SIGNALMENT: BREED: Italian Saddle. SEX: gelding. AGE: 11 years. MANTLE: bay. WEIGHT: 482 Kg. ATTITUDE: show jumping. ANAMNESTIC INFORMATION The Veterinarian reports, on the day following vaccination against Influenza and tetanus (adjuvant vaccine with immunostimulatory complex ISCOM, suspension for injection, in single dose), the onset of a systemic symptomatology, characterized by fever, depression, anorexia, generalized myalgia, jaundice, associated with neurological symptoms suggestive of involvement of the central nervous system (apathy, alteration of mental state with depression of central nervous responses and disorientation, postural abnormalities, ataxia and incoordination of movements). This clinical picture is considered consequent to an adverse reaction to vaccination, and therefore reported to the Ministry of Health by completing and sending the appropriate Reporting Forms of Suspected Adverse Reaction. None of the other treated horses, in addition to the subject considered, showed a similar reaction. The reports indicates also that the symptomatology lasted for about 14 days, during which a symptomatic and supportive therapy was undertaken with partial improvement of the clinical conditions. However, depression, apathy, ataxia, and incoordination persisted, accompanied by a progressive weight loss. Therefore it was decided by the Veterinarian to confer the horse to the Department of Medicine of the Horse Veterinary Hospital of the University of Milan, Azienda "Polo Veterinario di Lodi" for further investigations. PHYSICAL EXAMINATION At the general examination, the subject showed fair nutrition conditions (Body Condition Score: 3/5, body weight: 482 kg). The skin and coat showed no alterations; the presence of a state of edema affecting the region of the distal shin and the hindquarters of both hind limbs was detected. The rectal temperature was 37.2° C and the mucous membranes appeared congest; the capillary filling time was less than 2 seconds. There was mild lymphadenomegaly of the right intermandibular lymph node. On palpation, arterial pulse was normal, with a frequency of 32 bpm. The cardiac stroke was perceivable and, at the auscultation, the second tone was split; the heart rhythm was with no pericardial noises. At the functional examination of the breath, the respiratory frequency was 12 per minute, and the breath was normal. At the auscultation of the thorax, through the use of a respiratory bag, no anomalous lung noises were found. NEUROLOGICAL EXAM The mental state was normal, but the sensory appeared depressed. An alteration of posture with the limbs articulated and swaying of the rear train with proprioceptive deficit, tetraparesis and widespread muscle tremors were detected. Upon examination of the region, a deficiency of the 5th, 7th and 8yh pair of cranial nerves was detected (slight rotation of the head and low deviation of the bottom downwards, with a reduction of the sensitivity of the nasal septum and nostrils). The static examination of the neck and front limbs showed a limit of sensitivity at the dorsal surface of the forearm, carpus and metacarpus. The static examination of the region of the trunk, the hind limbs, the anal region and the tail shows no significant changes. On the dynamic examination, a moderate bilateral weakness of the hind limbs (positive wave test) was found, with difficulty in repositioning and resistance to the traction of the tail, marked ataxia, which worsened with increasing gait (from step to P 439 roceedings of 72nd Convegno Sisvet trot) , following a sudden stop and retreat, and bandage. In addition, the limb crossing test was positive for both the anterior and hind limbs. A lack of proprioception, primarily in the front limbs, was detectable for both the right and left hands. INSTRUMENTAL EXAMINATION An electrocardiographic examination was performed, which showed no changes in heart rhythm or myocardial conduction activity, and haematological and hematochemical tests, showing a slight decrease in the count of erythrocytes and hematocrit (RBC: 6.78 x 106/μL; , 3%), leukocytosis (WBC: 11.08 x 103/μL) with relative and absolute neutrophils (neutrophils: 88%, 9.8 x 103/μL) and mild relative and absolute lymphopenia (lymphocytes: 10%; 1, 1x103/μL), mild hyperbilirubinemia (total bilirubin: 2.8 mg dl), mild hypercalcaemia (calcium: 12.5 mg/dl), hypophosphoremia (phosphorus: 1.7 mg/dl), hypomagnesemia (magnesium: 1.21 mg/dl), slight decrease in iron concentration (iron 30 mg/dL), slight increase in the enzymatic LDH activity (LDH 569 U/L) and hyperfibrinogenemia (fibrinogen: 395 mg/dL). Protein electrophoresis showed a total hypoproteinemia (total protein: 5.7 g/dl) with hypoalbuminemia (albumine 3 g/dl, 52.7%) and a decrease in the fraction of α1-globulins (0.1 g/dl, 