Equine pleuropneumonia

Age-Related Differences in Short-Term Transportation Stress Responses of Horses

Transportation of horses on short journeys can lead to an increase in stress. There are known age-associated changes in immune and metabolic responses in horses; however, no research exists evaluating how age may influence these responses to transportation stress. Eleven mares within two age groups, aged (n = 5, 22 ± 1 year) or young (n = 6, 2 ± 1 year), were transported 1 hour and 20 minutes. Peripheral blood and saliva were collected before and after transportation at baseline (2 to 3 weeks prior to transportation), 24 hours pre-transport, 1 hour before loading, 15 minutes, 30 minutes, 1 to 3 hours, 24 hours and 8 days post-transport. Heart rates, rectal temperatures, under the tail temperatures, serum cortisol, plasma ACTH, serum insulin, salivary cortisol and salivary IL-6 were measured. Whole blood gene expression of the cytokines IL-1b, IL-2, IL-6, IL-10, IFNγ, and TNFα were determined through qPCR, and peripheral blood mononuclear cells were isolated, stimulated, and stained to determine IFNγ and TNFα production. Serum cortisol (P < .0001), salivary cortisol (P < .0001) and heart rate (P = .0002) increased in response to transportation with no age differences. Rectal (P = .03) and under the tail temperatures (P = .02) were increased in young versus aged horses. ACTH was higher in aged horses (P = .007) and post-transportation (P = .0001). Aged horses showed a greater increase in insulin compared with young horses (P < .0001). While age does not seem to impact cortisol responses to short-term transportation in horses, it did influence the post transportation insulin response to stress in aged horses.

Bacterial pneumonia in horses associated with Escherichia coli infection: report of five cases

ABSTRACT Respiratory diseases have a major impact on sport horses and are often cited as the second most common reason for loss of training days and significant veterinary costs. Adult horses most commonly develop pneumonia when bacteria aspirated from the environment, nose, or oropharynx reach the lower airways and overwhelm the pulmonary defense mechanisms. This article report five cases of bacterial pneumonia in horses associated with infection by Eschericia coli. Five Quarter horses, three males and two females, with ages varying from 5 to 12 years, were examined for diagnosis of respiratory disease characterized by apathy, cough and lack of appetite. Auscultation of the thorax revealed increased harsh breath sounds dorsally, crackles, wheezes, and dullness of respiratory sounds ventrally. Manipulation of the trachea and larynx induced cough. Culture results were positive for Escherichia coli. The therapeutic protocol consisted of anti-inflammatory, antibiotic therapy, and supportive care. Flunixin meglumine was administered intravenously at 24-hour intervals over eight days. Ceftiofur sodium was prescribed intramuscularly, q.d., for 15 days. Horses were clinically monitored daily until complete remission of clinical signs. None of the animals relapsed, and all returned to routine athletic activities.

Welfare of equidae during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of animal welfare legislation. This opinion deals with the protection of horses and donkeys during transport. While the opinion focuses primarily on road transport of horses, there are specific sections dealing with the transport of horses on roll-on-roll-off ferries, horses transported by air and the transport of donkeys. In addition, the opinion covers welfare concerns in relation to a specific scenario identified by the European Commission related to the transport of horses on long journeys to slaughterhouses. Current practices related to transport of horses during the different stages (preparation, loading and unloading, transit and the journey breaks) are described. Overall, 13 welfare consequences were identified as being highly relevant for the welfare of horses during transport based on severity, duration and frequency of occurrence: gastro-enteric disorders, handling stress, heat stress, injuries, isolation stress, motion stress, prolonged hunger, prolonged thirst, respiratory disorders, resting problems, restriction of movement, sensory overstimulation and separation stress. These welfare consequences and their animal-based measures are described. A variety of hazards were identified related to factors such as inexperienced/untrained handlers, lack of horse training, structural deficiencies of vehicles/facilities, poor driving skills/conditions, horse separation/regrouping, unfavourable microclimatic and environmental conditions and poor husbandry practices. The opinion contains general and specific conclusions in relation to the different stages of transport. Recommendations to prevent hazards and correct or mitigate welfare consequences have been developed. Recommendations were also developed to define quantitative thresholds for microclimatic conditions within the means of transport and for space allowance. The development of welfare consequences over time was assessed in relation to maximum journey time.

