Spinal Cord Compression in a Horse due to a Granular Cell Variant of Neurofibroma

A neurofibroma of granular cell subtype is described in a 7-year-old horse. The horse had a 3-month history of ataxia affecting the forelimbs and hindlimbs, suggesting a C1-C6 neuroanatomical localization. Post-mortem examination revealed an intradural mass arising from the right sixth cervical spinal nerve and compressing the spinal cord. Histologically, the mass was composed largely of wavy spindle cells (a mixture of Schwann cells, perineurial cells and fibroblasts) intimately associated with ropy collagen fibres. Approximately 25% of the spindle cells were swollen and contained densely-packed, eosinophilic and periodic acid-Schiff-positive cytoplasmic granules. Immunohistochemistry for S100 and glial fibrillary acidic protein antigens labelled a proportion of neoplastic cells, while the cytoplasmic granules were positive for S100 and neuron specific enolase. This is the first report of a neurofibroma with granular cell differentiation in an animal. Granular cell differentiation in other peripheral nerve sheath tumours of animals is briefly discussed.

Congenital Cystic Polypoid Rectal Hamartoma in a Newborn Foal

A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.

Serum bile acid concentrations, histopathological features, and short-, and long-term survival in horses with hepatic disease

BACKGROUND

Serum bile acid concentrations (SBA) and a histopathological biopsy score [Equine Vet J 35 (2003) 534] are used prognostically in equine hepatic disease.

HYPOTHESIS

Histopathologic features and scores, but not SBA, differ between survivors and nonsurvivors and correlate with histopathologic evidence of hepatic inflammation and fibrosis.

ANIMALS

Retrospective study. Records (1999-2011) of horses with hepatic disease diagnosed by biopsy and with concurrent measurements of SBA.

METHODS

Retrospective cohort study. Biopsies were examined for inflammatory cell infiltration including type and distribution, fibrosis, irreversible cytopathology affecting hepatocytes, hemosiderin, or other pigment deposition and bile duct proliferation. SBA, histopathological findings and a histological score [Equine Vet J 35 (2003) 534] were compared between short- (survival to discharge) and long-term (>6 months) survivors and correlations between SBA and histopathological findings investigated.

RESULTS

Of 81 cases 90% survived short-term and 83% long-term. Short-term and long-term nonsurvival were associated with SBA (P = .009; P = .006), overall (P = .001; P = .002) and parenchymal (short-term only; P = .01) inflammation, portal and bridging fibrosis (all P < .001), apoptosis or single cell necrosis (P < .001; P = .008), hemosiderin deposition in hepatocytes (P = .011; P = .028), biliary (both P < .001), vascular (P = .003; P = .045) and endothelial (P < .001; P = .02) hyperplasia, nucleic changes (P = .004; P < .001) and the histopathological score (both P < .001). SBA were significantly and positively correlated with overall (P = .001), parenchymal (P < .001) and portal (P = .004) inflammation and portal (P = .036) and bridging (P = .002) fibrosis.

CONCLUSIONS AND CLINICAL IMPORTANCE

SBA, histopathological findings and scores differ between survivors and nonsurvivors. SBA concentrations are associated with inflammation and fibrosis suggesting interference with hepatic function. A histopathological score >2 and, less so, SBA >20 μmol/L are specific but not sensitive indicators of nonsurvival.

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.

Suspected acorn toxicity in nine horses

REASONS FOR PERFORMING STUDY

Acorn toxicity has been anecdotally reported to cause fatal colitis and colic in horses but reports in the scientific literature are sparse.

OBJECTIVES

This study reports the diagnosis, treatment, prognosis and outcome of 9 cases with suspected acorn toxicity admitted to 2 referral hospitals.

STUDY DESIGN

Retrospective case series.

METHODS

Case records from 2004 to 2013 were reviewed. Horses were included in the study if they met 3 of 4 criteria: exposure to acorns; clinical and laboratory data suggesting alimentary or renal dysfunction; acorn husks in the faeces or gastrointestinal tract; and necropsy and histopathological findings consistent with acorn toxicity. Data collected included case history, clinical presentation, clinicopathological data, ultrasonographic findings, case progression, and necropsy and histopathological findings.

RESULTS

Nine horses met the inclusion criteria. Five cases presenting with haemorrhagic diarrhoea deteriorated rapidly and were subjected to euthanasia or died. Four cases showed signs of colic with gas distension, displacement of the large colon and diarrhoea. Three of these (33%) survived with medical management, the fourth was subjected to euthanasia. Post mortem examination of 6 cases demonstrated submucosal oedema of the large intestine and caecum (n = 6), acute tubular nephrosis (n = 6), diffuse necrohaemorrhagic and ulcerative typhlocolitis and enteritis (n = 4), and small intestinal oedema (n = 3).