1.7%). The finding of neutrophilic leucocytosis and hyperfibrinogenemia suggests the presence of an active systemic inflammatory state. The parasitological examination of faeces was negative. In addition, a nasal swab and blood collection (serum) were performed for PCR examination of type 1- 4 Equine Herpesvirus, neurotropic Flaviviruses and Equine Viral Arteritis, which resulted all negative. Serial blood samples were also collected for culture test, which scored negative. Subsequently, an X-ray and an ultrasound examination of the cervical spine were performed, which showed no alteration that would justify the observed symptoms. The cerebrospinal fluid was collected performed, at the lumbosacral level following sedation and containment. A PCR test was performed for type 1 and 4 Equine Herpesvirus DNA, neurotropic Flaviviruses, Equine Viral Arteritis and Borrelia burgdorferi, with negative results; a microbiological test showed a negative result, while the cytological examination and the microprotein dosage showed neutrophilic pleocytosis (30%) and a significant increase in total proteins (300 mg/dL). The electromyographic examination was normal. DIAGNOSIS On the basis of the medical history and the results of the investigations carried out, the diagnosis of immunocomplex associated meningitis and active systemic inflammation, referable to the condition of hyperreactivity of the immune system, was obtained, as a probable result of an adverse reaction to the administration of polyvalent vaccine. RECOVERY AND THERAPY Initially, the clinical symptomatology was controlled by administration of Flunixin Meglumine (1.1 mg kg I.V. once a day) and, subsequently to the negativity of the microbiological tests (blood and liquor) and of the PCR tests (nasal swab, blood and liquor), the anti-inflammatory treatment was modified with the use of dexamethasone according to a scalar protocol starting from 0.06 mg/kg administered once a day, associated with a systemic antibiotic treatment with ceftiofur at a dose of 2.2 mg/kg intramuscularly every 12 hours for 8 days, for prophylactic purposes. Subsequently, the antiinflammatory treatment Flunixin Meglumine was modified at the dose of 1.1 mg/kg I.V., once a day, and after a few days substituted with Fenilbutazone (4.4 mg/kg once a day) orally. Considering the possible side effects due to protracted administration of non-steroidal anti-inflammatory drugs, during the hospitalization the renal function was periodically monitored and at the same time a therapy with gastroprotectors and enteroprotectors (oral sucralfate at the dosage of 6 g every 12 hours) was P 440 roceedings of 72nd Convegno Sisvet adopted. Over the period of hospitalization, the evolution of the clinical picture was monitored through periodic neurological examination and laboratory tests, that showed a positive response to the therapeutic protocol, as showed by the progressive, though partial, regression of neurological deficits and re-entry within the normal range of the main haematological and hematochemical parameters (fibrinogenemia and leukocyte counts). Subsequently, during the period of hospitalization, attempts were made to gradually reduce the antiinflammatory drug therapy, which each time determined a relapse of the systemic symptoms (depression and hyperthermia) and of the orthopedic, ophthalmological and cardiological signs described below. These events forced the immediate resumption of anti-inflammatory treatment and the institution of the treatment that was more appropriate in relation to the arising complications. COMPLICATIONS RELATED WITH THE STATE OF HYPER-REACTIVITY OF THE IMMUNE SYSTEM, AND RELATED TREATMENT Orthopedic complications Fifteen days after admission, acute onset of 5/5 grade on the left hind limb was observed. Bilaterally, at the hind limbs, edema was present in the distal region of the shin and the hobble. On the other hand, no changes appeard to the front limbs. The palpation of the hind limbs was negative; the ultrasound examination of the plantar region of the shin showed the presence of a slight increase of anecogenous synovial fluid inside the synovial sheath of the flexor tendons. A cold shower several times a day of the involved limb and a compression bandage were applied. Over the next three days, a clear clinical improvement of the lameness was detected, until complete recovery. Three days after the remission of the symptoms of the hind left limb, however, the onset of an acute lameness of grade 5/5 of the opposite limb (hind right) was detected. The affected limb showed hot, painful edema of the distal region of the shin and the hobble. The palpation of the hind limbs was negative; the ultrasonographic examination of the plantar region of the shin showed the presence of a central anechoic