Journeys, Journey Conditions, and Welfare Assessment of Unbroken (Unhandled) Horses on Arrival at a Slaughterhouse in Italy

Transportation of horses to slaughterhouses can pose a welfare concern, in particular when horses are unbroken/unhandled. This study aimed to describe their journeys and journey conditions, document their welfare status on arrival in a slaughterhouse in Italy, and investigate possible associations between journey conditions and welfare issues. A total of 395 unbroken draft horses in 20 different consignments were assessed with a standardized protocol. The most common departure point (16/20 consignments, 80%) was a French assembly center, but many of these horses had Spanish passports, suggesting they had previously been transported from Spain to France. The average journey duration was 34 ± 14 h, including journey breaks (i.e., short stops inside the vehicle and long resting stops at control posts), while transit time was 24 ± 4 h. The drivers were well experienced, the trucks were well equipped (i.e., forced ventilation, drinkers), and the horses traveled loose in small groups (n ≤ 4 horses) within pens inside the vehicle. On arrival at the slaughterhouse, the horses self-unloaded and showed minimal behavioral and health problems. The prevalence of injuries, diarrhea/abnormal feces, and nasal discharge were 1.52%, 6.58%, and 4.30%, respectively. Cold temperatures, space allowance, and lack of feeding during transport were found to be the main hazards of those problems (all p < 0.05). Our findings confirm that the correct assessment of the fitness for transport, adequate journey conditions, and experienced staff are crucial factors to safeguard the welfare of unbroken horses during long journeys.

DIAGNOSIS AND MEDICAL AND SURGICAL MANAGEMENT OF CHRONIC INFECTIOUS FIBRINOUS PLEURITIS IN AN OKAPI (OKAPIA JOHNSTONI)

A 10-yr-old female okapi (Okapia johnstoni) at the San Diego Zoo Safari Park was evaluated for intermittent malaise, inappetence, occasional cough, abdominal splinting, and licking at both flanks. Physical examination revealed tachypnea, tachycardia, and fluid sounds on thoracic auscultation. Transthoracic ultrasound showed multiple uniform, anechoic filled structures in the right and left pleural space. Surgical exploration of the thoracic cavity revealed bilateral, mature, fibrous, compartmentalizing adhesions between the visceral and parietal pleura, confirming a diagnosis of chronic, infectious, fibrinous pleuritis. The suspected etiology was occult aspiration pneumonia secondary to historical episodes of regurgitation associated with general anesthesia. Culture of the pleural fluid and fibrous adhesions grew Trueperella (Arcanobacterium) pyogenes, Arcanobacterium haemolyticum, and few Fusobacterium species. Treatment consisted of chest-tube placement to establish drainage, thoracic lavage, unilateral surgical debridement, and long-term antibiotics. The animal made a complete clinical recovery over 7 mo.

The Association of Fibrinous Pleural Effusion with Survival and Complications in Horses with Pleuropneumonia (2002-2012): 74 Cases

BACKGROUND

Fibrinous parapneumonic pleural effusions are associated with decreased efficacy of pleural fluid drainage and increased risk of medical treatment failure in people, but similar associations have not been established in horses.

HYPOTHESIS/OBJECTIVES

We hypothesized that fibrin deposition in the pleural cavity of horses with parapneumonic effusions increases the risk of poor outcome.

ANIMALS

Seventy four horses with bacterial pleuropneumonia diagnosed by culture and cytology of tracheal aspirates, pleural fluid, or both, and pleural effusion diagnosed by ultrasonographic examination.