CONCLUSIONS

Acorn ingestion may be associated with typhylocolitis leading to diarrhoea, colic and acute renal tubular nephrosis. Recovery is possible in mildly affected cases; more severe cases show hypovolaemia, intractable pain, renal dysfunction and cardiovascular failure, and often succumb to the disease process. Disease is only seen in a small proportion of the population exposed to acorns and there seems to be an increased occurrence in certain years. Further investigation into factors predisposing to disease is required, but limiting exposure to acorns in the autumn seems prudent.

Rater agreement on gait assessment during neurologic examination of horses

Background

Reproducible and accurate recognition of presence and severity of ataxia in horses with neurologic disease is important when establishing a diagnosis, assessing response to treatment, and making recommendations that might influence rider safety or a decision for euthanasia.

Objectives

To determine the reproducibility and validity of the gait assessment component in the neurologic examination of horses.

Animals

Twenty‐five horses referred to the Royal Veterinary College Equine Referral Hospital for neurological assessment (n = 15), purchased (without a history of gait abnormalities) for an unrelated study (n = 5), or donated because of perceived ataxia (n = 5).

Methods

Utilizing a prospective study design; a group of board‐certified medicine (n = 2) and surgery (n = 2) clinicians and residents (n = 2) assessed components of the equine neurologic examination (live and video recorded) and assigned individual and overall neurologic gait deficit grades (0–4). Inter‐rater agreement and assessment‐reassessment reliability were quantified using intraclass correlation coefficients (ICC).

Results

The ICCs of the selected components of the neurologic examination ranged from 0 to 0.69. “Backing up” and “recognition of mistakes over obstacle” were the only components with an ICC > 0.6. Assessment‐reassessment agreement was poor to fair. The agreement on gait grading was good overall (ICC = 0.74), but poor for grades ≤ 1 (ICC = 0.08) and fair for ataxia grades ≥ 2 (ICC = 0.43). Clinicians with prior knowledge of a possible gait abnormality were more likely to assign a grade higher than the median grade.

Conclusion and Clinical Importance

Clinicians should be aware of poor agreement even between skilled observers of equine gait abnormalities, especially when the clinical signs are subtle.

Blood lactate concentrations in ponies and miniature horses with gastrointestinal disease

REASONS FOR PERFORMING STUDY

Clinical impression suggested that pony and miniature breeds (collectively referred to as ponies) presenting to a referral hospital for investigation of gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses.

OBJECTIVES

The study tested the hypothesis that ponies with gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses with similar disease severity.

STUDY DESIGN

Retrospective case-control study.

METHODS

Medical records from September 2006 to July 2011 were reviewed for ponies with a primary presenting complaint of gastrointestinal disease. Two larger breed horses with gastrointestinal disease were selected as controls for each case. Data collected included case details, historical and clinicopathological findings, diagnosis and outcome.

RESULTS

Information was collected on 50 ponies and 100 horses. Ponies had higher mean ± s.d. respiratory rates (27 ± 13 vs. 21 ± 13 beats/min; P = 0.01) and rectal temperatures (37.9 ± 0.6 vs. 37.4 ± 0.6°C; P = 0.006) and a longer median duration of clinical signs prior to presentation (10 h [1-72 h] vs. 6 h [1-120]; P<0.001). Median blood lactate concentrations on admission were higher in ponies than in horses (2.8 mmol/l [0.7-18.0] vs. 1.6 mmol/l [0.4-8.1]; P = 0.001). All other parameters relating to colic severity were not significantly different between groups, although more horses underwent exploratory laparotomy (19/50 ponies and 55/100 horses; P = 0.05). Median blood lactate concentrations in ponies with large intestinal disease, nonstrangulating lesions, undergoing medical treatment and surviving ponies were significantly higher than in horses in the same category. In contrast to horses, no differences in blood lactate concentrations exist between ponies with medical vs. surgical treatment, strangulating and nonstrangulating lesions and surviving and nonsurviving ponies.

CONCLUSION AND POTENTIAL RELEVANCE

Ponies might present with higher blood lactate concentrations than horses and might falsely be suspected of having a surgical lesion or a poorer prognosis if veterinarians are not aware of breed differences.

Putative intestinal hyperammonaemia in horses: 36 cases

REASONS FOR PERFORMING THE STUDY

Intestinal hyperammonaemia (HA) has been infrequently reported in individual horses; however, there have been no studies describing clinical and laboratory data as well as short- and long-term outcome in a larger number of cases.

OBJECTIVES

To describe clinical and laboratory data and short- and long-term outcome in a large group of horses with intestinal HA.

METHODS

Multi-centred, retrospective study; case records of horses with HA were reviewed and any horse with a clinical or post mortem diagnosis of intestinal HA was included. Hyperammonaemia was defined as a blood ammonium (NH(4) (+)) concentration ≥60 µmol/l and horses with a diagnosis of primary hepatic disease were excluded. Relevant data were recorded and, if appropriate, data from survivors were compared to nonsurvivors to identify potential prognostic indicators.