area at the distal third of the deep flexor tendon of the phalanges, compatible with an acute tendinitis, accompanied by a modest increase of anecogenous synovial fluid inside the synovial tendon sheath. In addition, the ultrasound examination of the plantar region of the moth showed a thickening of the digital plantar annular ligament, suggesting the presence of a chronic annular ligament lesion. We then started with a symptomatic treatment similar to that used for the left hind limb (repeated hydrotherapy and compression bandage) associated with the topical application of a gel based on escin and diethylamine (Reparil Gel). During the first days, the animal was kept at rest in the box. Subsequently, the monitoring through a physical and ultrasonographic examination showed a gradual improvement, characterized by progressive resorption of edema, recovery of limb support and disappearance of the lameness (15 days after onset), with ultrasound results suggestive of a progressive partial regeneration of the injured tendon fibers (35 days after onset). At the same time, in order to obtain a faster recovery, an orthopedic shoeing was performed, and a daily walk session of a few (5-10) minutes repeated three times a day was introduced. Ophthalmologic complications Sixteen days after admission, an acute onset of a severe right eyelid swelling accompanied by ocular purulent discharge, marked conjunctival hyperemia, complete corneal opacification, hyphaema and total visual deficit was detected. The fluorescein test for corneal ulceration resulted negative, both for the right and left eyes. Because of the complete corneal opacification, ophthalmoscopic examination resulted impossible to visualize the fundus of the right eye; hyperemia of the papilla of the left optic nerve was found. The ultrasound examination showed the presence of intensely hyperechoic material inside the hind chamber and the anterior chamber of the right eye, a marked edema and retinal detachment and severe chorioid hemorrhage; no clinically significant ultrasound changes were P 441 roceedings of 72nd Convegno Sisvet detected in the left eye. The alterations highlighted by the investigations performed were compatible with a diagnosis of severe irido-cyclo-corioid-retinitis of the right eye. The treatment included an oculoconjunctival lavage with sterile physiological solution and the topical application of an ophthalmic antibiotic ointment based on tetracycline, chloramphenicol and colistimethate four times a day, of eye drops with tropicainamide-based midriatic action, and of an flurbiprofen-based anti-inflammatory collyrium, twice a day. This therapeutic regimen was maintained for the entire duration of the admission; this treatment was subsequently integrated with the topical application of a dexamethasone-based ophthalmic ointment. The evolution of the ophthalmic condition in the right eye was monitored by a periodic ophthalmological, ophthalmoscopic and ultrasonographic examination. There was a progressive reduction in acute inflammatory symptomatology with disappearance of ocular drainage (after 5 days), edema, hyperemia and corneal opacification, accompanied by a gradual moderate atrophy of the eyeball and enophthalmos (progressively during the following 25 days onset). The visual impairment persisted. At the ophthalmoscopic examination, the visualization of the fundus of the eye was still impossible; the ultrasound examination showed progressive reduction of the accumulation of inflammatory material which, in the organization phase, appeared inside the hind chamber of the eye, with persistent retinal detachment. Cardiological complications As the last complication (49 days after admission), the appearance of a severe tachyarrhythmia (fc maximum 120 bpm) occurred. The electrocardiographic pattern showed an atrioventricular dissociation, characterized by the presence of premature ventricular complexes in pairs, triplets and in flaps, which evolved periodically in phases of persistent ventricular tachycardia. During the whole period of continuous monitoring by electrocardiographic tracing and Holter recording (lasting 48 hours), the persistent arrhythmia pattern alternated with short periods of spontaneous return to sinus rhythm. The return to a stable sinus rhythm occurred within 24 hours after the onset of arrhythmia, after restoration of anti-inflammatory therapy, without further recurrence. The echocardiographic examination, performed during the arrhythmia period and after the recovery of the normal sinus rhythm, showed thickening and hyperhogenicity of the valvular flaps of the aortic valve, associated with aortic regurgitation in the diastolic phase. The results of the diagnostic investigations carried out suggested the presence of a picture of endocarditis/acute