Jeannine M. Berger

Sequential Analysis of Anaplasma phagocytophilum msp2 Transcription in Murine and Equine Models of Human Granulocytic Anaplasmosis

ABSTRACT Anaplasma phagocytophilum causes human granulocytic anaplasmosis by inducing immunopathologic responses. Its immunodominant Msp2 protein is encoded by a family of >100 paralogs. Msp2 (msp2) expression modulates in the absence of immune pressure, and prolonged in vitro passage modulates in vivo virulence. Because programmed MSP2 expression occurs in Anaplasma marginale, we hypothesized a similar event in A. phagocytophilum in vivo, with specific Msp2 expression triggering immunopathologic injury or clinical manifestations of disease. We examined msp2 transcripts in 11 B6 mice and 6 horses inoculated with low- or high-passage A. phagocytophilum Webster strain. Blood was sequentially obtained through 3 weeks postinfection for msp2 reverse transcription-PCR. Horses were additionally assessed for clinical manifestations, seroconversion, complete blood count, blood chemistry, and cytokine gene transcription. In both species, there was no consistent emergence of msp2 transcripts, and all 22 msp2 variants were detected in both passage groups. Clinical severity was much higher for high-passage-infected than for low-passage-infected horses, preceded by higher levels of blood gamma interferon transcription on day 7. Antibody was first detected on day 7, and all horses seroconverted by day 22, with a trend toward lower antibody titers in low-passage-infected animals. Leukocyte and platelet counts were similar between experimental groups except on day 13, when low-passage-infected animals had more profound thrombocytopenia. These findings corroborate studies with mice, where msp2 diversity did not explain differences in hepatic histopathology, but differ from the paradigm of low-passage A. phagocytophilum causing more significant clinical illness. Alteration in transcription of msp2 has no bearing on clinical disease in horses, suggesting the existence of a separate proinflammatory component differentially expressed with changing in vitro passage.

Use of a gonadotrophin-releasing hormone vaccine in headshaking horses.

The aim of this study was to investigate the use of a gonadotrophin-releasing hormone (GnRH) vaccine in the treatment of headshaking in horses. Fifteen geldings received two doses of the GnRH vaccine four weeks apart. Serum was collected before and after vaccination to measure concentrations of luteinising hormone (LH) (10 horses) and follicle-stimulating hormone (FSH) (six horses). Owners recorded the frequency of seven common headshaking behaviours using a visual analogue scale (VAS) before vaccination and at two, four, eight, 12, 16 and 20 weeks after vaccination. Serum LH (P=0.008) and FSH (P=0.03) concentrations decreased significantly following vaccination. Although approximately one-third of the owners reported a subjective improvement in headshaking, serial scoring did not indicate a reduction in headshaking behaviours following vaccination with a commercial GnRH vaccine. Vaccination reactions were observed in four of 15 horses (27 per cent), including one case of severe, presumed immune-mediated, myositis.

Development of an ethogram for a pain scoring system in ridden horses and its application to determine the presence of musculoskeletal pain

ABSTRACT There is evidence that more than 47% of the sports horse population in normal work may be lame, but the lameness is not recognized by owners or trainers. An alternative means of detecting pain may be recognition of behavioral changes in ridden horses. It has been demonstrated that there are differences in facial expressions in nonlame and lame horses. The purpose of this study was to develop a whole horse ethogram for ridden horses and to determine whether it could be applied repeatedly by 1 observer (repeatability study, 9 horses) and if, by application of a related pain behavior score, lame horses (n = 24) and nonlame horses (n = 13) could be differentiated. It was hypothesized that there would be some overlap in pain behavior scores among nonlame and lame horses; and that overall, nonlame horses would have a lower pain behavior score than lame horses. The ethogram was developed with 117 behavioral markers, and the horses were graded twice in random order by a trained specialist using video footage. Overall, there was a good correlation between the 2 assessments (P < 0.001; R2 = 0.91). Behavioral markers that were not consistent across the 2 assessments were omitted, reducing the ethogram to 70 markers. The modified ethogram was applied to video recordings of the nonlame horses and lame horses (ethogram evaluation). There was a strong correlation between 20 behavioral markers and the presence of lameness. The ethogram was subsequently simplified to 24 behavioral markers, by the amalgamation of similar behaviors which scored similarly and by omission of markers which showed unreliable results in relation to lameness. Following this, the maximum individual occurrence score for lame horses was 14 (out of 24 possible markers), with a median and mean score of 9 (±2 standard deviation) compared with a maximum score of 6 for nonlame horses, with a median and mean score of 2 (±1.4). For lame horses, the following behaviors occurred significantly more (P < 0.05, chi‐square): ears back, mouth opening, tongue out, change in eye posture and expression, going above the bit, head tossing, tilting the head, unwillingness to go, crookedness, hurrying, changing gait spontaneously, poor quality canter, resisting, and stumbling and toe dragging. Recognition of these features as potential indicators of musculoskeletal pain may enable earlier recognition of lameness and avoidance of punishment‐based training. Further research is necessary to verify this new ethogram for assessment of pain in ridden horses.

