immunity strategies. Following the completion of the primary protocol, a TT booster dose IM should be administered within 5 years, and every 5 years thereafter. When followed, these protocols should provide adequate protection against tetanus in horses. Additional tetanus prophylaxis guidelines are provided for veterinarians attending a horse experiencing a known "risk event" (e.g. wound, hoof abscess, surgery, umbilical infection). When a correctly vaccinated horse experiences a risk event, pre-existing immunity provides protection against tetanus. When an unvaccinated horse or one with unknown vaccination status, or a foal born to an unvaccinated dam, experiences a risk event, TT IM and tetanus antitoxin (TAT) 1,500 IU SC should be administered simultaneously at separate sites, and the TT primary immunisation protocol should subsequently be completed for the horse's respective age. In previously immunised pregnant broodmares, a TT booster dose administered 4-8 weeks prior to parturition optimises the transfer of passive immunity against tetanus to the newborn foal via colostrum; provided that post-natal IgG concentration in serum is > 800 mg/dL (8 g/L), such foals should be passively protected against tetanus up to 6 months of age. Survivors of clinical tetanus must still receive the primary protocol for vaccination against tetanus. In summary, all horses in New Zealand and Australia should be vaccinated against tetanus with protection maintained throughout life via TT booster doses, facilitated by accurate medical record keeping and client education.Item Thromboelastography in obese horses with insulin dysregulation compared to healthy controls.(John Wiley and Sons, Inc., 2022-05-01) Lovett AL; Gilliam LL; Sykes BW; McFarlane DBACKGROUND: Both obesity and metabolic syndrome are associated with hypercoagulability in people, increasing the risk of cardiovascular disease and thromboembolic events. Whether hypercoagulability exists in obese, insulin-dysregulated horses is unknown. HYPOTHESIS/OBJECTIVES: To determine if coagulation profiles differ between healthy horses and those with obesity and insulin dysregulation. ANIMALS: Fifteen healthy horses (CON) and 15 obese, insulin-dysregulated horses (OBID). Individuals were university or client owned. METHODS: Case-control study. Obesity was defined as a body condition score (BCS) ≥7.5/9 (modified Henneke scale). Insulin dysregulation status was assessed by an oral sugar test (OST). Kaolin-thromboelastography and traditional coagulation variables were compared between groups. The direction and strength of the association between coagulation variables and BCS and OST results were determined using Spearman's correlation. RESULTS: Thromboelastography variables MA (OBID: 69.5 ± 4.5 mm; CON: 64.8 ± 4.3 mm; P = .007) and G-value (OBID: 11749 ± 2536 dyn/m2 ; CON: 9319 ± 1650 dyn/m2 ; P = .004) were higher in OBID compared to CON. Positive correlations between MA and BCS (R = 0.45, P = .01) and serum insulin (T0 : R = 0.45, P = .01; T60 : R = 0.39, P = .03), and G-value and BCS (R = 0.46, P = .01), and serum insulin (T0 : R = 0.48, P = .007; T60 : R = 0.43, P = .02; T90 : R = 0.38, P = .04) were present. CONCLUSIONS AND CLINICAL IMPORTANCE: Obese, insulin-dysregulated horses are hypercoagulable compared to healthy controls.Item Sarcoid within the oral cavity of a horse.(Elsevier B.V., 2024-02-01) Munday JS; Lewis MC; Leyland MHEquine sarcoids are common skin tumors that are thought to be caused by cross-species infection by bovine papillomaviruses (BPV). A 16-year-old horse developed a 1cm diameter mandibular gingival mass opposite the right second premolar tooth (406) and a 2cm diameter mass close to the commissure of the lips on the same side of the mouth. The right cheek was diffusely thickened. Histology of the smaller mass revealed a proliferation of mesenchymal cells covered by hyperplastic epithelium that formed thick rete pegs. BPV2 DNA was amplified from the mass. Although the mass had been incompletely excised, there was no recurrence after 5 months. The histological features and detection of BPV2 DNA is consistent with a diagnosis of equine sarcoid. Sarcoids have not previously been reported in the oral cavity of horses. It is hypothesized that trauma to the mouth may have been important for sarcoid development. Additionally, different BPV types may have variable ability to infect the gingiva. While rare, sarcoids are a differential for an oral mass in a horse.Item Kinetics of the Equid Herpesvirus 2 and 5 Infections among Mares and Foals from Three Polish National Studs(MDPI (Basel, Switzerland), 2022-04) Stasiak K; Dunowska M; Rola J; Paillot R; Freed EOEquid herpesvirus 2 (EHV-2) and 5 (EHV-5) are two γ-herpesviruses that are commonly detected from horses worldwide, based on several cross-sectional molecular surveys. Comparatively few studies examined the dynamics of γ-herpesvirus infection over time in a group of horses. The aim of the current study was to investigate the dynamics of EHV-2/5 infections among mares and their foals at three Polish national studs with different breeds of horses: Arabians, Thoroughbreds and Polish Konik horses. Nasal swabs were collected from each of 38 mare-foal pairs monthly for a period of 6 to 8 months. Virus-specific quantitative PCR assays were used to determine the viral load of EHV-2 and EHV-5 in each sample. All 76 horses sampled were positive for EHV-2 or EHV-5 on at least one sampling occasion. The majority (73/76, 96%) were infected with both EHV-2 and EHV-5. In general, the mean load of viral DNA was higher in samples from foals than from mares, but similar for EHV-2 and EHV-5 at most sampling occasions. There was, however, a considerable variability in the viral DNA load between samples collected at different times from the same foal, as well as between samples from different foals. The latter was more apparent for EHV-2 than for EHV-5. All foals became infected with both viruses early in life, before weaning, and remained positive on all, or most, subsequent samplings. The virus shedding by mares was more intermittent, indicating the existence of age-related differences. Overall, the data presented extend our knowledge of EHV-2/5 epidemiology among mares and foals.Item A Cross Sectional Survey of International Horse-Racing Authorities on Injury Data Collection and Reporting Practices For Professional Jockeys(Elsevier Inc, 2021-09) O'Connor S; Hitchens PL; Bolwell C; Annan R; McGoldrick A; Fortington LVJockey injuries are common in professional horse-racing and can result in life-threatening or career-ending outcomes. Robust injury data are essential to understand the circumstances of injury occurrence and ultimately identify prevention opportunities. This study aimed to identify jockey injury surveillance practices of international horse-racing authorities (HRAs) and the specific data items collected and reported by each HRA. A cross-sectional survey of representatives (e.g. Chief Medical Officer) from international HRAs was conducted. An online and paper questionnaire was designed comprised of 32 questions. Questions considered the barriers and facilitators to data collection within each HRA, and where available, what data were collected and reported by HRAs. Representatives from 15 international racing jurisdictions were included, of which 12 reported collection of race day injuries or falls, using varied definitions of medical attention and time loss. Six HRAs did not have a definition for a jockey injury, and eight HRAs had no parameters for describing injury severity. Race day exposure was collected by two HRAs. Results were commonly presented by HRAs as the number of injuries (n = 9/15) or proportion of injured jockeys (n = 6/15). The lack of a designated role for collection, collation and reporting of data was the main barrier for injury surveillance. Twelve HRAs agreed that mandatory collection would be a strong facilitator to improving practice. Enhancement and standardization of international jockey injury surveillance is required to move forward with evidence informed prevention. Concurrent investigation of how reporting practices can be best supported within existing HRA structures is recommended.