myocarditis. DIMISSION AND FOLLOW UP At the time of dismissal, the subject appeared in good nutrition status, with a body weight of 516 kg; the sensory condition was alert and the large organic functions were normal. As regards the neurological conditions, the initial deficit regressed to 80%. At the neurological examination, the sensory condition and the mental state appeared normal. Occasionally, a postural alteration was found, with the left anterior limb maintained in abduction position. At the head region, no alterations related to the nervous system were detected. On static examination there were no changes in the region of the neck, forelimbs, trunk, hind limbs, anus and tail. On dynamic examination, a moderate proprioceptive deficit were left, that could be detected primarily in the hindlimbs and could be evoked in a narrow vault with greater severity in the right hand. As regards the orthopedic conditions, the clinical and ultrasound examinations showed a progressive improvement of the tendon lesion of the right hind limb. It was suggested to continue the walk for 10- 20 minutes a day, preferably twice a day, and to perform concomitant hydrotherapy of the hind legs with cold water. It was also recommended to perform a night bandage with rest bands on both hind limbs. Finally, it was recommended to ascertain the evolutionary state of tendinopathy by performing periodic ultrasound examinations, possibly modifying and/or integrating the therapeutic protocol in agreement with the Veterinarian. P 442 roceedings of 72nd Convegno Sisvet As regards the ophthalmological conditions, the clinical examination of the right eye showed regression of the acute inflammatory symptomatology, to which was associated however a persistence of the atrophy of the eyeball and enophthalmos, without recovery of full vision. In this regard, the prognosis quoad functionem remains poor, due to the retinal detachment. On ophthalmoscopic examination, the visualization of the fundus of the eye was prevented by the accumulation of inflammatory material during the organization phase inside the hind chamber of the eye, which coul also be detected by ultrasound. It was recommended to continue for at least two weeks with a local therapy consisting of topical oculo-conjunctival application twice a day of Visumidriatic eye drops 1%, followed 10 minutes after the application of Colbiocin Unguento Oftalmico and Luxazone Unguento Oftalmico, and (after further ten minutes) and of Ocufen Collirio. It was recommended, at the end of the two weeks, to perform a clinical re-evaluation, and to suspend or modify the therapy after agreement with the Veterinarian. As regards the cardiac conditions, monitoring of myocardial conduction and aortic insufficiency was suggested by periodic monitoring. The recurrence of systemic symptoms and the appearance of serious autoimmune complications, in response to any attempt to reduce the anti-inflammatory treatment, highlight the instability of the current clinical situation, the need to prolong the treatment with anti-inflammatory drugs for at least 1 month starting from dismissal, and to consider the prognosis as questionable. In the follow-up, which took place by telephone after 2 months and 6 months from the date of dismissal, we were informed of the stabilization of the clinical picture after the suspension of antiinflammatory treatment, with gradual recovery and a slight sporting activity. DISCUSSION The close temporal relationship between the evident and severe clinical symptomatology (24 hours) and the administration of the vaccine, suggests the probable occurrence of an adverse reaction to the vaccine. The current legislation defines "adverse drug reaction" as "any harmful and unwanted effects resulting from the use of a medicinal product". The current definition, introduced in the European community in 2010 by the European Directive 2010/84 / EU, was implemented in Italy on July 2nd, 2012. This definition implies the manifestation of the phenomenon in relation to use, in compliance with the indications contained in the authorization to placing on the market, treatment errors and/or not compliant use according to the indications contained in the Marketing Authorization, such as overdose, improper use ("off label") and abuse. In particular, the occurrence of neurological symptoms associated with fever, the day following the vaccine administration, can be considered a "serious side effect". Such a serious adverse reaction is to be considered a rare occurrence, reported by some authors in humans and sporadically in some species in the veterinary field, but not mentioned in the literature in the equine species. Given these premises, it appears reasonable, based on some possible similarities with what is described in humans