Objective—To determine whether platelet growth factors are preserved in supernatants obtained from rehydrated trehalose-stabilized, freeze-dried (lyophilized) equine platelets and whether those growth factors stimulate fibroblast proliferation and migration and enhance fibroblast-associated contraction in a collagen gel assay.
Animals—6 clinically normal adult horses.
Procedures—Blood samples were obtained from 6 horses, and washed platelets were prepared via differential centrifugation. Washed platelets were freeze-dried in a physiologic buffer with a mixture of trehalose and polyethylene glycol 4000. Rehydrated platelet supernatants and releasates prepared from fresh washed platelets stimulated with thrombin or platelet-activating factor were evaluated for transforming growth factor β1 and platelet-derived growth factor-BB by use of ELISAs. Effects of rehydrated freeze-dried platelet supernatants on fibroblast proliferation, migration, and collagen gel contraction were compared with effects of 1%, 2.5%, or 10% fetal bovine serum (FBS).
Results—Supernatants from freeze-dried platelets contained similar amounts of growth factors as thrombin- and platelet-activating factor–stimulated platelet releasates. The supernatants significantly enhanced fibroblast proliferation and migration in a scratch assay, compared with FBS-free control or low (1%) FBS conditions. Additionally, supernatants from freeze-dried platelets enhanced contraction of fibroblast-seeded collagen gels, compared with the effect of 1% FBS.
Conclusions and Clinical Relevance—The preparation technique preserved platelet growth factors, enhanced fibroblast proliferation and migration, and improved fibroblastseeded collagen gel contraction under conditions of low FBS concentration; these platelet supernatant preparations may prove useful as an aid to conventional wound management.
Objective—To measure the frequency and magnitude of reduced fibrinogen binding in a population of horses from a Thoroughbred breeding farm.
Animals—444 Thoroughbred horses, 1 to 27 years old, including 316 females, 72 geldings, and 56 sexually intact males.
Procedures—Blood was collected from horses into tubes containingacid citrate dextrose adenine, and washed platelets were examined by use of flow cytometry for their ability to bind fibrinogen.
Results—Data regarding fibrinogen binding to activated platelets were normally distributed, with nearly identical amounts of variation regardless of sex. In 3 horses, fibrinogen binding to platelets was reduced from 67.6% to 83.4%, compared with normal platelets, which indicated an inability of platelets to aggregate in response to thrombin (0.1 U/mL).
Conclusions and Clinical Relevance—Platelet fibrinogen binding of the affected horses identified in this study was characteristic of a reported heritable bleeding disorder in which the reduction in fibrinogen binding correlated with prolonged bleeding times in template bleeding assays. The bleeding disorder is distinct from Glanzmann thrombasthenia, in which platelets fail to bind fibrinogen because of lack of αllb-β3 integrin on their surface. The prevalence of affected horses within the small sample population studied here (0.7% [n = 3]) is considerably higher than the prevalence of bleeding disorders within more genetically diverse groups.
Objective—To determine clinical signs, results of
diagnostic testing, and outcome in horses with internal
Corynebacterium pseudotuberculosis infection.
Procedure—Information pertaining to clinical data,
results of diagnostic tests, and costs of hospitalization
and treatment was extracted from medical
records of affected horses.
Results—Internal C pseudotuberculosis infection
was diagnosed on the basis of clinical signs, diagnostic
imaging, and clinicopathologic data, including
results of serologic tests and bacterial culture. The
most common clinical signs were concurrent external
abscesses, anorexia, fever, lethargy, weight loss,
and signs of respiratory tract disease or abdominal
pain. Clinicopathologic abnormalities included a geometric
mean reciprocal serum synergistic hemolysin
inhibition titer ≥ 512, leukocytosis with neutrophilia,
hyperglobulinemia, hyperfibrinogenemia, and anemia.
Specific organ involvement was diagnosed in 27
of 30 horses. Affected organs included the liver (18
horses), lungs (12), kidneys (7), and spleen (3); multiple
organs were affected in 10 horses. Treatment
with antimicrobials for a median of 36 days (range, 7
to 97 days) was usually successful, yielding an overall
survival rate of 71%.
Conclusions and Clinical Relevance—Early diagnosis
and long-term antimicrobial treatment were important
for a successful outcome in horses with internal
C pseudotuberculosis infection. Ultrasonographic imaging
was an important technique for identifying specific
organs affected, aiding in obtaining samples for a definitive
diagnosis, and monitoring response to treatment.
Pregnant mares with internal infections are at risk for
fetal loss. Preexisting chronic organ disease may be
associated with a poor prognosis. (J Am Vet Med Assoc