METHODS

Retrospective study of cases was from 2002 to 2012. Information obtained from the medical records included signalment, history, sonographic findings, treatments, and outcome. The primary outcome investigated was survival and secondary outcomes were development of complications and surgical intervention. Fisher's exact test and logistic regression were applied for categorical variables. A t-test was used to find differences in continuous variables between groups.

RESULTS

Seventy four horses met study criteria and 50 (68%) survived. Fibrinous pleural effusion was associated with higher respiratory rate and pleural fluid height at admission, necrotizing pneumonia, increased number of indwelling thoracic drains required for treatment, and decreased survival.

CONCLUSIONS AND CLINICAL IMPORTANCE

Fibrin accumulation in parapneumonic effusions is associated with increased mortality. Direct fibrinolytic treatment might be indicated in affected horses.

The Use of Recombinant Tissue Plasminogen Activator (rTPA) in The Treatment of Fibrinous Pleuropneumonia in Horses: 25 Cases (2007-2012)

Background

Information about treatment protocols, adverse effects and outcomes with intrapleural recombinant tissue plasminogen activator (rTPA) use in horses with fibrinous pleuropneumonia is limited.

Hypothesis/Objectives

Describe factors that contribute to clinical response and survival of horses treated with rTPA intrapleurally.

Animals

Horses with bacterial pneumonia and fibrinous pleural effusion diagnosed by ultrasonography, that were treated with rTPA intrapleurally.

Methods

Retrospective multicenter case series from 2007–2012. Signalment, history, clinical and laboratory evaluation, treatment, and outcome obtained from medical records. Regression analysis used to identify associations between treatments and outcomes.

Results

Thirty three hemithoraces were treated in 25 horses, with 55 separate treatments. Recombinant tissue plasminogen activator (375–20,000 μg/hemithorax) was administered 1–4 times. Sonographically visible reduction in fibrin mat thickness, loculations, fluid depth, or some combination of these was seen in 32/49 (65%) treatments. Response to at least 1 treatment was seen in 17/20 (85%) horses with sonographic follow‐up evaluation after every treatment. Earlier onset of rTPA treatment associated with increased survival odds. No association was found between cumulative rTPA dose or number of rTPA doses and survival, development of complications, duration of hospitalization or total charges. Clinical evidence of hypocoagulability or bleeding was not observed. Eighteen horses (72%) survived to discharge.

Conclusions and clinical importance

Treatment with rTPA appeared safe and resulted in variable changes in fibrin quantity and organization within the pleural space. Recombinant tissue plasminogen activator could be a useful adjunct to standard treatment of fibrinous pleuropneumonia, but optimal case selection and dosing regimen remain to be elucidated.

Development of a loop-mediated isothermal amplification method for detecting Streptococcus equi subsp. zooepidemicus and analysis of its use with three simple methods of extracting DNA from equine respiratory tract specimens

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a dominant pathogenic bacterium in equine pneumonia. We developed a specific loop-mediated isothermal amplification (LAMP) method, which targets the gene encoding sorbitol-6-phosphate 2-dehydrogenase (sorD), for detecting S. zooepidemicus and examined the clinical efficacies of its use in combination with each of 3 DNA extraction methods easily used by veterinary practitioners, namely the Loopamp PURE DNA Extraction Kit, InstaGene Matrix and a conventional boiling method. The LAMP method plus the Loopamp PURE DNA Extraction Kit gave higher rates of positivity than the other combinations in both clinical and spiked samples containing clinically significant concentrations (>1 × 10⁴ CFU/ml) of S. zooepidemicus.

Pleuropneumonia as a sequela of myelography and general anaesthesia in a Thoroughbred colt

A 3-year-old Thoroughbred colt was presented to the University Veterinary Centre Camden for evaluation of ataxia. The horse was anaesthetised to facilitate cervical radiography and myelographic examination of the spinal cord. Recovery from anaesthesia was uneventful. Five days after general anaesthesia the horse re-presented with pleuropneumonia. It was euthanased 24 hours after presentation on humane grounds. Necropsy revealed severe tracheal erosion over the middle third of the ventral surface of the trachea, pleuropneumonia and narrowing of the cervical cord between C4 and C6. It is postulated that extension and flexion of the neck during myelography resulted in movement of the endotracheal tube cuff, causing the tracheal lesion and predisposing the colt to pleuropneumonia. Severe tracheal lesions and pleuropneumonia have not been reported as sequela of equine myelography, and should be considered as possible complications following repeated cervical manipulation during myelography in the horse.