RESULTS

Thirty-six cases, 26 mature horses and 10 foals with intestinal HA were identified. Case histories included diarrhoea, colic and neurological signs and the most common clinical diagnosis was colitis and/or enteritis. The most common clinical and laboratory abnormalities included tachycardia, increased packed cell volume, hyperlactataemia and hyperglycaemia. Fourteen horses (39%) survived to discharge; NH(4) (+) concentration on admission was the only parameter significantly associated with survival. All surviving horses and foals for which follow-up information was available recovered completely and returned to their intended use without further complications.

CONCLUSIONS AND POTENTIAL RELEVANCE

Intestinal HA occurs in mature horses and foals and can be associated with severe clinical and laboratory abnormalities; further studies are required to investigate predisposing factors and delineate possible differences in aetiologies.

Acute lung injury/acute respiratory distress syndrome in 15 foals

REASONS FOR PERFORMING STUDY

Few reports exist in the veterinary medical literature describing clinical and pathological findings resembling conditions described as (ALI) and acute respiratory distress syndrome (ARDS) in man.

OBJECTIVES

To document history, clinical, laboratory and diagnostic findings, treatment and outcome of foals age 1-12 months diagnosed with ALI/ARDS at a referral hospital.

METHODS

Medical records, including radiographic, cytological, microbiological, serological and post mortem findings, were reviewed in a retrospective manner to identify foals with acute onset of respiratory distress, a partial pressure of arterial oxygen (PaO2) to fraction of oxygen in inspired gases (FiO2) ratio of < or = 300 mmHg, pulmonary infiltrates on thoracic radiographs or post mortem findings consistent with ALI/ARDS.

RESULTS

Fifteen foals age 1.5-8 months were included in the study. Seven foals had previously been treated for respiratory disease, and all foals developed acute respiratory distress <48 h prior to presentation. Findings on presentation included tachycardia and tachypnoea in all foals, with fever recorded in 8 cases. Eight cases met the criteria for ALI and 7 for ARDS. Radiographic findings demonstrated diffuse bronchointerstitial pattern with focal to coalescing alveolar radiopacities. An aetiological agent was identified in foals ante mortem (n = 6) and post mortem (n = 4). All foals were treated with intranasal oxygen and antimicrobial drugs; 13 received corticosteroids. Nine patients survived, 4 died due to respiratory failure and 2 were subjected to euthanasia in a moribund state. Follow-up was available for 7 foals; all performed as well as age mates or siblings, and one was racing successfully.

CONCLUSIONS

A condition closely meeting the human criteria for ALI/ARDS exists in foals age 1-12 months and may be identical to previously described acute bronchointerstitial pneumonia in young horses.

POTENTIAL RELEVANCE

ALI/ARDS should be suspected in foals with acute severe respiratory distress and hypoxaemia that is minimally responsive to intranasal oxygen therapy. Treatment with systemic corticosteroids, intranasal oxygen and antimicrobials may be beneficial in foals with clinical signs compatible with ALI/ARDS.

Severe hypertriglyceridaemia in clinically ill horses: diagnosis, treatment and outcome

REASONS FOR PERFORMING STUDY

Sporadic measurement of serum triglycerides in depressed and inappetant clinically ill horses revealed severe hypertriglyceridaemia without visible evidence of lipaemia on several occasions, leading to the inclusion of serum triglyceride concentrations in the routine serum biochemistry evaluation of our hospital. Since then, more cases have been identified and treated for hypertriglyceridaemia, raising questions about the prevalence, predisposing factors and significance of these findings.

HYPOTHESES

1) Severe hypertriglyceridaemia without visible opacity of the serum occurs more commonly in clinically ill and inappetant horses than previously described and 2) appropriate treatment using i.v. dextrose and/or partial parenteral nutrition would decrease serum triglycerides to normal limits and might result in improved appetite and attitude of the patient.

METHODS

The laboratory computer database from 2000 and 2001 was searched for increased serum triglycerides (> 5.65 mmol/l) in any horse breed, ponies and miniature breeds excluded. Data analysed included subject details, diagnosis, clinical and laboratory parameters, treatment, response to treatment and outcome.

RESULTS

Severe hypertriglyceridaemia was identified in 13 horses, with serum triglyceride concentrations 6.17-18.29 mmol/l, while none showed visible lipaemia. All horses had clinical and laboratory findings consistent with systemic inflammatory response syndrome and all but one had an increased serum creatinine concentration. Treatment with i.v. dextrose and/or partial parenteral nutrition resulted in decrease of the serum triglycerides to normal limits.

CONCLUSIONS

Severe hypertriglyceridaemia occurs in inappetant and clinically ill horses without evidence of serum opacity more commonly than previously described. The presence of systemic inflammatory response syndrome might predispose horses to hypertriglyceridaemia, while the increased creatinine concentration might be a predisposing factor or result of the condition. Horses identified in our study readily responded to treatment and appetite and attitude improved coincident with decrease of the serum triglycerides to normal limits.

POTENTIAL RELEVANCE

Hypertriglyceridaemia could perpetuate inappetance and depression in clinically ill horses and potentially predispose to fatty infiltration of the liver and other organ systems.