and other animal species, to consider what is reported in the literature, in order to explore the possible mechanisms underlying this reaction. In humans, dogs, sheep and cattle (Mayhew, 1989; Furr and Reed, 2008; Zani et al., 2009), meningitis are reported secondary to vaccine administration performed in the paraspinal musculature: the inflammatory reaction, of granulomatous type, that develops in the muscular planes near the vertebral apophysis can, by contiguity, deeply involve the meninges, causing the formation of abscesses or epidural collections. The affected animals show a rise in temperature, lethargy, paraplegia or paraparesis and ataxia, and show haematological tests characterized by neutrophilic leukocytosis. In addition, cytological examination of the liquor is characterized by moderate P 443 roceedings of 72nd Convegno Sisvet neutrophilic pleocytosis and a normal protein content, with a negative bacteriological examination. In all the described cases, the diagnosis was only possible at the autopsy or through RMI, since in no subject the radiographic examination showed any alteration. Other possible causes reported in literature as rare vaccine complications are reactions of immune origin (Tizard 2013). In particular, in humans, aseptic meningitis induced by the administration of some categories of drugs are reported; in a single case this symptomatology followed a vaccination against Hepatitis B. The immunological mechanisms involved seem to be linked to Type III hypersensitivity, with the formation of immune complexes in the meningeal vascular endothelium (Moris et al., 1999). These reactions could be caused by the vaccine or by the adjuvant (Tizard 2013). Also Guillain-Barré syndrome, an autoimmune neurological disorder in humans, can be triggered by the administration of the flu vaccine. It is also reported a single case in a dog that, following the administration of a polyvalent vaccine, showed a symptomatology attributable to the Guillain-Barrè syndrome, with the development of a polyneuritis secondary to the production of autoantibodies against the phospholipids of the peripheral nerves (Tizard 2013). Uveitis and retinocorioiditis developed in the horse about 1 month after vaccination, in association with bilateral hind arthrosinovitis, which could be caused by a Type III hypersensitivity reaction; in this case, the systemic diffusion of an excess of antigen-antibody complexes, beyond the removal capacity of the mononuclear-phagocytic system, may have determined the deposition of immunocomplexes at vascular level in different districts of the organism, and the consequent development of vasculitis (Tizard, 2013). Such reactions could be caused by the vaccine or by the adjuvant (Tizard, 2013). The administered vaccine contained an ISCOM adjuvant classified as "immunostimulant", that acts by promoting the production of cytokines by the antigen-presenting cells, to enhance the humoral and cell-mediated immunity. Some authors (Andersen et al., 2012) report that this type of vaccine induces an acute phase response of greater magnitude than vaccines with "depot" adjuvants (based on aluminum hydroxide). The greater immunogenicity of this adjuvant, associated with a hypersensitivity of the subject, could justify the immunocomplexes reactions. As regards the tendon injury at the right hind limb, it is possible that the excessive mechanical stress, resulting from the lack or reduced support of the left hind limb associated with neurological deficits, may have led to its onset. Even the severe tachyarrhythmia appears to be due to the hyperreactivity of the immune system. In particular, episodes of autoimmune endocarditis/myocarditis have been reported in humans and in various experimental animal models, depending on the administration of particular vaccine and adjuvant antigens. Gamma-globulin and complement deposition in the myocardium causes a variety of lesions, including inflammatory cell infiltration with areas of myocardial degeneration and valvulitis (Anard et al., 1983, Pericone et al., 2011). As regards the differential diagnosis, it was possible to exclude neurotropic virus infections by PCR on liquor. As regards other infectious agents, the multisystem and nonspecific symptomatology associated with fever may be suggestive of a Borrelia burgorferi infection; however, the period of the year in which the symptoms occurred (January), as well as the geographical location of the subject (Northern Italy), make extremely difficult for a specific carrier to transmit the spirochete.
|Titolo:||The "disruptive" patient|
|Settore Scientifico Disciplinare:||Settore VET/08 - Clinica Medica Veterinaria|
|Data di pubblicazione:||20-giu-2018|
|Tipologia:||Book Part (author)|
|Appare nelle tipologie:||03 - Contributo in volume|