A case control study of factors and infections associated with clinically apparent respiratory disease in UK Thoroughbred racehorses

A matched case control study was used to determine infections and other factors associated with clinically apparent respiratory disease in young racehorses in training in the UK. A total of 170 cases, defined as horses with sudden onset coughing, nasal discharge or pyrexia, were identified and matched to 632 non-affected controls by trainer and time period. Factors examined included age, sex, time since entry into the training yard, time since last race and different infections including tracheal and nasopharyngeal (NP) bacteria and viruses. Multivariable conditional logistic regression (CLR) modelling was used to evaluate the risk of being a case for variables after adjustment for other factors. Three analyses were conducted using clinical cases as outcomes, which were compared with: (i) controls without evidence of subclinical inflammatory airway disease (IAD) (ii) controls with evidence of subclinical IAD and (iii) all controls irrespective of IAD status. A fourth analysis was conducted comparing the two groups of controls, i.e. those with and without IAD. Younger horses and those that had entered training more recently were at increased risk of suffering episodes of clinically apparent respiratory disease. Among the infections, increasing numbers of Pasteurella/Actinobacillus spp. in tracheal washes were associated with increasing risk of clinical disease. Tracheal infection with Streptococcus zooepidemicus was associated with both clinical respiratory disease and subclinical IAD when compared with controls with no evidence of IAD. This explained the lack of association between clinical cases and S. zooepidemicus when all controls were used. Tracheal isolation of Mycoplasma felis was also associated with clinical disease after controlling for other factors. An inverse association was identified between risk of clinically apparent disease and isolation from tracheal washes of the transient, non-pathogenic bacteria Staphylococcus and Acinetobacter spp. There was no significant association identified between clinical disease and infection with equine herpesviruses-1 and -4, rhinoviruses-1 and -2 or adenovirus. Equine influenza was significantly associated with clinical respiratory disease but it was a very rare infection in this well-vaccinated population, only occurring in three cases.

The use of Baypamun N in crowding associated infectious respiratory disease: efficacy of Baypamun N (freeze dried product) in 4-10 month old horses

The efficacy of an immunomodulator, Baypamun N, was tested in 4-10-month-old horses which were exposed to stress by weaning, transport and commingling with yearlings from different breeders (crowding). Verum (n = 26) and placebo animals (n = 27) received three intramuscular injections of the investigational preparations (days 0, 2, 9) starting at the day of commingling in one stable. The incidence of acute respiratory disease was high during the first 4 weeks after commingling. Approximately 50% of all horses showed seroconversion due to field infection by EHV1 and EHV4 during the observation period. The clinical scores in the Baypamun N group were significantly reduced by 40.3% (P < 0.05) compared to the placebo group. The proportion of horses with purulent nasal discharge during the observation period (4 weeks) was also significantly reduced by 58.7% (P < 0.01) in the Baypamun N group. Fifty per cent of the horses injected with Baypamun N showed no purulent nasal discharge and therefore no signs of complicated disease of the upper respiratory airways in contrast to only 14.8% in the non-protected placebo group. The challenge conditions studied in this investigation were rather severe because of the permanent exposure of Baypamun N treated individuals to the non-separated and untreated horses (n = 51). This indicates that treatment with Baypamun N is a successful tool to avoid severe clinical consequences of stress in young horses.

Effect of transportation on lower respiratory tract contamination and peripheral blood neutrophil function

OBJECTIVE

To evaluate the effect of transportation on lower respiratory tract contamination and peripheral blood neutrophil function in horses and to compare results from transported horses with those obtained in earlier experiments from horses confined with heads elevated.