Can the presence of musculoskeletal pain be determined from the facial expressions of ridden horses (FEReq)

ABSTRACT Poor performance in horses is often attributed to rider or training problems or behavioral abnormalities. Riders often fail to recognize lameness. We need to determine if there are differences in facial expression in lame and nonlame horses when ridden, which may facilitate the identification of horses experiencing pain. A previously developed facial expression specific for ridden horses ethogram was applied blindly by a trained analyst to photographs (n = 519) of the head and neck of lame (n = 76) and nonlame (n = 25) horses acquired during ridden schooling‐type work at both trot and canter. These included images of 7 lame horses acquired before (n = 30 photographs) and after diagnostic analgesia had abolished lameness (n = 22 photographs). A pain score (0‐3; 0 = normal, 1‐3 = abnormal) was applied to each feature in the ethogram, based on published descriptions of pain in horses. Pain scores were higher for lame horses than nonlame horses (P < 0.001). Total pain score (P < 0.05), total head position score (P < 0.01), and total ear score (P < 0.01) were reduced in lame horses after abolition of lameness. Severely above the bit, twisting the head, asymmetrical position of the bit, ear position (both ears backward, one ear backward and one to the side, as well as one ear backward and one ear forward), and eye features (exposure of the sclera, the eye partially or completely closed, muscle tension caudal to the eye, and an intense stare) were the best indicators of pain. Application of the facial expression specific for ridden horses ethogram and pain score could differentiate between lame and nonlame horses. Assessment of facial expression could potentially improve recognition of pain‐related gait abnormalities in ridden horses.

Successful treatment of head shaking by use of infrared diode laser deflation and coagulation of corpora nigra cysts and behavioral modification in a horse

CASE DESCRIPTION A 15-year-old Saddlebred gelding used for competitive pleasure driving had a 1-year history of head shaking while pulling a cart. CLINICAL FINDINGS The horse had cystic corpora nigra in both eyes and concomitant classic and operant conditioned responses to wearing a bridle with bilateral eye covers (blinkers). TREATMENT AND OUTCOME Deflation and coagulation of the cysts with an infrared diode laser and behavior modification consisting of desensitization and counter-conditioning were used to successfully restore performance. CLINICAL RELEVANCE Behavioral changes in horses can result from a combination of physical and psychologic causes. A combination of appropriate medical treatment of physical abnormalities and a behavioral modification plan is necessary to successfully treat behavioral problems in these patients.

Behavioral observations and comparisons of nonlame horses and lame horses before and after resolution of lameness by diagnostic analgesia

&NA; Differentiation between alteration in behavior which is the result of pain and that reflecting other behavior is potentially challenging in ridden horses. A ridden horse ethogram has been developed, tested, and combined with a pain score. Nonlame horses generally had lower pain scores than lame horses, although there was a small overlap. To determine if the ethogram could be used to differentiate lame horses before and after diagnostic analgesia had substantially improved lameness, and to verify its use in comparison of nonlame and lame horses, a retrospective study was done. Video recordings of 10 lame horses were reviewed by a trained assessor before and after diagnostic analgesia resolved the baseline lameness and improved any gait abnormalities seen in canter. The ridden horse ethogram was applied to each horse under each circumstance that it was ridden. Occurrence (yes/no) for each of 24 behaviors was recorded. Data were combined with that of an additional 13 nonlame horses and 24 lame horses. After abolition of lameness, the total sum score of behaviors (P < 0.01), sum of facial (P < 0.05), sum of body (P < 0.05), and sum of gait (P < 0.05) scores were all significantly reduced. Fifteen behavioral markers occurred significantly more often in lame horses (P values 0.00–0.05), and an additional 4 markers were only seen in lame horses. For pooled data, all sum markers were significantly higher in lame horses compared with nonlame horses or after resolution of lameness (P < 0.05). The length of the video recordings was not standardized among horses, nor before and after diagnostic analgesia. It was not possible to hide the presence of lameness which could have biased the assessor. Application of the ridden horse ethogram was able to differentiate between lame horses before and after diagnostic analgesia and nonlame and lame horses, although there was some overlap.

Animal Behavior Case of the Month

owner, who worked from home. The dog was walked outside on a flat collar 3 times a day, had access to the living area during the day, and slept in its crate at night. Dry food and water were available ad libitum; intake was normal. Feces were normal in consistency and volume. The dog had had no formal obedience training. The dog was left alone in the apartment a few times a week for a few hours each time and spent that time in its crate. Whenever the owners expected to be gone for more than a few hours, they brought the dog to a day care facility. There, the dog spent its time loose in a large enclosure with other dogs and no human contact; the dog appeared eager to interact with other dogs. The dog always greeted the female owner by wagging its tail and jumping up on her. At the time of initial examination, the dog had been treated with clomipramine (3.2 mg/kg [1.5 mg/lb], PO, q 24 h) for 8 months, and the female owner indicated that she thought the medication might have had some positive effect on the dog. The owners’ goals were for the dog to be more comfortable with the male owner and other people and to learn more commands.