DESIGN

A prospective study.

PROCEDURE

Six horses were transported by road for 12 h. Clinical and haematological examination, transtracheal aspiration and cell function studies were conducted before and after transportation. Results obtained after transportation were compared to pre-transportation values.

RESULTS

After transportation, peripheral blood leucocyte and neutrophil numbers were increased and rectal temperatures were evaluated. Transtracheal aspirates showed an accumulation of purulent respiratory tract secretions with increased numbers of bacteria, particularly beta-haemolytic Streptococcus spp and members of the Pasteurellaceae family. Three horses also had increased numbers of bacteria from the Enterobacteriaceae family relative to corresponding samples from earlier studies. Phagocytosis by peripheral blood neutrophils was significantly reduced, while the oxidative burst activity of peripheral blood leucocytes was either unchanged or enhanced.

CLINICAL IMPLICATIONS

Bacterial contamination of the lower respiratory tract occurs as a routine consequence of transportation of horses and is likely to be an important determinant in the development of transport-associated respiratory disease. Inflammatory airway secretions and increased numbers of bacteria were rapidly cleared, without clinical evidence of significant pulmonary disease and without additional treatment, in normal horses that were allowed to lower their heads after transportation. Peripheral blood neutrophilia and a reduction in neutrophil phagocytic function were evident for at least 36 h after transportation, suggesting that horses may require a number of days to recover from the stress of transportation. As the potential role of bacteria from the Enterobacteriaceae family in the development of transport-associated respiratory disease has not been elucidated, horses which develop clinical disease following transportation should undergo thorough bacteriological investigation to ensure appropriate treatment.

Antibiotic prophylaxis of lower respiratory tract contamination in horses confined with head elevation for 24 or 48 hours

OBJECTIVE

To evaluate the administration of procaine penicillin prior to or during confinement with head elevation as a means of reducing the associated accumulation of inflammatory lower respiratory tract secretions and increased numbers of bacteria within the lower respiratory tract of confined horses.

DESIGN AND PROCEDURE

Two experiments were conducted to evaluate the efficacy of different dose rates and dosing frequencies. In experiment A a single low dose (15,000 IU/kg) of procaine penicillin was administered to four horses immediately prior to confinement with head elevation for 48 hours. The systemic leucocyte response, gross and cytologic characteristics of transtracheal aspirate and bacterial numbers in lower respiratory tract samples were compared with corresponding samples from two horses confined with heads elevated but not given penicillin. The efficacy of higher dose rates (20,000 IU/kg and 40,000 IU/kg) given before and during confinement with heads elevated for 24 hours was evaluated in experiment B.

RESULTS

Treatment with procaine penicillin had no effect on the systemic leucocyte response or on the accumulation of inflammatory lower respiratory tract secretions at any of the dosing schedules evaluated. The number of bacteria isolated from trans-tracheal samples was reduced at 12 hours for treated horses in experiment A and at 24 hours for experiment B. beta-haemolytic Streptococcus spp were not isolated from treated horses in either experiment. Bacterial species isolated from treated horses were predominantly Pasteurella and/or Actinobacillus spp, however, members of the family Enterobacteriaceae and a Staphylococcus sp were isolated from treated horses. One treated horse in experiment A developed clinically apparent pulmonary disease.

CONCLUSIONS

The prophylactic administration of penicillin before or during confinement did not reliably reduce bacterial numbers or prevent the accumulation of purulent lower respiratory tract secretions in horses confined with their heads elevated. Numbers of beta-haemolytic Streptococcus spp were reduced following treatment, suggesting that the repeated administration of procaine penicillin may have some merit as part of a strategy to prevent transport-associated respiratory disease. However, methods directed at minimising the duration of confinement with head elevation, augmentation of the clearance of accumulated secretions and prompt identification of animals in which airway inflammation has extended to the pulmonary parenchyma remain the best ways of minimising transport-associated respiratory disease.